nasa-gesdisc/es-publications-researchareas huggingface dataset:
Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait (2010)

Phytoplankton blooms appear in winter (NovJan) in the southwest of Luzon Strait, South China Sea, which is an oligotrophic region in general. To understand dynamic features of the winter phytoplankton bloom southwest of Luzon Strait, this study analyzes seven years (20002006) of remote sensing data of Chlorophyll a, sea surface temperature, and ocean vector winds, along with in situ observations of dissolved oxygen, nutrients (nitrate, phosphate, and silicate), and physical oceanographic parameters mixed layer depth, Ekman pumping velocity, and entrainment velocity. The results demonstrate that the winter phytoplankton bloom in the southwest of Luzon Strait is primarily induced by both Ekman pumping-driven upwelling (observed at about 50m under sea surface) and upper mixed layer entrainment. The area of winter phytoplankton blooms is about 2.58104km2, based on Empirical Orthogonal Function analysis. The seasonal variability of the bloom is associated with monsoonal wind forcing.

Research areas: Ecosystems, Atmospheric/Ocean Indicators
Volcanic ash fuels anomalous plankton bloom in subarctic northeast Pacific (2010)

Using multiple lines of evidence, we demonstrate that volcanic ash deposition in August 2008 initiated one of the largest phytoplankton blooms observed in the subarctic North Pacific. Unusually widespread transport from a volcanic eruption in the Aleutian Islands, Alaska deposited ash over much of the subarctic NE Pacific, followed by large increases in satellite chlorophyll. Surface ocean pCO2, pH, and fluorescence reveal that the bloom started a few days after ashfall. Ship-based measurements showed increased dominance by diatoms. This evidence points toward fertilization of this normally iron-limited region by ash, a relatively new mechanism proposed for iron supply to the ocean. The observations do not support other possible mechanisms. Extrapolation of the pCO2 data to the area of the bloom suggests a modest 0.01 Pg carbon export from this event, implying that even large-scale iron fertilization at an optimum time of year is not very efficient at sequestering atmospheric CO2.

Research areas: Ecosystems, Volcanic Eruptions
Variations in surface ozone at Nainital: A high-altitude site in the central Himalayas (2010)

Surface ozone measurements have been made for the first time at Nainital (29.37N, 79.45E, 1958 m amsl), a high-altitude site in the central Himalayas, between October 2006 and December 2008. Diurnal variations in ozone do not show the daytime photochemical build-up typical of urban or rural sites. The seasonal variation shows a distinct ozone maximum in late spring (May; 67.2  14.2 ppbv) with values sometimes exceeding 100 ppbv and a minimum in the summer/monsoon season (August; 24.9  8.4 ppbv). Springtime ozone values in the central Himalayas are significantly higher than those at another high-altitude site (Mt. Abu) in the western part of India. Seasonal variations in ozone and the processes responsible for the springtime peak are studied using meteorological parameters, insolation, spatial and temporal classifications of air mass trajectories, fire counts, and simulations with a chemical transport model. Net ozone production over the Northern Indian Subcontinent in regionally polluted air masses is estimated to be 3.2 ppbv/day in spring but no clear build-up is seen at other times of year. Annual average ozone values in regionally polluted air masses (47.1  16.7 ppbv) and on high insolation days (46.8  17.3 ppbv) are similar. Background ozone levels are estimated to be 3035 ppbv. Regional pollution is shown to have maximum contribution (16.5 ppbv) to ozone levels during MayJune and is about 7 ppbv on an annual basis, while the contribution of long-range transport is greatest during JanuaryMarch (811 ppbv). The modeled stratospheric ozone contribution is 216 ppbv. Both the trajectory analysis and the model suggest that the stratospheric contribution is 46 ppbv greater than the contribution from regional pollution. Differences in the seasonal variation of ozone over high-altitude sites in the central Himalayas (Nainital) and western India (Mt. Abu) suggest diverse regional emission sources in India and highlight the large spatial and temporal variability in ozone over the Indian region.

Research areas: Air Quality
Tropospheric ozone variations at the Nepal Climate Observatory-Pyramid (Himalayas, 5079 m a.s.l.) and influence of deep stratospheric intrusion events (2010)

Abstract. The paper presents the first 2 years of continuous surface ozone (O3) observations and systematic assessment of the influence of stratospheric intrusions (SI) at the Nepal Climate Observatory at Pyramid (NCO-P; 2757' N, 8648' E), located in the southern Himalayas at 5079 m a.s.l.. Continuous O3 monitoring has been carried out at this GAW-WMO station in the framework of the Ev-K2-CNR SHARE and UNEP ABC projects since March 2006. Over the period March 2006February 2008, an average O3 value of 4912 ppbv (1) was recorded, with a large annual cycle characterized by a maximum during the pre-monsoon (619 ppbv) and a minimum during the monsoon (3910 ppbv). In general, the average O3 diurnal cycles had different shapes in the different seasons, suggesting an important interaction between the synoptic-scale circulation and the local mountain wind regime.  Short-term O3 behaviour in the middle/lower troposphere (e.g. at the altitude level of NCO-P) can be significantly affected by deep SI which, representing one of the most important natural input for tropospheric O3, can also influence the regional atmosphere radiative forcing. To identify days possibly influenced by SI at the NCO-P, a specially designed statistical methodology was applied to the time series of observed and modelled stratospheric tracers. On this basis, during the 2-year investigation, 14.1% of analysed days were found to be affected by SI. The SI frequency showed a clear seasonal cycle, with minimum during the summer monsoon (1.2%) and higher values during the rest of the year (21.5%). As suggested by back-trajectory analysis, the position of the subtropical jet stream could play an important role in determining the occurrence of deep SI transport on the southern Himalayas.  We estimated the fraction of O3 due to SI at the NCO-P. This analysis led to the conclusion that during SI O3 significantly increased by 27.1% (+13 ppbv) with respect to periods not affected by such events. Moreover, the integral contribution of SI (O3S) to O3 at the NCO-P was also calculated, showing that up to 13.7% of O3 recorded at the measurement site could be possibly attributed to SI. On a seasonal basis, the lowest SI contributions were found during the summer monsoon (less than 0.1%), while the highest were found during the winter period (up to 24.2%). Even considering the rather large uncertainty associated with these estimates, the obtained results indicated that, during non-monsoon periods, high O3 levels could affect NCO-P during SI, thus influencing the variability of tropospheric O3 over the southern Himalayas.

Research areas: Air Quality, Atmospheric/Ocean Indicators
Tracking Cholera in Coastal Regions Using Satellite Observations1 (2010)

Jutla, Antarpreet S., Ali S. Akanda, and Shafiqul Islam, 2010. Tracking Cholera in Coastal Regions Using Satellite Observations. Journal of the American Water Resources Association (JAWRA) 46(4): 651-662. DOI: 10.1111/j.1752-1688.2010.00448.x Abstract: Cholera remains a significant health threat across the globe. The pattern and magnitude of the seven global pandemics suggest that cholera outbreaks primarily originate in coastal regions and then spread inland through secondary means. Cholera bacteria show strong association with plankton abundance in coastal ecosystems. This review study investigates the relationship(s) between cholera incidence and coastal processes and explores utility of using remote sensing data to track coastal plankton blooms, using chlorophyll as a surrogate variable for plankton abundance, and subsequent cholera outbreaks. Most studies over the last several decades have primarily focused on the microbiological and epidemiological understanding of cholera outbreaks. Accurate identification and mechanistic understanding of large scale climatic, geophysical, and oceanic processes governing cholera-chlorophyll relationship is important for developing cholera prediction models. Development of a holistic understanding of these processes requires long and reliable chlorophyll datasets, which are beginning to be available through satellites. We have presented a schematic pathway and a modeling framework that relate cholera with various hydroclimatic and oceanic variables for understanding disease dynamics using the latest advances in remote sensing. Satellite data, with its unprecedented spatial and temporal coverage, have potentials to monitor coastal processes and track cholera outbreaks in endemic regions.

Research areas: Public Health, Ecosystems
Towards malaria risk prediction in Afghanistan using remote sensing (2010)

Malaria is a significant public health concern in Afghanistan. Currently, approximately 60% of the population, or nearly 14 million people, live in a malaria-endemic area. Afghanistan's diverse landscape and terrain contributes to the heterogeneous malaria prevalence across the country. Understanding the role of environmental variables on malaria transmission can further the effort for malaria control programme.

Research areas: Public Health
Timescales of lateral sediment transport in the Panama Basin as revealed by radiocarbon ages of alkenones, total organic carbon and foraminifera (2010)

Paired radiocarbon measurements on haptophyte biomarkers (alkenones) and on co-occurring tests of planktic foraminifera (Neogloboquadrina dutertrei and Globogerinoides sacculifer) from late glacial to Holocene sediments at core locations ME0005-24JC, Y69-71P, and MC16 from the south-western and central Panama Basin indicate no significant addition of pre-aged alkenones by lateral advection. The strong temporal correspondence between alkenones, foraminifera and total organic carbon (TOC) also implies negligible contributions of aged terrigenous material. Considering controversial evidence for sediment redistribution in previous studies of these sites, our data imply that the laterally supplied material cannot stem from remobilization of substantially aged sediments. Transport, if any, requires syn-depositional nepheloid layer transport and redistribution of low-density or fine-grained components within decades of particle formation. Such rapid and local transport minimizes the potential for temporal decoupling of proxies residing in different grain-size fractions and thus facilitates comparison of various proxies for paleoceanographic reconstructions in this study area. Anomalously old foraminiferal tests from a glacial depth interval of core Y69-71P may result from episodic spillover of fast bottom currents across the Carnegie Ridge transporting foraminiferal sands towards the north.

Research areas: Land Surface/Agriculture Indicators
The Ocean-Sea Ice-Atmosphere System of the Hudson Bay Complex (2010)

Arctic marine water, vast inputs of fresh water, nearly complete seasonal ice cover, and dynamic coastal morphology make the Hudson Bay (HB) complex remarkable among the worlds large marine areas (LMEs). Each of these features is influenced by the climate. Together they enable Foxe Basin, Hudson Strait, Ungava Bay, Hudson Bay and James Bay which comprise the HB complex, to support a well developed Arctic marine food web far south of its normal range. The life history characteristics that enable biota to thrive in the region also make them sensitive and vulnerable to changes in the seasonal ice cover, freshwater inputs, and/or water levels that can stem from changes in climate.This introductory chapter summarizes current understanding of the physical, chemical, and biological conditions in the HB complex. It also provides examples of how some of the key climate-sensitive oceanographic parameters influence species ecology. The level of research effort in this region has been low relative to the Atlantic and Pacific coasts of Canada. This limits understanding and modeling of many key processes, particularly with respect to seasonal and inter-annual change. It also limits the differentiation of natural cyclical changes from those that are anthropogenically-driven and systematic. Over the coming decades, long-term, stable research will be required to better predict and mitigate the impacts of climate change, a growing human population, hydroelectric and non-renewable resource developments, shipping, and the long range transport of contaminants on this fascinating and potentially vulnerable ecosystem.

Research areas: Cryospheric Indicators, Atmospheric/Ocean Indicators, Ecosystems
The influence of mixing on primary productivity: A unique application of classical critical depth theory (2010)

Mixing and primary productivity was examined in upwelling influenced nearshore waters off south western Eyre Peninsula (SWEP) in the eastern Great Australian Bight (EGAB), the economically and ecologically important shelf region off southern Australia that forms part of the Southern and Indian oceans. Mixing/stratification in the region was highly temporally variable with a unique upwelling circulation in summer/autumn (NovemberApril), and downwelling through winter/spring (MaySeptember). Highest productivity was associated with upwelled/stratified water (up to 2958mgCm2d1), with low productivity during periods of downwelling and mixing (300550mgCm2d1), yet no major variations in macro-nutrient concentrations were detected between upwelling and downwelling events (silica>1molL1, nitrate/nitrite>0.4molL1, phosphate>0.1molL1). We hypothesise that upwelling enriches the region with micro-nutrients. High productivity off SWEP appears to be driven by a shallowing of mixed layer depth due to the injection of upwelled waters above Zcr. Low productivity follows the suppression of enrichment during downwelling/mixing events, and is exacerbated in winter/spring by low irradiances and short daylengths.

Research areas: Ecosystems, Atmospheric/Ocean Indicators
The impact of soil moisture modifications on CBL characteristics in West Africa: A case-study from the AMMA campaign (2010)

Within the framework of the AMMA campaign in 2006, the response of surface properties to precipitation and their effect on the state of the convective boundary layer (CBL) and on convective instability were analysed. The observation periods covered the pre-monsoon onset (SOP 1) and the mature monsoon phase (SOP 2) and were performed in southwest Burkina Faso. Precipitation caused a distinctive increase in the volumetric soil moisture content in the upper 20 cm of the soil. Coupled with the increase in soil moisture, a continuous decrease of surface and soil temperature with time was observed. Changes in surface temperature, albedo, and a higher availability of water affected the partitioning of the energy balance. Highest values of the Bowen ratio were found during SOP 1 when the surface was dry and vegetation sparse. In SOP 2, a higher vegetation cover made the albedo and Bowen ratio less sensitive to changes in soil moisture. Modifications of surface fluxes influenced the CBL conditions. The CBL height in SOP 1 was 1658 m and in SOP 2 877 m. The heat budget of the CBL was dominated by sensible heat flux convergence, whereas the moisture budget was controlled by both advection and latent heat flux convergence. It was confirmed by the measurements that the diurnal development of convective instability was dominated by the CBL evolution and controlled by changes in the mid- or upper troposphere to a minor degree only. Linear correlations were found between the near-surface equivalent potential temperature and both convective available potential energy and convection index. Copyright  2009 Royal Meteorological Society

Research areas: Land Surface/Agriculture Indicators, Atmospheric/Ocean Indicators
The impact of mesoscale convective systems on the surface and boundary-layer structure in West Africa: Case-studies from the AMMA campaign 2006 (2010)

Within the framework of the AMMA project, atmospheric, surface and soil observations were performed during the pre-onset phase of the monsoon (Special Observing Period SOP 1) and during the summer monsoon (SOP 2) in 2006. Based on several case-studies the paper investigates the impact of mesoscale convective systems (MCSs) on the surface and boundary layer (PBL), the recovery time of the surface and the PBL after MCS passages, and the differences between the two monsoon phases. In the pre-MCS environment the mean conditional and convective instabilities were higher in SOP 1 than in SOP 2 (e.g. CAPE = 1815 J kg1 and CAPE = 1295 J kg1, respectively). In both monsoon phases these instabilities, which were strongly reduced by MCSs, recovered within less than 2 days. Precipitation of the MCSs and the resulting soil moisture increase caused a significant decrease in the surface temperature by up to 10 K and an increase in evapotranspiration by up to 2.5 mm d1. In both phases of the monsoon, these surface anomalies and, hence, the conditions favourable for triggering MCSs by thermally induced circulation systems, diminished largely within 2 to 3 days. Due to the repeated passage of the first MCSs at intervals of a few days during SOP 1, the surface properties exhibited trends towards higher soil moisture, evapotranspiration and humidity, and lower albedo, temperature and Bowen ratio. After two weeks only, the mean conditions present in the summer monsoon were reached. In SOP 2 no significant trends could be detected. Copyright  2010 Royal Meteorological Society

Research areas: Land Surface/Agriculture Indicators, Atmospheric/Ocean Indicators
The Gulf: A young sea in decline (2010)

This review examines the substantial changes that have taken place in marine habitats and resources of the Gulf over the past decade. The habitats are especially interesting because of the naturally high levels of temperature and salinity stress they experience, which is important in a changing world climate. However, the extent of all natural habitats is changing and their condition deteriorating because of the rapid development of the region and, in some cases from severe, episodic warming episodes. Major impacts come from numerous industrial, infrastructure-based, and residential and tourism development activities, which together combine, synergistically in some cases, to cause the observed deterioration in most benthic habitats. Substantial sea bottom dredging for material and its deposition in shallow water to extend land or to form a basis for huge developments, directly removes large areas of shallow, productive habitat, though in some cases the most important effect is the accompanying sedimentation or changes to water flows and conditions. The large scale of the activities compared to the relatively shallow and small size of the water body is a particularly important issue. Important from the perspective of controlling damaging effects is the limited cross-border collaboration and even intra-country collaboration among government agencies and large projects. Along with the accumulative nature of impacts that occur, even where each project receives environmental assessment or attention, each is treated more or less alone, rarely in combination. However, their combination in such a small, biologically interacting sea exacerbates the overall deterioration. Very few similar areas exist which face such a high concentration of disturbance, and the prognosis for the Gulf continuing to provide abundant natural resources is poor.

Research areas: Ecosystems, Habitat Conversion/Fragmentation
The combined use of satellite data, air-mass trajectories and model applications for monitoring dust transport over Athens, Greece (2010)

This study focused on Saharan dust (SD) events over Athens, Greece, based on measurements of the daily aerosol optical depth at 550 nm (AOD550) and the fine-mode fraction (FM) derived from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations. Back-trajectories ending at Athens at altitudes of 500, 1000 and 4000 m were calculated by means of the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Several criteria were taken into account to identify the SD events. According to these criteria and the altitudes of the air masses, three dust transport mechanisms were identified: (1) vertical transport (VT), including the whole atmospheric column, (2) upper atmosphere transport (UAT), above the atmospheric boundary layer, and (3) boundary layer transport (BLT), only within the lower atmospheric levels. The Aerosol Index (AI) derived from Total Ozone Mapping Spectrometer (TOMS) data was found to be adequate for characterization of the dust load over Athens, while higher values of the AI were found in cases where the dust was transported in the upper atmosphere. The predictions of the Dust Regional Atmospheric Model (DREAM) were consistent with the satellite observations and back trajectories, indicating the suitability of the model for monitoring dust transport over the Mediterranean. The analysis presents three case studies, one for each transport mechanism, where the aerosol field deduced from satellites and models is presented over the Eastern Mediterranean. In conclusion, this study shows that the combination of remote sensing measurements and back-trajectory calculations constitutes a powerful tool for the identification of SD events over Athens, while modelling can monitor the spread of the dust.

Research areas: Air Quality
The Arabian Sea as a high-nutrient, low-chlorophyll region during the late Southwest Monsoon (2010)

Abstract. Extensive observations were made during the late Southwest Monsoon of 2004 over the Indian and Omani shelves, and along a transect that extended from the southern coast of Oman to the central west coast of India, tracking the southern leg of the US JGOFS expedition (19941995) in the west. The data are used, in conjunction with satellite-derived data, to investigate long-term trends in chlorophyll and sea surface temperature, indicators of upwelling intensity, and to understand factors that control primary production (PP) in the Arabian Sea, focussing on the role of iron. Our results do not support an intensification of upwelling in the western Arabian Sea, reported to have been caused by the decline in the winter/spring Eurasian snow cover since 1997. We also noticed, for the first time, an unexpected development of high-nutrient, low-chlorophyll condition off the southern Omani coast. This feature, coupled with other characteristics of the system, such as a narrow shelf and relatively low iron concentrations in surface waters, suggest a close similarity between the Omani upwelling system and the Peruvian and California upwelling systems, where PP is limited by iron. Iron limitation of PP may complicate simple relationship between upwelling and PP assumed by previous workers, and contribute to the anomalous offshore occurrence of the most severe oxygen (O2) depletion in the region. Over the much wider Indian shelf, which experiences large-scale bottom water O2-depletion in summer, adequate iron supply from reducing bottom-waters and sediments seems to support moderately high PP; however, such production is restricted to the thin, oxygenated surface layer, probably because of the unsuitability of the O2-depleted environment for the growth of oxygenic photosynthesizers.

Research areas: Ecosystems, Atmospheric/Ocean Indicators