nasa-gesdisc/es-publications-researchareas huggingface dataset:
Uncovering the trophic relationship between Themisto gaudichaudii and Salpa thompsoni in the Antarctic Polar Frontal Zone (2015)

Trophic dynamics of 2 abundant macrozooplankton species Salpa thompsoni and Themisto gaudichaudii were studied during the austral summer at 2 locations near the Antarctic Polar Front with contrasting low and high chlorophyll a (chl a) concentrations. Compound-specific stable isotope analysis, complemented by gut content and bulk isotope analyses, were used to investigate trophic interactions between species, and to assess their trophic positions in the pelagic food web. The results of the compound-specific stable isotope analysis placed S. thompsoni at the second trophic level and approx. 1 trophic level below T. gaudichaudii. Two forms of T. gaudichaudii appeared to feed at different trophic levels, with T. gaudichaudii bispinosa feeding at a higher trophic level (~3.3) than T. gaudichaudii compressa (~2.8). Isotope data coupled with gut content analysis indicated a regular consumption of salps in both areas, although a higher contribution of gelatinous prey was encountered in a chl a poor area. The food web baseline values (bulk 13C) varied regionally, highlighting 2 independent food webs albeit with a similar trophic structure. Overall, our findings suggested that in areas where S. thompsoni is highly abundant, T. gaudichaudii may be a significant predator of this species.

Research areas: Ecosystems
Uncertainties in anthropogenic aerosol concentrations and direct radiative forcing induced by emission inventories in eastern China (2015)

This study quantified the uncertainties in concentrations and direct radiative forcing of anthropogenic aerosols due to emissions in eastern China using a global chemistryaerosolclimate model. The emission inventories included three global inventories, ACCMIP (Atmospheric Chemistry & Climate Model Intercomparison Project), EDGAR-HTAP (Emission Database for Global Atmospheric Research for Hemispheric Transport of Air Pollution), and EDGAR Version 4.2, and one regional INTEX-B (Intercontinental Chemical Transport ExperimentPhase B) inventory. The uncertainties (a percentage of the standard deviation divided by the mean value across the four inventories) in the regional surface-layer aerosol concentrations due to emissions were 3.9% in sulfate, 40.0% in nitrate, 18.4% in ammonium, 11.1% in POA, 16.7% in SOA and 15.4% in BC. Compared with the ACCMIP model results based on a uniform emission inventory, the impacts of emissions were smaller. One exception is the regional surface-layer nitrate concentration, which had comparable uncertainties due to the emissions (40.0%) and the models (43.8%) because of the complex nitrate chemistry and the highly uncertain NH3 emission. The mean regional aerosol direct forcing at the top of the atmosphere between 1850 and 2006 was 3.6Wm2 under all-sky conditions and was enhanced up to 3.83Wm2 after the model assimilated the MODIS find-mode aerosol optical depth (AOD). The impact of the assimilation of absorption AOD is discussed. The uncertainties in aerosol direct forcing were smaller than those of the ACCMIP inter-model results, but still significant. An accurate emission inventory is essential for quantifying the role of aerosols in regional climate.

Research areas: Environmental Impacts
Time series model prediction and trend variability of aerosol optical depth over coal mines in India (2015)

A study of the assessment and management of air quality was carried out at 11 coal mines in India. Long-term observations (about 13 years, March 2000December 2012) and modeling of aerosol loading over coal mines in India are analyzed in the present study. In this respect, the Box-Jenkins popular autoregressive integrated moving average (ARIMA) model was applied to simulate the monthly mean Terra Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD550 nm) over 11 sites in the coal mines region. The ARIMA model was found as the most suitable model with least normalized Bayesian information criterion (BIC) and root mean square error and high value of R2. Estimation was done with the Ljung-Box test. Finally, a forecast for a 3-year period from January 2013 to December 2015 was calculated which showed that the model forecasted values are following the observed trend quite well over all mining areas in India. The average values of AOD for the next 3 years (20132015) at all sites are found to be 0.575  0.13 (Raniganj), 0.452  0.12 (Jharia), 0.339  0.13 (Bokaro), 0.280  0.09 (Bishrampur), 0.353  0.13 (Korba), 0.308  0.08 (Talcher), 0.370  0.11 (Wardha), 0.35  0.10 (Adilabad), 0.325  0.09 (Warangal), 0.467  0.09 (Godavari Valley), and 0.236  0.07 (Cuddapah), respectively. In addition, long-term lowest monthly mean AOD550 values are observed over Bishrampur followed by Cuddapah, Talcher, Warangal, Adilabad, Korba, Wardha, Godavari Valley, Jharia, and Raniganj. Raniganj and Jharia exhibit the highest AOD values due to opencast mines and extensive mining activities as well as a large number of coal fires. Similarly, the highest AOD values are observed during the monsoon season among all four seasons over all the mining sites. Raniganj exhibits the highest AOD value at all seasons and at all sites. In contrast, the lowest seasonal AOD values are observed during the post-monsoon season over Raniganj, Talcher, Wardha, Adilabad, Warangal, and Godavari Valley. Similarly, over Jharia, Bokaro, Bishrampur, Korba, and Cuddapah, the lowest AOD values are found in the winter season. Increasing trends in AOD550 have been observed over Raniganj, Bokaro, Bishrampur, Korba, Talcher, and Wardha as well as over Adilabad and Godavari Valley, which is in agreement with previous works. Negative or decreasing AOD trend is found only over Jharia, Warangal, and Cuddapah without being statistically significant. Seasonal trends in AODs have also been studied in the present paper.

Research areas: Air Quality, Environmental Impacts
The role of semi-volatile organic compounds in the mesoscale evolution of biomass burning aerosol: a modeling case study of the 2010 mega-fire event in Russia (2015)

Abstract. Chemistry transport models (CTMs) are an indispensable tool for studying and predicting atmospheric and climate effects associated with carbonaceous aerosol from open biomass burning (BB); this type of aerosol is known to contribute significantly to both global radiative forcing and to episodes of air pollution in regions affected by wildfires. Improving model performance requires systematic comparison of simulation results with measurements of BB aerosol and elucidation of possible reasons for discrepancies between them, which, by default, are frequently attributed in the literature to uncertainties in emission data. Based on published laboratory data on the atmospheric evolution of BB aerosol and using the volatility basis set (VBS) framework for organic aerosol modeling, we examined the importance of taking gas-particle partitioning and oxidation of semi-volatile organic compounds (SVOCs) into account in simulations of the mesoscale evolution of smoke plumes from intense wildfires that occurred in western Russia in 2010. Biomass burning emissions of primary aerosol components were constrained with PM10 and CO data from the air pollution monitoring network in the Moscow region. The results of the simulations performed with the CHIMERE CTM were evaluated by considering, in particular, the ratio of smoke-related enhancements in PM10 and CO concentrations (PM10 and CO) measured in Finland (in the city of Kuopio), nearly 1000 km downstream of the fire emission sources. It is found that while the simulations based on a "conventional" approach to BB aerosol modeling (disregarding oxidation of SVOCs and assuming organic aerosol material to be non-volatile) strongly underestimated values of PM10/CO observed in Kuopio (by a factor of 2), employing the "advanced" representation of atmospheric processing of organic aerosol material resulted in bringing the simulations to a much closer agreement with the ground measurements. Furthermore, taking gas-particle partitioning and oxidation of SVOCs into account is found to result in a major improvement of the agreement of simulations and satellite measurements of aerosol optical depth, as well as in considerable changes in predicted aerosol composition and top-down BB aerosol emission estimates derived from AOD measurements.

Research areas: Air Quality, Wildfires
The radiative impact of desert dust on orographic rain in the CevennesVivarais area: a case study from HyMeX (2015)

Abstract. The study is focused on Intensive Observation Period (IOP) 14 of the Hydrological Cycle in the Mediterranean Experiment first Special Observing Period (HyMeX SOP 1) that took place from 17 to 19 October 2012 and was dedicated to the study of orographic rain in the CevennesVivarais (CV) target area. During this IOP a dense dust plume originating from northern Africa (the Maghreb and Sahara) was observed to be transported over the Balearic Islands towards the south of France. The plume was characterized by an aerosol optical depth between 0.2 and 0.8 at 550 nm, highly variable in time and space over the western Mediterranean Basin. The impact of this dust plume, the biggest event observed during the 2-month-long HyMeX SOP 1, on the precipitation over the CV area has been analyzed using high-resolution simulations from the convection permitting mesoscale model Meso-NH (mesoscale non-hydrostatic model) validated against measurements obtained from numerous instruments deployed specifically during SOP 1 (ground-based/airborne water vapor and aerosol lidars, airborne microphysics probes) as well as space-borne aerosol products. The 4-day simulation reproduced realistically the temporal and spatial variability (including the vertical distribution) of the dust. The dust radiative impact led to an average 0.6 K heating at the altitude of the dust layer in the CV area (and up to +3 K locally) and an average 100 J kg1 increase of most unstable convective available potential energy (and up to +900 J kg1 locally) with respect to a simulation without prescribed dust aerosols. The rainfall amounts and location were only marginally affected by the dust radiative effect, even after 4 days of simulation. The transient nature of this radiative effect in dynamical environments such as those found in the vicinity of heavy precipitation events in the Mediterranean is not sufficient to impact 24 h of accumulated rainfall in the dust simulation.

Research areas: Atmospheric/Ocean Indicators
The influence of Sardinia on Corsican rainfall in the western Mediterranean Sea: A numerical sensitivity study (2015)

The interaction of orographic effects and moisture availability is of high importance to the
precipitation amount and distribution in the western Mediterranean and neighboring land
surfaces. In particular, the forecast of heavy precipitation events is still a challenge for operational
weather forecast models. In this study, the thermal and dynamical interactions between the two
neighboring islands of Corsica and Sardinia in the western Mediterranean Sea are investigated
using the COnsortium for Small-scale MOdeling (COSMO) model. Six cases with different synoptic
conditions are analyzed and the dependance of the Corsican rainfall on the presence and terrain
characteristics of Sardinia is investigated. Besides a reference run with standard model orography,
sensitivity runs with removed and flat island of Sardinia are performed. The numerical results
show that the daily precipitation amount over Corsica can increase by up to 220% of the amount
from the reference run. Whereas most of the sensitivity runs show a decrease of the precipitation
amount under strong synoptic forcing, there is no systematic relationship on days with weak
synoptic forcing. The differences in the precipitation amount are induced by (i) missing deviation
or missing blocking of the southerly flow by Sardinia and (ii) by the influence of cold pools
generated by deep convection over Sardinia. These differences can be attributed to changes of
low-level convergence and moisture/heat content and their effect on thermodynamic parameters,
like convective available potential energy or convective inhibition. Furthermore, the position and
translation speed of frontal systems over Corsica on days with strong synoptic forcing also depend
on the Sardinian orography. These results demonstrate the high sensitivity of numerical weather
prediction to the interaction of neighboring mountainous islands.

Research areas: Atmospheric/Ocean Indicators
The GAW-PFR aerosol optical depth network: The 20082013 time series at Cape Point Station, South Africa (2015)

AbstractA ground-based aerosol optical depth (AOD) climatology is presented for Cape Point (CPT) station, South Africa, for the 20082013 period. CPT is part of the Global Atmosphere WatchPrecision Filter Radiometer network which conducts long-term AOD measurements at remote background sites. AOD ( = 500 nm) and Angstrom exponent (368 to 862 nm; 368862) averages for the entire period were 0.059 and 0.68, displaying only a weak seasonality. Based on an established method for air mass classification using the in situ wind direction and 222Rn concentration, the following four air mass types were used to further investigate AOD: background marine, marine, mixed, and continental. AOD was similar for all types, but 368862 was distinctly lower (0.43) for background marine and higher (1.07) for continental air masses, illustrating the presence of coarse mode and anthropogenic aerosols, respectively. Trajectory cluster analysis of 5 day back trajectories confirmed/augmented this classification. AOD for background marine and marine air mass types were consistent with ship-based (Maritime Aerosol Network) and island (AErosol RObotic NETwork) measurements, suggesting that CPT is a suitable site to monitor pristine conditions in the South Atlantic and Southern Oceans when 222Rn concentrations are < 100 mBq m3.

Research areas: Validation
The footprints of Saharan air layer and lightning on the formation of tropical depressions over the eastern Atlantic Ocean (2015)

The roles of the Saharan Air Layer (SAL) and lightning during genesis of Tropical Depression (TD) 8 (2006) and TD 12 (2010) were investigated in relation to the interaction of the dust outbreaks with each system and their surrounding environment. This study applied data collected from the 2006 NASA African Monsoon Multidisciplinary Analysis and 2010 Genesis and Rapid Intensification Processes projects. Satellite observations from METEOSAT and Moderate Resolution Imaging Spectroradiometer (MODIS)Aerosol Optical Depth (AOD) were also employed for the study of the dust content. Lightning activity data from the Met Office Arrival Time Difference (ATD) system were used as another parameter to correlate moist convective overturning and a sign of cyclone formation. The AOD and lightning analysis for TD 8 demonstrated the time-lag connection through their positive contribution to TC-genesis. TD 12 developed without strong dust outbreak, but with lower wind shear (2 m s1) and an organized Mesoscale Convective System (MCS). Overall, the results from the combination of various data analyses in this study support the fact that both systems developed under either strong or weak dust conditions. From these two cases, the location (i.e., the target area) of strong versus weak dust outbreaks, in association with lightning, were essential interactions that impacted TC-genesis. While our dust footprints hypothesis applied under strong dust conditions (i.e., TD 8), other factors (e.g., vertical wind shear, pre-existing vortex and trough location, thermodynamics) need to be evaluated as well. The results from this study suggest that the SAL is not a determining factor that affects the formation of tropical cyclones (i.e., TD 8 and TD 12).

Research areas: Severe Storms
The fertilizing role of African dust in the Amazon rainforest: A first multiyear assessment based on data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (2015)

The productivity of the Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of long-range transported African dust is recognized as a potentially important but poorly quantified source of phosphorus. This study provides a first multiyear satellite-based estimate of dust deposition into the Amazon Basin using three-dimensional (3-D) aerosol measurements over 20072013 from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The 7 year average of dust deposition into the Amazon Basin is estimated to be 28 (848) Tg a1 or 29 (850) kg ha1 a1. The dust deposition shows significant interannual variation that is negatively correlated with the prior-year rainfall in the Sahel. The CALIOP-based multiyear mean estimate of dust deposition matches better with estimates from in situ measurements and model simulations than a previous satellite-based estimate does. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3-D nature of CALIOP aerosol measurements. The imported dust could provide about 0.022 (0.0060.037) Tg P of phosphorus per year, equivalent to 23 (739) g P ha1 a1 to fertilize the Amazon rainforest. This out-of-basin phosphorus input is comparable to the hydrological loss of phosphorus from the basin, suggesting an important role of African dust in preventing phosphorus depletion on timescales of decades to centuries.

Research areas: Ecosystems
The effects of precipitation, river discharge, land use and coastal circulation on water quality in coastal Maine (2015)

Faecal pollution in stormwater, wastewater and direct run-off can carry zoonotic pathogens to streams, rivers and the ocean, reduce water quality, and affect both recreational and commercial fishing areas of the coastal ocean. Typically, the closure of beaches and commercial fishing areas is governed by the testing for the presence of faecal bacteria, which requires an 1824 h period for sample incubation. As water quality can change during this testing period, the need for accurate and timely predictions of coastal water quality has become acute. In this study, we: (i) examine the relationship between water quality, precipitation and river discharge at several locations within the Gulf of Maine, and (ii) use multiple linear regression models based on readily obtainable hydrometeorological measurements to predict water quality events at five coastal locations. Analysis of a 12 year dataset revealed that high river discharge and/or precipitation events can lead to reduced water quality; however, the use of only these two parameters to predict water quality can result in a number of errors. Analysis of a higher frequency, 2 year study using multiple linear regression models revealed that precipitation, salinity, river discharge, winds, seasonality and coastal circulation correlate with variations in water quality. Although there has been extensive development of regression models for freshwater, this is one of the first attempts to create a mechanistic model to predict water quality in coastal marine waters. Model performance is similar to that of efforts in other regions, which have incorporated models into water resource managers' decisions, indicating that the use of a mechanistic model in coastal Maine is feasible.

Research areas: Water Quality
The effects of long-term climate variability on the trophodynamics of an estuarine ecosystem in southern South America (2015)

The trophodynamics of the Rio de la Plata ecosystem over a long time scale (from 1948 to 2008) were simulated using a food-web model forced by two environmental factors. The Atlantic Meridional Mode (meridional sea surface temperature anomalies) was used as regional forcing, and the Rio de la Plata (RdlP) runoff was applied as local forcing. The entire food web was impacted by the regional forcing on a decadal scale; at the inter-annual scale, this remote factor had partial effects on the base of the food web. The RdlP runoff impacted primary producers and secondary consumers at the inter-annual scale. The higher effects of the local forcing were temporally coupled with seven of the strongest El Nino events from 1950 to 2008 (19571958, 19651966, 19721973, 19821983, 19861987, 19911992, 19971998). In contrast, the lower effects of RdlP runoff on the food web were coupled with six of the strongest La Nina events since 1950 (19501951, 19541956, 1964, 19701971, 19741975, 19881989). Total system biomass (trophic web attribute) and a measure of system entropy (holistic indicator) were used to identify ecosystem degradation. The entropy and total biomass of the RdlP ecosystem showed two opposite phases: before and after the early 1970s. During the period 19481971, the system showed high entropy and low total biomass, indicating high degradation. This cycle was reversed after 1972, and prevailed until the beginning of the 2000s. During this new cycle, the system entropy decreased and it was compensated by an increase in total system biomass. A sustainable entropy gain occurred after 2003, suggesting a new period of ecosystem degradation. The findings are discussed in light of temporal changes in the structural properties of this coastal ecosystem.

Research areas: Ecosystems, Atmospheric/Ocean Indicators