nasa-gesdisc/es-publications-researchareas huggingface dataset:
Diagnostic Properties of Phytoplankton Time Series from Remote Sensing (2010)

Remote sensing provides our only window into the phytoplankton community on synoptic scales, permitting the construction of spatially distributed time series of biomass indexed as chlorophyll concentration. Data from the SeaWiFS mission have accumulated to the point where they meet the criterion of a 10-year series. The seasonal phytoplankton cycle is the dominant mode of temporal variability. The time series can be used to construct a variety of ecological indicators of the pelagic system useful in ecosystem-based management. These are reviewed and examples of their implementation are presented. Phenology of phytoplankton blooms is given particular attention. Interannual variation in some of the indicators is strong, presumably a response to variation in large-scale forcing. Examination of the results in the context of a simple phytoplankton-nutrient model enhances the interpretation. Remote sensing imagery also lends itself to the retrieval of information on community structure, in addition to biomass. More information will be recovered from satellite imagery if the remote-sensing program is coupled closely to a ship program on which appropriate bio-optical observations are made. The data series can be distilled to yield concise descriptions of the unfolding of ecosystem characteristics through time.

Research areas: Ecosystems
Atmospheric Pollution in the Hindu KushHimalaya Region (2012)

This paper presents a detailed review of atmospheric pollution observed in the Hindu KushHimalaya (HKH) region and its implications for regional climate. Data from in situ measurements made at high-altitude stations in the HKH region, observations from satellite-based instruments, and global climate modeling study results are discussed. Experimental observations discussed include both atmospheric measurements and data from snow and ice core sampling from different glaciers in the HKH region. The paper focuses on the atmospheric brown cloud loadings over the Himalayas, particularly black carbon (BC) and ozone, which have links to regional climate and air-pollutionrelated impacts. Studies show elevated levels of anthropogenic ozone and BC over the Himalayas during the pre-monsoon season with concentrations sometimes similar to those observed over an average urban environment. The elevated concentration observed over the Himalayas is thought to come from the lowlands, especially the highly populated areas of the Indo-Gangetic Plains. The implications of high BC loading in the Himalayan atmosphere as well as elevated BC deposition on snow and ice surfaces for regional climate, hydrological cycle, and glacial melt are discussed.

Research areas: Air Quality
Anomalous intraseasonal events in the thermocline ridge region of Southern Tropical Indian Ocean and their regional impacts (2012)

The present study explores the mechanisms responsible for the strong intraseasonal cooling events in the Thermocline Ridge region of the southwestern Indian Ocean. Air sea interface and oceanic processes associated with Madden Julian Oscillation are studied using an Ocean General Circulation Model and satellite observations. Sensitivity experiments are designed to understand the ocean response to intraseasonal forcing with a special emphasis on 2002 cooling events, which recorded the strongest intraseasonal perturbations during the last well-observed decade. This event is characterized by anomalous Walker circulation over the tropical Indian Ocean and persistent intraseasonal heat flux anomaly for a longer duration than is typical for similar events (but without any favorable preconditioning of ocean basic state at the interannual timescale). The model heat budget analysis during 1996 to 2007 revealed an in-phase relationship between atmospheric fluxes associated with Madden Julian Oscillation and the subsurface oceanic processes during the intense cooling events of 2002. The strong convection, reduced shortwave radiation and increased evaporation have contributed to the upper ocean heat loss in addition to the slower propagation of active phase of convection, which supported the integration of longer duration of forcing. The sensitivity experiments revealed that dynamic response of ocean through entrainment at the intraseasonal timescale primarily controls the biological response during the event, with oceanic interannual variability playing a secondary role. This study further speculates the role of oceanic intraseasonal variability in the 2002 droughts over Indian subcontinent.

Research areas: Atmospheric/Ocean Indicators
An inter-comparison of model-simulated eastwest climate gradients over South Africa (2012)

This study examines how the eastwest gradient of climate over South Africa is represented in terms of mean rainfall, tropospheric humidity and circulation, and surface latent heat flux in the satellite era 1980-2001. Inter-comparisons of NCEP2 reanalysis and GPCP satellite-gauge merged rainfall with coupled general circulation model (GCM) simulations from generic CMIP-3 are made, with a focus on the maize belt 25-29S, 25-30E. The summer climatology is analysed for the zonal gradient in vertical atmospheric structure and the annual cycle of rainfall. A wet bias is found in most simulations over the eastern mountains, but in two GCMs (CSM3, PCM) it extends over the western plateau. The east-west gradient in vegetation affects the vertical flux of surface moisture into the atmosphere. ECMWF reanalysis and SAFARI-2000 flux tower data reveal that this process is triggered during daytime heating, so model ability to handle the diurnal cycle is crucial. Inter-annual variability is briefly studied and two operational ensemble models (CFS and ECHAM4) simulate and forecast summer rainfall variations with positive correlation to observed values. The AIRS satellite night and day relative humidity structure is contrasted for dry and wet January months. All five generic CMIP-3 models: GFDL2, CSM3, PCM, HADen, ECHAM4 project a drying trend in the maize area over the period 20002050, using the SRES A1B scenario. Recommendations for observing the surface and mixed layer moisture fluxes are given.

Research areas: Validation
An assessment of the surface longwave direct radiative effect of airborne dust in Zhangye, China, during the Asian Monsoon Years field experiment (2008) (2012)

In AprilJune 2008, NASA Goddard's ground-based mobile laboratories (SMART-COMMIT) were deployed to Zhangye China (39.0N; 101W) to support the Asian Monsoon Years field experiment and the East Asian Study of Tropospheric Aerosols and Impact on Regional Climate. One of the primary objectives at Zhangye, a semi-arid region located between the Taklimakan and Gobi Deserts, was to capture and characterize dust aerosols near the source and to quantify their direct radiative effects (DRE). A regional dust optical model was constructed by combining previously measured soil mineralogy data at Zhangye with COMMIT's particle microphysical measurements. During a 2-week period of heightened dust activity, retrieved longwave (LW) aerosol optical thickness () from SMART's Atmospheric Emitted Radiance Interferometer was used in the Fu-Liou radiative transfer model to derive LW instantaneous DRE (DRELW) at the surface, top of atmosphere, and heating rate profiles for cloud-free conditions. Conservatively, surface instantaneous DRELW and LW forcing efficiency range from about 220 Wm2 and 3135 Wm21 (0    0.83), respectively. The significance of DRELWrelative to its shortwave counterpart was estimated to be between 51 and 58%, but of opposite sign, partly compensating shortwave surface cooling. Compared to Saharan dust observed during the NAMMA-2006 field experiment at Cape Verde, dust LW forcing efficiency for this study was found to be a factor of two larger stemming from differences in environmental and surface conditions, aerosol absorption, and Zhangye's close proximity to major desert sources. Relative to observed and modeled ranges in surface DRELW for clouds (3080 Wm2) and greenhouse gases (2 Wm2), this study's upper range in DRELW represents a significant perturbation to the climate system with important implications for better understanding regional changes in surface temperatures and moisture budgets.

Research areas: Validation
A case study of the association of total ozone variability with major earthquakes in Greece during 20012010 (2012)

Recent studies have suggested that variation of the total ozone content may be a precursor tool for earthquake forecasts. The main aim of this analysis is to examine whether the total ozone variability before and after the eight large earthquakes (M w  6.0) of the decade 20012010 in Greece could be related with these earthquake events. The results clearly show that the association of total ozone fluctuation with earthquake occurrence in the time window of 2 weeks before and after each of these large earthquake events is not statistically significant.

Research areas: Earthquakes
Analysis of optical and physical properties of aerosols during crop residue burning event of October 2010 over Lahore, Pakistan (2015)

Aerosols released from biomass burning affect the tropospheric chemistry, radiation budget and cloud processes and hence can cause significant climate modifications. Due to certain economical reasons, the open burning of crop residue has become popular in Pakistan. In the present work we have analyzed the optical and physical properties of aerosols during crop residue burning over Lahore, a central location of Pakistan. The data from ground based Aerosol Robotic Network (AERONET), satellite based MODIS and CALIPSO remote sensing instruments have been used for the characterization of aerosols during crop residue burning event of October 2010. The maximum value (2.75) of daily mean AOD was observed on 20 October 2010 and the next highest value of 2.64 was observed on 19 October 2010, indicating heavy aerosol loading over Lahore on both days due to intense crop residue burning. The fine mode AOD values ranged from 0.14 to 2.68 (on 20 October 2010) with average value of 0.87 during October 2010 over Lahore. It was found that fine mode aerosols have greater contribution than coarse mode aerosols towards total aerosol burden indicating the presence of fine mode (crop residue burning) aerosols over Lahore. Cluster analysis showed that the mixed aerosols (biomass burning and urban-industrial) were present during the heavy aerosol loading period over Lahore. The highest volume concentration of fine mode occurred on 19 and 20 October 2010 representing the dominance of fine mode aerosols. Due to scattering of incoming solar radiation by intense smoke observed on 19 and 20 October 2010 high values of SSA (0.95) were found. HYSPLIT model backward trajectories showed that the winds transported aerosols from southeast and northwest directions.

Research areas: Environmental Impacts
An improved methodology for deriving high-resolution surface shortwave radiative fluxes from MODIS in the Arctic region (2015)

The Arctic is experiencing an unprecedented increase in surface air temperature and decrease in sea ice extent. The causes of these changes are still being debated; radiative fluxes are believed to play an important role in this warming. The primary motivation for this study is to advance the quality and resolution of currently available information on surface shortwave (solar) irradiance (SWR) for the Arctic. Such information is needed to meet the challenge for accurate estimates of heat input into the open waters. An inference scheme that utilizes the Moderate Resolution Imaging Spectroradiometer (MODIS) observations is optimized for high latitudes and implemented at 5 km for 2007 at an hourly time scale. Evaluation of the 5 km based SWR estimates against hourly ground observations at Barrow site shows a mean bias of 7.9 W m2 (3% of mean values), a standard deviation of 58.2 W m2 (23% of mean value), and a high correlation of 0.95. Evaluation of the SWR estimates against daily ground measurements at these latitudes shows good agreement with surface observations at three sites, with a mean bias of 1.9 W m2 (1.1% of mean values), a standard deviation of 31.5 W m2 (17.8% of mean value), and a high correlation of 0.96. Information at this high resolution and good quality can lead to improved estimates of heat input into the complex Arctic domain. For the Beaufort Sea domain (70N80N, 120E50E), the differences can amount to 116 MJ m2 ( 7%) of the total solar input of this region.

Research areas: Sun-Earth Interactions, Cryospheric Indicators
Aerosols and Temperature Rise in the Northwestern Himalaya, India (2015)

Aerosols, the important constituents of our atmosphere, indicate a colloidal system of particulate, gaseous and volatile organic compounds. Aerosols play a significant role in affecting adversely the radiative balance of the Earth as well as the air temperature . Moreover, these not only influence the visibility and overall air quality, but also adversely affect health of living organisms in an ecosystem. In this context, the present attempt at Mohal (1,154 m, 77.12E, 31.91N) in the Kullu valley of Himachal Pradesh in the northwestern Himalayan region explains the ever increasing columnar aerosols, their relationship with black carbon (BC) aerosols, impact of local meteorological conditions, long range transport sources and their collective impact on radiative forcing and resultant temperature rise. The aerosol optical depth (AOD) having been under observation for the last half a decade (20062010) shows higher values at shorter wavelengths and lower at longer wavelengths. At a representative wavelength of 500 nm, AOD is found to be increasing at the rate of 1.9 % per annum from 2006 to 2010. Overall, AOD values in all the wavelengths (3801,025 nm) were found between 0.2380.242, reflecting an increasing trend at the rate of 0.84 % per annum. The monthly mean concentration of BC aerosols is noticed maximum with 6,617 ng m3 in January, 2010. The pollution loads in terms of AOD values translate into a temperature rise by ~0.54 K day1. The local as well as transported aerosols together contribute to the existing aerosols in the present study region. The local sources possibly belong to anthropogenic aerosols including vehicular emissions, biomass burning (like fuel wood for cooking), forest fires, open waste burning, etc. While the transported aerosols most probably include fine mineral dust from the desert regions and the sulphate aerosol from the oceanic regions with the movement of air masses prior to the western disturbances and monsoonal winds in the region.

Research areas: Air Quality, Environmental Impacts
A new tool for predicting drought: An application over India (2015)

This is the first attempt of application of atmospheric electricity for rainfall prediction. The atmospheric electrical columnar resistance based on the model calculations involving satellite data has been proposed as a new predictor. It is physically sound, simple to calculate and not probabilistic like the standardized precipitation index. After applying this new predictor over India, it has been found that the data solely over the Bay of Bengal (BB) are sufficient to predict a drought over the country as a whole. Finally, two independent new methods to predict drought conditions and a preliminary forecast of the same for India for year 2014 have been given. Unlike the existing drought prediction techniques, the identification of drought conditions in a pre-drought year during 19811990 and 20012013 over India has been achieved 100% successfully using the suggested new methods. The association between rainfall and this new predictor has also been found on the sub-regional scale. So, the present predictor is expected to get global application and application in climate models. From the analysis, generally, a long period rising trend in aerosol concentration over the BB causes weak monsoon over India but that for a short time i.e. in pre-monsoon period strengthens it.

Research areas: Droughts
Complementary nature of surface and atmospheric parameters associated with Haiti earthquake of 12 January 2010 (2010)

Abstract. The present paper describes surface (surface air temperature) and atmospheric parameters (relative humidity, surface latent heat flux) over the epicenter (1827 25   N 7231 59   W) of Haiti earthquake of 12 January 2010. Our analysis shows pronounced changes in surface and atmospheric parameters few days prior to the main earthquake event. Changes in relative humidity are found from the surface up to an altitude of 500 hPa clearly show atmospheric perturbations associated with the earthquake event. The purpose of this paper is to show complementary nature of the changes observed in surface, atmospheric and meteorological parameters. The total ozone concentration is found to be lowest on the day of earthquake and afterwards found to be increased within a week of earthquake. The present results show existence of coupling between lithosphere-atmosphere associated with the deadly Haiti earthquake.

Research areas: Earthquakes
At-sea Observations of Marine Birds and Their Habitats before and after the 2008 Eruption of Kasatochi Volcano, Alaska (2010)

Kasatochi volcano, an island volcano in the Aleutian chain, erupted on 78 August 2008. The resulting ash and pyroclastic flows blanketed the island, covering terrestrial habitats. We surveyed the marine environment surrounding Kasatochi Island in June and July of 2009 to document changes in abundance or distribution of nutrients, fish, and marine birds near the island when compared to patterns observed on earlier surveys conducted in 1996 and 2003. Analysis of SeaWiFS satellite imagery indicated that a large chlorophyll-a anomaly may have been the result of ash fertilization during the eruption. We found no evidence of continuing marine fertilization from terrestrial runoff 10 months after the eruption. At-sea surveys in June 2009 established that the most common species of seabirds at Kasatochi prior to the eruption, namely crested auklets (Aethia cristatella) and least auklets (Aethia pusilla) had returned to Kasatochi in relatively high numbers. Densities from more extensive surveys in July 2009 were compared with pre-eruption densities around Kasatochi and neighboring Ulak and Koniuji islands, but we found no evidence of an eruption effect. Crested and least auklet populations were not significantly reduced by the initial explosion and they returned to attempt breeding in 2009, even though nesting habitat had been rendered unusable. Maps of pre- and post-eruption seabird distribution anomalies indicated considerable variation, but we found no evidence that observed distributions were affected by the 2008 eruption.

Research areas: Volcanic Eruptions, Ecosystems
Trans-Pacific transport of Asian dust and CO: accumulation of biomass burning CO in the subtropics and dipole structure of transport (2009)

Abstract. In May 2003, both MODIS aerosol optical depth (AOD) and carbon monoxide (CO) measurements from MOPITT show significant trans-Pacific transport to North America. We apply the global chemical transport model, GEOS-Chem, to analyze the main features of the long-range transport events. Enhancements of MOPITT CO over the tropical Pacific are much broader than MODIS AOD enhancements. We find in model simulations that a substantial fraction of the CO enhancements in the subtropics in May is due to biomass burning in Southeast Asia in April. Biomass burning CO was recirculated into the subtropical high-pressure system and lingered for a much longer period than aerosols transported at higher latitudes. Simulated AOD enhancements are due to a combination of dust, sulfate, and organic and elemental carbons. Dust contribution dominates the AOD enhancements in early May. Model results indicate that dust transport takes place at higher altitude than the other aerosols. MODIS observations indicate a bias in model simulated pathway of dust AOD transport. Sensitivities of dust transport pathways are analyzed in the model. The dipole structure of transport over the Pacific is found to be the key factor leading to the high sensitivity of simulated transport pathways to source location and wind field.

Research areas: Environmental Impacts
The effects of wind and rainfall on suspended sediment concentration related to the 2004 Indian Ocean tsunami (2009)

The effects of rainfall and wind speed on the dynamics of suspended sediment concentration (SSC), during the 2004 Indian Ocean tsunami, were analyzed using spatial statistical models. The results showed a positive effect of wind speed on SSC, and inconsistent effects (positive and negative) of rainfall on SSC. The effects of wind speed and rainfall on SSC weakened immediately around the tsunami, indicating tsunami-caused floods and earthquake-induced shaking may have suddenly disturbed the oceanatmosphere interaction processes, and thus weakened the effects of wind speed and rainfall on SSC. Wind speed and rainfall increased markedly, and reached their maximum values immediately after the tsunami week. Rainfall at this particular week exceeded twice the average for the same period over the previous 4years. The tsunami-affected airsea interactions may have increased both wind speed and rainfall immediately after the tsunami week, which directly lead to the variations in SSC.

Research areas: Earthquakes
Strontium isotopes and major ion chemistry in the Chambal River system, India: Implications to silicate erosion rates of the Ganga (2009)

The dissolved concentrations of major ions and Sr isotopes (87Sr/86Sr) were measured in the headwaters of the Chambal river and its tributaries draining the Deccan Trap basalts and the Vindhyan sediments of peninsular India. The total dissolved solids (TDS) ranged from 181 to 547 mg L1; much higher than the global mean river water. A significant fraction of solute abundance in the Chambal river is derived from sodium salts, unlike the Himalayan rivers which exhibit dominance of (Ca+Mg) salts. It is estimated that the Chambal river supplies about one-third of sodium via the Yamuna to the Ganga at Rajshahi (Bangladesh), with only 6.5% of water discharge. The presence of Na salts not associated with chloride in the Chambal headwaters constraints the application of Na (Na corrected for Cl) as an index of silicate derived component. This finding brings out the need to revisit the estimates of silicate erosion rate (SER) and associated CO2 consumption in the Ganga basin, downstream Allahabad, based on Na as an index. The Sr concentration in the Chambal tributaries varied from 1.9 M to 5.9 M and 87Sr/86Sr ratio from 0.70923 to 0.71219. Unlike the Himalayan Rivers, Sr isotope composition in the Chambal river is far less radiogenic as the major sources of Sr to the Chambal are the Deccan Trap basalts and the Vindhyan sediments, which are low in 87Sr/86Sr. The Sr isotope budget of the Ganga, based on available data of the Chambal, Betwa, Ken, Yamuna and the Ganga shows that, weathering of the Deccan Trap basalts and the Vindhyan sediments (the drainage basin of the Chambal, Betwa and the Ken) contribute 70% of the dissolved Sr to the Ganga at Varanasi. This study highlights the key role of peninsular rivers draining the Deccan and the Vindhyan regions in the major ion and Sr budget of the Ganga.

Research areas: Land Surface/Agriculture Indicators