bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiyear ENSO dynamics as revealed in observations, CMIP6 models, and linear theory
Authors: Iwakiri Tomoki , Watanabe Masahiro
Published: February 2023

El Niño–Southern Oscillation (ENSO) events occasionally recur one after the other in the same polarity, called multiyear ENSO. However, the dynamical processes are not well understood. This study aims to elucidate the unified mechanisms of multiyear ENSO using observations, CMIP6 models, and the theoretical linear recharge oscillator (RO) model. We found that multiyear El Niño and La Niña events are roughly symmetric except in some cases. The composite multiyear ENSO reveals that anomalous ocean heat content (OHC) in the equatorial Pacific persists beyond the first peak, stimulating another event. This prolonged OHC anomaly is caused by meridional Ekman heat transport counteracting geostrophic transport induced recharge–discharge process that otherwise acts to change the OHC anomaly. A meridionally wide pattern of sea surface temperature observed during multiyear event is responsible for the Ekman heat transport. CMIP6 multi-model ensemble shows a significant correlation between the ENSO meridional width and the occurrence ratio of multiyear ENSO. A multiyear ENSO-like oscillation was simulated using the linear RO model that incorporates a seasonally varying Bjerknes growth rate and a weak recharge efficiency representing the effect of Ekman transport. When the recharge efficiency parameter was estimated using reanalysis data based on geostrophic transport alone, a multiyear ENSO rarely occurred, confirming the importance of Ekman transport in retarding the recharge–discharge process.
Patch establishment of the summer annual saltwort plant (Salsola inermis Forssk.) increases N cycling rates and soil N-oxide emissions in Israel’s Negev Desert
Authors: Yagle Isaac , Segoli Michal , Gelfand Ilya
Published: February 2023

Vegetation patchiness is hypothesized to affect the spatial heterogeneity of resources and soil nutrient distribution in drylands. Nutrient accumulation under perennial vegetative patches leads to faster nitrogen (N) cycling in times of water availability. Compared to perennials, annual plant patches have a shorter life cycle, and labile nutrient buildup can occur more quickly in these patches due to faster nutrient turnover rates of litterfall and root death. The buildup of these labile nutrient pools, in surface soils under annual plant patches over time, may indirectly facilitate succession by other plants, thus aiding in the establishment of fertility islands. To understand how the establishment of annual plant patches affects soil nutrient dynamics, we planted replicated patches of a widespread local summer annual plant, saltwort (Salsola inermis Forssk.), and assessed how these patches influence the soil N cycle and soil N oxides (N2O and NO) emissions. We also assessed rates of surface litter decomposition of the saltwort plant. We found that rates of soil N transformations and soil N oxides emissions were highest under the plant patch, while they decreased across the patch-to-bare-soil gradient. Water extractable organic carbon (WEOC) accumulation increased in the surface soil beneath the plants and was associated with a large burst in soil N oxides emissions within the patch, following dry soil wetting by the first winter rains. Soil N2O emission pulse increased by 5.2 folds, whiles NO increased by 95.8 folds. Each N-oxide gas, however, had a different post-wetting pattern, with N2O peaking a few hours after wetting and NO after one day. We measured a second pulse in soil N oxide emissions after the third rain event. This pulse occurred only with the plant patch and not outside the patch and was reduced by 54% and 31% for N2O and NO respectively. However, the temporal (peaking) pattern of the second N-oxides pulse was similar to that of the first pulse. Suggesting a reduction in substrate availability as a cause of the reduced pulse. We also found 43% mass loss from the plant litter after 12 months of decomposition. Together, these results suggest that the establishment of saltwort plants affects soil nutrient dynamics and accumulation, thus creating nutrient-rich microsites for potential succession by other annuals and perennials, leading to fertility island establishment in the Negev Desert ecosystem.
Field optical clocks and sensitivity to mass anomalies for geoscience applications
Authors: Lion Guillaume , Pajot-Métivier Gwendoline , Diament Michel
Published: February 2023

350 years ago, the pendulum clock for astronomical observations was diverted to become an instrument for measuring gravity. The measurement of the parallax of Mars by Richer and Cassini from Cayenne and Paris showed that the period of a periodic oscillator depends on the gravity field. A link was thus established between the improvement of time measurement and the knowledge of the phenomena that govern it. Since then, the performance and nature of clocks have evolved considerably. Today, atomic clocks are used in various fields that are essential to modern society, such as the realisation of international atomic time (TAI), satellite navigation (GNSS), geodesy, the traceability of trading events, etc.In the framework of the french ANR ROYMAGE, we are interested in the contribution of a transportable optical field clock for geoscience applications by using the principle of chronometric geodesy. The idea is based on the gravitational redshift, a relativistic effect that predicts that the beat of a clock depends on the speed at which it is moving and the strength of the surrounding gravitational potential. In practice, this means that if we compare the beat of two clocks, then it is possible to directly measure a difference in gravitational potential (or a change in height) between these two clocks. This type of measurement is original because classical geodetic techniques only allow to determine the potential indirectly from gravimetric and classical levelling data.In this work, we model the gravitational signature (potential, acceleration and tensor) of a mass anomaly as a function of its geometry, depth, size and density contrast. These synthetic simulations allow us to identify which types of structures can be detected by clock comparison measurements with a relative frequency uncertainty fixed at 10-17-18-19 (i.e. a vertical sensitivity of less than 10 cm - 1 cm - 1 mm respectively). We are also interested in the spatial resolution required for a clock measurement to detect two mass anomalies depending on its orientation. Finally, we show that this new chronometric observable combined with gravimetry and gradiometry data could allow a better separation of the sources by adding an additional constraint thanks to the medium and long wavelength gravitational information it provides.The authors acknowledge the support of the French Agence Nationale de la Recherche (ANR) under reference ANR-20-CE47-0006.
Significant Temporal and Spatial Differences in Greenland Ice Sheet Surface and Subsurface Meltwater Persistence Revealed by Multi-Frequency Radiometry
Authors: Colliander Andreas , Mousavi Mohammad , Kimball John , Miller Julie , Burgin Mariko
Published: February 2023

Increasingly more significant portions of the Greenland ice sheet are undergoing seasonal melting-refreeze cycles due to climate warming. The process begins with the arrival of warm temperatures and increased solar radiation in the spring and summer seasons generating meltwater on the ice sheet’s surface. Meltwater percolates to deeper ice layers, either refreezing within the firn, creating longer-term meltwater pockets (firn aquifers), or generating peripheral runoff. Depending on the location and climate, the refreeze duration, the depth of infiltration, and meltwater persistence are temporally and spatially complex. Multi-frequency passive microwave measurements in the 1.4 GHz to 36.5 GHz range can distinguish seasonal meltwater between the immediate surface and the deeper firn layers, as demonstrated at experiment sites on the Greenland ice sheet. Here we explored the multi-frequency melt response at the pan-Greenland scale. We employed 1.4 GHz brightness temperature (TB) measurements from the NASA Soil Moisture Active Passive (SMAP) satellite and 6.9, 10.7, 18.9, and 36.5 GHz TB measurements from the JAXA Global Change Observation Mission-Water Shizuku (GCOM-W) satellite. The results show that the frequency-dependent response was consistent across the ice sheet. The multi-frequency melt indications match with lasting seasonal subsurface meltwater with delayed refreezing compared to the surface. These results suggest persistent seasonal subsurface meltwater occurrences that are spatially and temporally significant but concealed from the high-frequency observations. Similar to the surface melt with significant interannual variations, the results show that the subsurface meltwater cycle exhibits substantial spatial and temporal variations from year to year.
How does the 'window' of overland flow generating rainfall react to Clausius-Clapeyron scaling?
Authors: Schmid Bernhard
Published: February 2023

Rainfall on an infiltrating microcatchment or hillslope will trigger overland flow, if it is long and intense enough. It is, naturally, of interest to know, what 'enough' means in quantitative terms, i.e. with respect to a given soil and an intensity-duration-frequency (IDF) relationship of selected return interval.Fully impervious surfaces excepted, an initial phase of the process exists, during which detention storage will be filled and water infiltrates into the soil. The end of that phase (if any) marks the lower limit to the overland flow generating rainfall 'window'. Further to the right of the IDF-curve longer events causing overland flow follow, until a point is reached, where no more overland flow forms, this time because the rainfall intensity has become too low to overcome infiltration. The interval between these two end points has been termed the 'rainfall window'. A closed form expression for its length is given subsequently, and its response to rainfall events subject to Clausius-Clapeyron scaling will be discussed. An IDF relationship of the formis assumed, with r the rainfall intensity, td the storm duration and f the Clausius-Clapeyron scaling factor (parameters s = 0.0597 m and  b = 540 s in the examples below). Using a Green-Ampt type infiltration model and assuming p = 1, the following closed form expression has been derived:with Ksv vertical saturated permeability and Sav averaged suction at the wetting front.The Clausius-Clapeyron relationship, i.e. a 7% increase in rainfall depth per additional degree centigrade of warming, may yield an order of magnitude of what to expect from climate change. Here, f = 1.07 will be assumed for 1 K increase in temperature, and f = 1.14 for 2 K.The examples given here use a present-day IDF relationship of 20 years' return interval (roughly valid in the Austrian Alps) and initial loss of 0.5 mm. The rainfall window was computed using soil data from Columbia sandy loam, Guelph loam and Ida silt loam. Future warming was assumed as 1.0 and 2.0 K, resp.In the case of the most pervious soil of the three (Columbia sandy loam, vertical saturated permeability Ksv = 0.0139 mm/s) the (short) rainfall window showed a length of 22 min (present), 27 min (1 K warming) and 31 min (2K), an increase of 22% and 43%, resp.The 'medium' soil, Guelph loam (Ksv = 0.00367 mm/s), started from a window length of 109 min (present), rising to 123 min and 138 min for 1K and 2K resp. (increases of 13% and 26%).In case of the finest soil, Ida silt loam (Ksv = 0.000292 mm/s), the overland flow generating window of rainfall was longest and amounted to 44 h (present), 48 h (1K: 9% increase) and 52 h (17% increase).In conclusion it may be stated that notable increases in the overland flow generating rainfall window are to be expected due to future warming. Overland flow events tend to become more frequent as more storms will qualify as triggers.
Breathing at Sleep: Respiration in Arctic Lakes During Polar Nights
Authors: Asirok Ezgi , Kirillin Georgiy , Grossart Hans-Peter
Published: February 2023

Polar nights are unique periods to understand metabolism in ice-covered lakes from physical and biological perspectives. Despite the nearly zero primary production, polar nights cannot be disregarded as periods of biological stagnation, and recent data on biological processes and biogeochemical interactions are not yet fully understood, but can provide valuable information on lake ecosystem functioning in the absence of sunlight. Seasonally ice-covered Arctic Lake Kilpisjärvi at the latitude of 69° N experiences night time conditions from December to mid-January. Here, we use the continuous high-frequency time series of high-resolution temperature and oxygen from Kilpisjärvi to understand temperature and depth-related changes in respiration levels for three years from 2019 to 2022. In parallel, we aim to derive vertical microbial community composition by analysing water samples from different depths during the ice-covered period and correlate the outputs with oxygen dynamics to understand bacterial adaptations along biogeochemical gradients in Lake Kilpisjarvi.
Mesoscale dynamics and its influence on coastal upwelling in the northern Gulf of Guinea
Authors: Thiam Abdoul Karim , Alory Gaël , Dadou Isabelle , Morel Yves , Napolitano Dante , Cardot Camille , Aguedjou Micael , Morvan Guillaume , Jouano Julien
Published: February 2023

Very little is known on mesoscale dynamics in the northern Gulf of Guinea, off West Africa. The purpose of our work is to quantify these mesoscale eddies dynamics in this region (0°N-7°N, 10°W-10°E) and their impact on the near-surface ocean and particularly in the coastal upwelling along the northern coast between 2°W and 2°E. We used a regional simulation of the NEMO model at 1/36° resolution of the year 2016 with daily outputs, validated with in situ and satellite data. On average, four cyclonic and four anticyclonic eddies were detected per day with a mean radius of 75 km and 72 km, respectively. Their lifetime is of the order of few days to a month with associated sea level anomaly from 0.5 cm to more than 1cm. The largest eddies with a relatively long life span are located between 2°N and 4°N, east of Cape Palmas (Ivory Coast) and Cape Three Points (Ghana). We then focused on the July-August-September upwelling period, during which we detected a cyclonic eddy east of the Cape of Three Points, from mid-July to mid-August 2016 with an average radius of 75 km. This cyclone is quasi-stationary and is located in the core of coastal upwelling.Using a heat budget, we show that this eddy has an influence on sea surface temperature (SST) with a double effect. It expands offshore the upwelled cold and salty waters from July 14 to 24, then from July 25 until the dissipation of the cyclone, it weakens this upwelling by advection of warm offshore waters towards the coast, which mix with the upwelling cold waters and warm them.A lagrangian study shows that the eddy waters come from the coastal upwelling, then mix with warmer offshore waters and later are transported eastward by the Guinea Current.In conclusion, this study demonstrates the key role of eddies in SST intra-seasonal variability in the northern Gulf of Guinea.Keywords : Gulf of Guinea, Modeling, Eddy, Coastal upwelling, Lagrangian simulation.
Rainfall thresholds estimation for debris flow occurrence in Peru
Authors: Millan Carlos , Lavado-Casimiro Waldo , Felipe-Obando Oscar
Published: February 2023

The objective of this work is to estimate regional rainfall thresholds obtained from a combination of high-resolution gridded rainfall data and debris flow events. The debris flow events were associated with rainfall data, determining triggering and non-triggering rainfall events. The method for determining the thresholds is based on an empirical–statistical approach, and the predictive performance of the thresholds is evaluated whit “true skill statistics”. The validation of the thresholds was carried out by selecting one year of the debris flow dataset to focus on the operability evaluation of thresholds in early warning systems in Peru. In addition, another validation method based on a random selection of the events was used to compare the validation procedure. The thresholds were determined for 11 rainfall regions in Peru. The best predictive performance is the mean daily intensity-duration I-D threshold curve, followed by accumulated rainfall E. This study is highly important to Peru because is one of the first approximations of rainfall thresholds at a regional scale in Peru.
Morphometric signatures of neotectonic activity in Kotdwar region, northwestern Himalaya, India.
Authors: Kralia Abhishek , Thakur Mahesh
Published: February 2023

Tectonics plays a crucial role in shaping a landscape, especially in young mountain chains like the Himalayas, where thrusts and faults govern the landform features. This study uses morphometric analysis to assess the tectonic evolution in the Haridwar-Kotdwar foothills. The region is bound by the E-W trending Main Boundary Thrust (MBT) and Himalayan Frontal Thrust (HFT) in the north and south, respectively. N-S trending faults divide the region into three segments or blocks with distinct tectonic and stratigraphic setups. The results of the morphometric analysis reveal that the E-W trending Boksar Thrust (BT) and Haldu Paro Thrust (HPT) in segment 2 are neotectonically active. The high values of Ksn and Chi-Ksn reveal signatures of neotectonic activity along BT and HPT in segment 2, whereas no such signatures are observed along these thrusts in segment 3. There is an increased incision in segment 2, which can also be ramifications of tectonic activity along BT and HPT. The Gradient Length Anomalies (GLA) show negative anomalies along BT, HPT and MBT, which is evidence of upliftment along these thrusts. The values of the hypsometric index also show an increasing trend with an increase in the area, also ascertaining the signatures of tectonic activity in segment 2. Similar signatures of neotectonic activity are not seen in the morphometry results of segments 1 and 3, making segment 2 the most active block in the region. Therefore, this study helps understand the tectonic evolution of the Haridwar-Kotdwar region and the seismic hazard in this region.
Magnetic Switchbacks Heat the Solar Corona
Authors: Akhavan-Tafti Mojtaba , Kasper Justin , Huang Jia , Thomas Luke
Published: February 2023

Magnetic switchbacks are short magnetic field reversals ubiquitously observed in the solar wind. The origin of switchbacks remains an important open science question, because of switchbacks’ possible role in the heating and acceleration of the solar wind. Here, we report observations of 501 robust switchbacks, using magnetic and plasma measurements from the first eight encounters by the Parker Solar Probe (PSP). More than 46% (6%) of switchbacks are rotational (tangential; TD) discontinuities (RD), defined as magnetic discontinuities with large (small) relative normal components of magnetic field and proton velocity. Magnetic reconnection in the solar atmosphere can be a source of the observed RD-type switchbacks. It is discovered that: 1) the RD-to-TD ratio exponentially decays with increasing heliocentric distance at rate 0.06 [RS-1], and 2) TD-type switchbacks contain 64% less magnetic energy than RD-type switchbacks, suggesting that RD-type switchbacks may relax into TD-type switchbacks. It is estimated that relaxing switchbacks generated via magnetic reconnection in the solar atmosphere can transfer an additional 16% of the total reconnected magnetic energy into heating and/or accelerating the solar corona, within 11.6 [RS] of the reconnection site. The roles of turbulence and/or waves in dissipating this energy into heating and/or accelerating the solar corona plasma are the remaining open science questions.
Atmospheric Rivers and Surface Melt Events Over the Greenland Ice Sheet
Authors: Neff William , Shupe Mathew , Cox Christopher , Gallagher Michael
Published: February 2023

In the summer of 2012, nearly the entire Greenland Ice Sheet (GIS) melted  as warm air and thin clouds moved over the GIS in association with an Atmospheric River (AR) (Bennartz et al. 2013, Neff et al. 2014).  More recently surface melt as well as rainfall have been observed at Summit Station Greenland.  While these events garner much media attention, systematic mass loss in the ablation zones around the ice sheet (particularly along the southwest coast), in the transition to the accumulation zone and vulnerable glacier systems (Mattingly et al. 2021) is important to forecast sea level rise.  In this analysis, we use a simple detection method to identify ARs along the Greenland west coast using reanalysis data at two points (60N/310W and 65N/305W) at 850 hPa, namely wind speed and direction and total integrated water vapor.  We show a comparison between ERA5, NCEP/NCAR, and the Twentieth Century Reanalysis to show the efficacy of this approach and the ability to track ARs over the past hundred years. The approach exploits the barrier effect of the GIS, which extends to about 700 hPa.This use of reanalysis data is then coupled with the calculation of the fraction of melt in a series of latitude-longitude boxes at various locations around the ice sheet using the MEaSURES data set (Mote 2016) for the period 2000-2012. We then develop composite synoptic maps for geopotential height, total column water vapor, and Omega (for vertical velocity) for each class of event (e.g. strong ARs) and their subsequent evolution over 3 to 5 days. A key finding is that ARs that first impact the west coast later transport moisture to the SE coast leaving a residue of moisture along the west coast as the associated blocking high moves to the east.  In addition, we show how strong ARs along the west coast reflect geopotential height patterns very similar to those presented in (Gallagher et al. 2018) that are also associated with warmer temperature and increased opaque cloudiness at Summit Station.  Finally, we examine how various extreme events fit into this picture and affect the meteorology at Summit Station, including dramatic changes in boundary layer structure.ReferencesBennartz, R., M. D. Shupe, D. D. Turner, V. P. Walden, K. Steffen, C. J. Cox, M. S. Kulie, N. B. Miller and C. Pettersen (2013). Nature 496(7443): 83-86.Gallagher, M. R., M. D. Shupe and N. B. Miller (2018. Journal of Climate."  31(21): 8895-8915.Mattingly, K. S., T. L. Mote and X. Fettweis (2018). Journal of Geophysical Research: Atmospheres.Mote, T. L. (2016). MEaSUREs Greenland Surface Melt Daily 25 km EASE-Grid 2.0, version 1. https://doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0533.001.Neff, W., G. P. Compo, F. M. Ralph and M. D. Shupe (2014). Journal of Geophysical Research-Atmospheres 119(11): 6520-6536.Mattingly et al., EGU General Assembly 202
Occurence of selected hydroxy derivatives of polycyclic aromatic hydrocarbons in wastewater treatment plant
Authors: Styszko Katarzyna , Pamuła Justyna , Sochacka-Tatara Elżbieta , Pac Agnieszka
Published: February 2023

Evidence of the causal-empirical link between man-made chemicals present in industrial and household products, often leakage into the environment, and the effects on public health is growing, although still limited. These include, among other things, air pollutants in the environment associated with the highest prevalence of asthma, as well as respiratory and cardiovascular diseases in urban populations. There is strong evidence of health risks posed by human exposure to organic air pollutants such as PAH (polycyclic aromatic hydrocarbons) from combustion processes (solid fuels, coal and biomass) and communication. Generally, PAHs are formed during incomplete combustion and pyrolysis of organic material in a wide range of temperatures, up to over 1200 ° C. After entering the body, PAHs are transported to the alveoli and then spread throughout the body with the blood. The biological effects that PAHs cause in the human body are short-term, chronic, or long-term health effects, i.e. carcinogenicity, immunotoxicity, or developmental toxicity, genotoxicity. After entering the human body, PAHs undergo a complicated metabolism process and are excreted in the form of OH-PAHs with urine and faeces.The purpose of the study was to analyse selected OH-PAHs in influent and effluent wastewater from the wastewater treatment plant (WWTP). Analysed PAH metabolites are: 1- and 2-hydroxynaphthalene, 2- and 9-hydroxyfluorene, 9-hydroxyphenenthrene, 1-hydroxypyrene, and 3-hydroxybenzo(a)pyrene. The wastewater samples came from the largest WWTP in Kraków. OH-PAH concentration levels were determined by gas chromatography with mass spectrometry (GC-MS), preceded by the extraction of analytes into the solid phase and their derivatization.The concentrations of the analyzed compounds were at the level of ng/L. Regardless of the season of sampling for analysis (summer and winter), the highest concentrations, even up to 400 ng/L, were found in 2-hydroxynaphthalene and 9-hydroxyfluorene in influents. 1-hydroxypyrene, which according to literature reports is considered a marker of exposure to PAHs, was observed for influent and effluent samples only in winter at the level of only a few ng/L. Keywords: Hydroxy derivatives of polycyclic aromatic hydrocarbons, Biomarker, WastewaterAcknowledgments: A Research project financed by program “Initiative for Excellence – Research University” for the AGH University of Science and Technology. The research was supported  by Research Subsidy AGH 16.16.210.476.
Mars pickup ion plume under different IMF conditions from MAVEN observations
Authors: Dong Yaxue , Brain David , Ramstad Robin , Fang Xiaohua , Ma Yingjuan , McFadden James , Halekas Jasper , Espley Jared , Curry Shannon
Published: February 2023

Ions originating from the upper atmosphere of Mars may be picked up by the impinging solar wind and interplanetary magnetic field (IMF), which forms an energetic ion plume from the dayside of the planet as a key feature of the Martian induced magnetosphere and an important ion escape channel. Consisting of mostly ions in the beginning phase of the pickup process, the orientation and morphology of the plume are largely controlled by upstream IMF conditions.Using data from the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we will perform a thorough investigation of the pickup ion plume under different upstream IMF conditions. Previous statistical ion flux maps by Dong et al. [2015; 2017] from MAVEN data show the plume as a more spatially spread-out feature than that in many simulation models [e.g. Jarvinen et al. 2016 and others], which is possibly due the effects of highly variable IMF conditions for the data used in those maps. We will investigate how the plume appears with selected data under quasi-steady IMF conditions. Furthermore, we will compare the plume under strong and weak IMF conditions, as well as the conditions with IMF approximately perpendicular or parallel to the solar wind direction. The morphology of the plume and characteristics of escaping pickup ions under different IMF conditions will be discussed and compared with available model results to better understand how IMF affects the formation of the plume and ion escape through this channel.
A climate based dengue early warning system for Pune, India
Authors: Yacob Sophia , Mathew Koll Roxy
Published: February 2023

Dengue incidence has grown dramatically in recent decades, with about half of the world’s population now at risk. Climate plays a significant role in the incidence of dengue. However, the climate-dengue association needs to be clearly understood at regional levels due to the high spatial variability in weather conditions and the non-linear relationship between climate and dengue. The current study evaluates the impacts of weather on dengue mortality in the Pune district of India, for a 15-year period, from 2001 to 2015. To effectively resolve the complexity involved in the weather-dengue association, a new dengue metric is defined that includes temperature, relative humidity, and rainfall-dependent variables such as intraseasonal variability of monsoon (wet and dry spells), wet-week counts, flushing events, and weekly cumulative rains. We find that high dengue mortality years in Pune are comparatively dry, with fewer monsoon rains and flush events (rainfall > 150 mm), but they have more wet weeks and optimal humid days (days with relative humidity between 60–78%) than low dengue mortality years. These years also do not have heavy rains during the early monsoon days of June, and the temperatures mostly range between 27–35°C during the summer monsoon season (June–September).  Further, our analysis shows that dengue mortality over Pune occurs with a 2-5 months lag following the occurrence of favourable climatic conditions. Based on these weather-dengue associations, an early warning prediction model is built using the machine learning algorithm random forest regression. It provides a reasonable forecast accuracy with root mean square error (RMSE) = 1.01. To assess the future of dengue mortality over Pune under a global warming scenario, the dengue model is used in conjunction with climate change simulations from the Coupled Model Intercomparison Project phase 6 (CMIP6). Future projections show that dengue mortality over Pune will increase in the future by up to 86 percent (relative to the reference period 1980–2014) by the end of the 21st century under the high emission scenario SSP5-8.5, primarily due to an increase in mean temperature (3°C increase relative to the reference period). The projected increase in dengue mortality due to climate change is a serious concern that necessitates effective prevention strategies and policy-making to control the disease spread.
Coupling artificial intelligence techniques and remote sensing data for water quality simulation of lakes
Authors: Khorashadi Zadeh Farkhondeh , Khorashadizadeh Saeed , Nkwasa Albert , van Griensven Ann
Published: February 2023

Freshwater lakes are a major resource for human populations. To support water quality (WQ) management for lakes, both WQ monitoring and WQ modeling are essential. Conventional approaches, such as process-based models, are usually used for WQ modelling, however, these approaches require a large number of data (meteorological, topographical, hydrological, and WQ data) with high computational demands. Recently, artificial intelligence (AI) techniques are increasingly recommended in WQ modelling to tackle these challenges. In this study, the application of AI techniques for simulating/predicting water quality for large lakes using remote sensing (RS) is investigated. Specifically, the study aims to develop a robust AI model for turbidity in Lake Victoria, using the lake basin precipitation data and the sediment concentrations of the inflow rivers. To develop the AI model, the freely available remote sensing turbidity data for the lake is used as a reference data. Two models using a multi-layer perceptron neural network (MLPNN) and least square support vector regression (LSSVR) have been trained based on three different scenarios. Some performance indices such as mean absolute relative error and percent bias have been selected for model evaluation. According to the obtained results, LSSVR is more accurate than MLPNN in both training and testing phases of all scenarios. The results indicate that AI-based models are potential tools that can be adopted for WQ simulations of large lakes. Additionally, this study illustrates the potential of the use of remote sensing data to support model development, as an alternative to in-situ measurements, especially in data-scarce regions.Keywords: Water quality, artificial intelligence, remote sensing, sediment concentration, turbidity
Systemic solar wind condition causing distortion of the predicted magnetic reconnection location at the dayside magnetopause as observed by MMS
Authors: Trattner Karlheinz , Fuselier Stephen , Petrinec Steven , Burch Jim , Ergun Robert
Published: February 2023

Across the Earth’s magnetopause, magnetic reconnection has been observed as either the anti-parallel and/or component reconnection scenarios. The magnetic reconnection location prediction model known as the Maximum Magnetic Shear model combines these two scenarios and predicts long reconnection lines crossing the dayside magnetopause along a ridge of maximum magnetic shear. The model has been tested and validated and predicts the dayside reconnection location correctly for 84% of the events. Observed magnetic reconnection events for which the model fails share common characteristics, which indicates that for these conditions additional factors have an influence on the location of the dayside reconnection line. One of these specific conditions results in a set of so-called Knee events for which the anti-parallel reconnection region lines up along the draped Interplanetary Magnetic Field (IMF) lines. For these events, magnetic reconnection remains in the anti-parallel reconnection region as long as it is crossed by the draped IMF. Compared to the usual events, this effect results in a deflection of the connection points between the anti-parallel and component reconnection regions (known as anchor points). This study investigates if the location of the entire component reconnection line or only the anchor points are affected by this deflection.  Using two Knee events with confirmed magnetic reconnection location observed by MMS, this study describes how the entire component reconnection line across the dayside magnetopause is deflected if the relative magnetic shear between the maximum magnetic shear location and the deflected magnetic shear location is less than ~5°. 
Unlocking seasonal variations in climate and Indigenous foraging practices associated with paleo-ENSO on the Great Barrier Reef: clues from marine gastropod shells
Authors: Alidoostsalimi Mahsa , Prendergast Amy , Drysdale Russell , Brown Josephine , McNiven Ian , Ulm Sean
Published: February 2023

In recent years, there has been a growing interest in using archaeological marine mollusc shells as a paleoclimate archive by virtue of their ability to preserve high-resolution paleoclimatic and paleoenvironmental information in multiple biogeochemical proxies. Moreover, valuable information about past environments, human-environmental interactions, and seasonal foraging practices can be obtained via the analysis of marine gastropods from archaeological sites. Rochia nilotica is the most common shell in coral reef ecosystems across the Indo-Pacific Ocean and archaeological shell middens in the Great Barrier Reef (GBR); however, its application as a paleoclimate and paleoenvironment archive to reconstruct the Mid-to-Late Holocene ENSO (El Niño-Southern Oscillation) has not yet been investigated. In this study, we compare temporally successive oxygen isotope and trace element records (δ18O, Mg/Ca, Sr/Ca, and Ba/Ca) in modern R. nilotica shells with instrumental environmental records to test whether we can quantitively reconstruct past environmental parameters. Preliminary results show that modern R. nilotica reliably records environmental factors (e.g. sea surface temperature and salinity) in equilibrium with the surrounding environment at a seasonal scale. These proxies will ultimately be applied to reconstruct localised Mid-to-Late Holocene ENSO records at sub-seasonal scales in the Great Barrier Reef. Results obtained from this ongoing research can be used to compare with climate model simulations to provide a more robust reconstruction of paleo ENSO behavior and offers an opportunity to decipher the long-term shellfish management strategies of Indigenous peoples in the GBR environment to provide a baseline for future marine resource management in the GBR.
From soils to clouds - An integrated atmospheric boundary layer observatory in a temperate forest of eastern Canada
Authors: Helbig Manuel , Nick Nickerson , Deklan Mengering , Lukas Rudaitis , Jillian Ryan , Lidia Benítez-Valenzuela , Chance Creelman , Mara Taylor
Published: February 2023

Temperate forests have been shown to substantially impact near-surface climate and atmospheric boundary layer dynamics through a range of complex land-atmosphere feedback mechanisms. For example, forests can reduce water loss to the atmosphere during periods of high vapour pressure deficit, thereby preventing or delaying severe drought impacts. Reducing water loss during periods of high atmospheric water demand comes at the expense of reduced forest productivity and may contribute to additional warming of near-surface air temperatures through increased partitioning of energy to sensible heat. Understanding how land-atmosphere interactions in forested landscapes modify regional and local climate is thus crucial for the design of efficient national and international climate mitigation and adaptation strategies.To better understand complex land-atmosphere interactions in a typical forested landscape of eastern Canada, we have established an integrated atmospheric boundary layer observatory in a temperate forest in New Brunswick, Canada. Observations will be used to quantify environmental, plant physiological, and atmospheric feedbacks and their impacts on near-surface climate. Here, we present the instrumental setup and preliminary results from the integrated observatory. Forest soils are monitored using soil temperature, volumetric soil moisture, soil water potential, and snow depth measurements and are complemented by soil CO2 efflux measurements using forced diffusion chamber systems. Detailed vertical profiles of air temperature and humidity, wind speed and direction, and light are measured from the forest floor to a height of 28 m (i.e., 18 m above the forest canopy) using six weather stations. At the top of the flux tower at 28 m above ground, net ecosystem CO2 exchange and evapotranspiration of the forested landscape is measured using the eddy covariance technique along with longwave and shortwave radiation fluxes. A ceilometer will be added to the observatory in spring 2023 to continuously observe cloud base height and atmospheric boundary layer height. The integrated measurements will produce datasets that can be used to diagnose complex land-atmosphere interactions, to characterise forest microclimate, and to validate coupled land-atmosphere models.
Investigation of Non-linearity of Daily, Monthly, and Yearly Streamflow and the Correlation Between Non-linearity and Catchment Area
Authors: Khazaeiathar Mahshid , Schmalz Britta
Published: February 2023

Streamflow prediction by using time series models is one of the practical methods that can play an important role in water resource management.  But choosing the correct model based on the linear or non-linear streamflow behavior is so crucial. Additionally, streamflow non-linearity can be affected by physiographic characteristics of watershed.  In this study, streamflow non-linearity of daily, monthly and yearly time series and its relationship with the hydrometric station area have been examined. To fulfill this purpose, ten hydrometric stations with various catchment area were selected in Hesse state in Germany. The Brock-Dechert-Scheinkman (BDS) test for testing non-linearity patterns in time series, was used to test non-linearity. The results showed that daily streamflow time series exhibit strong non-linearity. In addition, as the timescale increases, the intensity of nonlinearity decreases. Monthly and yearly streamflow time series showed less evidence of non-linearity. Furthermore, regarding the investigation of the relationship between streamflow non-linearity and watershed area, pearson and spearman tests were used. The results revealed that in none of the time scales, daily, monthly, and yearly there is no significant correlation between these two parameters. It should be noted that the novelty of this article is examining the relationship between intensity of the non-linearity and watershed area as a factor in choosing the best fitted model for time series.
Confronting models with data: carbon-phosphorus interaction under elevated CO2 in a mature forest ecosystem (EucFACE)
Authors: Jiang Mingkai , Medlyn Belinda , Wårlind David , Knauer Jürgen , Goll Daniel , Yu Lin , Fleischer Katrin , Zhang Haicheng , Yang Xiaojuan , Zaehle Sönke , Ellsworth David , Smith Benjamin
Published: February 2023

The importance of phosphorus (P) in plant function and ecosystem biogeochemistry has led to the addition of a P cycle to a range of vegetation models, but the predictions of these P-enabled models have rarely been evaluated with ecosystem-scale data. Here, we confronted eight state-of-the-art, P-enabled models with data from EucFACE, a P-limited Eucalyptus forest subject to long-term Free-Air CO2 Enrichment. We evaluated the capability of the models to capture the observed elevated CO2 responses in this ecosystem. We show that the inclusion of phosphorus-cycle is necessary to more realistically simulate ecosystem function and biogeochemistry, but this enhanced capacity did not directly translate into improved prediction accuracy. Specifically, models diverged in capturing the observed CO2 responses, with simulation accuracy depending upon model assumptions about plant physiology, allocation, plant-soil interactions and soil nutrient processes. Confronting models with experimental responses observed at EucFACE represents a valuable opportunity to improve our understanding of the carbon-phosphorus interaction under rising CO2, and is an important step towards more accurate predictions of the future land carbon sink under climate change.
A Multi-Index Examination of Future Fire Season Length and Severity Over the United States
Authors: Bukovsky Melissa , Kessenich Lee , McGinnis Seth , Mearns Linda , Abatzoglou John , Cullen Alison
Published: February 2023

Our goal is to better understand the potential effects of climate change on fire danger for the near (2030-2060) and far (2069-2099) future.  We examine changes in fire season length and severity using multiple regional climate model (RCM) simulations and multiple fire indexes for the entire United States.  As different fire indexes make different assumptions about fuel and soil conditions, and different fire indexes are favored for different applications in different regions, we use 8 indexes, with 2 variations on 3 of those, for 11 measures of fire behavior.  We examine changes in the number of days above the 80th, 90th, and 97th percentiles of these indexes, corresponding to thresholds used to assign descriptors of fire danger as high, very high, and severe.  To define fire season length, we use the number of days above the 80th percentile for each given index.     We employ thirteen simulations produced for the North American component of the Coordinated Regional climate Downscaling Experiment (NA-CORDEX), leveraging RCP8.5 emission scenario simulations for the future projections.  From these simulations, we calculate the KBDI (Keetch-Byram Drought Index), mFFWI (modified Fosberg Fire Weather Index), CFWI (Canadian Fire Weather Index), FM100 and FM1000 (100- and 1000-hour Fuel Moisture), ERC (Energy Release Component), BI (Burning Index), and SFDI (Severe Fire Danger Index).  Two fuel scenarios, G and LAF, are input into ERC, BI, and SFDI.  By mid-century, most regions are projected to see an increase in the length of fire season, though the magnitude of this projected change varies considerably by region and fire index (and the latter’s sensitivity to precipitation).  Agreement on a lengthening of the season by up to 50% is strongest across simulations and fire indexes over the Southern Plains and Southwest U.S.  Changes in fire season severity are largest and most consistent across indexes for the U.S. west of the Mississippi River, excluding the intermountain West, where uncertainty is higher across the indexes and RCMs.  An approximately 2- to 6-fold increase in the number of days that reach the severe fire danger threshold is projected by mid-century.  Simulations for the far future are qualitatively similar, but the projected changes are quantitatively worse and more widespread.
Relationship between the Tropical Cyclone Forecast Skill and the Western North Pacific Summer Monsoon in the ECMWF Monthly Ensemble
Authors: Tsai Hsiao-Chung , Lo Tzu-Ting , Chen Meng-Shih , Chen Yun-Jing , Kuo Jui-Ling , Hsu Han-Yu
Published: February 2023

In this study, week-1 to week-4 forecasts of tropical cyclones (TCs) in the western North Pacific are evaluated. The CWB TC Tracking System 2.0 (Lo et al. 2021) is used to objectively detect TCs in the 46-day ECMWF ensemble (ENS) forecasts in the 2021 season and also the reforecasts during 2001-2020. Preliminary evaluations of the probabilistic TC activity forecasts in the 20-year reforecasts show promising forecast skills. The reliability diagrams indicate slight over-forecasting bias in the weeks 1-4 forecasts, and the AUCs (Area Under Curves) are ranging from 0.91 (week-1) to 0.80 (week-4). The relationship between the TC activity forecast skill and the western North Pacific summer monsoon (WNPSM) is also investigated. The WNP monsoon index (WNPMI) proposed by Wang et al. (2001) is computed to provide a measure for the summer monsoon, and the TC forecast skills are evaluated under different levels of the WNPMI. To identify the potential false alarms, a spatial-temporal track clustering technique (Tsai et al. 2019) is implemented to objectively group similar vortex tracks in the 51-member forecasts. The corresponding ensemble mean track for each cluster is then used for performing the event-based verifications after the end of season. More details about the TC forecast verifications in weeks 1-4 using the ECMWF monthly ensemble will be presented in the meeting.
Newly discovered moonquakes from Apollo short-period seismometer data
Authors: Onodera Keisuke , Imagawa Yuki , Tanaka Satoshi
Published: February 2023

The beginning of planetary seismology dates back to the Apollo lunar seismic observations (1969 – 1977), where two types of seismometers were deployed at four places on the nearside of the Moon. The seismic observation package consisted of (i) two horizontal and one vertical long-period (LP) sensors and (ii) one vertical short-period (SP) sensor. About 8 years of observation brought us 13000 seismic events and contributed to the understanding of the internal structure and the seismicity of the Moon (see Nunn et al., 2020 and Garcia et al., 2019 for the recent review).On the other hand, because the existing moonquake catalog by Nakamura et al. (1981) builds on the LP data, it has been expected that there are potential events only observable in the SP data (Nakamura, 2021, pers. comm.). Referring to the already cataloged events, shallow moonquakes and thermal moonquakes excite the energy at a high-frequency range more sensible with the SP sensor (> 1-2 Hz). Especially, shallow moonquakes being used to define the lunar seismicity (Banerdt et al., 2020), it is of great importance to investigate the SP data for re-evaluating the current seismic activities on the Moon.In this study, utilizing the re-archived Apollo lunar seismic data by Nunn et al. (2022), we searched for undetected moonquakes by looking into the coherence between the reference moonquakes and the SP time series. As a result, we succeeded in discovering seismic events that were not cataloged before. A new SP event catalog will be released with our future publication. In the presentation, we will show the newly detected moonquakes and describe their characteristics. ReferencesBanerdt et al. (2020), Nat. Geosci.,13, 183–189.
Garcia et al. (2019), Space Sci. Rev., 215, 50.
Nakamura et al. (1981), UTIG Technical Report, 18.
Nunn et al. (2020), Space Sci. Rev., 216, 89.
Nunn et al. (2022), Planet. Sci. J., 3 219.
 