pinecone/core-2020-05-10-deduplication huggingface dataset:
An investigation of the effect of transient climate change on snowmelt, flood frequency and timing in northern Britain

Climate change is almost certain to affect snow and ice processes. Even at lower latitudes, changes in snow cover at high altitudes can significantly affect catchment hydrology. This paper uses data from a transient Regional Climate Model projection (HadRM3Q0) for 1950-2099 (A1B emissions) to drive hydrological models for three nested catchments on the river Dee in north-east Scotland, to assess potential changes in flood frequency and timing using annual maxima and moving-window analyses. Some results are also shown for an upland catchment in northern England. Modelling is performed both with and without a snow module, to demonstrate the effects of snowfall/melt and how these change through time and vary between catchments. Modelled changes in flood magnitude and timing are non-linear, with most changes for daily mean flows not significant. For longer duration (30-day) flows with snow there are significant decreases in peak magnitude, particularly for the smaller higher altitude Dee catchments, with peaks occurring months earlier in future (changes without snow are generally not significant). There is a general convergence in results with and without snow later in the period, as snow processes become less important, but convergence occurs at different times for different catchments and occurs differently for daily and 30-day peak flows due to the differential effects of snow at different durations. This highlights the importance of including snow processes for such catchments, particularly for longer duration flows, but also highlights the complexity of interactions: Physical catchment properties, the balance between precipitation occurrence and temperature, and how this balance alters as the climate changes will each be critical in determining the impact on the magnitude and timing of peak flows, making it hard to generalise results
A baseline climatology of sounding-derived parameters associated with heavy rainfall over Gauteng, South Africa

Irene weather office sounding data are considered a proximity sounding for the Gauteng
province of South Africa. Sounding-derived parameters are analysed for 35 austral summers
from 1977 to 2012. The goal of this study is to provide a climatology of sounding-derived
parameters commonly used as ingredients to forecast heavy rainfall. The emphasis is placed
on identifying those variables that distinguish between climatology and heavy rainfall events.
Special attention is given to how the critical values associated with heavy rainfall change from
early to late summer.
During early summer (October to December), the atmospheric circulation over Gauteng is
markedly extra-tropical in nature. Heavy rainfall occurs in a conditionally unstable atmosphere
and is associated with conditions conducive to the development of severe storms, such as
large wind shear and convective available potential energy (CAPE) values, strong upper
tropospheric winds and large temperature lapse rates. In late summer (January to March), the
atmosphere takes on distinct tropical characteristics and becomes increasingly convectively
unstable. During this time of year there is abundant moisture in circulation and the storms that
develop are highly efficient in producing precipitation. Forecasting heavy rainfall in early
summer requires different techniques than in late summer.
Sounding parameters, which provide information about the moisture content of the
atmosphere, are capable of distinguishing between climatology and heavy rainfall during all
summer months. The only other variables capable of doing this are the average meridionial
wind direction in the 800 to 600 hPa layer, the mean layer equivalent potential temperature,
the Showalter Index (SI), the K-Index (KI) and the Elevated K-Index (EKI). However, critical
values associated with heavy rainfall for all these parameters change month by month.http://onlinelibrary.wiley.comjournal/10.1002/(ISSN)1097-00882016-01-31hb201
Greenland precipitation trends in a long-term instrumental climate context (1890-2012): evaluation of coastal and ice core records

Here, we present an analysis of monthly, seasonal, and annual long-term precipitation time-series compiled from coastal meteorological stations in Greenland and Greenland Ice Sheet (GrIS) ice cores (including three new ice core records from ACT11D, Tunu2013, and Summit2010). The dataset covers the period from 1890 to 2012, a period of climate warming. For approximately the first decade of the new millennium (2001-2012) minimum and maximum mean annual precipitation conditions are found in Northeast Greenland (Tunu2013 c. 120mm water equivalent (w.e.) year-1) and South Greenland (Ikerasassuaq: c. 2300mm w.e. year-1), respectively. The coastal meteorological stations showed on average increasing trends for 1890-2012 (3.5mm w.e. year-2) and 1961-2012 (1.3mm w.e. year-2). Years with high coastal annual precipitation also had a: (1) significant high number of precipitation days (r2 = 0.59); and (2) high precipitation intensity measured as 24-h precipitation (r2 = 0.54). For the GrIS the precipitation estimated from ice cores increased on average by 0.1mm w.e. year-2 (1890-2000), showing an antiphase variability in precipitation trends between the GrIS and the coastal regions. Around 1960 a major shift occurred in the precipitation pattern towards wetter precipitation conditions for coastal Greenland, while drier conditions became more prevalent on the GrIS. Differences in precipitation trends indicate a heterogeneous spatial distribution of precipitation in Greenland. An Empirical Orthogonal Function analysis reveals a spatiotemporal cycle of precipitation that is linked instantaneously to the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation and with an â�¼6 years lag time response to the Greenland Blocking Index. Â© 2014 Royal Meteorological Society
Snowfall variations in Japan and its linkage with tropical forcing

In this study, the causes of inter-annual variability of wintertime snowfall in the coastal plain facing the Sea of Japan over the past 33 years (1980–2012) are investigated. The observational evidence showed that intensified cold air intrusion from the Eurasian continent towards Japan in combination with anomalous cyclonic circulation favours in situ heavy snowfall. The composite analysis of the tropical convection during the heavy snow winters indicates that enhancement of convection in the vicinity of the Philippines, including the eastern Indian Ocean, is responsible for the emergence of anti-cyclonic circulation over the Asian continent and subsequent anomalous cyclonic circulation around Japan. Idealized experiments by use of the linear baroclinic model (LBM) were conducted to elucidate the origin of the teleconnection. We put idealized diabatic heating in the LBM under the wintertime atmospheric circulation and examined the heat-induced response. The experimental results clearly indicated that the intensified convection over the maritime continents and the neighbouring oceans is primarily responsible for the pair of the anti-cyclonic and cyclonic circulation. Thus, a study of the predictability of the tropical forcing may shed light on the predictable dynamics of snowy winters in Japan
Do global warming-induced circulation pattern changes affect temperature and precipitation over Europe during summer?

Future climate change projections are not limited to a simple warming, but changes in precipitation and sea level pressure (SLP) are also projected. The SLP changes and the associated atmospheric circulation changes could directly mitigate or enhance potential projected changes in temperature and precipitation associated with rising temperatures. With the aim of analysing the projected circulation changes and their possible impacts on temperature and precipitation over Europe in summer [June–July–August (JJA)], we apply an automatic circulation type classification method, based on daily SLP, on general circulation model (GCM) outputs from the Coupled Model Intercomparison Project phase 5 (CMIP5) database over the historical period (1951–2005) and for climate under two future scenarios (2006–2100). We focus on summer as it is the season when changes in temperature and precipitation have the highest impact on human health and agriculture. Over the historical observed reference period (1960–1999), our results show that most of the GCMs have significant biases over Europe when compared to reanalysis data sets, both for simulating the observed circulation types and their frequencies, as well as for reproducing the intraclass means of the studied variables. The future projections suggest a decrease of circulation types favouring a low centred over the British Isles for the benefit of more anticyclonic conditions. These circulation changes mitigate the projected precipitation increase over north-western Europe in summer, but they do not significantly affect the projected temperature increase and the precipitation decrease over the Mediterranean region and eastern Europe. However, the circulation changes and the associated precipitation changes are tarnished by a high uncertainty among the GCM projections.Peer reviewe
A comparison of SSM/I-derived global marine surface specific humidity datasets

Satellite-based microwave sensors have, since the 1980s, provided a means to retrieve near-surface marine specific humidity (qa), accurate estimation of which is necessary for climate and air–sea interaction applications. Seven satellite measurement-derived monthly mean humidity datasets are compared with one another and with a dataset constructed from in situ measurements. The means, spatial and temporal structures of the datasets are shown to be markedly different, with a range of yearly, global mean qa of ∼1 g kg–1. Comparison of the datasets derived using the same satellite measurements of brightness temperature reveals differences in qa that depend on the source of satellite data; the processing and quality control applied to the data; and the algorithm used to derive qa from the satellite measurements of brightness temperature. Regional differences between satellite-derived qa due to the choice of input data, quality control and retrieval algorithm can all exceed the accuracy requirements for surface flux calculation of ∼0.3 g kg–1 and in some cases can be several g kg–1 in monthly means for some periods and regions
A long-term perspective of wind power output variability

The study of the wind power output variability comprises different time scales. Among these, low-frequency variations can substantially modify the performance of a wind power plant during its lifetime. In recent years, other temporal scales such as the short-term variability or the climatological conditions of wind and the corresponding generated power have been investigated in depth. However, the study of longer decadal and multidecadal variations is still in its early stages. In this work, the wind power output long-term variability is analysed for two locations in Spain, during the period 1871-2009. This is attained by computing the annual wind speed probability density functions derived from an ensemble of atmospheric sea level pressure data set through a statistical downscaling based in evolutionary algorithms. Results reveal significant trends and periodicities in multidecadal bands including 13, 25 and 46years, as well as significant differences among both sites. The impact of the leading large-scale circulation patterns (NAO, EA, SCAND and AMO) on wind power output and its stationarity is analysed. Results on both locations show non-stationary significant and opposite seasonal couplings with these forcings. Finally, the long-term variability of the reconstructed Weibull parameters of the annual wind speed distributions is used to derive a linear model to estimate the annual wind power
Circulation-type classification derived on a climatic basis to study air quality dynamics over the Iberian Peninsula

A circulation-type classification is derived for the 1983-2012 climatic period to characterize air quality dynamics over the Iberian Peninsula (IP). Sensitivity tests to automatic classification techniques and other factors affecting the classification (number of patterns, temporal and spatial resolution, domain size, etc.) are performed to objectivize the set-up that maximizes its quality. The ERA-Interim reanalysis and the cost733class classification software are used. The identified circulation types (CTs) are described in terms of frequency, persistence, transitions, and location of isobaric systems. The temporal stability of the classification is evaluated following a cross-validation process that compares the results of the climatic and yearly classifications, leading to the identification of a representative year. Moreover, a representative day for each CT is identified using an objective score that minimizes the absolute value difference of the daily grid with respect to the average CT grid. The reference set-up uses a cluster-based technique (Ck-means) on a daily mean sea-level pressure database. Six CTs are identified, which are consistent with synoptic patterns found in the literature. Furthermore, the CTs of the climatic period are temporally stable showing similar characteristics in terms of frequency and location of high- and low-pressure systems as those of the representative year (2012). As a first application of the CT classification, 1h-maximum NO2 concentration maps from the CALIOPE Air Quality Forecasting System is analysed for the representative days. Synoptic circulation controls the origin and strength of advection explaining transport and NO2 background concentration over the IP. However, there is a strong spatial heterogeneity: in central, northern, and southern IP; NO2 concentrations are controlled by the synoptic circulation, whereas in Spanish Mediterranean coastal areas, a combination of synoptic and mesoscale dynamics explains the NO2 concentration patterns.Postprint (author's final draft
An analysis of rainfall across the British Isles in the 1870s.

Monthly records for the period 1871–1970 from 91 stations across the British Isles are used to place very high rainfall totals during the 1870s, 1872 and 1876–1877 in particular, in context. Comparisons are drawn with 2012 and the winter of 2013–2014, both of which were exceptionally wet in parts of the British Isles. Traditional Lamb weather type count and objective measures of atmospheric circulation obtained from reanalysis of surface pressure charts are used to classify the weather conditions under which these very high rainfall totals were generated. The normally wettest locations in the British Isles, i.e. the uplands in the north and west, were not unusually wet in the 1870s, whereas locations with extremely high rainfall totals (relative to mean annual rainfall) tended to be further south and east in the lowlands. These exceptionally high totals were associated with a high frequency of cyclonic weather types and high scores for atmospheric vorticity; at the same time, the frequency of anticyclonic weather and of westerly winds tended to be very low. The winter of 2013–2014, remarkably wet in southern England, was somewhat different in that both the frequency of westerly air flow and the resultant flow were very high and so were vorticity and the frequency of cyclonic weather types; the year 2012 experienced similar atmospheric conditions. The results confirm the importance of cyclonic weather for large rainfall totals across much of the British Isles; strong westerly winds seem only to favour the uplands and northwest coastal locations
A study of the air-sea interaction in the South Atlantic Convergence Zone through Granger causality

Air-sea interaction in the region of the South Atlantic Convergence Zone (SACZ) is studied using Granger causality (GC) as a measure of directional coupling. Calculation of the area weighted connectivity indicates that the SACZ region is the one with largest mutual air-sea connectivity in the south Atlantic basin during summertime. Focusing on the leading mode of daily coupled variability, GC allows distinguishing four regimes characterized by different coupling: there are years in which the forcing is mainly directed from the atmosphere to the ocean, years in which the ocean forces the atmosphere, years in which the influence is mutual and years in which the coupling is not significant. A composite analysis shows that ocean-driven events have atmospheric anomalies that develop first and are strongest over the ocean, while in events without coupling anomalies develop from the continent where they are strongest and have smaller oceanic extension.Peer ReviewedPostprint (author's final draft
A conceptual model for assessing rainfall and vegetation trends in Sub-Saharan Africa from satellite data

Policymakers, governments and aid agencies require operational environmental monitoring in support of\ud
evidence-based policy-making and resource deployment in crisis situations. For Africa, this is only feasible at sub-continental\ud
scale with a large network of automated meteorological stations, a large number of highly coordinated field observers or with\ud
satellite remote sensing. The challenge with satellite data lies in the derivation of meaningful environmental indicators. This\ud
article describes a conceptual framework for understanding satellite-derived indicators of rainfall and vegetation greenness\ud
trends over Africa. It attributes observed vegetation changes to climatic (i.e. rainfall linked) and non-climatic drivers. A\ud
decade of annual rainfall and vegetation data over sub-Saharan Africa was analysed using satellite-based rainfall estimates\ud
[Famine Early Warning System Rainfall Estimation 2.0 (FEWSNET RFE 2.0)] from National Oceanic and Atmospheric\ud
Administration’s (NOAA’s) Climate Prediction Centre and the Normalized Difference Vegetation Index (NDVI) obtained\ud
from the Satellite Pour l’Observation de la Terre Vegetation (SPOT-VGT) sensor. Rainfall and vegetation greenness trends\ud
were analysed for 759 administrative regions of sub-Saharan Africa to identify those regions that have experienced a negative,\ud
positive or stable rainfall/vegetation trend over the period 2001–2010. The character of the relationship between the annual\ud
rainfall and max NDVI trends were examined to identify areas where the changes in greenness could be attributed to\ud
climatic (rainfall) and non-climatic (human land use or ecological disturbance) changes. Regions where increasing rainfall was\ud
associated with vegetation greening were found in West Africa, Central African Republic, West Cameroon and northeastern\ud
part of South Africa, whereas areas with evidence of ‘climatic vegetation degradation’ were located in Southern Madagascar,\ud
Nigeria, Kenya and the Garden Route region of South Africa.Peer-reviewedPost-prin
Numerical modelling of heavy rainfall event over Madeira Island in Portugal: sensitivity to different micro physical processes

Madeira Island, Portugal, experienced intense heavy rainfall on 20 February 2010 which caused loss of more than 40 lives and great damage. This is recorded as one of the major flash flood events during the past three decades. This heavy rainfall episode is simulated using the Advanced Research Weather Research Forecasting (ARW) model at a cloud resolving grid resolution of 1 km. A nested two-way interactive four-domain configuration centred on the island and forced laterally by the 6 hourly NCEP FNL 1 ◦ data are used. Four experiments with different cloud microphysical parameterizations are performed to examine the model sensitivity to cloud microphysics on heavy rainfall simulations. Analysis of the synoptic meteorological conditions indicated that the extreme rainfall resulted due to the effect of regional orography on the prevailing large scale flow with conditionally unstable moist air. Results indicate that the model is able to reproduce the heavy rainfall with good agreement. The experiment with the Ferrier scheme produced more rainfall than the other three experiments, as well as overestimating the quantity of rainfall. Analysis of simulated cloud microphysical properties indicated that the model-produced heavy rainfall is sensitive to different cloud microphysics schemes. Model quantitative rainfall comparisons at different stations indicate that the Lin and Thompson schemes produced a more realistic simulation of heavy rainfall with relatively better correlation and higher threat score than the other two schemes. The associated dynamic and thermodynamic parameters are well produced in these two simulations
Interannual summer streamflow variability over Romania and its connection to large-scale atmospheric circulation

In this study, the spatial and temporal variability of summer (June–July–August, JJA) streamflow over Romania, as recorded at 46 hydrological stations over the period 1935–2010 is analysed. An empirical orthogonal function analysis and a canonical correlation analysis (CCA) were used to characterize the spatial and temporal variability of summer streamflow and its relationship with large-scale atmospheric factors. The dominant summer mode captures in-phase variability of river flow anomalies over the entire country, while the second mode of variability is characterized by a northwest–southeast dipole, emphasizing the influence of topography over the streamflow variability. Based on a CCA analysis, more than 50% of the summer streamflow variability is shown to be influenced by cloud cover and summer temperatures, via the modulation of precipitation and potential evapotranspiration. In general, positive (negative) streamflow anomalies, at country level, are associated with cyclonic (anticyclonic) circulation, the advection of moist (warm and dry) air, enhanced (reduced) precipitation and positive (negative) cloud cover anomalies
Interannual variability of the onset of the South China Sea summer monsoon

This article investigates the year-to-year variability of the onset of the South China Sea summer monsoon (SCSSM) and the possible influences exerted by the surface temperature anomalies over land and sea. Early and late monsoon onsets are related to the temperature anomalies in different regions. It is found that an early onset follows negative sea surface temperature (SST) anomalies in the central tropical Pacific (CP) Ocean during the preceding winter and spring, corresponding to a CP La Niña. In contrast, a late onset is preceded by the negative surface air temperature anomalies over land in the central Asian continent. Negative SST anomalies in the central-eastern equatorial Pacific Ocean and the associated warming in the western Pacific induce an anomalously enhanced Walker circulation. This anomalous Walker cell leads to an increase in convection, causing more latent heat release and a subsequent decrease of surface pressure. The anomalous Walker cell and the enhanced latent heat release weaken the Western North Pacific subtropical high and the Philippine Sea anticyclone, favouring a westerly flow from the Indian Ocean, resulting in an early SCSSM onset. On the other hand, negative land surface temperature anomalies cool the atmosphere over land, and locally modify the Hadley circulation, accompanied by the anomalous divergence in the low-level atmosphere over the western equatorial Pacific. This divergence anomaly reduces the latent heat release and strengthens the anticyclone in the Philippine Sea, thus preventing the westward extension of the westerlies from the Indian Ocean and causing a late SCSSM onset.This research was jointly supported by the Geographical Modeling and Geocomputation Program under the Focused Investment Scheme of The Chinese University of Hong Kong, the National Basic Research Program (973 Program) of China (No. 2012CB955800), and the National Natural Science Foundation of China (No. 41401052).This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/joc.436