Satellite observations show high aerosol loadings over the Arabian Sea in boreal summer, which have great impacts on the Indian monsoon due to absorbing dust aerosols. However, the compositions, ...origins, transport pathways, and decadal trends of these aerosols have not been well studied. In this study, using multiple satellite retrievals, a back trajectory model, and reanalysis data, we found that (1) aerosol optical depth (AOD) over the Arabian Sea and Arabian Peninsula have a summer peak and dust aerosols dominate the AOD; aerosol reanalysis data tend to considerably underestimate dust AOD compared to satellite data, indicating challenges of extracting dust from total AOD; (2) aerosols over the Arabian Sea are largely transported from South and East Arabian Peninsula by cyclonic winds in the lower troposphere (850 hPa) and from Iran–Afghanistan–Pakistan by anticyclonic winds in the middle troposphere (500 hPa); (3) both case studies and composite analyses show that extremely high aerosol loadings over the Arabian Sea is associated with an abnormally low pressure over the Arabian Sea and the Middle East; and (4) significant positive trends in AOD over the Arabian Peninsula and the Arabian Sea exist during 2000–2011 but disappear during 2000–2016, indicating a strong interdecadal variability of dust activities. This study revealed pathways linking dust emissions in the Middle East to high summertime AOD over the Arabian Sea and identified the atmospheric conditions favorable for dust emissions and transport.
Plain Language Summary
Tiny particles in air are of great importance in climate system by changing the Earth's radiation balance and clouds. Satellites observe very high concentrations of particles over the Arabian Sea and the Middle East in the boreal summer. This study examined the chemical compositions of these particles over the Arabian Sea and their origins, transport pathways, and long‐term changes using multiple satellite products, numerical simulations, and statistical methods. It is found that dust aerosols dominate the particles over the Arabian Sea in the summer. These dust aerosols are lifted from the dry deserts over the Arabian Peninsula to the air and transported to the Arabian Sea under favorable wind patterns. The findings here can benefit future studies on interactions between the Middle East dust particles and regional climate.
Key Points
Mineral dust aerosols dominate (38–54%) the extremely high aerosol loadings over the Arabian Sea in summer
These dust aerosols are transported from the Middle East and the Thar Desert by cyclonic (at altitude of 500 m) and anticyclonic (5000 m) flows
Dust aerosols show a strong interdecadal variability over the Arabian Sea and the Middle East during 2000–2016
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We investigated the impacts of vegetation and groundwater dynamics on warm season precipitation by using the Weather Research and Forecasting (WRF) model coupled with a modified Noah land surface ...model (LSM). The modified Noah LSM was augmented with an interactive canopy model and a simple groundwater model (SIMGM). A series of experiments performed shows that incorporating vegetation and groundwater dynamics into the WRF model can improve the simulation of summer precipitation in the Central United States. The enhanced model produces more precipitation in response to an increase in the latent heat flux. The advantage of incorporating the two components into the model becomes more discernable after 1 month. The model results suggest that the land‐atmosphere feedback is an important mechanism for summer precipitation over the Central United States. Vegetation growth and groundwater dynamics play a significant role in enhancing the persistence of intraseasonal precipitation in regional climate models. Their combined effects act to favor a stronger land‐atmosphere feedback during the summer season. The simulated diurnal cycle of precipitation is improved by the WRF model with the augmented Noah LSM. Moreover, we found that the coupling between the soil moisture and the lifting condensation level (LCL) is enhanced by adding the two components to the WRF model. The impact of groundwater is significant when the soil moisture is relatively dry. This study suggests that incorporating vegetation and groundwater dynamics into a regional climate model would be especially beneficial for seasonal precipitation forecast in the transition zones.
Somatic mutations accumulate with age and are associated closely with human health, their characterization in longevity cohorts remains largely unknown. Here, by analyzing whole genome somatic ...mutation profiles in 73 centenarians and 51 younger controls in China, we found that centenarian genomes are characterized by a markedly skewed distribution of somatic mutations, with many genomic regions being specifically conserved but displaying a high function potential. This, together with the observed more efficient DNA repair ability in the long‐lived individuals, supports the existence of key genomic regions for human survival during aging, with their integrity being of essential to human longevity.
By systematically analyzing the somatic mutation landscapes of 73 centenarians and 51 controls using whole genome sequencing, Wang et al. identified a number of genomic regions (viz., CSM‐FRs) that are free of any somatic mutations in the centenarians but are always mutated in the general older people. Importantly, the high conservation and function potential of these genomic regions indicate the necessity of their integrity for human longevity.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Texas is subject to severe droughts, including the record-breaking one in 2011. To investigate the critical hydrometeorological processes during drought, we use a land surface model, Noah-MP, to ...simulate water availability and investigate the causes of the record drought. We conduct a series of experiments with runoff schemes, vegetation phenology, and plant rooting depth. Observation-based terrestrial water storage, evapotranspiration, runoff, and leaf area index are used to compare with results from the model. Overall, the results suggest that using different parameterizations can influence the modeled water availability, especially during drought. The drought-induced vegetation responses not only interact with water availability but also affect the ground temperature. Our evaluation shows that Noah-MP with a groundwater scheme produces a better temporal relationship in terrestrial water storage compared with observations. Leaf area index from dynamic vegetation is better simulated in wet years than dry years. Reduction of positive biases in runoff and reduction of negative biases in evapotranspiration are found in simulations with groundwater, dynamic vegetation, and deeper rooting zone depth. Multiparameterization experiments show the uncertainties of drought monitoring and provide a mechanistic understanding of disparities in dry anomalies.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Background
The effect of corticosteroids on influenza A(H1N1)pdm09 viral pneumonia patients remains controversial, and the impact of dosage has never been studied.
Methods
Using data of hospitalized ...adolescent and adult patients with influenza A(H1N1)pdm09 viral pneumonia, prospectively collected from 407 hospitals in mainland China, the effects of low‐to‐moderate‐dose (25‐150 mg d−1) and high‐dose (>150 mg d−1) corticosteroids on 30‐day mortality, 60‐day mortality, and nosocomial infection were assessed with multivariate Cox regression and propensity score‐matched case–control analysis.
Results
In total, 2141 patients (median age: 34 years; morality rate: 15.9%) were included. Among them, 1160 (54.2%) had PaO2/FiO2<300 mm Hg on admission, and 1055 (49.3%) received corticosteroids therapy. Corticosteroids, without consideration of dose, did not influence either 30‐day or 60‐day mortality. Further analysis revealed that, as compared with the no‐corticosteroid group, low‐to‐moderate‐dose corticosteroids were related to reduced 30‐day mortality (adjusted hazard ratio aHR 0.64 95% CI 0.43‐0.96, P=.033). In the subgroup analysis among patients with PaO2/FiO2<300 mm Hg, low‐to‐moderate‐dose corticosteroid treatment significantly reduced both 30‐day mortality (aHR 0.49 95% CI 0.32‐0.77) and 60‐day mortality (aHR 0.51 95% CI 0.33‐0.78), while high‐dose corticosteroid therapy yielded no difference. For patients with PaO2/FiO2 ≥300 mm Hg, corticosteroids (irrespective of dose) showed no benefit and even increased 60‐day mortality (aHR 3.02 95% CI 1.06‐8.58). Results were similar in the propensity model analysis.
Conclusions
Low‐to‐moderate‐dose corticosteroids might reduce mortality of influenza A(H1N1)pdm09 viral pneumonia patients with PaO2/FiO2<300 mm Hg. Mild patients with PaO2/FiO2 ≥300 mm Hg could not benefit from corticosteroid therapy.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
River discharge is one of the most critical renewable water resources. Accurately estimating river discharge with land surface models (LSMs) remains challenging due to the difficulty in estimating ...land water storages such as snow, soil moisture, and groundwater. While data assimilation (DA) ingesting optical, microwave, and gravity measurements from space can help constrain theses storage states, its impacts on runoff and eventually river discharge are not fully understood. In this study, by taking advantage of recently published land DA results that jointly assimilate eight different combinations of observations from the Moderate Resolution Imaging Spectroradiometer (MODIS), Gravity Recovery and Climate Experiment (GRACE), and Advanced Microwave Scanning Radiometer for EOS (AMSR-E), we quantify to what degree multi-sensor land DA improves the river discharge simulation skills over 40 global river basins, and investigate the complementary strengths of different satellite measurements on river discharge. To be more specific, river discharge is updated by feeding gridded runoff from the eight multi-sensor DA simulations into a vector-based river routing model named the Routing Application for Parallel computatIon of Discharge (RAPID). Our modeling results, including 7-year simulations at 177,458 river reaches globally, are used to study the seasonal to interannual variability of river discharge. It is found that assimilating GRACE has the greatest impact on global runoff patterns, leading to the most pronounced improvements in spatial river discharge in the middle and high latitudes with the R2 increased by 0.16. The seasonal variation of spatial discharge is most skillful during the boreal summer. However, our evaluation also shows model and DA still struggle to generate reasonable variability and averaged discharge over permafrost regions. Finally, by assessing how different satellites add value to discharge forecasts, this study paves the way for more advanced multi-sensor satellite data assimilation to predict the terrestrial hydrological cycle.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Since winter 2011, a record‐breaking drought has occurred in California. Studies found that the drought is mainly caused by a persistent high‐pressure system off the U.S. West Coast, which is linked ...to Pacific sea surface temperature anomalies. The water cycles associated with the droughts and floods are still not clearly understood. Here we show that the atmospheric circulation off the West Coast not only controls the atmospheric convergence and formation of precipitation but also largely determines surface wind speed, which further affects the evaporation over the eastern North Pacific, the major evaporative moisture source for California precipitation. Because of this mechanism, the ocean evaporation over the eastern North Pacific has been reduced during the recent drought. However, the ocean evaporation anomalies have little direct influence on California precipitation, especially during dry years, mainly because of their weak amplitudes. The California droughts cannot be readily attributed to the reduced ocean evaporation. The association between increased Pacific evaporation and floods over California is somewhat stronger.
Key Points
Atmospheric circulation off U.S. West Coast controls surface wind speed and ocean evaporation
Ocean evaporation has little direct influence on California precipitation because of its weak variability
Ocean evaporation has stronger influence on California precipitation in wet years than in dry years
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
As a key component of the National Flood Interoperability Experiment (NFIE), this article presents the continental scale river flow modeling of the Mississippi River Basin (MRB), using ...high‐resolution river data from NHDPlus. The Routing Application for Parallel computatIon of Discharge (RAPID) was applied to the MRB with more than 1.2 million river reaches for a 10‐year study (2005‐2014). Runoff data from the Variable Infiltration Capacity (VIC) model was used as input to RAPID. This article investigates the effect of topography on RAPID performance, the differences between the VIC‐RAPID streamflow simulations in the HUC‐2 regions of the MRB, and the impact of major dams on the streamflow simulations. The model performance improved when initial parameter values, especially the Muskingum K parameter, were estimated by taking topography into account. The statistical summary indicates the RAPID model performs better in the Ohio and Tennessee Regions and the Upper and Lower Mississippi River Regions in comparison to the western part of the MRB, due to the better performance of the VIC model. The model accuracy also increases when lakes and reservoirs are considered in the modeling framework. In general, results show the VIC‐RAPID streamflow simulation is satisfactory at the continental scale of the MRB.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
As an important part of biogeochemical cycling, the nitrogen cycle modulates terrestrial ecosystem carbon storage, water consumption, and environmental quality. Modeling the complex interactions ...between nitrogen, carbon and water at a regional scale remains challenging. Using China as a testbed, this study presents the first application of the nitrogen-augmented community Noah land surface model with multi-parameterization options (Noah-MP-CN) at the regional scale. Noah-MP-CN parameterizes the constraints of nitrogen availability on photosynthesis based on the Fixation and Uptake of Nitrogen plant nitrogen model and the Soil and Water Assessment Tool soil nitrogen model. The impacts of nitrogen dynamics on the terrestrial carbon and water cycles are investigated by comparing the simulations with those from the original Noah-MP. The results show that incorporating nitrogen dynamics improves the carbon cycle simulations. Noah-MP-CN outperforms Noah-MP in reproducing leaf area index (LAI) and gross primary productivity (GPP) for most of China, especially in the southern warm and humid regions, while the hydrological simulations only exhibit slight improvements in soil moisture and evapotranspiration. The impacts of fertilizer application over cropland on carbon fixation, water consumption and nitrogen leaching are investigated through a trade-off analysis. Compared to halved fertilizer use, the actual quantity of application increases GPP and water consumption by only 1.97% and 0.43%, respectively; however, the nitrogen leaching is increased by 5.35%. This indicates that the current level of fertilizer use is a potential concern for degrading the environment.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
To improve snowpack estimates in Community Land Model version 4 (CLM4), the Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover fraction (SCF) was assimilated into the Community Land ...Model version 4 (CLM4) via the Data Assimilation Research Testbed (DART). The interface between CLM4 and DART is a flexible, extensible approach to land surface data assimilation. This data assimilation system has a large ensemble (80‐member) atmospheric forcing that facilitates ensemble‐based land data assimilation. We use 40 randomly chosen forcing members to drive 40 CLM members as a compromise between computational cost and the data assimilation performance. The localization distance, a parameter in DART, was tuned to optimize the data assimilation performance at the global scale. Snow water equivalent (SWE) and snow depth are adjusted via the ensemble adjustment Kalman filter, particularly in regions with large SCF variability. The root‐mean‐square error of the forecast SCF against MODIS SCF is largely reduced. In DJF (December‐January‐February), the discrepancy between MODIS and CLM4 is broadly ameliorated in the lower‐middle latitudes (23°–45°N). Only minimal modifications are made in the higher‐middle (45°–66°N) and high latitudes, part of which is due to the agreement between model and observation when snow cover is nearly 100%. In some regions it also reveals that CLM4‐modeled snow cover lacks heterogeneous features compared to MODIS. In MAM (March‐April‐May), adjustments to snow move poleward mainly due to the northward movement of the snowline (i.e., where largest SCF uncertainty is and SCF assimilation has the greatest impact). The effectiveness of data assimilation also varies with vegetation types, with mixed performance over forest regions and consistently good performance over grass, which can partly be explained by the linearity of the relationship between SCF and SWE in the model ensembles. The updated snow depth was compared to the Canadian Meteorological Center (CMC) data. Differences between CMC and CLM4 are generally reduced in densely monitored regions.
Key Points
This work interfaced CLM4 with DART
MODIS snow cover is assimilated into DART/CLM4
The RMSE of snow cover and snow depth is reduced
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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