wetland methane emissions is essential to the estimation of the global methane budget. We examine the seasonal and inter-annual variability in wetland methane emissions simulated in the Community Land Model (CLM4MeC). Methane emissions from both the Carbon-Nitrogen (CN, i.e. CLM4.0) and the Biogeochemistry (BGC, i.e. CLM4.5) versions of the CLM are evaluated. We further conduct simulations of the transport and removal of methane using the Community Atmosphere Model (CAM-chem) model using CLM4MeC methane emissions from both CN and BGC along with other methane sources and compare model simulated atmospheric methane concentration with observations. In addition, we simulate the atmospheric concentrations based on the TransCom wetland and rice paddy emissions from a different terrestrial ecosystem model VISIT. Our analysis suggests CN wetland methane emissions are higher in tropics and lower in high latitudes than BGC. In CN, methane emissions decrease from 1993 to 2004 while this trend does not appear in the BGC version. In the CN versions, methane emission variations follow satellite-derived inundation wetlands closely. However, they are dissimilar in BGC due to its different carbon cycle. CAM-chem model simulations with CLM4MeC methane emissions suggest that both prescribed anthropogenic and predicted wetlands methane emissions contribute substantially to seasonal and inter-annual variability in atmospheric methane concentration. It also suggests that different spatial patterns of wetland methane emissions have significant impacts on N-S atmospheric CH4 concentration gradients and growth rates. This study suggests that large uncertainties still exist in terms of spatial patterns and magnitude of global wetland methane budgets, and that substantial uncertainty comes from the carbon model underlying the methane flux modules.

P-1116-13

Effects of multiple global environmental
changes and fire on soil greenhouse gas
emissions: feedbacks to climate change

A. Niboyet (1); B. Hungate (2); J. Brown (2); P. Dijkstra (2)
; J. Blankiness (3); KJ. Van Groenen (2); X. Le Roux (4)
; P. Leadley (5); L. Barthes (6); R. Barnard (6); C. Field (7)

(1) AgroParisTech, Institute of ecology and environmental sciences - Paris, Thiverl-Grignon, France; (2) Northern Arizona University, Biological sciences, Flagstaff, United States of America; (3) Earth Research Institute, Emb, Santa Barbara, United States of America; (4) INRA, Laboratoire d'ecologie microbienne, Villeurbanne, France; (5) Université Paris-Sud, Laboratoire ecologie, systématique et evolution, Orsay, France; (6) INRA, Umr agroécologie, Dijon, France; (7) Carnegie Institution for Science / IPCC WGII, Stanford, CA, United States of America

Global environmental changes are expected to alter
ecosystem carbon and nitrogen cycling, but the combined
effects of multiple simultaneous environmental changes
are poorly understood. Furthermore, little is known about
the combined effects of chronic global environmental
changes and ecological disturbances on ecosystem
functioning. In particular, these combined effects on soil
emissions of greenhouse gases might be critical as they
could accelerate climate change.

We assessed the responses of soil nitrogenous oxide (N2O) production, an important greenhouse gas, to elevated CO2, warming, increased precipitation, and enhanced nitrogen deposition, as well as their interactions, in an annual grassland as part of the Jasper Ridge Global Change Experiment (CA, USA). In addition, we took advantage of an accidental, low-severity wildfire that burned part of this long-term global change experiment to investigate the role of nitrogen, fire and chronic global environmental changes on soil N2O emissions. We examined the responses of soil N2O emissions, as well as the responses of the two main microbial processes contributing to soil N2O production - nitrification and denitrification - and of their main drivers.

We found that elevated precipitation increased soil N2O emissions, especially in combination with added nitrogen and warming. Furthermore, we show that the fire disturbance greatly increased soil N2O emissions over a three-year period, and that elevated CO2 and enhanced nitrogen supply amplified fire effects on soil N2O emissions: emissions increased by a factor of two with fire alone and by a factor of six under the combined influence of fire, elevated CO2 and nitrogen. We then provide evidence that these responses were caused by increased

microbial denitrification, resulting from increased soil
moisture and soil carbon and nitrogen availability.

Our results indicate that the combined effects of multiple simultaneous environmental changes and fire can exceed their effects in isolation, thereby creating unexpected feedbacks to soil greenhouse gas emissions. In our data and across the literature, single-factor responses tended to overestimate interactive responses, except when global change was combined with disturbance by fire, in which case interactive effects were large. Thus, for chronic global environmental changes, higher order interactions dampened responses of N2O emissions to multiple global environmental changes, but interactions were strongly positive when global change was combined with disturbance.

These findings highlight the need to further explore
the impacts of ecological disturbances on ecosystem
functioning in the context of global change to see how
much these combined impacts might play critical roles
in shaping ecosystem processes that in turn feed back to
climate change.

P-1116-14

Changing environmental controls affect
the strength of the permafrost carbon
feedback

C. Schaedel (1); M. Bader (2); E. Schuur (1); R. Bracho (3); P. Capek (4); BS. De (5); K. Diakova (4); J. Ernakovik, (6) I. Hartley (5); CM. Iversen, (7); E. Kane, (8); RJ. Norby, (7) J. O'Donnell (9); T. Roy Chowdhury (10); H. Santruckova, (4) G. Shaver, (11); C. Treat, (12); M. Waldrop, (12); K.P. Wickland, (13); C. Knoblauch, (14)

(1) Northern Arizona University, Center for Ecosystem

Science and Society, Flagstaff, AZ, University of States of America;

(2) New Zealand Forest Research Institute, Auckland, New Zealand; (3) University of Florida, School of forest resources

and conservation, Gainesville, FL, United States of America;

(4) University of South Bohemia, Faculty of science, Ceské

Budejoice, Czech Republic; (5) University of Exeter,

Geography, college of life and environmental sciences,

Exeter, United Kingdom; (6) CSIRO, Division of land and

water, Glen Osmond, SA, Australia; (7) Oak Ridge National

Laboratory, Environmental Science division and climate

Change in the Oak Ridge National Laboratory, United States of America; (8) Michigan State University, Department of

plant biology, East Lansing, MI, United States of America;

(9) National Park Service, Arctic network, Anchorage, AK,

United States of America; (10) Pacific Northwest Laboratory,

Richland, WA, United States of America; (11) Marine

Biological Laboratory, The ecosystem center, Woods Hole,

MA, United States of America; (12) United States Geological

Survey, Menlo Park, CA, United States of America; (13) United

States Geological Survey, Boulder, CO, United States of America; (14) University of Hamburg, Institute of soil science,

As the global climate warms the Arctic is experiencing
rapid increases in temperature causing permafrost
(phenially frozen ground) to thaw and thereby exposing
large quantities of previously frozen organic matter to
microbial decomposition. High latitude ecosystems store
almost twice as much carbon in soils and permafrost than
what is currently contained in the atmosphere. Warmer
temperatures in the Arctic will not only increase carbon
emissions from previously frozen organic matter in the
permafrost zone but also indirectly affect the carbon
cycle through changes in regional and local hydrology.
As permafrost degrades due to warming, soil drying will
occur in upland ecosystems, providing a result of increased natural
change as the water table moves further down. On the contrary,
low lying areas can turn into anoxic environments as
the topography and the underlying permafrost layer
prevent runoff. These changes in soil surface hydrology
and oxygen availability in permafrost ecosystems have
broad impacts on the amount and form (carbon dioxide or
methane) of carbon release from newly thawed permafrost
and have the potential to further increase the permafrost
carbon feedback. In order to successfully include the
permafrost carbon feedback into models relevant to IPCC
reports it is important to provide data sets that serve as
constraints for complex models assessing the carbon-
climate feedback from high latitude soils.

We have compiled a database of 26 incubation studies with soils from active layer and permafrost from across the entire permafrost zone to quantify a) the effect size of

We have compiled a database of 26 incubation studies with soils from active layer and permafrost from across the entire permafrost zone to quantify a) the effect size of
increasing temperatures and b) the changes from aerobic to anaerobic environmental soil conditions on carbon release from permafrost. Results from two different meta-analyses show that a 10°C increase in temperature increased carbon release by a factor of two in the three most important permafrost ecosystems (boreal forest, peatland and tundra). Under aerobic incubation conditions, soils released on average 3.4 times more carbon than under anaerobic conditions which was consistent for all three ecosystems as well as for soils with different organic carbon concentrations. While the lack of oxygen in anaerobic incubations reduced the amount of total carbon release it increased the amount of the more potent greenhouse gas methane. Even if accounting for the higher global warming potential of methane one unit of soil released more than twice as much carbon under aerobic incubation conditions than under anaerobic conditions.

This pan-arctic synthesis shows that carbon release from newly thawed organic matter in high latitude ecosystems is highly affected by increasing temperatures but that changes in soil moisture and oxygen availability have an even larger impact on carbon release. The permafrost carbon feedback is stronger in an aerobic environment as the faster decomposition offsets the higher heat trapping capacity of methane occurring under anaerobic conditions over a 100-year timescale.

## P-1116-15

### Topography and geochemistry influence methane response to permafrost thaw

L. Smith (1); M. Conrad, (2); MS. Torn (3); J. Curtis, (2); O. Chafe, (2); B. Markus (2)

(1) University of California Berkeley, Energy and Resources Group, Berkeley, CA, United States of America; (2) Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America; (3) Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA, United States of America

Arctic wetlands are currently net sources of atmospheric CH4. CH4 emissions in Arctic tundra vary widely in space and time, with proximate controls—substrate availability, competition, and substrate composition among decomposition processes, CH4 oxidation, and CH4 transport—dependent on local climate, soil, hydrology, and biology. These complex controls and high spatial and temporal variability make it difficult to characterize current CH4 processes and predict their responses to climate change. We investigated these processes in Arctic polygon tundra, across a permafrost thaw gradient from low-centered (intact) polygons to flat- and high-centered (degraded) polygons. We asked: (1) how do CH4 production and consumption vary with permafrost thaw and microtopographic feature, and (2) how do subsurface CH4 processes relate to surface CH4 and CO2 fluxes? We made measurements in 3 microtopographic features (polygon centers, rims, and troughs) across the permafrost thaw gradient. Measurements included surface CH4 and CO2 fluxes, concentrations and stable isotope compositions of CH4 and DIC at 3 depths in the soil profile, and soil moisture and temperature. We found clear patterns in CH4 processes with permafrost degradation, as well as polygon feature and month. More degraded sites had lower CH4 emissions, a different primary methanogenic pathway, and greater CH4 oxidation than intact permafrost sites, to a greater degree than soil moisture or temperature could explain. Surface CH4 flux decreased from 190 nmol m-2 s-1 in intact polygons to 9 nmol m-2 s-1 in degraded polygons. Stable isotope signatures of CH4 and DIC showed that acetate cleavage dominated CH4 production in low-centered polygons, while CO2 reduction was the primary pathway in degraded polygons. We see evidence that distinct patterns of water flow and geochemistry between intact and degraded polygons contribute to these observations, through transport of redox-active species among high-centered polygon features. These findings suggest that future Arctic tundra CH4 emissions will depend not only on profile-scale changes in soil moisture and inundation, but also on the effect of warming on larger-scale geomorphic, geochemical, and hydrological factors. Wetland drainage due to ice wedge degradation may reduce CH4 emissions across the landscape, even in inundated inter-polygon troughs.

## P-1116-16

### Feedbacks between climate change and the terrestrial biosphere

BD. Stocker (1); S. Williams, (2); IC. Prentice (1)

(1) Imperial College London, Department of Life Sciences, Ascot, United Kingdom; (2) Imperial College, Physics department, London, United Kingdom

Land ecosystems are absorbing ~25% of anthropogenic CO2 emissions but emit a range of other greenhouse gases and indirectly regulate their concentrations in the atmosphere through the emission of chemically active compounds. Terrestrial greenhouse-gas emission rates and the energy exchange between the land surface and the atmosphere are sensitive to climate and atmospheric CO2 and thus represent a feedback to anthropogenic climate change. Recent research using coupled Earth System Models has demonstrated that land-based feedbacks may amplify climate change through positive feedbacks that have previously not been accounted for. Here, we present a comprehensive compilation of feedback strength estimates from individual land-mediated forcing agents (CO2, CH4, N2O, albedo, etc.) and their interactions based on observational data and Earth system modeling. Today, the dominant negative feedback arising from the CO2-stimulated land C sink compensates smaller positive feedbacks from non-CO2 forcing agents. Under a future business-as-usual scenario, these positive feedbacks exert an increasingly strong additional warming. Anthropogenic land use change and inputs of reactive nitrogen by atmospheric deposition and fertilizers act to further shift the balance of feedbacks towards more positive values. This may be mitigated by protection of forest ecosystems and a more efficient use of mineral fertilizers in agriculture.

## P-1116-17

Modeling high-Arctic permafrost thawing impact on greenhouse gas exchange in Northeast Greenland

W. Zhang (1); E. Bo (2); G. Schurgers, (2); J. Hollesen (2); PE. Jansson (3); P. Miller (1); B. Smith (1)

(1) Lund University, Department of physical geography and ecosystem science, Lund, Sweden; (2) University of Copenhagen, Department of geosciences and natural resource management, Copenhagen, Denmark; (3) Royal Institute of Technology, Department of land and water resources engineering, Stockholm, Sweden

Frozen organic carbon stored in northern permafrost soils may become vulnerable due to the rapid warming of the Arctic. The loss of carbon through the emissions of CO2 and CH4 may imply a critical warming potential, resulting in positive feedbacks to global climate change. However, positive and negative feedback dynamics associated with thawing permafrost and ecosystem biogeochemistry on a landscape scale is still unclear. Here, we combine two contrasting modeling techniques to model the high-Arctic ecosystems in Northeast Greenland. Firstly, the Coup (Coupled Heat and Mass Transfer Model for soil-plant-atmosphere system) model is validated with three years' measurements of active layer depth and soil carbon content. Secondly, to account for the transient impacts of climate change to potential vegetation dynamics, we employ the leaf area index, projective cover fraction and climatic forcing produced by a regional Earth system model (RCA-GUESS), which simulates climate as well as vegetation dynamics, as the driving data to the Coup model to project future active layer depth and greenhouse gas exchange. Comparing to the Coup model driven with static vegetation properties of the validation period, we are able to quantify the effects of vegetation dynamics on the magnitude and timing of active layer depth, and ecosystem greenhouse gas exchange in the high-Arctic subject to the scenarios in different representative concentration pathways (RCP2.6, 4.5 and 8.5) as simulated with the regional Earth system model.
# Effects of nitrogen deposition on photosynthesis of an alpine meadow ecosystem in Eastern Qinghai-Tibetan Plateau

L. Zhang (1) ; S. Yan (1)

(1) Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Key Laboratory of Ecosystem Network Observation and Modeling, Beijing, China

Responsions of leaf and canopy photosynthesis to global change play an important role in global carbon cycling. Due to human activities, especially the burning of fossil fuels, the extensive use of farmland ecosystem nitrogen and continuous development of animal husbandry, the nitrogen input level into ecosystem increases significantly. However, the effects of increasing atmospheric nitrogen deposition on leaf and canopy photosynthesis of grassland ecosystems in Qinghai-Tibetan Plateau are unclear. In this study, we measured leaf nitrogen content, photosynthesis, and leaf area index in an alpine meadow ecosystem in Eastern Qinghai-Tibetan Plateau, based on a multi-form N addition experiment. Maximum rates of carboxylation (Vcmax) and electron transport (Jmax) were calculated from A-Ci curves measured with an LI-6400 portable photosynthesis system. The results showed that leaf nitrogen content in Stipa aliena growing with a high-level nitrogen input (40 kg N ha⁻¹ yr⁻¹) increased by 6.2% and 9.7% in 2012 and 2013. Vcmax and Jmax at 25°C increased by 46.5% and 39.8% in 2012, 37.9% and 25.4% in 2013, respectively. Meanwhile, leaf area index of the alpine meadow ecosystem also had an increase of 45.0% in 2012 and 21.9% in 2013. Positive effects of nitrogen addition on leaf nitrogen content, leaf photosynthetic capacity, and canopy leaf area undoubtedly resulted in an increase in gross primary production of the alpine meadow ecosystem.

# Carbon Cycle Response to Artificial Atmospheric Carbon Dioxide Removal

K. Zickfeld (1)

(1) Simon Fraser University, Vancouver, BC, Canada

Artificial removal of carbon dioxide from the atmosphere (CDR) is increasingly discussed as a complementary approach to CO₂ emission reductions, particularly in the context of stringent climate targets. The efficiency of CDR is determined by the interplay between the natural carbon sinks on land and in the ocean and atmospheric CO₂ levels. Only a few studies have explored the response of the global carbon cycle to CDR. Here, we use an Earth System model of intermediate complexity – the University of Victoria Earth System Climate Model (UVic ESCM) – to explore the response of the carbon cycle to atmospheric CO₂ removal under a range of idealized scenarios, which differ in the total amount and rate of negative emissions, and the initial state of the system. We perform two sets of model simulations: one where a drop in atmospheric CO₂ to a target level and maintenance at that level is prescribed (P), and one where an equivalent amount of negative CO₂ emissions is prescribed over a given period of time, with atmospheric CO₂ left to evolve freely thereafter (E).

Results indicate that for both simulation sets, CO₂ outgasses from the terrestrial biosphere and the ocean during the atmospheric CO₂ removal phase. The amount of outgassing is sensitive to the experimental setup (P versus E simulations) and the rate and amount of CO₂ removal. For P simulations we find that the lower the target atmospheric CO₂ level, the larger the outgassing from natural sinks, and the larger the negative emissions required to maintain the target level. The efficiency of CDR – defined for P simulations as the cumulative negative emissions required to achieve a unit decrease in atmospheric CO₂ – is independent of the rate of removal in the long-term, but increases significantly for scenarios with larger amounts of CDR.

# 1117 - Understanding decadal variations in the climate system and implications for the future

## ORAL PRESENTATIONS

### K-1117-01

#### Global and regional climate variability: a pause for thought

E. Hawkins (1)

(1) University of Reading, Dept. of meteorology, Reading, United Kingdom

Our experience of how climate changes depends on the interaction between externally driven changes, such as those due to greenhouse gases, aerosols and volcanic eruptions, and internal climate variations, both globally and locally. The recent slowdown in global temperature rise has dramatically highlighted these interactions and challenged the climate community to understand, explain and communicate the complex issues involved.

This talk will focus on some of the history of our understanding of climate variability, the links between changes in global temperature and regional climate, and the limits on the precision with which we can make climate projections. The concept of 'climate emergence' will also be discussed as a useful framework to help understand the role of climate variability and to help communicate the many plausible possibilities for how regional climate may change over the coming decades.

### K-1117-02

#### Past and future European climate trends: uncertainty due to internal variability

L. Terray (1) ; C. Deser (2)

(1) CERFACS/CNRS, Sciences de l'Univers au CERFACS,

URA1875, Toulouse, France; (2) National Center for Atmospheric Research, Climate analysis section, Boulder, United States of America

This talk will highlight the relative importance of internally generated versus externally forced climate trends over the past and next fifty years at local and regional scales over Europe. The assessment is based on a large ensemble of climate simulations performed with the CESM1 NCAR model that cover the 1920-2100 period. The ensemble contains a large number of integrations (30), each of which is subject to identical natural and anthropogenic radiative forcing but initialized from a slightly different atmospheric state. The large ensemble shows that natural climate variability superimposed upon forced climate change results in a large range of possible trends for surface air temperature and precipitation over the past and next fifty years. A variant of the flow-analogue approach is used to partition the temperature and precipitation changes due to internal variability into dynamical and thermodynamical components. Internal thermodynamical changes are shown to be more important in summer while dynamical ones are the dominant contributors in winter. Removing the unpredictable dynamical contribution results in a significant increase of the signal to noise ratio, particularly in winter. The thermodynamical changes are shown to be linked with the ocean, sea-ice and land surface conditions. While large ensembles are needed to fully characterize the forced response at global and regional scales, they also provide a robust estimation of the uncertainties due to internal variability that is needed to better characterize model structural differences. This is important for a wide range of stakeholders as the partial masking of human-induced climate change by internal multidecadal variability is an important consideration for policy and planning efforts.
The Pacific decadal oscillation, revisited

M. Newman (1) ; M. Alexander (2) ; T. Ault, (3) ; K. Cobb (4) ; C. Deser (5) ; E. Dilorenzo (4) ; N. Mantua (6) ; A. Miller (7) ; S. Minobe (8) ; H. Nakamura (9) ; N. Schneider (10) ; D. Vimont (11)

(1) University of Colorado / CIRECS and NOAA / ERL/PSD, Boulder, CO, United States of America; (2) NOAA / ERL/PSD, Boulder, United States of America; (3) Cornell University, Ithaca, United States of America; (4) Georgia Tech, Atlanta, United States of America; (5) National Center for Atmospheric Research, Climate analysis section, Boulder, United States of America; (6) NOAA / NMFS Southwest Fisher Science Center, Santa Barbara, United States of America; (7) Scripps Institute of Oceanography, La Jolla, United States of America; (8) Hokkaido University, Sapporo, Japan; (9) University of Tokyo, Tokyo, Japan; (10) University of Hawaii, International Pacific Research Center, Honolulu, United States of America; (11) University of Wisconsin, Madison, United States of America

Since its identification in the late 1990's as the dominant pattern of North Pacific sea surface temperature (SST) variability, the Pacific decadal oscillation (PDO) has been connected both to other parts of the climate system and to impacts on natural resources and marine and terrestrial ecosystems. Variability associated with the PDO has often been confused with externally forced climate change including anthropogenic effects. Subsequent research, however, has found that the PDO is not a single physical mode of climate variability but instead largely represents the combination of three groups of processes: (1) changes in ocean surface heat fluxes and Ekman (wind-driven) transport related to the Aleutian low, due to both local, rapidly decorrelating, unpredictable weather "noise" and to remote forcing from interannual to decadal tropical variability (largely El Nino) via the "atmospheric bridge"; (2) ocean memory, or processes determining oceanic thermal inertia including "re-emergence" and oceanic Rossby waves, that act to integrate this forcing and thus generate added PDO variability on decadal time scales; and (3) decadal changes in the Kuroshio-Oyashio current system forced by the multi-year history of basin-wide Ekman pumping, manifested as SST anomalies along the subarctic front at about 40°N in the western Pacific ocean. Thus, the PDO represents the effects of different processes operating on different timescales, with few of its apparent impacts due to extratropical SST anomalies. This talk presents a review of the PDO, and discusses corresponding implications for climate diagnosis, including of PDO climate impacts and predictability (both oceanographic and atmospheric); potential decadal «regime»-like behavior; simulations of the PDO in climate models; the interpretation of paleoclimate multicentennial reconstructions of the PDO; and its impacts on marine ecosystems. We conclude with some suggested "best practices" for future PDO diagnosis and forecasts including investigating the potential role of the PDO in the global temperature hiatus.

Importance of Atlantic decadal variability for near-term assessment and predictability of western Amazon dry-season dry and wet events

K. Fernandes (1) ; W. Baethgen, (2) ; L. Verchot (3) ; A. Giannini (1) ; M. Pinedo-Vasquez (3),

(1) Columbia University, International Research Institute for Climate and Society (IRI), Palisades, NY, United States of America; (2) Columbia University, International Institute for Climate and Society (IRI), Palisades, NY, United States of America; (3) CIFOR, Bogor, Indonesia

The drought of 2005 was a "1 in 100 years" event in western Amazon resulting in fire damage to over 300,000 hectares of rainforest in the Brazilian state of Acre and 22,000 hectares in the province of Coronel Portillo in Peru. In 2010 another severe drought resulted in the isolation of entire communities as this Negro River, a major northwestern Amazon tributary, registered its lowest water level in over 100 years. The Amazon ecosystem is sensitive to repeated occurrence of droughts, which interferes with the forest's natural ability to recover from stress and undermine climate change mitigation efforts to reduce CO2 emissions from deforestation and forest

degradation. Whether this apparent increase in drought severity and frequency is related to natural low-frequency modes of climate variability, to anthropogenic influence on climate, or to a combination of both is explored here.

A modest negative trend in dry-season precipitation is observed in western Amazon over the period 1935-2012, which along with a multi-decadal pattern of reduced moisture transport from the tropical Atlantic worked to enhance the severity of the recent droughts. Most of the western Amazon dry-season precipitation decadal variability is attributable to decadal fluctuations of the north-south gradient (NSG) in Atlantic sea surface temperature (SST). The observed western Amazon and NSG decadal co-variability is well reproduced in Global Climate Models (GCMs) pre-industrial control (PIC) and historical (HIST) experiments that were part of the Intergovernmental Panel on Climate Change fifth assessment report (IPCC-AR5). This suggests that unforced or natural climate variability, characteristic of the PIC simulations, determines the nature of this coupling, as the results from HIST simulations (forced with greenhouse gases (GHG) and natural and anthropogenic aerosols) are comparable in magnitude and spatial distribution. Decadal fluctuation in the NSG also determines shifts in the probability of repeated dry and wet events in western Amazon, as there is a 56% chance of 3 or more years of dry events per decade when NSG>0 compared to 19% when NSG<0. The HIST and PIC model simulations also reproduce the observed shifts in probability distribution of dry and wet events as a function of the NSG decadal phase, suggesting there is great potential for decadal predictability based on GCMs. Persistence of the current NSG positive phase may lead to continuing above normal frequencies of western Amazon dry-season droughts.

Stochastic low-frequency variability in the eddying ocean: mid-latitude imprints, possible atmospheric impacts

T. Penduff (1) ; L. Terray (2) ; S. Leroux (1) ; G. Sérazin (1) ; B. Barnier (1) ; J.M. Molines (1) ; L. Bessière (2)

(1) LGGE, MEOM, Grenoble Cedex 9, France; (2) CERFACS / CNRS, Sciences de l'Univers au CERFACS, URA1875, Toulouse, France

Laminar Ocean General Circulation Models (2° to 1° resolution) used in recent climate projections are being progressively replaced by turbulent ocean models (about 1/4° resolution) in the perspective of the next CMIP exercise. Atmospherically-forced ocean experiments show that this resolution increase improves the physical consistency of simulations, but also allows the ocean to spontaneously generate a substantial variability up to interannually-to-multidimensional mesoscales, simultaneously with idealized studies, this low-frequency intrinsic variability (LFIV) is negligible when mesoscale oceanic eddies are not explicitly resolved, and spontaneously emerges in the turbulent regime.

This non-linearly driven oceanic LFIV has a stochastic character, and a more stringent signature on the upper ocean temperatures in mid-latitude regions where air-sea fluxes are maximum in Nature. Seasonally-driven global eddy ocean simulations exhibit the strong, large-scale imprints of this stochastic LFIV on several climate-relevant oceanic indices: sea-surface height (SSH) and temperature (SST) in western boundary current systems and the Antarctic Circumpolar Current, Meridional Overturning Circulation (AMOC) throughout the Atlantic Ocean, etc.

How these low-frequency intrinsic variability modes are impacted, and may or not be paced, by the interannually-varying atmosphere is an important question about climate uncertainty. The ongoing OCCIPIT project aims at investigating these questions probabilistically through a 50-member ensemble of 1/4° global ocean/sea-ice 57-year hindcasts, driven by the same 1958-present atmospheric forcing. Present results demonstrate that initial state perturbations spontaneously grow, cascade toward long space and time scales and non-linearly saturate. The resulting ensemble spread describes the atmospherically-paced stochastic LFIV (uncertainty), with marked imprints on oceanic variables at large space and time scales both at the surface (SSH, SSH) and below (AMOC, mode/intermediate/deep water mass properties and depths, etc.)
This ensemble experiment will provide the first probabilistic description of the global ocean state and evolution over the last decades, and a measure of the actual constraint exerted by the atmosphere on low-frequency ocean variability. The imprint of this stochastic LIFV on the upper-ocean thermal fields and AMOC will then provide insights into how this eddy-driven low-frequency oceanic "noise" might ultimately impact the atmosphere and climate predictability in future coupled climate projections.

## O-1117-04

### Contribution of sulfate anthropogenic aerosols to the Euro-Mediterranean climate trends since 1980 using a regional coupled modelling approach

P. Nabat (1); S. Somot (1); M. Mallet (2); A. Sanchez-Lorenzo (3); M. Wild (4)

(1) Métoé-France / CNRM-GAME, Toulouse, France; (2) Laboratoire d'Aerologie, Toulouse, France; (3) University of Girona, Department of physics, Girona, Spain; (4) ETH, Zurich, Institute for atmospheric and climate science, Zurich, Switzerland

Since the 1980s, sulfur emissions have considerably been reduced in industrialized countries, notably in Europe, thus leading to a decrease of sulfate aerosol concentration over the Euro-Mediterranean region. Meanwhile, an increase of incoming solar radiation reaching the surface, known as the brightening effect, has been observed over the same period but global and regional climate models still have trouble in reproducing the all-sky surface solar radiation trends and their consequences on climate.

In order to investigate the consequences of this aerosol trend on regional climate and its role in the observed changes during the last three decades, the present study introduces an original approach, through the use of a fully coupled regional climate system model (CNRM-CRCM). The latter includes the different components of the regional climate system, namely the atmosphere (with ALADIN-Climat), the ocean (with NEMOMED), the land surface (with ISBA) and the rivers (with TRIP). This approach enables us to take into account the high-frequency feedback of the sea surface temperature (SST) on the atmosphere, as well as the river-ocean-atmosphere feedback. Aerosols are included in ALADIN-Climat through monthly interannual climatologies, coming from a combination of satellite-derived and model-simulated products, and considered as the best possible relevant estimation of the atmospheric aerosol content for the five most relevant species (sea salt, desert dust, sulfates, black and organic carbon aerosols). Simulations using the lateral boundary forcing of the ERA-INTERIM reanalysis have been carried out over the period 1980-2012 with and without the trend in sulfate aerosols. The scattering of the incoming solar radiation by sulfate aerosols leads to important changes in the Euro-Mediterranean climate. Comparisons between both simulations and homogenized surface observations reveal that our model is able to reproduce the all-sky surface shortwave radiation trends only when the aerosol trend is included. This improvement is particularly visible in regions where aerosols have been strongly reduced (i.e., Central Europe, Po Valley). Aerosol changes explain 81 ± 16 per cent of the simulated brightening over the 1980-2012 period, while the direct effect has been found to be the main cause of the simulated brightening.

As a result of this brightening effect, when including the aerosol decrease, the surface temperature trend is higher and closer to homogenized surface observations, indicating that aerosols explain 23 ± 5 per cent of the observed warming between 1980 and 2012. The use of an atmosphere-ocean coupled model enables us to show that Mediterranean sea surface temperature changes are also better reproduced using the aerosol trend. Air-sea fluxes have consequently been modified by this evolution in the sulfate aerosol content, as well as river flow.

Overall, our results demonstrate the importance of changes in aerosol loads for the understanding of regional climate variability.

## O-1117-05

### Volcanic Forcing: new initiatives to establish its impacts on climates of the Southern Hemisphere

P. Harvey (1); S. Grab (1); F. Engelbrecht, (2)

(1) University of Witwatersrand, Geography, archaeology and environmental studies, Johannesburg, South Africa;

(2) Centre for Scientific and Industrial Research, Natural resources and the environment, Pretoria, South Africa

In the northern hemisphere (NH), 1816 is well known as 'the year without a summer'. But what happened in the southern hemisphere (SH) in 1816, or for that matter following other major tropical or SH volcanic eruptions? Whilst recent work has taken on an increasingly global focus on volcanic forcing as a driving mechanism influencing climate, the emphasis has largely been on the NH where most of the world's landmass and people have been impacted by large scale volcanic eruptions. To this end, the work of the present study has shed light, hence our initiative to investigate: a) past impacts of major volcanic eruptions on SH climate and environment/society, and b) to model the climatic impacts of such eruptions on specific SH landmasses such as southern Africa, South America, Australia and New Zealand.

Several numerically based studies and experiments have confirmed global temperature decelerations during years immediately following major volcanic eruptions, and in particular, this correlation seems to be driven by considerably cooler than normal summers which more than compensate for warm winter anomalies over the NH (e.g. Briffa et al., 1998; Fischer et al., 2007; Miller et al., 2012). Such work has additionally been supported with longer-term tree ring density and frost ring data for North America and Europe, demonstrating a clear environmental response as an signature to such events (e.g. D'Arrigo and Jacoby, 1999; Breitenmoser et al., 2012). Recent modeling approaches have demonstrated the association between high northern latitude volcanic eruptions and the dispersion of aerosols, which remain mostly confined north of 30°N (Oman et al., 2006), and the connection to Arctic/sub-Arctic ice growth development and consequent sea-ice/ocean feedbacks causing hemispheric cooling (Miller et al., 2012). Thus, much is known and much has been learned from volcanic forcing events on NH climates and environments, but to what extent are these patterns mirrored in the SH?

Given the scarcity of SH instrumental records covering the Tambora and other major historical period volcanic events, little is known about their impact in southerly latitudes. Here we triangulate evidence from a variety of proxies including historical documentary sources, tree ring and speleothem data, to demonstrate that major tropical or SH volcanic eruptions are usually followed by extreme climate events across much of the SH. For instance, in southern Africa, such events may be followed by exceptionally hot summers and severe winters (with unusually early and/or late frosts and heavy snowfall events) (Grab and Nash, 2010). Whilst this temporally mirrors austral winters and summers in the NH (which are warmer and cooler respectively), the cooling anomalies are seasonally reversed between the hemispheres. In addition, data thus far suggest that one to two years following such a major eruption has [have] a very high probability of experiencing very wet [floods] or very dry [drought] conditions, but that the relationship is not linear owing to other climate drivers such as ENSO cycles. This work is ongoing and seeks further evidence to substantiate these new findings.

Finally, we present our current and future aims to model the climatic impacts (all major climate parameters) of major volcanic eruptions across various spatial and temporal scales in the SH using the Variable-Resolution Earth System Model (VRESM) and its atmospheric component the Conformal Cubic Atmospheric Model (CCAM) (see Engelbrecht et al., 2011). The models will be integrated as a simulation of events evolving in size (from Toba to Pinatubo or smaller), and will test the associations between geographic location (longitude/latitude) and event magnitude to establish spatial, temporal and type/magnitude of climatic impacts in the SH.
P-1117-01

## Calibration and Validation of Summer Monsoon Rainfall over Bangladesh Using PRECIS Model

MN. Ahasan (1)

(1) SAARC Meteorological Research Centre (SMRC), Synoptic Division, Dhaka, Bangladesh

A regional climate model named PRECIS is employed in generating rainfall scenarios for SAARC region. PRECIS generated rainfall scenario is calibrated with ground-based observed rainfall during 1961-1990 in Bangladesh. Through calibration regression coefficients such as slope and constant are obtained at 27 observational sites over Bangladesh. The regression coefficients are utilized in validation of PRECIS generated rainfall during 2000 to 2006. Better performance of PRECIS through validation encourages employing it in rainfall forecasting for Bangladesh. In this work rainfall forecast for Bangladesh is performed experimentally for 2009. The monsoon rainfall is projected surplus 0.29 mm/day or 2.03% in 2009 and it will be surplus 0.44 mm/day or 14.02% in post-monsoon. It will deficit 0.11 mm/day (2.08%) and 0.01 mm/day (1.44%) in pre-monsoon and dry season respectively. Through the analysis of monsoon rainfall in Bangladesh this work discloses that PRECIS simulated rainfall is not directly useful in application purposes. Without calibration with ground-truth data model outputs are very risky in providing long-term rainfall prediction. However, after performing calibration excellent result is obtained in estimating rainfall in Bangladesh with R2 is 0.94 and correlation is 0.97. The encouraging results of this work can be taken as the starting point of SMRC to do more realistic research on long-term rainfall forecasting. The monsoon rainfall forecasting approach using down scaling of regional climate model outputs is very new in Bangladesh and also in SMRC. This persuades result suggests extending the work for other SAARC countries in a consecutive research project. Model run with other ensembles and with high horizontal resolution are also under consideration with the improvement of computational facilities in the Centre. After completion of the calibration and validation of PRECIS for SAARC region the projected rainfall is supposed to be posted through SMRC website (www.saarc.org) which is now available only for Bangladesh. Completion of such job of type is really necessary for SAARC region where SMRC can play important role as a regional meteorological research centre.

P-1117-02

## Crops response to climate variability and societal implications on rural dwellers of Nigeria

S. Ayanlade (1)

(1) Obafemi Awolowo University, Ile-Ife, Nigeria, Dept. of Geography, Ile-Ife, Osun, France

This study examines impacts of climate variability on the yield of eight major crops in the guinea ecological of Nigeria, using both quantitative and qualitative methods. The Guinea ecological zone represents a rich agricultural area for Nigeria, sometime call "the food basket zone of the country." Several studies have been show that variability of rainfall has significant implication not only on the differences in the types of crops cultivated but also the rate of yield of such crops. Majority of these studies were based on assessment of two to four crops. Thus, the present study apply GIS techniques to examine the climate variability and its implications on the eight crops (Cassava, yam, Maize, sorghum, Groundnut, Cowpea, Cocoyam and Nion), majorly cultivated in the area. Rainfall, temperature and the crops yield dataset from 1982 to 2012 were used in the analysis. A year is divided into two growing seasons. These seasons are: early growing season (April-June) and late growing season (July- October) with regard to seasonal differences and the crops yields. The results show that during the past decades the yields of these crops were associated with climate variability, which vary differently in the year with high rainfall than the year with low rainfall. The study found out that the crops yield

have been dominated by reduction in the number of rain days during the middle of the rainy season and there is evidence of a significant change in the crop yield as climate varied. The study concluded by recommending the need to encourage rain fed agriculture and agricultural research to improve crop yields.

P-1117-03

## Diatoms evidence for past two centuries major changes in seasonal sea surface conditions prior the instrumental period in the southern Gulf of California

L. Barbara (1) ; S. Schmidt (2) ; J. Urrutia Fucugauchi (1) ; L. Perez Cruz (1)

(1) Universidad Nacional Autónoma de México, Instituto de geofísica, Mexico D.f., Mexico; (2) CNRS, UMR 5805 EPOC, Université Bordeaux, Pessac, France

Studies on laminated marine sediments have enabled to exploit annual to subseasonal information of oceanic and climatic conditions of the past, and particularly in the Gulf of California where there are excellent laminated records, underlying anoxic basins. These studies, however, are based on resin-embedded thin sections and present only qualitative snapshots of the past environments. Any of them have compared high resolution records with instrumental data, in order to reconstruct the environmental conditions and document the variability on interannual to decadal timescales beyond the instrumental period.

Here, we describe environmental conditions in the eastern part of Carmen Basin in the southern Gulf of California, over the past two centuries using diatom census counts in the DiPALV-C33 marine sediment box core. Diatom census counts show progressive changes since AD 1850, marked by persistent warm stratified and nutrient limited water conditions on the Gulf eastern sector. In parallel, inferred environmental conditions provide evidence for reduced seasonal upwelling during the last century and limiting primary productivity, concurrent with increase of storm hurricane frequency. We propose that these multi-decadal sea surface variations are mainly governed by synoptic and regional wind fields in relation to the position and intensity of the atmospheric low and high-pressure trough around the Gulf of California. However, both ENSO and PDO variability patterns in the last century cannot explain the regional trend observed in this study, probably due to the effect of local processes on the response of our biological proxies.

P-1117-04

## Mechanisms relating the MJO to intra-seasonal variability of the surface climate in the Americas

EH. Berbery (1) ; M. Natoli (2)

(1) University of Maryland, Earth System Science Interdisciplinary Center/CICS-MD, College Park, Maryland, United States of America; (2) University of Maryland, Earth system science interdisciplinary center, College Park, Maryland, United States of America

This study uses the NCEP's Climate Forecast System Reanalysis (CFSR) to revisit the dynamical mechanisms associated with the Madden-Julian Oscillation (MJO) that affect the surface climate over the Americas. During the boreal cold season, North America sees a notable eastward propagation in temperature anomalies through the MJO evolution. Despite the smaller land area, temperature effects in South America during the austral cold season appear clearer than in North America and more appropriately connected to MJO convection. This is especially true over subtropical portions of the continent. These structures are related to the MJO enhanced tropical convection that can induce anomalous upper-tropospheric cyclonic circulation on the leading edge of the MJO enhanced convection and anomalous anti-cyclonic circulations trailing the convection. During each hemisphere's winter season, and connected with these patterns, enhanced direct circulations favor changes in the subtropical and polar jet streams. Intra-seasonal changes in the divergent circulation in upper levels modulate the Rossby Wave Source centers around 30-45° latitude and the propagation of Rossby waves, as noted in the wave activity fluxes, into the extratropics inducing near-surface
temperature and precipitation anomalies.

During the corresponding summer seasons, the diagnostics show that precipitation patterns are more directly connected to the convection anomalies rather than the circulation anomalies. The Americas see enhanced precipitation in the monsoon regions when the large scale upper tropospheric divergence associated with the MJO connection to the western hemisphere. Similarly, suppressed precipitation in these regions is observed when the large scale upper tropospheric convergence passes over the continents.

## P-1117-05

### Climate Change Studies over Western-Ghat region using Remote Sensing & GIS Modelling

**N. Bhat (1); KC. Gouda (2)**

(1) Shri Madhwa Vadiraja Institute of Technology and Management, computer sc & engg, Udupi, Karnataka, France; (2) CSIR CMMACS, CEMP, BANGALORE KARNATAKA, India

Western Ghat region is one of the major mountain system in the Indian subcontinent, extending in the western part of Indian from Kerala in South till Maharashtra in north and the total area is about 160,000 Sq. km. The western ghat is of important from different point of view starting from the flora and fauna to medicin al plant to the rich region of river systems and the orography is most important for its role in the Rainfall during Monsoon and other seasons. In the study the remote sensing data from different sources like MODIS, TRMM, IRS and the multi-source observations from reanalysis products like NCEP, ERA-40, JMA and the high resolution observations like IMD are being used to study the climate change and quantified in terms of the different climate parameters mainly temperature, rainfall, humidity etc. The IRS and Landsat data are being analysed in the GIS Modelling frame work to see the signature in the Land Use and Land Cover Change detactiona tation at high resolution over the mountain region. Finally the spatiotemporal analysis of the climate change are presented. Various algorithm and visualisation to understand the climate change over the mountain region are developed and presented very usefully friendly way which can be easily used by the users of different sectors for the better understanding of the climate change.

## P-1117-06

### Temperature impact on Non-Communicable Diseases in Africa - a Blind Spot in Research

**A. Bunker (1) ; E. Diboulo, (2) ; A. Sié, (3) ; R. Sauerborn (4)**

(1) University of Heidelberg, Network Ageing Research and Institute of Public Health, Heidelberg, Germany. (2) Swiss Tropical and Public Health Institute, Epidemiology and Biostatistics, Basel, Switzerland; (3) Centre de Recherche en Santé de Nouna, Nouna, Burkina Faso; (4) Heidelberg University, Institute of public health, Heidelberg, Germany

The mean temperature in northwest rural Burkina Faso, in the Nouna Health and Demographic Surveillance System (HDSS) region, is projected to increase under different climate change scenarios by the end of the 21st Century.[1] The Nouna HDSS consists of approximately 100,000 people, and is one of several International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH) sites that collect health and demographic data across populations in low-and-middle income countries. As life expectancy increases in Burkina Faso and people live for longer with chronic and degenerative diseases, non-communicable disease will play a greater role in contributing to the burden of disease. This study assesses the impact of 18 years of temperature exposure on non-communicable disease years of life lost, an indicator of premature mortality, in the Nouna HDSS population.

Preliminary analysis used all-cause mortality data from the Nouna HDSS, to conduct a survival analysis and calculate the outcome variable, years of life lost, for 12,769 deaths between 1993-2000. A time-series regression analysis using the generalized additive model, adjusted for time-

trends and seasonality was used to study the impact of mean temperature on all-cause mortality. Results indicate that a 1°C increase in temperature was associated with a 1.024 relative risk increase (p value=0.029) in all-cause mortality per 1°C increase in mean temperature above 30°C (1 day lag). We will present an extended 18-year cause-specific time-series analysis on the impact of mean, maximum and minimum temperature on non-communicable disease years of life lost, including the lagged effects.

As life expectancy at the Nouna HDSS increases, the burden on non-communicable disease is likely to increase with higher temperatures. Targeted preventive measures are required to alleviate this burden.

[1] David M Hondula, Joacim Rocklý, and Osman A Sankoh, "Past, Present, and Future Climate at Select INDEPTH Member Health and Demographic Surveillance Systems in Africa and Asia," Global Health Action 5, no. 0 (November 23, 2012), doi:10.3402/gha.v5i0.19083.

## P-1117-07

### Farmers' perceptions of climatic trend in Allada plateau in southern Benin

**A. Cayossi Ulrich (1) ; A. Abel (2) ; G. Hervé, (3) ; EK. Agbossou (4) ; V. Pierre, (1) ; C. Baron (3)**

(1) université d'Abomey-Calavi, COTONOU, Benin; (2)

Université d'Abomey-Calavi, Graduate research program on climate change and water resources, Abomey-Calavi, Benin; (3) CIRAD, Montpellier, France; (4) UNIVERSITY OF ABOMEY-CALAVI, Faculty of agronomic sciences, Abomey-Calavi, Benin

Although several studies show an increase in agricultural production in West Africa in connection with the improvement in rainfall, farmers perceive otherwise. This study highlights the differences between farmers' perceptions of changes in precipitation and their impacts on agricultural production and scientific observations in the Guinea region where two rainy seasons coexist. For this purpose, it compared precipitation data (from 1951 to 2010) and potential yields of corn (from 1970 to 2010), simulated by SARRA-H model, to farmers' perceptions of changes in precipitation collected from 201 farm managers spread over 67 villages in Southern Benin. The study clearly shows that farmers do not make any distinctions between the long rainy season and short rainy season in terms of changes in rainfall and agronomic impacts. On the contrary, climate analysis results, and agronomic simulation reveal that the long rainy season and short one are not affected in the same way by atmospheric forcing. Consequently, these two rainy seasons have opposite agronomic trends. Since 1970, the long rainy season has a rainfall deficit coupled with a poor temporal distribution of rainfall and a shortening in its duration which led to a sharp drop in potential crop yields. Conversely, since the late 1980s, the short rainy season rainfall recorded a surge which causes a sharp increase in agricultural yields. This pessimistic perceptions of farmers on the evolution of rainfall in both rainy seasons influences their choice of management of the farming calendar of the short rainy season, worsening food insecurity in the study area.

## P-1117-08

### On the characteristics of climate change in Scandinavia and its association with the Northern Atlantic Oscillation (NAO) and sea ice

**Y. Chen (1) ; S. Stefan (1)**

(1) Uni Research Climate, Bjerknes Centre for Climate Research, Climate Data Service, Bergen, Norway

We analyzed some characteristics of climate change over Scandinavia using CRU data (1901- 2012), and both temperature and precipitation exhibit well-documented positive trends. However, the spatial variability of the trends is large with some areas showing high significance (northern Norway and Sweden) and others none at all (central Finland). The scenarios simulated by NorESM and ECHAM9 models exhibit continued warming and increased rainfall in the 21st century over Scandinavia. Given the
Temperature effects of the large volcanic eruption events during the past 100 years over China

Z. Hao (1); D. Sun (1); J. Zheng (1)

(1) Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences, Beijing, China

Based on the meteorological temperature data and the records of volcano events, the temporal and spatial temperature characteristics after the different types of large volcanoes which were classified by the geographic latitudes were identified in China five climatic regions, and the effects of the large volcanic events on regional temperature were analyzed. The results showed that there were significant differences between the temperature variation during winter years and the summer years after different large volcanic eruptions, northeast region was warmer in winter year after the large volcanic eruptions at the middle and high latitudes, other regions mainly appeared temperature decrease, northeast and northwest regions which were sensitive to climatic change was cooler. In addition, there was an obvious secondary cooling process during the summer year and in some regions obvious during the winter year, the change of cooling even more obvious than the first cooling process. At the same time, the impact of large volcanic eruptions was different in five climate regions, regional temperature variation related to latitude after large volcanic eruptions at equatorial and high latitudes, but this variation related to longitude after volcanic eruptions at low and middle latitudes.

A Study of Multi-decadal Global Sea Surface Temperature Variability Based on CMIP5 and Reanalysis Data

S. Henson (1); C. Beaulieu (1); L. Zhang, (1)

(1) University of Southampton, Ocean and earth science, Southampton, United Kingdom

The analysis of long-term changes in the distribution (mean, variance and extremes) of climate variables is essential for a full understanding of climate change and its impacts. The majority of climate change studies have focused on changes in the mean climate, therefore underestimating how changes in climate variability latitude after large volcanic eruptions at equatorial and high latitudes, but this variation related to longitude after volcanic eruptions at low and middle latitudes.

Noticing this, we explore the patterns of sea surface temperature variability by looking at the observed sea surface temperature data record from 1854 to 2014. We investigate the global yearly and monthly sea surface temperature variability changes. For example, annual mean sea surface temperature and intra-annual variability (measured by the standard deviation and range). We also investigate the global and regional decadal changes in sea surface temperature variability, for example, using normalized probability density functions for different periods of anomalies in the data set.

In addition to the analysis of observational data, we assess how sea surface temperature variability may change in the future using model projections. We analyse the model projections by targeting the RCP8.5 (business-as-usual emission scenario) and the RCP4.5 (mitigation scenario) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). This allows us to verify whether mitigation has an impact on projected changes in climate variability.

Comprehending the changes in climate variability is important for our society. Revealing the potential patterns of sea surface temperature variability can help us better understand the climate variability.

Correlation between Polar motion and climate variables during 1962-2013

M. Huang (1)

(1) Institute of Geographical Sciences and Nature Resources

Research, Chinese Academy of Sciences, Beijing, China

Polar motion is a significant Earth orientation parameter, but our understanding of its relation to climate forcing remains highly uncertain. In this study, the relationships between the polar motion excitation and climate variables are examined. High correlations are found between the excitation and annual mean climate variables, such as air temperature, atmospheric pressure, horizontal wind at various altitudes, pressure, temperature, and pressure gradient, especially at 1000 hPa level. High correlation coefficients between the excitation and climate variables are found for the regions of the Arctic, Antarctic and Indian Ocean, with the center values exceeding 0.72. Two abrupt changes in polar motion excitation time series are detected and the accompanied changes of climate variables are also studied. Since the polar motion can be accurately measured by satellite, the accurately determined polar motion can be used as an indicator for monitoring and understanding the global climate change.

Climate change vulnerability of fishery-dependent coastal communities in Bangladesh

N. Islam (1); MM. Islam (1)

(1) Sylhet Agricultural University, Department of Coastal and Marine Fisheries, Sylhet, Bangladesh

Being situated in a deltaic geographic setting, Bangladesh is considered as one of the most climate-vulnerable countries on earth. The country frequently faces different climate change related events such cyclones, rising tidal floods, erosion and inundation, saline water intrusion which are further compounded by degraded natural resources base. In contrast to other climate vulnerable communities, many few research have conducted in Bangladesh on vulnerability of fishery-based livelihoods to climate change impacts. Based on a fieldwork with four fishing communities in Patukhali region of south-west coastal Bangladesh, the present study assessed vulnerability of fishery-based livelihoods to climatic change and variability. Bottom - up research approach was adopted in the study and participants' information was collected through 70 individual interviews and focus group discussion. The result revealed multi-faceted vulnerabilities on different scales that impinge on the livelihoods of already resources-poor fishers' community in coastal Bangladesh. In line with global evidences, the level of vulnerabilities differs among the communities and across households within a community. Being dependent on climate sensitive fisheries resources, fishers' vulnerability further depend on their level of exposure, and adaptive capacity. For instance, fishers' level of exposure varied depending on areas of their fishing. Fishers with limited asset base usually do fishing in rivers and estuaries thus less exposed to extreme events, however when disaster stuck in their living places they are more vulnerable due to limited adaptive capacity. The case is reverse in case of better off fishers. They go for sea fishing thus more exposed to extreme events; however has better adaptive capacity due to strong financial capabilities. In both cases, fishers reported an increase of climate change-induced extreme events such as storm surge, strong wind, higher wave and stronger current during fishing operation that often cause loss in physical capitals and subsequent financial hardship. Loss of fishers' lives is also common as a deadly consequence during fishing in sea. A number of internal and external factors regulate adaptive capacity of fishing communities in the study areas. Adaptive capacity of fishers often undermine by different internal factors, many of which are人为 factors, lack of modern fishing appliances, inadequate and poor infrastructure of cyclone shelter, complexities and non-availability of scheduled credit during crises period, exploiting relationship between fishers and fish entrepreneur (money lender) lack of alternatives livelihood opportunity etc. To illustrate, with absence of state loan facility, fishers often have to take loan from moneylender at higher interest rate that create long term debt bondage with fish entrepreneur that weaken fishers' adaptive capacity. A number of external factors such as lack of security during deep sea fishing, also make fishers' lives more vulnerable by influencing their financial and social capabilities. For instance, increased risk of piracy in the bay causes financial loss of fishers in the form of ransom pay, bodily harm including death as well as loss of fishing gears and craft. In the above-mentioned, the present study submits
that to make climate resilient fishing communities in Bangladesh, it is important to address no-climate related external factors, along with climate change related factors for a more holistic adaptation policy.

P-1117-16

Assessment of Regional Climate Models over Côte d'Ivoire and Analysis of Future Projections over West Africa

K. Kouadio (1); A. Konare (2); A. Diawara (3); K. Dje (4); V. Oyaji (5); D. Diehiou (6)

(1) LAPA-MF, Université Félix Houphouët-Boigny;

WASCAL, Federal University of Technology Akure, Abidjan,

Ivory Coast; (2) Universite Félix Houphouët Boigny, Cocody,

Uf ssm, Abidjan, Ivory Coast; (3) University Félix Houphouët

Boigny - Cocody Abidjan, Physic, Abidjan, Ivory Coast; (4)

Société d'exploitation et développement Aéroportuaire et

Météorologique, Abidjan, Ivory Coast; (5) WASCAL-GRP-

WACS, Federal University of Technology Akure, Akure,

Nigeria, Federal University of Technology Akure, Akure, and

for Development (IRD), LTHE - University Grenoble Alpes,

Grenoble Cedex 9, France

The ability of six Regional Climate Models (RCMs) used in AMMA-ENSEMBLES project is assessed over six meteorological stations in Côte d'Ivoire. The ensemble mean of the models is also used for the prediction of climate change over the two periods: the period 1995-2005, the present-day simulations, is used to evaluate the skills of the models over the country and the years 2010-2013, for assessment of the future climate change scenario used. The results show that the skills of the models vary from one station to another and from one season to another. None of the models considered, presents an excellent performance over the entire country and in all the seasons. Generally, the ensemble mean of all the models presents better results when compared with the observation. These results suggest that the choice of any model for study over the country may depend on the focus of interest: intensity or variability of the rain and also on area of interest. The projection for 2020-2040, future climate change over West Africa shows that the Sahel exhibits a tendency to be drier while wetter Guinea coast is observed.

P-1117-17

Recent Observations and Experiences of Glaciers response to Intrinsic Climatic Variability: the Himalayan Inquest

P. Kumar (1); M. Sharma (2)

(1) Jawaharlal Nehru University, Centre for the Study of Regional Development, Delhi, India; (2) Jawaharlal Nehru University, Centre of the study of regional development, Delhi, India

The earth's climate has undergone a many phases of both long and short term fluctuations in the past; more so during the late Quaternary period. However, the recent climatic fluctuation has become a bone of contention among scientist for as to what causes these changes; to be precise, through the human actions. Therefore, the understanding the varying role of natural and human actions needs to be precisely quantified for a better understanding and impact thereof. The Himalayan environment, with one of the sensitive parameters in the form of ice and glaciers, provides an indispensable laboratory for evaluating and understanding climate variability through these fluctuations in space over a longer temporal scale. Many climate scientists agree on the warming trend of climate past few decades. There are no concrete studies on regional climatic variability especially at the higher altitudes. As a layman we understand that climate changes regionally, based on latitude, altitude, aspect, and land- cover and so on a lack of climatic data in the Himalayan region limits us to assess just this sensitive key in the form of glaciers on a longer time scale, given the understanding that response time is very large. Now the question arises, how much do we know about the changing climate in the Himalayas? We present here the land surface temperature (LST, MODIS) data of the higher altitudes and behavior of glaciers for past one decade in the Himalaya and an assessment among the point source data of the land surface temperature based data analyzed. Point source data of Bhojbras has taken from the Automatic Weather Station (AWS), Snow and

Avalanche Study Establishment (SASE). The grid source data are satellite based Land Surface Temperature (LST) temperature data obtained from Moderate Resolution Imaging Spectroradiometer (MODIS). A strong relationship emerges between satellite based and ground based data, a useful indicator if considered, especially in case of high altitude and a complex climate system like the Himalaya. The analysis of data are provides a very strong and positive correlation (0.887), which means 89 percent of SASE data, is explained by the MODIS data, which is very encouraging. The coefficient of determination is 0.7870; therefore, about 78.7% of the variation in the SASE data is explained by MODIS data. The root mean square error (standard deviation of regression) is 2.4569, which is very close also provides a better fit. All the station values are represented on the simple line; and a simple trend line lines have been drawn on temporal framework. The daily data trend of all the station does not show significant results in a simple regress line (2000-2013). But the yearly trend line data shows variability as; Harsil (0.241), Bhairaghatti (0.157), Bhojbras (0.158), Kalapani (0.208), Rudugaira (0.104), Raktavarn (0.0103) and Chaturga (0.134) which is highly significant. There is a high variability in the elements but is not reflected as such in the study area during the last thirteen years. Trend lines show downward dip, meaning that there has been, without any doubt, temperature has dropped during 2000-2013. It is but true that temperature has been a highly variable component in the high altitudes and may vary on the hourly and daily basis. But the thirteen years of data for five different stations portray a declining trend. Behavior of minimum and maximum temperature variability is not similar, each at varied nature in different stations. Given that we have not been able to assess precipitation characteristics for the same duration for these stations, it is highly speculative to assume that these line may in a longer temperature scale would uphold the Himalayan glacier beyond the limit of imagination. Indeed the last 100 years glacier responses with differential rate due to their different geomorphological, geographical, climatic conditions and especially the response time. Same types of results are observed in Western Himalaya, particularly in case of Gangotri glacier, which is retreating with an alarming rate until. Although since 2001 rate of retreat has been slow down and particularly 2007 onwards there are no significant changes in glacier snout. Interestingly terrestrial records are showing that two of its tributary glaciers as Rakatavarn and Chaturgaati glacier are showing positive change in their mass and terminus position since 1994. It propounds the complexity of glacier responses even within same geographical and climatic conditions, which means behavior of glacier is identical in nature, with self strength of mind.

P-1117-18

Simulations of Future Climatological Conditions in Central Asia CORDEX Region 8 by Using RegCM4.3.5

L. Kurnaz (1); MT. Turp (2); T. Ozturk, (3); M. Turkes (4)

(1) Bogazici, Center for climate change and policy studies

and department of physics, Istanbul, Turkey; (2) Bogazici,

Institute of environmental sciences, Istanbul, Turkey; (3)

Isik University, Physics department, Istanbul, Turkey; (4)

Bogazici, Center for climate change and policy studies, Istanbul, Turkey

In this work, projected future changes in mean surface air temperature and precipitation climatology, inter-annual and seasonal variability and climatic aridity/humidity conditions for the period 2010-2100 over the large Central Asia region with respect to present climate from 1970 to 2000 were simulated based on the RCP4.5 and RCP8.5 emission scenarios. Regional Climate Model (RegCM4.3.5) of the International Centre for Theoretical Physics (ICTP) was used for projections of future and present climate conditions. HadGEM2 global climate model of the Met Office Hadley Centre and MPI-ESM-MR global climate model of the Max Planck Institute for Meteorology were downscaled to 50 km for the CORDEX Region 8. We investigated the seasonal time-scale performance of RegCM4.3.5 in reproducing observed climatology over the domain of Central Asia by using 2 different global climate model outputs. For the future climatology of the domain, the regional model predicts relatively high warming in the warm season and northern part of the domain at cold season with a decrease in precipitation almost all part of the domain. The results of our study show that surface temperatures in the region will increase from 1 °C up to
more than 7 °C on average according to the emission scenarios during the period 2010-2100 with respect to past period 1970-2000. Therefore, the projected warming and decrease in precipitation and more resultant or associated increased aridity and more frequent and severe drought events very likely adversely affect the ecological and socio-economic systems of this region, which is already characterised with mostly arid and semi-arid climate and ecosystems.

P-1117-19

Spring temperatures in the far-western
Nepal Himalaya since AD 1640 reconstruc-
ted from Picea smithiana tree-ring widths

U. Kuwar Thapa (1) ; SK. Shah, (2) ; DR. Bhuju, (3) ; NP. Gaire (4) ; S. St. George (1)

(1) University of Minnesota, Geography, Environment and Society, Minneapolis, Minnesota, United States of America;
(2) Birbal Sahni Institute of Paleobotany, Lucknow, India; (3) Central Department of Environmental Science, Tribhuvan university, Kathmandu, Nepal; (4) Nepal Academy of Science and Technology, Faculty of Science, Lalitpur, Nepal

Nepal Himalaya has heated rapidly over the last four decades (more than twice the mean global rate), with this warming being even more pronounced in higher elevations. Unfortunately, because climate records in most of the country does not go extend prior to AD 1880, these short records make it more difficult to gauge the rate and (potential causes) of recent changes or enact long-term plans for resource management in the Nepal Himalaya under changing climate.

We conducted dendroclimatic study in order to extend the temperature record in western Nepal Himalaya beyond the instrumental record. For this, we developed a new, 422-year long tree-ring width chronology (Spanning AD 1591-2012) from Picea smithiana (Wall.) Boiss in Khapad National Park, which is located in the far-western Nepalese Himalaya. Seasonal correlation analysis revealed significant indirect relationship with spring temperature (March-May) and lead to the reconstruction of March-May average temperature for the past 373 years (AD 1640-2012). The reconstruction was found significant based on validation statistics commonly used in tree-ring based reconstruction. Furthermore, it was validated through spatial correlation with gridded temperature data. This temperature reconstruction identified several periods of warming and cooling. The reconstruction did not show the significant pattern of cooling during the Little Ice Age but there were few cold episodes recorded. However, the reconstructed temperature revealed the recent warming for last three decades as recorded in the stations. Wavelet analysis revealed high frequency variability (2-7 years) of spring temperature in western Nepal Himalaya for last four centuries, which can be linked to global climate system, El-Nino Southern Oscillation (ENSO). Significant negative correlations were found between the spring temperature in western Nepal and temperatures of monsoon and post monsoon seasons over the equatorial Pacific Ocean. This showed western Nepal Himalaya has linkages with climatic variability in a global scale.

This multi-centennial reconstruction of temperature in western Nepal Himalaya would serve as a basis for Ministry of Environment, Science and Technology to develop climate change adaptation strategies, including the National Adaptation Program of Actions and Local Adaptation Plans of Action. Future climate modeling shall also possible with this long available estimated temperature record for west Nepal.

P-1117-20

Drought monitoring with root zone soil
moisture derived from ASCAT satellite
data over the East Asian region

JH. Lee (1) ; J. Im (1)

(1) UNIST, Urban and env engineering, Ulsan, Republic of Korea

Several studies showed that semi-arid regions of Asia are vulnerable to climate change induced drought (Alimullah Miyani, 2014). While drought has often occurred over the East Asia, we have little understanding of drought at

a large scale in that region. Accordingly, there is a need to establish an appropriate drought monitoring and prediction system. There are different types of drought such as agricultural drought or hydrological drought (Rhee et al., 2010). The factors that influence drought are interconnected through land-atmosphere interactions. One of the major factors is soil moisture, which can be effectively used to monitor agricultural drought. The surface soil moisture information from ASCAT satellite data is employed to provide root zone soil moisture for drought monitoring. This approach suggests several merits, when compared to the MODIS Vegetation Index-based indicators or precipitation-based indices often applied to drought monitoring. First, it is difficult to characterize the dynamics of soil dryness with the vegetation indices such as leaf-area-index (LAI) or normalized vegetation index (NDVI), as some vegetation species well grow up in dry soils. Secondly, it is difficult to monitor the deep soil that is actually important for predicting the agricultural productivity solely with the precipitation indices, because it is still unknown whether precipitation will infiltrate into the soils, evapotranspiration, or run off.

For these reasons, root zone soil moisture is considered a key indicator for agricultural drought monitoring due to its direct relationship with agricultural productivity and its climatic implication over the land (Lee, 2014). In this study, we use an exponential filter to infer root zone soil moisture from the satellite-retrieved surface soil moisture dynamics. The spatial distribution of soil moisture profiles over this region is evaluated with other datasets such as SMOS and ECMWF data. The 1D soil moisture profile is validated with newly obtained in-situ observations (e.g. precipitation, soil moisture) from the Monsoon Asian Hydro-Atmosphere Scientific Research and Prediction Initiative (IMRAS) research program under the framework of The Global Energy and Water Cycle Experiment (GEWEX). The role of soil moisture on the East Asian monsoon circulation is also assessed.

Reference

Reference

1 Alimullah M, Droughts in Asian least developed countries: Vulnerability and sustainability, 2014, Weather and Climate Extremes, http://dx.doi.org/10.1016/j.wace.2014.06.003.

2 Lee, J. H. 2014. Spatial-scale prediction of the SVAT soil hydraulic variables characterizing stratified soils on the Tibetan Plateau from an EnKF analysis of SAR surface soil moisture. Vadose Zone Journal.

3 Rhee, J., Im, J., Carbone, G.J. 2010. Monitoring agricultural drought for arid and humid regions using multi-sensor remote sensing data, Remote Sensing of Environment, Volume 114, Pages 2875-2887, http://dx.doi.org/10.1016/j.rse.2010.07.005.

P-1117-21

Global warming and cause-and-effect rela-
tions in solar cycles 20-23

B. Lilia (1)

(1) Institute of terrestrial magnetism, ionosphere, and radiowave propagation of RAS, Solar terrestrial, Moscow, Troitsk, Russia

Since the early works by Bernard Vonnegut and Edward Ney that related cosmic radiation to the weather a lot of controversial results were discussed. Thereby we have studied solar activity and interplanetary space conditions, which can have an influence on galactic cosmic ray (CR) and on global temperature. In this connection the solar wind and interplanetary magnetic field parameters and cosmic ray variations have been compared with geomagnetic activity represented by the equatorial Dst index from the beginning 1965 to the end of 2012. The important drivers in interplanetary medium which have effect on cosmic rays as CMES (coronal mass ejections) and CIRs (corotating interaction regions) undergo very strong changes during their propagation to the Earth. Because of this CMES, coronal holes and the solar spot numbers (SSN) do not adequately reflect peculiarities concerned with the solar wind arrival to 1 AU. Therefore, the geomagnetic indices have some inestimable advantage as continuous series other the irregular solar wind measurements. We have compared the yearly average variations of Dst index and the solar wind parameters with cosmic ray data from Moscow, Climax, and Haleakala neutron monitors during the solar cycles 20-23. The descending phases of these
solar cycles (CSs) had the long-lasting solar wind high speed streams occurred frequently and were the primary contributors to the recurrent Dst variations. They also had effects on cosmic rays variations. We show that during the 11-year solar cycles 20-23, the IMF B, global temperature and Dst variations were correlated with the cosmic ray count rate. We demonstrate that the detrended annual means of global surface air temperature in 1965-2012 show the maxima during CRs and Dst index minima. It proves that CRs play essential role in climate change and main part of climate variations can be explained by mechanism of action CRs modulated by the solar activity on the state of lower atmosphere and meteorological parameters. Following this we have to seek for another ways of looking for global warming reason, first of all, as a man impact on climate.

P-1117-22

## Solar wind effects on climate change

### B. Lilia (1)

(1) Institute of terrestrial magnetism, ionosphere and radiowave propagation of RAS, Solar terrestrial, Moscow, Troitsk, Russia

Climate change in connection with evolution of Dst index and cosmic rays (CR) variations is analyzed. We considered Dst index evolution from the point of view of solar variability, cosmic rays and climate during SCs 20-23. It is shown that together with other solar and interplanetary parameters the long-term variations of the Dst-index can be used for studies of this kind of solar-terrestrial relationship. During the descending phases of these solar cycles the long-lasting solar wind high speed streams occurred frequently and were the primary contributors to the recurrent Dst variations and had effects on cosmic ray variations. We have studied conditions in interplanetary space, which can have an influence on galactic cosmic rays (CRs) and climate. We show that long-term cosmic ray count rate variations in SCs 20-23 were modulated by solar activity, by the B of IMF which are correlated with Dst variations. On the long-term scale, the correlation CRs count rate in term of the B of IMF and Dst index is much higher than the correlation between solar spot numbers.

P-1117-23

## Local climate assessments in data scarce mountain areas; for example Kullu distric, Himachal Pradesh, India

### A. Linsbauer (1); N. Salzmann (1); M. Rohrer (2)

(1) University of Fribourg, Department of Geosciences, Fribourg, Switzerland; (2) Meteodat GmbH, Zurich, Switzerland

High-mountain regions like the Himalayas and their adjacent downstream areas are often highly affected by climatic changes, climate variability and/or related extremes. As a result of cascading effects of rising air temperatures, melting glaciers, thawing permafrost - as well as anthropogenic water usage or changes in forest and agro-biodiversity - vulnerability of people's livelihood has broadened and increased. However, climatic impacts assessments on physical and societal systems are often limited due to the scarcity of reliable long-term observations, particularly in remote high mountain regions, which additionally also hampers robustness of future projections. Since livelihoods in remote high-mountain regions are particularly vulnerable to climate related impacts, and have typically only low adaptive capacities, studies assessing climate variability pattern of the past and for the future are an important basis for sound impact assessments, and as such for preparing and planning adequate adaptation measures. Key for such studies and measures are climatic baselines.

Within the Indian Himalayas Climate Adaptation Programme (IHCAP) integrated vulnerability and hazard and risk assessments are on the way for the Kullu district in Himachal Pradesh, India, for the sake of supporting adaptation planning there. Related to these studies, the present work aims to provide an approach and according results for climatological baseline generation for regions without respective observations available or accessible. Here, we use observational gridded data sets (CRU, GPCC, TRMM, Berkeley) and Reanalyses (ERA-I, MERRA, NCEP/NCAR-R1, CR20) to provide spatially and temporally

continuous data. For the grid boxes covering the area of interest, the time series for temperature and precipitation are analysed and possible trends and variations are assessed for the time window 1981-2010, as well as the entire time line of the respective gridded dataset. Preliminary analyses reveal that the 2m air temperatures have slightly increased over time, whereas the 500 hPa temperatures do not portray this trend clearly. Seasonal analysis for the same time window for the 500 hPa temperatures shows a clear seasonal linear trend for winter (DJF), whereas there is no clear linear trend visible for spring (MAM), summer (JJA) and autumn (SON) temperatures. Precipitation amounts seem to have significantly decreased in MAM and JJA for the period 1981-2010.

As gridded datasets are prone to inhomogeneities, an 'ensemble' of observational and reanalysis datasets are analysed and possible uncertainties are discussed. In conclusion it is important to state that global observational datasets and reanalysis are not a surrogate for ground and upper air in-situ measurements and 'allow only a very coarse estimation of air temperature and precipitation trends. Nevertheless, it often remains the only option for local studies.

P-1117-24

## Spatial pattern of recent rainfall trends in Serbia (1961-2009)

### J. Lukovic (1); B. Bajat (2); D. Blagojevic (2); M. Kilibarda (2)

(1) University of Belgrade, Department of Geography, Belgrade, Serbia; (2) University of Belgrade, Department of civil engineering, Belgrade, Serbia

This study examines a spatial pattern of annual, seasonal and monthly rainfall trends in Serbia. The study used data from 63 weather stations between the period of 1961-2009. The rainfall series was examined by applying the nonparametric method of the Mann-Kendall test and Sen's method to determine the significance and magnitude of the trends. Significant trends have not been detected for the whole country at an annual scale. Seasonal trends at the confidence level of 97.5%, however, indicate a slight decrease in winter (5 stations out of 63) and spring (7 stations out of 63) precipitation and an increase in autumn precipitation (10 stations out of 63). Results for monthly rainfall trends also generally showed a nonsignificant trend with the exception of a negative trend in May (6 stations out of 63) and positive trend for October (9 stations out of 63). Calculated global autocorrelation statistics (Moran's I) indicate a random spatial pattern of rainfall trends on annual, seasonal, annual and monthly timescales with exceptions for March, June and November. Overall, results suggest that only weak, mostly nonsignificant trends are present in Serbia in the period 1961-2009. To obtain spatial pattern of rainfall trends web mapping techniques are used applying recently developed package plotGoogleMaps.

P-1117-25

## Evaluation of regional climate models in the context of AGRHYMET

### M. Ly (1)

(1) AGRHYMET Regional Centre, Training and Research, Namie, Niger, Republic of

The AGRHYMET regional Center is a specialized institution of the Permanent Interstates Committee Drought Control in the Sahel (CILSS) composed presently of thirteen member states. It has the objective to contribute to achieve food security for agroclimatology and hydrological applications with emphasis on rural and natural resource management. It contributes to achieve food security for increasing agricultural production in the CILSS member states by providing training and information to stakeholders and partners. For these missions some innovative projects have been initiated in the recent years to help countries to achieve the Millennium Development Goals (MDG) throughout their ability to analyse the climate change impacts. In this regard AGRHYMET has just initiated a climate modelling activities to examine the present and future climate for identifying the climate related risks in the main sectors and provide information for decision-makers. In the Sahel, food security is highly reliant on rainfed agriculture, and thus the intra-seasonal variability of rainfall including the onset dates, the cessation dates, the length of the rainy season remain an
important factors to investigate. The aim of this work is to provide improved knowledge and evidence on current and probable future climate conditions, for use by decision makers in the region. It will also enhance the capabilities of the above mentioned characteristics of the rainy from regional climate simulations. Some approaches are then used in the region through the regional seasonal outlook forum (PRESAO) to determine a suitable planting date aiming to minimize the water stress in the growing period and then optimizing the staple crop yields in the Sahelian and the guinean cost countries. The exercise is focusing to analyse the divergence of regional climate models in the CORDEX experiment on intra-seasonal variability of daily rainfall as well as the likely occurrence of long dry and/or wet spells during the critical growth of the dominant crop varieties sown by West African farmers.. The project outputs will contribute to significantly lower uncertainties by developing better and more tailored climate change knowledge to inform the user communities on climate related risks, as well as enhance their resilience to food insecurity and other climate related disasters.

P-1117-26

Effects of Drastic climatic variability in Pakistan

U. Mehmood (1); U. Aslam (2)

(1) University of Management and Technology, Department of political science, Lahore, Pakistan; (2) university of the Tunjap, Lahore, Pakistan

Weather and climate have very important socio-economic impacts. Climate of Pakistan have become unpredictable. This study describes the effects of intense flooding during 2010 and severe drought since December 2013 in Pakistan. Because of rapidly growing population and industrialization in Pakistan, the waste material is getting into the atmosphere and contaminating it and producing greenhouse gases. In late July 2010, heavy monsoon rains in Pakistan increased the water level in Indus River which caused heavy flooding in southern Pakistan. During the wet spel from 27 to 30 July Risalpur, Islamabad, Peshawar, Lahore, and Rawalpindi received rainfall of 415 mm, 394 mm, 333 mm, 288 mm, and 219 mm respectively. More than one fifth of Pakistan land was under water and 20 million people were affected and there was a large-scale destruction of property, livelihood, and infrastructure. On the contrary, currently most of the areas of southern Pakistan (i.e. Tharparkar district) are facing a severe drought since December 2013. More than 120 malnourished children have died and about 175,000 families have been affected and some of them have been forced to leave their homes and move to阙 areas. There is a need to explore the causes of climatic variability and sophisticated methods of weather forecasting so that damages can be minimized to a greater extent.

P-1117-27

Climate Variability and Waterborne Diseases: Case of Typhoid Fever and Enteric Viral Hepatitis in Meknes province, Morocco

O. Mouhaddach (1); A. El Yaacoubi (1); I. Boularab (1); M. Bend-Daoud (1); MP. Kestemont (2); S. El Jaafari (1)

(1) Moulay Ismail University, Faculty of science, Meknes, Morocco; (2) Catholic University of Louvain, Lsm, Louvain-la-Neuve, Belgium

Background: In spite of all efforts deployed by health officers to control the waterborne diseases, Meknes stills the most severely affected province in Morocco. Various factors may explain this trend, including climatological and environmental ones.

Therefore, this study was carried in Meknes province and aims to understand the impact of climatological factors on typhoid fever and enteric viral hepatitis temporal variability, and to highlight the relation between climatological and environmental factors in this case, over the period 2004-2013.

Methods: Due to non-normal distribution of our input data, Spearman correlation was used. In order to point out the relevant periods of the year where the infection by Salmonella typhi and hepatitis viruses A & E, was strongly correlated to climate conditions, namely air temperature and rainfall, a new statistical approach was used, Partial

Least Squares.

Results: The results reveal a temporal periodicity of typhoid and enteric viral hepatitis recorded cases, and the presence of significant positive correlation between the studied factors and the cases.

Partial Least Squares regression showed two relevant periods where the number of typhoid and viral hepatitis recorded cases increased, in coincidence with rise of air temperature and decrease of rainfall. The first period started from the end of March to the beginning of June, while the second one extended from the beginning of August to the end of October.

In fact, need of water for irrigation is more required during these two periods which are characterized by water scarcity. The wastewater reuse in irrigation is a common practice during the hot season, what may explain this typhoid and enteric viral hepatitis temporal variability.

Conclusion: This study identified some of climatological and environmental determinants of waterborne diseases in Meknes Province which currently exhibits the highest incidence in Morocco. This knowledge can be used to design intervention measures to reduce and control the said diseases in this area.

P-1117-28

Evaluation of model simulation of the Southeast Asia climate under the Southeast Asia Regional Climate Downscaling (SEACLID)/CORDEX Southeast Asia project

G. Narisima (1); F. Cruz (2); J. Dado (3); F. Tangang (4); L. Juneng (4); T. Phan Van (5); T. Ngo-Duc (5); L. Trinh-Tuan (5); T. Nguyen-Xuan (5); J. Santisirisomboon (6); P. Singhruck (7); D. Gunawarapians (8); E. Aldrian (8); JX. Chung (4); ST. Ngaih (4); TW. Teh (4)

(1) Ateneo de Manila University, Physics Department, Quezon City, Philippines; (2) Manila Observatory, Quezon City, Philippines; (3) Tokyo Metropolitan University, Department of geography, Hachioji, Japan; (4) National University of Malaysia, School of environmental and natural resource sciences, Bangi, Selangor, Malaysia; (5) VNU Hanoi University of Science, Hanoi, Vietnam; (6) Ramkhamhaeng University, Bangkok, Thailand; (7) Chulalongkorn University, Bangkok, Thailand; (8) Agency for Meteorology, Climatology and Geophysics, Jakarta, Indonesia

In the face of future climate change impacts, high-resolution climate projections are essential in developing appropriate adaptation measures. The Southeast Asia Regional Climate Downscaling/CORDEX Southeast Asia (SEACLID/CORDEX-SEA) project aims to generate these projections through a collaborative effort in regional climate downscaling. However, before downscaling global climate projections, a regional climate model is first evaluated to determine its performance in simulating the climate over the SEA region. In this study, simulations using the 4th version of the International Centre for Theoretical Physics (ICTP) Regional Climate Model system (RegCM4) have been conducted over the SEA domain (80°E-145°E, 15°S-40°N) at 36 km spatial resolution for the period of 1989-2008 using the ECMWF ERA Interim data as a reference. The results of the simulations are compared with observed data and rainfall with observed data show areas where the regional model tends to enhance (or reduce) biases from the boundary forcing. For example, there is a consistent cold bias over the Tibetan plateau and Indochina, especially during the boreal winter. However, the seasonal cycles are generally well-represented in the model. The correlation between model and observed data also tends to be high over the mainland Asia continent but low over the Maritime Continent, which may either be due to the model or to uncertainties in the observation data used. Results also indicate relatively higher similarities for both seasonal and inter-annual variabilities in the temperature and rainfall extremes among the different model experiments performed over mainland Asia compared to the Maritime continent. These results emphasize the need to evaluate and appropriately configure the regional climate model, particularly for the SEA region.
## Atmospheric Systems and Thermal Comfort Index in Presidente Prudente (Brazil) in January-March 2014 period

M. Noli Da Fonseca (1); MC. Silva, (2); PRD. Alves, (1)

(1) UFPR, Curitiba, Paraná, Brazil; (2) UFPR, Curitiba, Brazil

Since humanity's beginnings man has a concern with the phenomena that originate in the atmosphere. The city of Presidente Prudente is located in the western portion of the state of São Paulo, with a population estimated at 218,960 inhabitants (IGBE, 2013). The city is situated at an average altitude of 472m above sea level and has a great diversity of land use, because the neighborhoods are densely built. With regard to the climate, the city is located in a tropical climate system, a climate transition area, thus hurting the performance of most air systems present in South America. Thus, this research is to identify the performance of weather systems and its relation to the thermal comfort of Presidente Prudente in the first quarter, February and March 2014. For this purpose, we applied initially to Rhythmic Analysis methodology developed by Monteiro (1971) and index calculations Thermal Comfort. Given this, it was found that the feeling of «great discomfort» prevailed during the three-month study, and in the second half of January and the first half of February this feeling was linked to the phenomenon Lock Atmospheric, which caused an increase of up to 5°C in temperature and made cities registrassem record highs. Moreover, the action of «atmospheric blocking» and the daytime heating caused the sensation of «maximum discomfort» was set up, which is active mainly in the afternoon.

## Analysis of the Effects of Climate Variability on Crop Yield in Imo State of Nigeria

F. Okorie (1)

(1) Imo State University, Owerri, Geography and Environmental Management, Owerri, Imo State, Nigeria, Federal Republic of

Agriculture is one of the sectors that are strongly affected by climate variability and change especially in developing countries of the world which Nigeria is among. Africa is considered the most vulnerable region in the world in terms of climate variations and change due to its physical and socio-economic characteristics. In Nigeria, it is well known that climate has varied in time and space and it will continue to vary in future. Many variations in rainfall particularly have occurred for the different climatic regions and individual locations in Nigeria. In the Southeast, Imo state for example, droughts have been relatively less persistent, while rainfall is observed to be increasing and temperature increases and reduces moderately over the years compared with other states in the Northern parts of the country. Many parts of Imo state in Southeastern Nigeria experience flood disasters following excessive rainfall which destroy their farmland and wash away their crops. One major issue with respect to climate variability affects its influence on crop yields. Some studies have shown that fluctuations in rainfall and temperature regimes are the atmospheric driving forces that are responsible for the changes in the climate systems of Imo state and other parts of the Southeastern Nigeria. The yield and quality of food crops is central to the wellbeing of humans and is directly affected by changes in climatic systems. Climate variability affects crop cultivation, uncertainties in the onset of the farming season due to changes in rainfall characteristics (early rain may not be sustained) and the instance of heavy rain may become smothered by heat waves which can lead to an unusual sequence of crop planting which results to poor harvest. Extreme weather events such as thunderstorms, heavy rainfall and extreme temperature also devastate farmlands and leads to poor yield of crops. Pest and crop diseases migrate in response to climatic variations and change. In the study, 15 years (1999-2013) climatic data (rainfall and temperature) generated from the archives of Nigeria Meteorological Agency (NIMET) and crop yield data on selected crops from Agricultural development program (ADP), Owerri, Imo state were examined. After data analysis, the result shows fluctuations in temperature and rainfall pattern in the state with negative effects on crop yield, which also affects humans socioeconomically.

Based on this, it is suggested that farmers should adopt good farm management techniques in order to adapt to the prevailing climate variability.

## Climate variability and susceptibility to desertification in Maranhão State, Brazil

S. Oliveira Sa (1); CMDA. Eloi (1); JR. Lopes (1); EP. Araújo (1); GA. Reschke (1); CWS. Dias (1); JA. Nogueira (1); C. Gehring (2)

(1) Maranhão State University, Agroenvironmental Center, São Luis, MA, Brazil; (2) Maranhão State University, Post-graduate program in agroecology, São Luis, MA, Brazil

Desertification is a serious global problem. Its impact is greater in developing countries, because it can increase hunger, malnutrition and rural exodus. This paper investigates the susceptibility to desertification in the State of Maranhão, the transition zone between Amazonia, inland Cerrado and the semi- arid Northeast Provinces of Brazil. For this purpose, we spatially interpolate data from 84 climatological stations in operation >20 years throughout the state, provided by the National Hydro-meteorological Network developed by National Water Agency. There is a marked contraction and rural exodus in the areas affected the transition-zone between Amazonia and the semi- arid Northeast. Rainfall distribution is very unequal, followed by rapid water-loss via evapotranspiration after the end of the rainy season. Total rainfall varies from about 700.0 to 2784.0 mm/year, with highest rainfall in August (531.3 mm) and April (523.5 mm), whereas March is the driest month (17.1 mm), monthly and annual potential evapotranspiration varies from 20.6 – 302.2 mm/month and 276.0 – 2300.0 mm/year respectively, and annual water deficiency varies from 53.0 to 1421.0 mm/year. In the months of August and September we registered water deficiencies throughout the entire State. The highest rates of annual and monthly water surpluses are 1678.9 mm/year and 424.6 mm/month, respectively. 20.1% (66.854 km2) of the total area of the State of Maranhão, is susceptible to desertification, affecting an estimated 361 thousand inhabitants. Coincidentally, the counties with desertification risk are among the least developed and poorest of Maranhão State and of Brazil. Exposure is especially high in the indigenous population (55.2% of the State's total indigenous population). Until recently, Maranhão was not included in Brazil's map of desertification, and public awareness of desertification risks continues almost absent. Our results demand an increased public awareness, and call for the development and implementation of policy and management strategies designed to counteract and avoid desertification risks, in order to avoid increased rural poverty, food insecurity and further rural exodus.

## Spatial and Temporal Variability of Precipitation over the Gandaki River Basin of Nepal Himalaya

J. Panthi (1)

(1) The Small Earth Nepal (SEN), Research, Kathmandu, Nepal

Landslides, floods, and droughts are recurring natural disasters in Nepal related to too much or too little water. The summer monsoon contributes more than 80% of annual rainfall, and rainfall spatial and inter-annual variation is very high. The Gandaki River, one of the three major rivers of Nepal and one of the major tributaries of the Ganges River, covers all agro-ecological zones in the central part of Nepal. Time series tests were applied for different agro-ecological zones of the Gandaki River Basin (GRB) for rainfall trends of four seasons (pre-monsoon, post-monsoon and winter) from 1981 to 2012. The non-parametric Mann-Kendall and Sen's methods were used to determine the trends. Decadal anomalies relative to the long term average were analyzed using the APHRODITE precipitation product. Trends in number of rainy days and timing of the monsoon were also analyzed. We found that the post-monsoon, pre-monsoon and winter rainfalls are decreasing significantly in most of the zones but monsoon rainfall is increasing throughout the basin. In the hill region, the annual rainfall is increasing but the rainy days do not show any trend. There is a tendency of the late departure of monsoon from Nepal, indicating an increase in its duration. These seasonally
and topographically variable trends may have significant impacts for the agriculture and livestock smallholders that form the majority of the population in the GRB.

P-1117-33

Early warning of climate variability and
change from seasonal forecasts

KA. Peterson (1); A. Scaife (1); C. Maclachlan (1); A. Arribas (1); A. Maidens (1); M. Gordon (1); A. Brookshaw (1); J. Camp (1); D. Fereday (1)

(1) Met Office, Hadley Centre, Exeter, United Kingdom

Projections of future climate suggest that extreme events such as drought, floods, storms, cold spells, and heatwaves will all change their regional frequency of occurrence due to long term climate change. However, on planning timescales of months to years in advance, the timing and occurrence of extreme or unprecedented events is determined by climate variability. In particular, it depends on the superposition of climate variability and climate change. In order to advise on the risk of imminent extremes we therefore need climate predictions which accurately take into account current climate variability. This requires initialisation of the current state of the climate in the atmosphere, ocean, sea ice, and land surface as well as the changes in radiatively active greenhouse gases and aerosols.

Here we discuss near term climate predictions from the Met Office Hadley Centre out to seasonal lead times. We show twice of predictability of the leading modes of climate variability in both the tropics (El Nino Southern Oscillation) and the extratropics (North Atlantic/Arctic Oscillation). We show how this can lead to predictability for regional climate extremes and discuss the prospects for improved warnings and adaptation to imminent extreme events.

P-1117-34

Ability of a high regional climate model to
represent a key climatic features over West
Equatorial Africa

W. Pokam (1)

(1) Department of Physics-Higher Teacher Training
College-University of Yaounde 1, Physics, Yaounde, Centre,
Cameroon

Climate dynamics over West Equatorial Africa (WEA) is dominated by four prominent features. At lower level, two cells of wetterlies (LLW) in the discernible, controlled by a different mechanisms. At middle level, African easterly jet prevails with a northern component (AEJ-N) discernible year round, and a southern cell discernible from September to February. The upper troposphere is dominated by the Tropical Easterly Jet (TEJ) which drivers over the region vary with season. Surface processes over WEA play a prominent role on the variability of the atmospheric dynamic over the region.

This underlines the complexity of atmospheric features over WEA, and the requirement of fine scale climate model for investigating locally driven atmospheric circulations. High resolution (25 Km) regional climate model HadRM3P was evaluated in its capacity to capture and model key dynamical features over WEA.

Results show the ability of HadAM3P to reproduce features related to the development of the two cells of LLW over WEA. HadAM3P do well in locating the core speed of the two cells of LLW and simulate well their annual variability. HadAM3P does a well job in simulating characteristics of AEJ-N and AEJ-S. The height of the core speed of the two components of AEJ is well simulated, together with their annual latitudinal migration. In upper troposphere, TEJ is well captured by HadRM3P.

However, some biases appear in the simulations. Investigation of the reasons behind these biases leads to highlight some mechanisms over the region. Exploration of the overestimation of the strength of LLW shows that HadRM3P overestimates surface temperature over the coastal region in WEA. This leads to overestimation of local vertical convergence of sensible heat flux from the surface, inducing a warm bias of diabatic heating. This promotes

positive bias of vertical motion and in turn overestimation of LLW. This reveals the key role of surface condition over coastal region in WEA for the development of LLW.

Analysis show that during the main rainy season over WEA, from September to November, the prominent feature for the development of uplifts is diabatic heating release by condensation throughout the depth of the troposphere over WEA, rather than jet streak type circulation associated to the development of AEJ-S and AEJ-N.

P-1117-35

Stochastic Dynamical Cascade for
Downscaling Precipitation signals over
Complex topographies in the High Andes

A. Posadas (1); E. Duffaut (2); C. Jones (3); L. Carvalho (3); M. Carbajal (4); H. Heidinger (3); R. Quiroz (5)

(1) International Potato Center, Production System and Environment/ICRAF, Nairobi, Kenya; (2) Electrical and computer engineering, George Mason University, Virginia, United States of America; (3) Earth Research Institute, Department of geography, Santa Barbara, California University, United States of America; (4) International Potato Center, Production system and environment, Lima, Peru; (5) International Potato Center, Crops systems intensification and climate change, Lima, Peru

Global Climate Models (GCMs) suggest that rising concentrations of greenhouse gases will have significant implications for climate at global and regional scales. Less certain is the extent to which meteorological processes at individual sites will be affected. Downscaling climate techniques are used to bridge the spatial and temporal resolution gaps between what climate models are currently able to provide and what decision-makers require. Among the most important impacts of regional-scale prediction of climate change is to assess how food production will affect the food security. Regional scale precipitation and temperature simulations are crucial to understand how global warming will affect fresh water storage and the ability to grow agricultural crops. Precipitation and temperature downscaling improve the coarse resolution and poor local representation of global climate models and help decision-makers to assess the likely hydrological impacts of climate change, and it would also help crop modelers to generate more realistic climatic-change scenarios. Thus, a spatial downscaling method was developed based on the multiplicative random cascade disaggregation theory, considering a β-lognormal model describing the rainfall precipitation distribution and using the Mandelbrot-Kahane-Peyriere (MKP) function. The Multifractal downscaling technique, complemented by a heterogeneity filter, was applied to a 15 years (01/11/1998-03/31/2012) daily rainfall time series produced by the Weather Research and Forecasting model (WRF-15 km grid spacing). A downscaled signal of approximately 1 km grid spacing was generated for a 220 km x 220 km region within the high plateau of the Andes. The model parameters were estimated from gauged daily rainfall data registered over 15 years from 18 weather stations. A detailed testing of the model was undertaken by comparing statistical characteristics of the spatial and temporal variability rainfall between the rainfall fields obtained from the rain gauge network and those generated by the simulation model. The potential advantages of this methodology are discussed.

P-1117-36

Volcanic Eruptions, Carbonaceous Aero-
sols and ENSO Events

K. Potts (1)

(1) Kyna Keju Pty Ltd, Adelaide, South Australia, Australia

El Niño/Southern Oscillation (ENSO) events are the dominant mode of variability in the global climate responsible for significant variations across the world including drought in Australia and Indonesia, floods in the Americas and a generally increased global temperature. An El Niño commences when the Trade Winds blowing across the Pacific Ocean relax, reduce in strength or even reverse. This is a major perturbation of the Walker Cell, the major zonal atmospheric circulation system over the tropical Pacific Ocean, and, as the literature, IPCC and the USA Climate Change Science Program suggest that
aerosols can affect the large-scale atmospheric circulation and hydrologic cycle I examine the relationship between certain volcanic eruptions and carbonaceous aerosol plumes and ENSO events and demonstrate a causal link exists between the eruptions, aerosols and ENSO which logically must be that the volcanic eruptions and aerosols trigger and then sustain ENSO events until the eruptions end and the aerosol plume dissipates enabling the climate system to recover to a non-ENSO state.

P-1117-37

Heating and cooling rate calculations for realistic volcanic ash clouds and applications to climate simulations

A. Prata (1); S. Siems (1)

(1) Monash University, School of earth, atmosphere and environment, Melbourne, Victoria, Australia

The radiative effects of long-lived stratospheric volcanic sulphate aerosols have been widely studied, while the impacts of short-lived, but more strongly absorbing volcanic silicate particles have seen less attention. Silicate ash injected into the stratosphere by the 1982 eruptions of El Chichón volcano were estimated to have induced a net radiative heating rate of up to 20 K per day. This research involves the use of satellite measurements to determine important characteristics of dispersing volcanic ash clouds in order to develop new knowledge on the radiative effects of silicate ash on the atmosphere. Ten explosive volcanic eruptions (VEI ≥ 4), occurring over the last decade (2006–present), have been considered in this study. Hyperspectral infrared and satellite-based lidar remote sensing measurement techniques have been used to detect and quantify volcanic cloud heights, thicknesses, mass loadings and microphysical properties. These measurements are well suited to provide this size and compositional information. Finally, the new data has been used to provide some realistic estimates of the radiative impact of silicate ash on the atmosphere using a 1D radiative transfer model. The significance of the results and possible applications to climate simulations are discussed.

P-1117-38

Observed connections between temperature increase and the altitude of snowfall / snow pack in the Swiss Alps

M. Rebetez (1); G. Klein, (2); C. Marty, (3); C. Rixen, (3); Y. Vitasse, (3); G. Serquet, (2)

(1) WSL Swiss federal research institute, Neuchâtel, Switzerland; (2) University of Neuchâtel, Institute of geography, Neuchâtel, Switzerland; (3) WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland

The consequences of global warming are particularly visible in mountain areas. The impact of changing temperatures on the snow to rain ratio is highly critical for alpine ecosystems as well as for winter tourism. Knowledge of the decrease in snow amount is still poor, due both to high interannual variability and to the frequent lack of data.

Here, we analyse snowfall and snow pack for up to 100 years at 140 stations, spanning elevations from 200 to 3500 m asl in Switzerland. Our method allows to assess the impact of changing temperatures on snowfall while minimizing the impact of variability in precipitation frequency and intensity.

Our results show the connection between the decrease in snowfall / snow pack and the increase in temperature. This decrease was stronger at locations with temperatures closer to the melting point. These locations depend both on elevation and season. The current frequency of snowfall for December, January and February are similar to those of the 1960s for November and March. These changes also result in a decrease in snowpack and in earlier snowmelt, particularly at higher elevation.

The transfer in altitude of snowfall affects the beginning and end of the ski seasons. Currently approximately every second precipitation day already consists of rain up to 1400 m asl in November and March.

The amount of snow available for water storage and

runoff during the spring and summer months is declining, because more and more winter precipitation will directly contribute to runoff. Impacts can also be expected on the alpine vegetation, which will experience a shorter snow season and possibly be more exposed to late spring frost events, irrespective of variability or changes in precipitation.

P-1117-39

First signs of climate change in Lyon (France) according to Köppen and Hess-Brezowsky classifications

F. Renard (1); W. Langlois De Septerville (1); B. Lédée (1)

(1) University Jean Moulin Lyon 3 - UMR 5600 EVS, Department of Geography, Lyon, France

The Greater Lyon (France) gathers human and environmental issues that can be affected by climate change by heat waves and intense precipitation. The objective of this work is to identify recent trends of climate change using the annual climate types from the Köppen-Geiger classification and the catalog situations of Hess-Brezowsky, to assess the dynamics and evolution of heat waves and heavy precipitation.

1. Annual climate types in Lyon since 1922

The Köppen-Geiger climate classification is the most used method to categorize the earth's climates. The methodology used is the one detailed in Kottek et al. (2006) and Rubel and Kottek (2010). Rainfall and temperature data are from the weather station of Lyon-Bron (Météo-France). The annual climate types is calculated, for each year (1922 - 2013), and analyzed by decades. All years are placed in the category of warm temperature climate, with the exception of the types of dry weather and its evolution. Regarding temperatures, two types are identified in Lyon since 1922: warm and hot summer. There has, since 1965, a strong increase of the years with hot summer at the expense of warm summer. Indeed, absent for the decade 1965-1975, the hot summers represent 30%, 40%, 80% and 70% for the following decades. Thus, the hot summer type is the majority since the 1995-2005 decade. An additional study on heat waves shows also an increase of the latter.

Concerning rainfall, the proportion of dry winters is constant with about 20% of the years of this type by decades. Fully humid and dry summer years have high variability for the decades before 1995, where they are since observed in the same proportions (40% each). This first study on rainfall is complemented by studying the evolution of the weather types causing rainfalls, using the Hess-Brezowsky classification.

2. Rainfall atmospheric patterns evolution since 1881

Greater Lyon floods are caused by rainfalls with different characteristics. Their natures (intensity, water height, duration) are known since 1988 thanks to the Lyon 30 rain gauges network. In addition, rain is measured daily, since 1881, using Lyon-Bron station. The second part of this study relates the different types of rainfall to atmospheric circulation, and highlights trends related to climate change.

A comparison of many atmospheric circulation type catalogs has been made, and the method of Hess-Brezowsky (Gestengarbe and Werner 1999, 2005) was chosen to identify the types of rainy weather and its evolution. Since 1881, most of the rainfalls occur with southerly (22%) and westerly (31%) circulations. However, most of extreme rainfalls in terms of intensity, water height or duration are due to southerly regimes, with 57%; 47% and 34% respectively. Concerning the evolution of synoptic circulations since 1881, it is noticed a sharp and steady decrease of north-west and north regime, as well as north-east and north regimes, whereas southerly regimes have strongly increased, going from 20% of rainy weather in 1881 to about 45% in 2013. Regarding intense precipitation and focusing on the sub-types of circulation (Großwetterlagen GWL), it is noticed that the GWL «zonal Ridge across Central Europe» is the most frequent, with a strong increase since 1881, according to the Mann-Kendall trend test. This is the same results for the «cyclical south-westerly» and «trough over western europe» GWLs that have strongly increased since 1881. According to these results, it can be expected an increase in hot summer and
an intensification of rainfall in the Greater Lion.

Gerstengarbe F.-W., Werner P., 1999 : Katalog der
GroßwetterlagenEuropas (1881–1998), nach Paul P. Hess
und Helmut Brezowsky. Potsdam, Germany.

Gerstengarbe F.-W., Werner P.-C., 2005 : Katalog der
GrosswetterlagenEuropas (1881-2004) Nach Paul
Hess Und Helmut Brezowsky. 6. Verbesserte und
Ergänzte Auflage, PIK Report No. 100, Potsdam Institut für
Klimafolgenerschung, 153 p.

Kottek, M., J. Grieser, C. Beck, B. Rudolf, and F. Rubel, 2006:
World Map of the Köppen-Geiger climate classification
updated. Meteorol. Z., 15, 259–263

Rubel, F., and M. Kottek, 2010: Observed and projected
climate shifts 1901-2100 depicted by world maps of the
Köppen-Geiger climate classification. Meteorol. Z., 19,
135-141

P-1117-40

Average Bias of Diurnal Precipitation Over
Maritime-Continent

F. Royan (1)

(1) Indonesian Agency for Meteorology Climatology and
Geophysics, Research and Development Center, Jakarta,
Indonesia

Numerical simulation of diurnal precipitation over
maritime-continent were investigated using WRFV3.5.1.
The numerical model use input data from GFS and from
GFS+RTGSST data then the average bias from both
input data shows that the precipitation is bigger in the
earlier part of the year until 00 UTC. In the
March, Most of the diurnal precipitation are on southern
part of Indonesia, In June, most of the diurnal precipitation
are almost around Indonesia, in September, most of
the diurnal precipitation are on northern part of Indonesia and
in December, most of the diurnal precipitation are around
Indonesia, except south of Java. It's also revealed, that the
diurnal precipitation over ocean is strongest in June rather
than Land.

P-1117-41

Spatio-temporal characteristics of the
recent rainfall recovery in West Africa

S. Sanogo (1); A. Ba (1); AH. Fink (2); JA. Omotosho (3); R.
Redl (4); V. Ermert (4)

(1) Department des Sciences des Techniques et des
Technologies du Bamako (USTB-), Faculty of science and
technique (fst, der-physics), Bamako, Mali; (2) Karlsruhe
Institute of Technology (KIT), Institute of meteorology and
climate research, Karlsruhe, Germany; (3) Federal University
of Technology, Akure, Wascal graduate research programme
in west african climate system, Akure, Nigeria, Federal
Republic of; (4) University of Cologne, Institute of geophysics
and meteorology, Cologne, Germany

Using daily (monthly) rainfall data from 167 (254) stations across West Africa with at least 80% data availability for the 31-year period 1980-2010 and the gridded African Rainfall Climatology Version 2 (ARC2) for the period 1983-2010,linear trends in year and monthly rainfall totals were investigated. Measures of the Expert Team on Climate Change Detection and Indices (ETCADI) and two rainy season onset and retreat definitions were employed to assess the corresponding trends in frequency and intensity of daily rainfall and changes to monsoon season length. A rotated Empirical Orthogonal Functionanalysis yielded two homogeneous rainfall regions, the Sahel and Guinea Coast, in terms of interannual to decadal rainfallvariability, and this led to analysis of station data and Standardised Precipitation Index for the two regions. Results showthat the majority of stations in the Sahel between the West Coast and 15+ E shows a statistically significant positive rainfallfalloff for annual totals. The August-October period exhibits the largest rainfall recovery in the Sahel and the date of threat of the rainy season significantly moved later into the year by 2 days per decade. The recovery is reflected both in morainy days associated with longer wet spell duration and more extreme rainfall events. Trends along the Guinea Coast are weak and non-significant except for extreme rainfall related indices. This missing significance is partly related to the hiatusin rainfall increase in the 1990s, but also to the larger international rainfall variability. However, the tendency towards a moreintense second rainy

season suggests a later withdrawal of rains from the West
African subcontinent. ARC2 trends are broadlyconsistent
where ground calibration was undertaken, but are dubious
for Nigeria and Ghana, and especially for the Guinea, Jos
and Cameroon Line highlands due to missing gauge data.

P-1117-42

Characteristics of Hydro-Climatic variables
In Nigeria during episodes Of Sea Surface
Temperature Anomalies in the Gulf of
Guinea

M. Sholademi (1)

(1) Nigerian Meteorological Agency, Applied Meteorological Services, Lagos, Nigeria, Federal Republic of

This study examined the characteristics of hydro-climatic
variables in Nigeria at various Agro-ecological zones (Forest,
Southern-Guinea-Savanna, Northern-Guinea-Savanna and
Sudan-Savanna) during different episodes of sea surface
temperature anomaly (SSTA) in the Gulf of Guinea (GOG)
region. The study utilizes SSTA and continental climatic data
spanning 40 years; and with the aid of advance statistical
analysis to determine onset of rain, cessation of rain,
duration of rain and frequency of occurrence of rain day
using rainfall-potential-evapo-transpiration model. Results
showed that SST is critical to climate monitoring at the local,
regional and hemispheric scales. The result further display
how to enhance optimal schedule of farm operations,
proper adaptation and mitigation practices against extreme
weather events arising from observed warming trends in
both the SST and the near air surface temperature. Further
analysis is made for SSTA as a forecasting tool in the
prediction of hydro-climatic variables that is essential for
optimal agricultural practices.

P-1117-43

Studies on Climatic parameter influencing
milk production in Cattle in South West
Nigeria

M. Sholademi (1); A. Sholademi (1)

(1) Nigerian Meteorological Agency, Applied Meteorological Services, Lagos, Nigeria, Federal Republic of

This study further advance the knowledge of climatic
indices applicable to the mitigation strategies aimed at
reducing the vulnerability of cattle milk production in south
west Nigeria. It shows that milk production in the tropics is
affected by environmental factors of which climate appears
to be most critical. We adopted Coche and Franquin
(1967) model of 0.1P<sub>c</sub>P<sub>o</sub>PE lactation method. The
experiment was a 2x2x3 factorial arrangement of two
cattle breed, two locations and three seasons. Analysis of
variance (ANOVA), correlation and regression was used to
test the strength of relationship

between climatic parameters and milk yield. The result
shows that sunshine duration and evaporation are the
dominant climatic parameters affecting milk production
irrespective of breed and location. Furthermore, milk
production in the study area was highest during the dry
season with mean value as (approximately 331 litres/cow/
day). However, no significant interactive effect of cattle,
breed, location and season on the lactation yield of cattle
is observed in the study.

P-1117-44

Influences of climatic variability on coastal
oceanography of benin

Z. Sohou (1); TC. Guidi (2); CL. Hini (3); R. Djiman (4); DE. Fiogbe (5)

(1) Benin Fisheries and Oceanographic Research Institute (IRHOB), Biological Oceanography, Godomey, Benin; (2) Institute of Technology Lokossu, University of Abomey-Calavi (Benin); Industrial engineering and maintenance, a chair of mechanical and energy, Lokossu, Benin; (3) Faculty of Agronomic Sciences, University of Abomey-Calavi, Faculty of Agronomic Sciences,., Abomey-Calavi, Benin; (4) Fisheries and Oceanological Research Institute of Benin (IRHOB), Physical oceanography, Cotonou, Benin; (5) Science and Technic Faculty of Abomey-Calavi University, Zoology
department, Abomey-Calavi, Benin
In article are analyzed temporary ranks for average monthly air temperature at Cotonou station Kazakhühn(06° Nord, 002° 23' East) during 10 years (from 1975 to 1984) with every fifteen days discretization of accounting in. For same the period are used average monthly temperatures of the ocean surfaces near the capital of the Republic of Benin, Cotonou. Authors calculated correlation coefficients for humidity of air; air temperature; sea surface water temperature. Research of interrelations between sea surface water temperature variations and salinity changes on depth, allow to identify a mesolimnion zone; gives the chance to understand distinctively within a year, concerning lifting of deep waters (upwelling). Also authors carried out calculations of correlation coefficients between monthly bioproduction of a pelagic species of fish (Sardinellamaderensis), as «the upwellingindicator», with air temperature. In addition in article are represented fields of sea water temperatures and the salinity, received with use of SURFER program.

P-1117-45

Rectification of El Nino-Southern Oscillation into Climate Anomalies of Decadal and Longer Time Scales: Results from Forced Ocean GCM Experiments

DZ. Sun (1); T. Zhang, (1); Y. Sun, (2); Y. Yu, (3)

(1) National Oceanic and Atmospheric Administration, ERL/PSD, Boulder, United States of America; (2) Chinese Academy of Sciences, Institute of oceanology, Qingdao, China; (3) Chinese Academy of Sciences, Institute of atmospheric physics., Beijing, China

To better understand the causes of climate change in the tropical Pacific on the decadal and longer time scales, the rectification effect of ENSO events is delineated by contrasting the time-mean state of two forced ocean GCM experiments. In one of them, the long-term mean surface wind stress of 1950-2011 is applied, while in the other, the surface wind stress used is the long-term mean surface wind stress of 1950-2011 plus the interannual monthly anomalies over the period. Thus, the long-term mean of the surface wind stress in the two runs are identical. The two experiments also use the same relaxation boundary conditions, that is, the SST is restored to the same prescribed values. The two runs, however, are found to yield significantly different mean climate for the tropical Pacific. The mean state of the run with interannual fluctuations in the surface winds is found to have a cooler warm pool, smaller thermocline water, and warmer eastern surface Pacific than the run without interannual fluctuations in the surface winds. The warming of the eastern Pacific has a pattern that resembles the observed decadal warming. In particular, the pattern features an off-equator maximum as the observed decadal warming. The spatial pattern of the time-mean upper-ocean temperature differences between the two experiments is shown to resemble that of the differences in the nonlinear dynamic heating, underscoring the role of the nonlinear ocean dynamics in the rectification. The study strengthens the suggestion that rectification of ENSO can be a viable mechanism for climate change of decadal and longer time scales.

P-1117-46

Sub-Saharan Africa Climate in CMIP5

W. Thiai (1)

(1) S. National Centers for Environmental Prediction, NOAA, College Park, United States of America

This paper examines the Sub-Saharan Africa climate in CMIP5. First we evaluate the historical simulations of continental and regional climatology with a focus on a core set of thirteen models. Second, we compare the CMIP5 climate projections with the historical simulations. We use both RCP 4.5 and RCP 8.5 model simulations. We evaluate the historical runs for a set of basic surface climate and hydrological variables and their extremes for the continent for the period 1979-2005. In addition, we conducted evaluations for selected regional climate processes relevant to the African climate, including the West African monsoon, the Greater Horn of Africa spring and fall bimodal rains, and the southern Africa warm season. For temperature and climate variables, we use ERA-I and NCEP reanalysis as proxy for observations. For precipitation, we use GPCP and CMAP. Models are able to reproduce the

observed spatial patterns of basic climate and hydrological variables but with considerable differences across models and regions in the magnitude and sign of errors. The variability in surface air temperature compares reasonably well with observations. For West Africa precipitation, the north-south migration of the ITCP is fairly well captured in 10 of the 13 models. However, while GPCP and GPCP place the area of maximum precipitation in August around 10°N, only a few of the models (3 out of 13) captured this precipitation. Results from a similar analysis for the Greater of Africa and for southern Africa are presented. The ability of the models to capture extreme events such as drought or flood events has also been investigated and the results presented.

Examining the projected changes in precipitation and temperature trends, we present the differences from the seasonal mean between the last 27 years of the 21st century (2003-2009) and the period spanning 1970-2005. For DJF southern Africa rainfall season, precipitation changes are significant for only four of the models. Two of these models exhibit a drying trend over southern Africa, one exhibit a wet trend, and one model shows dryness in the northeastern part of southern Africa and wetness in the south. For the MAM season, only the CSIRO and HADGEM2 show a reduction in rainfall across south central Africa. For the JJA season, MIROC exhibits a wet trend in West Africa, while CSIRO reduces precipitation there. Precipitation changes in all other models are not significant. For the OND season, CanESM2, CSIRO and HadGEM2 exhibit a wet trend over East Africa, though there are some differences in the location of the changes in intensity. None of the models depicts a significant dry trend over this region. For temperature, however, all the models project positive temperature changes across Africa. Finally, the dynamic patterns associated with the changes in precipitation and air temperature are presented.

P-1117-47

Changes induced by dust on West African
Monsoon features

NE. Toure (1) ; A. Konare (2) ; KO. Ogunjobi (3) ; S. Silue (4) ; I. Diallo (5) ; A. Diedhiou (6)

(1) Université Félix Houphouët Boigny, Cocody Abidjan /
Federal University of Technology Akure, UFR SSMT, Abidjan,
Ivory Coast; (2) Université Félix Houphouët Boigny, Cocody,
Ufss Abidjan, Ivory Coast; (3) Federal University of
Technology Akure, Meteorology and climate science, Akure,
Nigeria, Federal Republic of; (4) Université Pelleforo Gon
Coulibaly de Korhogo, Physics, Korhogo, Ivory Coast; (5)
Université Cheikh Anta Diop, Ecole supérieure polytechnique,
Dakar, Senegal; (6) Institute of Research for Development
(IRD), LTHE- University Grenoble Alpes, Grenoble Cedex 9,
France

The generation and transportation of dust from North Africa are thought to modulate the West African Monsoon (WAM) features. In this study we investigated the relationship between the Saharan Air Layer located above Atlantic Ocean (OSAL) and WAM features, including Monsoon flow, African Easterly Jet (AE), and Tropical Easterly Jet (TEJ) over West Africa using the RegCM4 regional model. Toward this purpose, we performed two sets of experiments from 2000-2010, one including dust and one without dust effect over the West African domain, encompassing the whole West Africa and a large part of the adjacent Atlantic Ocean. An intercomparison of the two simulations show that dust load into the atmosphere has an effect on both the wind and temperature structure at different levels, inducing observed changes in WAM system during JJAS seasons. These changes lead over to a westward shift and slight strength of AE core over tropical Atlantic which is associated to (2) a weak TEJ and (3) lastly to West Africa monsoon penetration over land. Moreover despite the prescribed Sea Surface Temperature, correlations have been found between Aerosol Optical depths in OSAL and wind, suggesting that mechanism relationship between dust and WAM features is well reproduced by RegCM4.

P-1117-48

Perceived Effects of Climate Change
on Nomadic Practice of the Gujjar and
Bakarwal Tribe in Kashmir Valley, India: A
Socio-Demographic Analysis

J. Tufail (1)
(1) JAWAHARL NEHRU UNIVERSITY, CENTRE FOR THE STUDY OF REGIONAL DEVELOPMENT, SCHOOL OF SOCIAL SCIENCES, DELHI, India

Despite the effects of climate change being evident at a global scale, its negative impact will severely affect those communities highly dependent on natural resources. Significant discussion has been focused on the possibility of climate change as a driver of extreme precipitation and attendant events in 1900s and is contributed greatly to the present-day climate variability. In turn increased frequency of summer extreme events are attributed to larger-scale atmospheric circulation change that responsible for significant spatial in broader scale (also across Europe) and intraseasonal contrasts. Growth in extreme precipitation is detected in the latest decade due to deeper European trough with frequent cut-off lows, and its interaction with blocking high over the East Europe, and their greater time residence. The latter became strengthened in the late July-August, providing great weather contrast across Europe, causing rains and floods in the West and greater frequency of droughts in the East.

The study examined perceived effects of climate change on gazing, livestock performance and examined the coping strategies the nomadic to climate change. Multistage sampling technique was used to select 140 respondents for the study. Data were analysed using percentages, frequencies, tables and Chi square statistical tools. The result of the study showed that 37.5% of the respondents were between the ages of 51–60 years with an average age of 49.8 years. The results revealed that 67.5% of the pastoralists strongly agreed that the pattern of rainfall in recent time affects pasture availability. Consequently 47.5% and 52.5% of them reported a decrease in milk production and increase in livestock's mortality rate respectively due to the effect of climate change. A significance relationship was established between factors of climate change and milk production of the herd (calculated x2 = 52.00, tabulated x2=7.8147. p≤0.05). It is therefore recommended that the pastoralists be trained in forage conservation techniques. They should also be encouraged to use resources to enjoy economics of scale by the extension workers. Grazing reserves should be developed by the government to fast track the disposition of the pastoralists to sedentary life. It was recommended that animal production/veterinary services should be stepped up, diversify their production to include crops and other sources of income generation and establish more gazing reserves.

P-1117-49

## Summer precipitation in Ukraine - observations, modeling and controlling factors

V. Tymofeyev (1) ; V. Martazinova (2)

(1) Ukrainian Hydrometeorological, Kiev, Ukraine; (2) Ukrainian Hydrometeorological, Climate and long-range forecast, Kiev, Ukraine

Summer atmospheric precipitation in Ukraine is studied via climatology, atmospheric circulation and simulation in operative and climate models. Climatology of summer precipitation in Ukraine is studied with special attention to recent decades' with growing number of extreme events contributed greatly to the present-day climate variability. Trends in total precipitation amounts and other indexes obtained between early and late season; trends in extreme parameters in threshold values are found statistically significant; they are used for regionalization of spatial changes.

Spatial inhomogeneity is found in precipitation indexes across Ukraine, greatest growth in the daily intensity of extreme precipitation occurred between 1990s and 2000s. Precipitation changes are analyzed against near-temperature (SAT) variability, showing great intraseasonal contrast, on the background of general seasonal warming. Early summer became much wetter in

2000s with numerous extreme events, and period from August till mid-August is much drier causing greater frequency of droughts or heat waves in the last decades. In contrast, early period of global warming in 1970s-mid-1980s has been characterized by much drier climate in the early summer.

It is shown that it is convection intensification that resulted in significant growing extreme precipitation and attendant events in 2000s and is contributed greatly to the present-day climate variability. In turn increased frequency of summer extreme events are attributed to larger-scale atmospheric circulation change that responsible for significant spatial in broader scale (also across Europe) and intraseasonal contrasts. Growth in extreme precipitation is detected in the latest decade due to deeper European trough with frequent cut-off lows, and its interaction with blocking high over the East Europe, and their greater time residence. The latter became strengthened in the late July-August, providing great weather contrast across Europe, causing rains and floods in the West and greater frequency of droughts in the East.

Ability of WRF ARW and NMM models to reproduce different scales' convection is assessed. Types of mesoscale fields responsible for extreme rainfall events are to the strong convection development are recognized within the larger-scale synoptic systems, threat potential is assessed to increase during the last decade. Transition between atmospheric scales can be used to assessing general threat of extreme precipitation.

Many uncertainties in climate models outputs are detected not reproducing well observed growth in extreme precipitation in the recent decade as well as spatial variability. One of the main challenges facing the recent climate change is intensification of convective potential and summer showers on the background of further warming; many uncertainties exist in future climate projections. Our own model of the atmospheric circulation change is developed, and scenarios are built, on the basis smaller rate of near-surface warming and variable precipitation. Recommendations for sustainable development for national economy, mainly for agriculture are given.

P-1117-50

## Instability intraseasonal of rainfall and its implications on agricultural activities in the middle of Benin Republic (West Africa)

I. Yabi (1) ; S. Zakari (2) ; PAB. Chabi (2) ; F. Afouda (2)

(1) University of Abomey-Calavi, Department of Geography, Abomey-Calavi, Benin; (2) University of Abomey-Calavi, Department of geography, Abomey-Calavi, Benin

Until now rainfed agriculture is the main occupation of the people and is the basis of socio-economic development of rural areas of Benin (food security, monetary income). Furthermore inter-annual variability (which has already been the subject of several studies), it is necessary to understand the intra-seasonal rainfall perturbations which depend mainly cropping calendars in this region known for its agricultural potentials.

Daily rainfall amounts of 4 stations (Dassa-Zoumé, Savolou Save and Bante) for the period 1941 to 2010, obtained the National Direction of Meteorology (DNM) were used. Determining the beginning of the end and the length of the dry season was done according to the criteria: Gueye and Sivakumar (1992) used by Sane et al. (2008). Similarly, the frequency of the beginning, the end and the length of the seasons was made at the frequencies 8 years out of 10, 5 years out of 10 and 2 years out of 10 by calculating the cumulative frequency to better appreciate the risks. Moreover, years of rupture (in season length) were verified by Pettit test at significance level α = 5 %. Moreover, the frequency and magnitude of dry sequences (false start of the rains, drought pockets at the heart of the events) and sequences (risk of flooding and water profusion) were analyzed by Zakari et al. (2012) to better characterize the qualities of the seasons.

On average, the first (large) rainy season lasts 120 days (3rd decade of March in the second decade of July-while the second (small) rainy season is longer than 70 days (3rd decade of August to October ), this distribution allows two crop seasons per year (farmers cropping calendars are modeled on that distribution), although the
## Analysis of the West African Heat Waves and their Associated Dynamics Factors using Regional Climate Models Outputs

F. Yoroba (1); K. Benjamin (1); A. Diawara (2); A. Diedhiou (3); Y. Kouadio (1)

(1) University Felix Houphouët Boigny - Cocody - Abidjan, Physic, Abidjan, Ivory Coast; (2) University Felix Houphouët Boigny - Cocody Abidjan, Physic, Abidjan, Ivory Coast; (3) Institute of Research for Development (IRD), LTHE - University Grenoble Alpes, Grenoble Cedex 9, France

Diagnostics combining Regional Climate Models Outputs and Station-based temperature Data from 1962 to 2013 indicate characteristics signals of heat waves over the West Africa. These heat waves can be associated with the occurrence of the record warm days during December, January and February (DJF) and the specific atmospheric circulation like Saharan heat low. Heat waves for various continential conditions are shown to occur as isolated spatial and temporal events, and not as part of larger-scale systems over continental-size domains. An examination of the physical processes associated with heat waves showed mutually consistent climatic relationships, such that heat waves were associated with reduced rainfall and consequently reduced soil moisture content, evaporation, and increased insolation at the surface. These combined changes created the surface temperature increase intrinsic to the heat waves.

second is short and uncertain. But in reality, the region is characterized by a high occurrence of late start of the rains (between 15 and 30% for the great season, between 10 and 25% for early season) and ends early (20 and 35% for the great season) and 10 and 20% for early season). It follows a significant trend towards shorter lengths of the seasons, making the crop seasons uncertain. In these episodes and the appearance of dry spells especially at the beginning at the end of the seasons that negatively affect agricultural activities. The degradation of the quality of rainy season has increased since the 1970s in keeping with the decline in seasonal and annual rainfall totals. It should be noted that the relative improvement of annual rainfall totals recorded since the 1990s has not induced an improvement in the quality of agricultural seasons in the region. So the years considered normal (average) or even surplus concerned with intra-seasonal volatility rain. In this context of quality degradation rainy season, the region has per moment of high rainfall sequences in the heart of the seasons, causing disastrous floods for crops and / or harvests.

It is therefore appropriate that agricultural promotion policies and strategies integrate these intra-seasonal rainfall fluctuations while taking into account the knowledge and logical farmers in order to define strategies for adapting agriculture to climate change in this region.

# 1118a - Attribution of extreme events: How are high impact extreme events changing and why ?

## ORAL PRESENTATIONS

### K-1118a-01

#### Are humans exacerbating climate and weather extremes?

F. Zwiers (1)

(1) University of Victoria, Vancouver, Canada

This talk will review some of the recent research on extremes, pointing to aspects of changes in extremes in which we have higher and lower levels of confidence. The body of evidence indicating a human contribution to observed climate change has continued to strengthen as indicated by the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). This continued development includes an accumulating body of evidence suggesting that temperature and precipitation extremes have both changed in response to human influences on the climate. The research on temperature extremes is well established, with recent work indicating that temperature extremes have continued to warm over land despite the recent global warming "hiatus", and that anthropogenic forcing has substantially increased the odds of extreme warm years and summers, both globally and regionally. The evidence on precipitation extremes is less well established, although there is increasingly strong evidence that human influence is detectable in observations at the largest scales that are resolvable in available international compilations of daily precipitation records. In contrast, assessments of historical and projected changes in droughts and storminess remain cautious, due to both data limitations and uncertainty in process understanding and modelling. Despite uncertainties and limitations in knowledge, observed and projected changes in the simple temperature and precipitation indicators in which we have greatest confidence provide ample evidence that adaptation is required now, and that further adaptation will be required in the future under all RCP forcing scenarios.

### K-1118a-02

#### Detecting and attributing impacts of recent climate change on multiple systems worldwide – certainties, uncertainties and new research questions

W. Cramer (1); G. Hansen, (2); M. Auffhammer (3); C. Huggel (4); D. Stone (5)

(1) IMBE, cnrs, aix marseille university, ird, avignon university, Aix-en-Provence, France; (2) Potsdam Institute for Climate Impact Research, Potsdam, Germany; (3) University of California, Berkeley CA, United States of America; (4) University of Zürich, Department of geography, Zürich, Switzerland; (5) Berkeley Lab, Berkeley CA, United States of America

Due to rapidly growing scientific evidence, based on growing stocks of observations as well as on improved methodologies, it is widely accepted that recent climate change has triggered changes in numerous systems worldwide. Most cited examples concern hydrological systems, the cryosphere, and many biological systems in the ocean and on all continents. The recent IPCC assessment, which was based on an unprecedented trans-disciplinary community effort, found more widespread impacts than previous reports, covered a greater range of impacted system types but also identified regions and systems with insufficient research and monitoring effort. Updating the report, three key questions will be addressed: a) To which extent have human systems been impacted, either directly or through cascading impacts through natural systems? b) How much is known about impacts in poorly observed regions? c) To which extent can the impacts of anthropogenic climate change be distinguished from those of natural climate variability?

### K-1118a-03

#### Attribution of extreme events : Taking attribution science to the limits

P. Stott (1)

(1) UK Meteorological Office, Hadley Centre, Exeter, United Kingdom

Around the World recent heatwaves, floods and droughts have demonstrated the vulnerability of citizens to such extreme weather. However, scientifically robust information about the extent to which recent extreme weather events can be linked to climate variability and change is often lacking. There is therefore a clear need to develop better information on weather and climate risks as part of the development of climate services to enable citizens to better deal with the effects of climate change.

This paper describes recent progress in developing the
science needed to deliver such much needed reliable and
timely information about weather and climate risks. It
focuses on two important developments in particular.

An annual report published each September in the Bulletin of the American Meteorological Society seeks to explain extreme events of the previous year from a climate perspective. This report has demonstrated the capability to deliver assessment of extreme events quickly while also showing how the scientific capabilities of such studies is developing rapidly with an increasing number of types of event being considered with larger geographical coverage.

One of the main international groups working to further the development of this science is the EUCLEIA project, a European funded project with eleven partners. EUCLEIA (European CLIMATE and weather Events: Interpretation and Attribution) is developing an attribution system to deliver reliable and user-relevant attribution assessments on a range of timescales; on a fast track basis in the immediate aftermath of extreme events, on a seasonal basis to stakeholder groups and annually to the annual attribution reports in the Bulletin of the American Meteorological Society.

We will illustrate the presentation with some of the main scientific highlights of this work while also exploring how such scientific information can be best developed and applied in future.

O-1118a-01

Attribution of record high daily tempera-
tures in Australia in 2013

D. Karoly (1); M. Black (1); A. King (2); M. Allen (3); F. Otto (4); S. Rosier, (5); S. Lewis, (6)

(1) University of Melbourne, School of Earth Sciences, University of Melbourne, VIC, Australia; (2) University of Melbourne, School of Earth Sciences, Melbourne, Victoria, Australia; (3) University of Oxford, School of Geography and Environment and Dept of Physics, Oxford, United Kingdom; (4) University of Oxford, Oxford, United Kingdom; (5) NIWA, Wellington, New Zealand; (6) Australian National University, School of earth sciences, Canberra, Australia

There has been increasing scientific interest in
understanding the climate factors associated with extreme
weather and climate events. This has led to the series of
special supplements in the Bulletin of the American
Meteorological Society over the last three years on
"Explaining extreme weather events from a Climate Perspective".
A wide range of extreme events has been considered in
the studies included in these supplements, ranging from
heavy rainfall and drought events to record hot and
cold seasons. However, there have been no studies so far on
the attribution of record high daily temperatures at single
sites.

The Australian summer of 2012–13 was the hottest summer averaged across Australia since reliable records began in 1910. Lewis and Karoly (2013) showed that human influences on climate have very likely increased the likelihood of extreme summer average temperature across Australia such as in 2012–13 by at least a factor of five. Here we present an analysis of the contribution of human-caused climate change to the frequency of events such as the record high daily temperatures that occurred across Australia on 7 January 2013 and in Sydney on 18 January 2013.

The recently launched citizen science distributed computing project weather@home ANZ (http://www.climateprediction.net/weather@home/australia-new Zealand-heat-waves/) has generated very large ensembles of simulated regional daily weather data needed for the attribution of extreme events. By comparing the frequency of extreme daily temperatures in the model simulations for 2013 and for a counter-factual world without any human influences on the regional climate, we assess the role of human influences on the likelihood of these two cases of record high daily temperatures in Australia in 2013.

Lewis, S.C., and D. J. Karoly (2013) Anthropogenic
contributions to Australia's record summer temperature of
2013. Geophys. Res. Lett., 40, 3705–3709. DOI: 10.1002/
grl.50673

O-1118a-02

Human influence on climate in the 2014
Southern England winter floods and their
impacts

N. Schaller (1) ; A. Kay (2) ; R. Lamb (3) ; N. Massey (1) ;
G. Van Oldenborgh (4) ; F. Otto (1) ; S. Sparrow (1) ;
R. Vautard (5) ; P. Yiou (5) ; A. Bowery (1) ; S. Crooks (2) ;
C. Huntingford (2) ; W. Ingram (1) ; R. Jones (6) ; T. Legg (6) ;
J. Miller (1) ; D. Wallom (1) ; A. Weisheimer (1) ; P. Stott (7) ;
M. Allen (1)

(1) University of Oxford, Oxford, United Kingdom; (2) CEH,
Wallington, United Kingdom; (3) JBA, Skipton, United
Kingdom; (4) KMNI, De Bilt, Netherlands; (5) Laboratoire des
Sciences du Climat et de l'Environnement, Saclay, France; (6)
Met Office, Exeter, United Kingdom; (7) UK Meteorological
Office, Hadley Centre, Exeter, United Kingdom

The whole winter of 2013/2014 was characterized
by a near-continuous succession of westerly storms.
Accumulated rainfall during January 2014 was the largest
ever recorded for that month across much of southern
England, including the Radcliffe Observatory record
in Oxford that begins in 1767. Severe floods resulted,
causing major disruption.

So far, quantifying any contribution from human influence on climate to such weather events and resulting floods has been difficult due to the large natural variability of winter precipitation in the North Atlantic and European regions. The emerging science of probabilistic event attribution however increasingly allows us to evaluate the extent to which human-induced climate change is affecting localised weather events. Under the project "European CLimate and weather Events: Interpretation and Attribution" (EUCLEIA), an end-to-end attribution study is performed for the first time. An ensemble of 134,354 general circulation model simulations is run using the citizen science project weather@home. We find that the frequency of days in January in zonal flows increases jointly with increases in precipitation as a result of anthropogenic climate change. The best estimate of the change in risk of extreme (1-in-100-year in pre-industrial conditions) precipitation for January in southern England is an increase by 42%, but the uncertainty range includes no change or an increase by over 150% due to uncertainty in the pattern of anthropogenic warming. Further, we partition the impact of greenhouse gases to dynamic changes in atmospheric circulation and to thermodynamic increasing water loading, demonstrating that both mechanisms played a role. A hydrological model driven by the model-simulated precipitation gives similar increases in risk compared to precipitation for 30-day peak river flows for the Thames at Kingston. Given these river flows we estimate that anthropogenic climate change has placed an additional 3,500 properties in the Thames catchment (upstream of the tidal reach through London) at risk of flooding from rivers over a broad range of return-times. Our study provides for the first time an estimate of the scale of precipitation-related damages in a specific region due to the effects of anthropogenic changes in the composition of the atmosphere on climate.

O-1118a-03

Role of soil moisture vs. recent climate
change for heat waves in western Russia

M. Hauser (1) ; R. Orth (1) ; S. Seneviratne (1)

(1) ETH, Zurich, Institute for atmospheric and climate
science, Zurich, Switzerland

Using the framework of event attribution, anthropogenic
climate change was found to have a discernible influenceon
the occurrence-probability of heat waves, such as the one
in Russia in 2010. Soil moisture, on the other hand, is an
important physical driver for heat waves as its availability
has a large influence on the partitioning of the available
surface net radiation into latent and sensible heat flux.
The presented study investigates the relative importance
of both controls, soil moisture and increasing greenhouse
gas concentrations, on heat waves in the region of the
2010 Russian heat wave. This is done with a large number
of ensemble members from climate simulations with and
without interactive soil moisture for both, the 2000s
and the 1960s. The simulations allow to determine the
occurrence-probability of heat waves with and without
the soil moisture-temperature feedback and to compare
# 1118b - Attribution of extreme events: How are high impact extreme events changing and why ?

## ORAL PRESENTATIONS

### K-1118b-01

#### Framing Extreme Event Attribution from the Bottom up – an Enquiry into the Social Representations of key stakeholders, of the Press and of Climate Scientists

JP. Vanderlinden (1) ; I. Meinke, (2) ; M. Schwab, (2) ; N. Capellini, (1) ; SH. Von (2) ; C. Winter, (2) ; C. Pacteau (3) ; Y. Remvikos, (1)

(1) University of Versailles-Saint-Quentin-en-Yvelines,
Observatory of versailles-saint-quentin-en-yvelines/cear,
Guyancourt, France; (2) Helmholtz-Zentrum Geesthacht,
Zentrum for Material- und kustenschung, Geesthacht,
Germany; (3) CNRS, Gis climat environment sociétés, Paris,
France

Attribution of extreme weather events has recently generated a lot of interest simultaneously within the general public, the scientific community, and stakeholders affected by meteorological extremes. This interest calls for the need to explore the potential convergence of the current attributions science with the desire and needs of stakeholders. Such an enquiry contributes to the development of climate services aiming at quantifying the human responsibility for particular events.

Through interviews with climate scientists (internationally and within Germany), through the analysis of the press coverage of extreme meteorological events (heat wave in the Paris area, storm surges in the baltic sea), and through stakeholder (private sector, government services and local and regional government) focus groups, we analyze how social representations of the concepts associated with extreme event attribution are theorized. From the corporations generated in the course of this enquiry, we build up a grounded, bottom-up, theorization of extreme weather event attribution. This bottom-up theorization allows for a framing of the potential climate services in a way that is attuned to the needs and expectations of the stakeholders.

From apparently simple formulations: "what is an extreme event?", "what makes it extreme?", "what is meant by attribution of extreme weather events?", "what do we want to attribute?", "what is a climate service?", we demonstrate the polyphony of these terms and propose ways to address the challenges associated with the juxtaposition of four highly loaded concepts: extreme - event - attribution - climate services.

### O-1118b-01

#### Attribution of extreme climate events in coupled and uncoupled GCM experiments

B. Dong (1) ; R. Sutton (1) ; S. Len (1)

(1) NCAS-Climate, Department of Meteorology, Reading,
United Kingdom

Extremes of weather and climate events at global and regional scales can have devastating effects on human society and the environment, and there is overwhelming evidence that these extreme events are changing. Interest in attributing the risk of these extreme events to anthropogenic climate change is increasing and understanding these past changes is critical for reliable projections of future changes. However, there is still no consensus about the best methodology for event attribution. A common approach relies on experiments in which the time periods of interest are simulated using an atmospheric general circulation model (AGCM) forced by prescribed sea surface temperatures (SSTs), with and without anthropogenic influences. A potential limitation of these experiments is the lack of explicit atmosphere-

ocean coupling, and therefore a key question is whether the attribution statements derived from such studies are in fact robust. In this research, we have carried out climate model experiments to test attribution conclusions in a situation where the answer is known - a so called "perfect model" approach. The study involves comparing attribution conclusions derived from experiments with a coupled climate model (specifically an AGCM coupled to an ocean mixed layer model) with conclusions derived from parallel experiments with the same atmosphere model forced by SSTs taken from the coupled model experiments. We analyse and compare the changes in surface air temperature and precipitation in response to anthropogenic forcing in the coupled and uncoupled experiments, assessing both seasonal mean changes and extreme events. Our experimental design also allows comparison with observed changes. Our results demonstrate that whilst the AGCM method has some strengths, it also has significant limitations and may lead to erroneous attribution conclusions in some situations.

### O-1118b-02

#### Unreliable climate predictions overestimate attributable risk of extreme climate events

O. Bellprat (1) ; F. Doblas-Reyes (2)

(1) Catalan Institute for Climate Science (IC3), Climate Forecasting Unit, Barcelona, France; (2) IC3, Barcelona, Spain

Climate predictions are increasingly being used to attribute single extreme climate events to anthropogenic factors by retrospective predictions. The reliability of the systems to predict extreme events might be an important aspect in such an assessment, yet limited hindcast periods which cover only a small number of extreme events in the past are a small part of an idealized framework based on a synthetic forecast model. This limitation is here circumvented. The framework allows to perform large number of predictions and to compute the fraction of attributable risk (FAR) on extreme events. Varying the forecast reliability shows that unreliable climate predictions are prone to overestimate the FAR due to ensemble overconfidence, which leads to unrealistically small probabilities for the event to occur without climate change. We show under which conditions forecast reliability becomes important an factor and give an outlook for future event attribution systems using climate predictions

### O-1118b-03

#### Investigating human influence on Southern France heavy precipitation events

A. Ribes (1) ; S. Thao, (1)

(1) CNRM-GAME, Métré France - CNRS, Toulouse, France

In spite of a relatively dry mean climate, the Mediterranean regions in Southern France use to experience heavy rainfalls over short durations - typically a few minutes to one day. If compared to the rest of mainland France, 10-yr return values of maximum daily precipitation are two to four times larger over this area. The 2014 fall season was particularly severe, with 11 events exceeding the 190mm/ day threshold, flash floods and several fatalities.

The possible link between such events and anthropogenic climate change has not been specifically addressed so far. Several approaches might be proposed to deal with this issue, including the realisation of specific climate model experiments. Unlike many other studies, we only focus on past observations and investigate the significance of recent trends in such events. Trends are investigated in terms of magnitude, frequency, and extent of events. Some statistical challenges arise to properly account for spatial dependencies among locations. While previous studies looked at trends locally or over a small neighborhood, here
we propose an aggregated diagnosis for the whole region (about 100 stations). The consistency of these trends with the change regulated by state of the art climate models is also discussed. Main results suggest that observationally based estimates of the human influence on heavy precipitation events are still weakly constrained over such a limited area.

### O-1118b-04

## Attribution of the June-July 2013 heat wave in the southwestern United States

H. Shiogama (1); M. Watanabe (2); Y. Imada (3); M. Mori (2); Y. Kamae (1); M. Ishii (3); M. Kimoto (2)

(1) National Institute for Environmental Studies, Tuskuba, Japan; (2) the University of Tokyo, Kashiwa, Japan; (3) Meteorological Research Institute, Tsukuba, Japan

A severe heat wave occurred in the southwestern United States (US) during June and July 2013. To investigate the effects of natural variability and anthropogenic climate change on this event, we generated large ensemble simulations of possible weather using the MIROC5A climate model forced by "historical external forcing agents, sea surface temperature (SST) observations and sea ice (SIC) observations" both with and without human influence. It was suggested that both the anthropogenic warming and an atmospheric circulation regime related to the natural variability of SST and SIC made the heat wave event more likely. On the other hand, no significant human influence was found in atmospheric circulation patterns. These results were robust for two different estimates of anthropogenic signals on SST and SIC.

### O-1118b-05

## Attributing regional effects of the 2014 Jordanian drought to external climate drivers

D. Mitchell (1); R. Zaaboul, (2); K. Bergaoui, (2); F. Otto (1); R. McDonnell, (2); S. Dadson, (1); M. Allen (1)

(1) University of Oxford, Oxford, United Kingdom; (2) ICBA, Dubai, United Arab Emirates

Throughout 2014, the regions of Jordan, Israel, Lebanon and Syria have experienced a persistent drought with clear impacts on the local populations. In this study we look at how the probability of such a drought has changed under climate change, with a specific focus on the flow rate of the Litani river and the water level of Lake Tiberias (AKA the Sea of Galilee). Both of which hold major societal, political and religious importance. To perform the analysis we make use of distributed computing power to run thousands of modelled years of 2014 with slightly different initial conditions. We use an atmosphere only model (HadAM3p) with a nested 50 km regional model covering Africa and the Middle East. These data are downscaled to 1 km. Two separate experiments and simulations, 1. For all known climate forcings that are present in 2014, and 2. For a naturalised 2014 scenario where we assume humans never impacted the climate. For observations, we use station data obtained from the Jordanian Ministry of Water. Using a combination of these local station observations and model data we are able to make clear statements on the attribution of a 2014-like draught event to human causal factors.

### O-1118b-06

## Distinguishing natural and anthropogenic influences on extreme fire danger in Australia

M. Black (1); D. Karoly (1); T. Lane, (1); L. Alexander (2)

(1) University of Melbourne, School of earth sciences, Melbourne, Australia; (2) University of New South Wales, Climate change research centre, Sydney, Australia

In the aftermath of the 2013 Blue Mountains wildfires in New South Wales, Australia, the scientific community was faced with the challenge of quantifying the event's link to different causal factors, including human-induced climate change. While there are a number of recorded attribution studies for temperature and precipitation-related events, no such study exists for fire weather.

This study investigates how the likelihood of extreme fire weather in south-east Australia has been changed due to the competing influences of human-induced climate change and modes of inter-annual climate variability. Our analysis benefits from the use of the recently launched weather@home Australia-New Zealand distributed computing citizen science project to generate very large ensembles of regional climate model simulations over Australia. The likelihood of extreme fire weather is examined for different phases of the El Niño Southern Oscillation under present climate conditions and climate conditions with no human influences.

## 1118-POSTER PRESENTATIONS

### P-1118-01

## Contribution of soil initial conditions for the occurrence of the 2003 and 2010 heat waves

O. Bellprat (1); C. Prodhomme (2); F. Doblas-Reyes (2) (1) IC3, Climate Forecasting Unit, Barcelona, France; (2) IC3, Barcelona, Spain

Dry soil moisture condition before both 2003 and 2010 heat wave over western Europe and Russia, respectively have been suggested to play an essential role on the occurrence of the event. In order estimated the impact of soil initial conditions on those two heat waves, we run two sets of seasonal hinders with the general circulation model EC-Earth2.3. The initialization of those hinders is done either using climatological or realistic land surface initialization in May, June, July and August using the ERA5 reanalysis. Results show that the 2003 heat wave is predictable either with climatological or realistic land- surface initial condition and for all considered start dates. This feature clearly shows that the 2003 heat waves was predictable. Conversely, the 2010 heat wave is reproduced in May only if the land is realistically initialized, while in June the event is not predicted by none of the hinders. The present study will investigate the processes behind the occurrence of the two heat waves.

### P-1118-02

## Evaluation of Mechanisms of Extreme Temperatures over Europe and North America

I. Colfescu (1); S. Tett (1); G. Hegerl (1)

(1) University of Edinburgh, School of Geosciences, Edinburgh, United Kingdom

The 20th century reanalysis is used to investigate changes in the monthly frequency, location and intensity of temperature extreme events during the first half of the 20th century for North America and Europe. Using composite analysis the main synoptic weather patterns associated to the events are identified in the 20th Century Reanalysis and compared to those associated with events in the latter 20th century. An assessment of the capability of CMIP5 models to simulate these extreme events and their mechanisms is also performed by comparing the model patterns with those obtained from the 20C reanalysis.

### P-1118-03

## Attribution of Extreme Summers in Northern Europe

B. Dong (1); S. Len (1); R. Sutton (1)

(1) NCAS-Climate, Department of Meteorology, Reading, United Kingdom

The summer climate of northern Europe exhibits large variability from year to year and on longer timescales. In extreme summers the region experiences heat waves, droughts, or floods. This presentation will discuss the characteristics and drivers of variability in northern European summers with a particular focus on the summer of 2012, which was a record wet summer in northern Europe and was associated with widespread flooding, and the contrasting warm dry summer of 2013. The wet summer of 2012 was not an isolated event but rather one in a cluster of wet summers that have occurred more
frequently in the 21st century than in the last decades of the 20th century. Wet summers are associated with a southerly position of the North Atlantic storm track and a negative phase of the Summer North Atlantic Oscillation, with the opposite pattern for dry summers. The magnitude of decadal variability in these features suggests a role for forcing from outside the dynamical atmosphere. Climate model experiments have been carried out to identify the drivers of variability and to attribute the factors that influenced the summers of 2012 and 2013. The implications of these findings for future summers in northern Europe will be discussed.

P-1118-04

The extreme wet 2013/2014 winter season in Western Europe in a changing climate

N. Hempelmann (1) ; P. Yiou (1) ; R. Vautard (1)

(1) Laboratoire des Sciences du Climat et de l'Environnement, Saclay, France

Southern UK and North Western France witnessed records of precipitation amounts during the winter of 2013/2014. How this specific extreme seasonal event is linked to climate change remains a difficult issue, due to the large inter-annual variability of precipitation amounts. Using observational records and the new EURO-CORDEX regional climate projections ensemble, we find that over the regions hit by the 2013/2014 event, recent trends in winter precipitation have increased. The estimates from observations are consistent with those from climate simulations. The non-significant change of the return period of the seasonal precipitation is found to be reduced.

We also address the issue whether precipitation amounts would have changed across past decades as a result from external changes than those of the regional atmospheric flow, we used the methodology of circulation analogues, computed from anomalies of sea level pressure over the North Atlantic region. Seasonal precipitations in the regions under study are well reproduced by flow analogues. We find that Southern U.K. precipitations occurring with analogue flows takes place in the same region. The current are on average weaker than those taken from analogue flows from analogue flows in the past few decades.

P-1118-05

Climate change induced temporal varia-
bility of droughts in Ukraine – the role of
North Atlantic Oscillation

V. Khokhlov (1) ; N. Yermolenko (1)

(1) Odessa State Environmental University,
Hydrometeorological Institute, Odessa, Ukraine

We used the multiscalar drought index – standardized precipitation evapotranspiration index – to investigate spatiotemporal droughts variability caused by the climate change. The index was calculated using the 0.5 degree grid data on the temperature and precipitation for Ukraine. The two periods with different trends of global temperature – 1951–1980 and 1981–2010 – were used to reveal a climate change impact.

The analysis revealed the periods with moistest and driest conditions. The moistest years were registered in the end of 1970s – start of 1980s. Moreover, both the number and intensity of droughts increase significantly since 1980, especially for the Southern Ukraine. During the 2006–2009 the most extreme and long drought was observed in the Odessa region. The analysis also showed that hydrological droughts begin with some delay from the meteorological ones, and have maximal duration.

We used CUSUM method in order to detect specific years, when the significant change points occurred in the time series of droughts. This method also detected the start of 1980s as the years of transition from the moist to the dry

conditions.

The cross-wavelet transform was applied to reveal a connection between the droughts in Ukraine and teleconnection patterns in the North Atlantic. The analysis showed that the North Atlantic Oscillation (NAO) has a maximal effect on the droughts in Ukraine. The anti-phase relation is registered for the joint fluctuations with the periods 2–3 years and is most prominent in the southern Ukraine. On the contrary, the NAO has a small impact on the Northern Ukraine. This fact can be explained by the orientation of main storm tracks for positive and negative phases of the NAO.

P-1118-06

Understanding the role of anthropogenic
climate change behind changes in regional
heatwaves

S. Perkins, (1) ; E. Fischer, (2)

(1) University of New South Wales, Climate change research centre, NSW, Sydney, Australia; (2) ETH Zurich, Zurich, Switzerland

Since 1950, heatwaves have been increasing in their intensity, frequency and duration over many global regions. This period of time includes the temperature 'hiatus', where global average temperature did not significantly change since 1998. This study makes use of a 21-member of a single GCM to determine whether changes in heatwaves over various global regions are a result of anthropogenic, and whether observed changes and discrete heatwave events could have occurred without human influence on the climate.

The 21-member ensemble of the Community Earth System (CESM) global climate model is a novel tool, in that it provides a considerable estimate of internal climate variability that is not readily obtainable from most other model ensembles. Each of the historical and future simulations has identical prescribed external forcings, the former of which is based on observations. However, they differ only slightly in their atmospheric initial conditions, commencing on 1st January 1950. The resulting simulations provide a unique sample of a large range of 'possible' climates that are all equally plausible under the same external conditions and physical mechanisms of the model. This is distinctive from a multi-member model ensemble such as the 5th Phase of the Climate Model Intercomparison Project, where each participating model has a different physical set-up. Moreover, the version CESM employed in this study provides a 980-year control simulation, allowing for substantial research into climate conditions without influence from human activity.

Firstly, this study explores whether a hiatus occurred for regional heatwaves. Results show that for many global regions there is a large range in plausible heatwave trends during the ~15 year hiatus period, thus inhibiting the robustness of any one estimate, including that of observations. Next it is explored whether similar heatwave trends are possible without anthropogenic climate change. Similar to absolute changes heatwave intensity, frequency and duration, we conclude that the rate of change (i.e. trend magnitudes) in heatwaves since 1950 is primarily a result of human influence on the climate system.

Lastly, the fraction of attributable risk methodology (FAR) is employed to determine whether the likelihood of particular heatwave events have increased due to human influence on the climate. For all regions, it is very likely >90% probability that there has been a FAR increase in what is now considered the 1-in-20 year heatwave events. Moreover, for some regions, there is little evidence the current 1-in-20 year heatwave event would have occurred at all without anthropogenic activity. Such results highlight that there is already a signal in anthropogenic climate change in the extreme events we observe today.

P-1118-07

Scenarios for extreme climate characteris-
tics

P. Szabo (1)

(1) Hungarian Meteorological Service, Climate modelling group, Budapest, Hungary
State-of-the-art regional climate models (RCMs) are the best tools to provide detailed and quantitative information about future climate change at regional and local scales since it describes physical processes affecting regional climate features in detail. The results obtained from a regional climate model of around 10-25 km horizontal resolution are of good basis for local impact assessments instead of using low resolution global climate model outputs. However, model simulations have different sources and magnitude of uncertainties, the climate modelling and community strives to deliver the projection results together with their uncertainties for impact studies. To assess uncertainty in the simplest way, at the Hungarian Meteorological Service two RCMs are run covering Central-Eastern Europe: REMO (25 km) adapted from Max Planck Institute for Meteorology and ALADIN-Climate (10 km) from Métoé-France.

Local impact assessments are mainly based on daily minimum and maximum temperature (besides daily mean values). According to observational data, our local climate over Hungary is warming up more rapidly than the global

temperature. The main question of our investigation is whether the record highs increase or the record lows decrease faster. Using observations we calculate how many record high daily maximum temperature and record low daily minimum temperature are set in each year over a grid point. Current record high to record low ratio is above one: it is around 3 to 1 in Hungary with an average of 3.6 in the last 5 years and 2.6 in the last 10 years. Relative increase of record highs to record lows is shown for the two locally run RCMs from 1961 to 2000, however, the increasing ratio could eventuate that record lows could disappear in the whole country around the end of the 21st century.

We give results for the record high daily precipitation, as well. Compared to the theoretical stationary climate conditions, observations show only an intensification in the inter-annual variability of average records in Hungary. The two models also do not expose robust results: only one model shows a clear increase in record high daily precipitation for the end of the 21st century.

# 1119a - Extreme hydrological events: Deciphering changes in hazard and risk at different time-scales

## ORAL PRESENTATIONS

### K-1119a-01

#### Review of Hydrological norms for Climate Change Resilient Hydraulic Infrastructures in Africa (RESIHYST-Africa): towards a regional programme

A. Amani (1)

(1) UNESCO, Hydrologic international programme, Nairobi, Kenya

In order to address the current and future water needs and to boost the economic growth of African countries, it is crucial to improve substantially the current rate of mobilization of renewable water resources which is less than 5%. Hydraulic infrastructures (Dams) with various sizes are needed to increase substantially the level of water storage. For road construction, urban water drainage and flood protection other types of hydraulic infrastructures are needed. In many African countries, guidelines and hydrological norms currently used by engineers and managers are obsolete.

In West Africa for example, particularly francophone countries, the hydrological norms for the design of hydraulic infrastructures currently used were established during 60-70s. These norms were established based on hydrological data collected from around 200 experimental basins in West and Central African countries for a period of 3 to 5 years during and following the International Hydrological Decade which led to the creation of the UNESCO International Hydrological Porgamne. In regard to the ecological and climate changes recorded within the region and the huge consequence on infrastructures safety and with the future climate change, there is an urgent need to review and adapt these norms for a resilient design of hydraulic infrastructures in the region. Within the framework of its International Hydrological Programme and on the request of countries through a resolution of IHP Africa national committees UNESCO has initiated a regional programme to address the issue of hydrological norms for the design of hydraulic infrastructures within the context of climate change with a focus for the first phase on West and Central Africa. The first phase of the programme will concern 26 countries from ECOWAS and ECCAS. Two experts working meetings have been held in Ouagadougou. Twelve baseline studies have been conducted in the following countries: Senegal, Niger, Ivory Coast, Guinea, Togo, Benin, Chad, Cameroon, Congo, CAR, DRC and Rwanda.

The regional programme will have the following components: i) Data and hydrological monitoring; new basins should be monitored in partnership with hydrological services and universities and all available climate and

hydrological data capitalized: ii) Analysis, Methods and Modelling: Based on the available and collected new data, hydrological research will be conducted focusing on techniques, methods and hydrological modelling for a robust and adapted assessment of discharges taking into account non the stationarity; iii) Operational tools: proposition of new adapted hydrological tools (guidelines, softwares,..) and iv) Capacity building and promotion of the new tools: capacity building at various levels including technician, engineer, graduate and a wide dissemination of the new tools will be considered.

There is an urgent need to mobilize key stakeholders and donors for the funding of the programme which has been endorsed by ECCAS and ECOWAS.

### K-1119a-02

#### Extreme seasonal hydrological events in the Amazon Basin

JC. Espinoza (1); J. Ronchail (2); N. Filizola (3); P. Frazy (4) 
JL. Guyot (5); JM. Martinez (6); L. Noriega (7); W. Santini (5); F. Timouk (8)

(1) Peruvian Geophysical Institute IGP, SCAH, Lima, Peru;

(2) LOCEAN and Université Paris 6 Institut d'Etude de la Terre, Paris, France (3)

(3) Federal University of Amazonas, Manaus, Brazil (4); IRD (Brazil), Manaus, Brazil; (5) IRD, Lima, Peru; (6) IRD, GET Laboratory, Toulouse, France; (7) Servicio Nacional de Meteorologia e Hidrologia, La Paz, Bolivia; (8) IRD, La Paz, Bolivia

The Amazon basin is the world's major hydrological system. Its watershed covers about 6,000,000 km², almost 5% of the total continental mass. Annual discharge is the greatest in the world (±200,000m³/s). During the last decades, an intensification of extreme seasonal hydrological events (drougths and floods) has been reported in the Amazon region, producing strong impacts on humans and natural systems. In this contribution we propose a synthesis of the key aspects of the recent extremes droughts and floods in the Amazon basin from the Andean regions to the lowland rainforest, including their causes and main impacts. Our results are based on large-scale climate data and observed hydrological information coming from the whole Amazonian countries, in the context of the SO-HYBAM observatory. A trend towards an intensification of the hydrological cycle has been reported during the last decades. For instance, in the Peruvian Amazon, a significant discharge diminution trend (p<0.01) is noticed during the low-water season; indeed discharge decreased by 30% after the 1990s when comparing to the 1970-1989 period. However, no trend is observed during the high-water season but extreme floods have recently occurred (e.g. 1999, 2012). Extreme hydrological events have been frequently related to sea surface anomalies in the Pacific and Atlantic oceans. For instance, intense rainfall and subsequent floods have been associated with La Niña events (e.g. 1989, 1999, 2011 and