nasa-gesdisc/es-publications-researchareas huggingface dataset:
Profiles of the atmospheric temperature response to the Saharan dust outbreaks derived from FORMOSAT-3/COSMIC and OMI AI (2010)

Based on the data from the Formosa (Taiwan) Satellite (FORMOSAT)-3/Constellation Observing System for the Meteorology, Ionosphere, and Climate (COSMIC), combined with the Ozone Monitoring Instrument (OMI) aerosol index (AI) and reflectivity, this work calculates profiles of the atmospheric temperature response to Saharan dust outbreaks (SDOs), which is one component of the Saharan Air Layer (SAL) over the North Atlantic marine boundary layer. Our results show that warming of the SAL occurs below 5km, with maximum warming located at 23km altitude. The warming of the atmosphere below 5km and above the surface also shows positive correlation between the OMI AI values and the 23km maximum warming temperatures. Cooling in the upper troposphere occurs at 57km altitudes and only appears in late summer months (JulyAugust). The amount and the vertical extent of the cooling depend on the amount of the OMI AI values. These analyses seem to support the cooling hypothesis of Dunion and Marron (2008) for the atmospheric layer about the SAL: that elevated dust loading leads to enhanced warming in the SAL, which leads to more strong vertical ascent and adiabatic cooling in the upper troposphere; and more dust loading leads to more net radiative cooling in the layer above the SAL. The net cooling of the SAL in the lower troposphere appears to be limited to close to the surface. Hence, our analysis shows that temporal variation of the vertical extent of the warming and cooling of the atmosphere due to the SAL is a complex function of the time and the amount of dust loading associated with the SAL. In this work we provide a very strong observational evidence, based upon the new FS3/C constellation, of the thermal impact of Saharan dust. In particular, we demonstrate that the surface cooling consequent to high optical thickness (and corresponding to a low level  about 2km  heating) which was hypothesized by previous work on theoretical background, is actually very real.

Research areas: Atmospheric/Ocean Indicators
Precursory signals using satellite and ground data associated with the Wenchuan Earthquake of 12 May 2008 (2010)

Multi-satellite sensor and ground observation data were analysed soon after the Wenchuan Earthquake of magnitude 7.9 (according to the USGS) or 8.0 (according to Xinhua, the Chinese News Agency) that occurred on 12 May 2008. This earthquake was felt by millions of people living in a number of countries; it took 65 000 lives and made millions of people homeless, damaged small and large infrastructure, and large surface manifestations were observed on the surface. Soon after the earthquake multi-satellite sensor and ground observatory data were analysed to study changes in ground, meteorological and atmospheric parameters. A detailed analysis of these data shows pronounced anomalous changes prior to the Wenchuan Earthquake event. Analysis of Atmospheric InfraRed Sounder (AIRS) data at different pressure levels clearly shows characteristic behaviour of the air temperature and relative humidity compared to other days. Such changes are observed up to 500 hPa, with maximal change at the lower levels. Changes in the surface, atmosphere, meteorological and ionospheric parameters prior to the Wenchuan Earthquake are complementary to one another and show the existence of a strong coupling between land, atmosphere and ionosphere, associated with the Wenchuan Earthquake.

Research areas: Earthquakes
Potential source regions of biogenic aerosol number concentration apportioning at King George Island, Antarctic Peninsula (2010)

Nowadays it is well accepted that background aerosols in the boundary layer over remote oceans are of marine origin and not aged continental. Particularly in the Atlantic sector of the Southern Ocean at least four main important regions exhibit significant ocean primary productivity. They are the BellingshausenAmundsen Sea, the Weddell Sea, the southern Argentinean shelf and the southern Chilean coast. In this work, we have combined ground-based continuous atmospheric sampling of aerosol number concentration (ANC), over-sea dimethyl sulphide (DMS) measurements, chlorophyll a (chl a) concentration provided by Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite images, in situ meteorological data and monthly regional NCEP-NCAR re-analysis wind fields in order to investigate the relative contribution of each of the above regions to the apportionment of the ANC at King George Island (KGI), South Shetland Islands. Our results suggest that, at least during the period from September 1998December 1999, the southern Argentinean shelf acted as the main contributor to the ANC measured in KGI.

Research areas: Ecosystems
Ocean Emission Effects on Aerosol-Cloud Interactions: Insights from Two Case Studies (2010)

Two case studies are discussed that evaluate the effect of ocean emissions on aerosol-cloud interactions. A review of the first case study from the eastern Pacific Ocean shows that simultaneous aircraft and space-borne observations are valuable in detecting links between ocean biota emissions and marine aerosols, but that the effect of the former on cloud microphysics is less clear owing to interference from background anthropogenic pollution and the difficulty with field experiments in obtaining a wide range of aerosol conditions to robustly quantify ocean effects on aerosol-cloud interactions. To address these limitations, a second case was investigated using remote sensing data over the less polluted Southern Ocean region. The results indicate that cloud drop size is reduced more for a fixed increase in aerosol particles during periods of higher ocean chlorophyll A. Potential biases in the results owing to statistical issues in the data analysis are discussed.

Research areas: Atmospheric/Ocean Indicators
Observations of Saharan dust layer electrification (2010)

Electrification of atmospheric dust influences the coagulation, wet removal and fall speeds of dust particles. Alignment of dust particles can also occur in fair weather atmospheric electrical conditions if the particles are charged. However, very few electrical measurements made in elevated dust layers exist. Balloon-borne charge and particle instrumentation have been used to investigate the electrical properties of elevated Saharan dust layers. Soundings from the Cape Verde Islands, which experience frequent Saharan dust outbreaks, intercepted several dust layers. Two balloon soundings during summer 2009 detected dust particles in layers up to 4 km altitude. Simultaneous electrical measurements showed charge inside the dust layers, with a maximum measured charge density of 25 pC m  3, sufficient to influence wet removal processes.

Research areas: Atmospheric/Ocean Indicators
Nitrogen oxides and PAN in plumes from boreal fires during ARCTAS-B and their impact on ozone: an integrated analysis of aircraft and satellite observations (2010)

Abstract. We determine enhancement ratios for NOx, PAN, and other NOy species from boreal biomass burning using aircraft data obtained during the ARCTAS-B campaign and examine the impact of these emissions on tropospheric ozone in the Arctic. We find an initial emission factor for NOx of 1.06 g NO per kg dry matter (DM) burned, much lower than previous observations of boreal plumes, and also one third the value recommended for extratropical fires. Our analysis provides the first observational confirmation of rapid PAN formation in a boreal smoke plume, with 40% of the initial NOx emissions being converted to PAN in the first few hours after emission. We find little clear evidence for ozone formation in the boreal smoke plumes during ARCTAS-B in either aircraft or satellite observations, or in model simulations. Only a third of the smoke plumes observed by the NASA DC8 showed a correlation between ozone and CO, and ozone was depleted in the plumes as often as it was enhanced. Special observations from the Tropospheric Emission Spectrometer (TES) also show little evidence for enhanced ozone in boreal smoke plumes between 15 June and 15 July 2008. Of the 22 plumes observed by TES, only 4 showed ozone increasing within the smoke plumes, and even in those cases it was unclear that the increase was caused by fire emissions. Using the GEOS-Chem atmospheric chemistry model, we show that boreal fires during ARCTAS-B had little impact on the median ozone profile measured over Canada, and had little impact on ozone within the smoke plumes observed by TES.

Research areas: Air Quality, Wildfires
Monitoring spatio-temporal variations in aerosols and aerosolcloud interactions over Pakistan using MODIS data (2010)

Clouds are important elements in climatic processes and interactions between aerosols and clouds are therefore a hot topic for scientific research. Aerosols show both spatial and temporal variations, which can lead to variations in the microphysics of clouds. In this research, we have examined the spatial and temporal variations in aerosol particles over Pakistan and the impact of these variations on various optical properties of clouds, using Moderate Resolution Imaging Spectroradiometer (MODIS) data from the Terra satellite. We used the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for trajectory analysis to reveal the origins of air masses, with the aim of understanding these spatial and temporal variabilities in aerosol concentrations. We also documented seasonal variations in patterns of aerosol optical depth (AOD) over Pakistan, for which the highest values occur during the monsoon season (JuneAugust). We then analyzed the relationships between AOD and four other cloud parameters, namely water vapour (WV), cloud fraction (CF), cloud top temperature (CTT) and cloud top pressure (CTP). Regional correlation maps and time series plots for aerosol (AOD) and cloud parameters were produced to provide a better understanding of aerosolcloud interaction. The analyses showed strong positive correlations between AOD and WV for all of the eight cities investigated. The correlation between AOD and CF was positive for those cities where the air masses were predominantly humid, but negative for those cities where the air masses were relatively dry and carried a low aerosol abundance. These correlations were clearly dependent on the meteorological conditions for all of the eight cities investigated. Because of the observed AODCF relationship, the co-variation of AOD with CTP and CTT may be attributable to large-scale meteorological variations: AOD showed a positive correlation with CTP and CTT in northern regions of Pakistan and a negative correlation in southern regions.

Research areas: Atmospheric/Ocean Indicators
Modeling and Predicting Seasonal Influenza Transmission in Warm Regions Using Climatological Parameters (2010)

Background Influenza transmission is often associated with climatic factors. As the epidemic pattern varies geographically, the roles of climatic factors may not be unique. Previous in vivo studies revealed the direct effect of winter-like humidity on air-borne influenza transmission that dominates in regions with temperate climate, while influenza in the tropics is more effectively transmitted through direct contact. Methodology/Principal Findings Using time series model, we analyzed the role of climatic factors on the epidemiology of influenza transmission in two regions characterized by warm climate: Hong Kong (China) and Maricopa County (Arizona, USA). These two regions have comparable temperature but distinctly different rainfall. Specifically we employed Autoregressive Integrated Moving Average (ARIMA) model along with climatic parameters as measured from ground stations and NASA satellites. Our studies showed that including the climatic variables as input series result in models with better performance than the univariate model where the influenza cases depend only on its past values and error signal. The best model for Hong Kong influenza was obtained when Land Surface Temperature (LST), rainfall and relative humidity were included as input series. Meanwhile for Maricopa County we found that including either maximum atmospheric pressure or mean air temperature gave the most improvement in the model performances. Conclusions/Significance Our results showed that including the environmental variables generally increases the prediction capability. Therefore, for countries without advanced influenza surveillance systems, environmental variables can be used for estimating influenza transmission at present and in the near future.

Research areas: Public Health
Mesoscale variability along the east coast of India in spring as revealed from satellite data and OGCM simulations (2010)

Since mesoscale features like meanders have great importance in nourishing the coastal fisheries, satellite data analyses and a numerical modeling study were carried out for the east coast of India during spring inter-monsoon time (March-May), when biological productivity is high. During this time, the East India Coastal Current (EICC) system appears as a northward flowing western boundary current of a seasonal subtropical gyre in the Bay of Bengal prior to the summer monsoon with a more intense upwelling in the coastal region. A relatively clear sky permits satellite remote sensing of Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a), whose patterns were verified against geostrophic velocity in altimeter data: i.e., phytoplankton grows in colder and nutrient richer water bounded by the seaward meanders. Progression of meanders in the coastal current was revealed and compared with an eddy-resolving Ocean General Circulation Model (OGCM), which is capable of modeling wind-driven general circulation and each stage of the meander growth. The numerical solutions provided the following results, in reasonable agreement with the linear stability theory using a two-and-a-half layer quasi-geostrophic model. Baroclinic instability plays a key role for the meander growth and eddy generation, while meanders in the coastal current are initiated by isolated mesoscale rotations propagating westward. The baroclinically unstable meanders have a wavelength of 500700 km, grow in one month and propagate downstream of the coastal current at several kilometers per day. The instability is not strong enough for the meanders to detach an eddy from the western boundary current.

Research areas: Land Surface/Agriculture Indicators
MedREM, a rainfall erosivity model for the Mediterranean region (2010)

This paper presents and assesses the model MedREM, in which annual-based climate and rainstorm data are used to estimate the long-term (R)Universal Soil Loss Equations and its Revisions (USLE) annual rainfall erosivity over a large region. Two known models of rainfall erosivity (named after the first author of the original paper, Torri and Yang) were also assessed and compared with the MedREM. Yang and Torri models are both based on the annual precipitation models. MedREM also takes annual maximum daily precipitation data into account, and incorporates a longitude-dependent coefficient. The test area was a large region centered on the Mediterranean basin, in which 66 weather stations were available  43 Italian and 23 out-of-Italy sites (12 countries, about 3050 latitude North, and 1050 longitude East)  with multi-year data of (R)USLE annual erosivity. The three models were calibrated against (R)USLE rainfall erosivity data from 55 stations and evaluated over a validation dataset from 11 Italian stations. On the validation dataset, the MedREM estimates generally compared well with the (R)USLE data according to NushSutcliffe coefficient (0.87 against 0.76 and 0.73 with Torri and Yang model, respectively). Implications for erosivity modelling were discussed in the context of climatic features concluding that accurate estimations of site-specific annual erosivity for the Mediterranean region require process-based model with spatially-explicit parameterization.

Research areas: Land Surface/Agriculture Indicators
Long-standing environmental conditions, geographic isolation and hostsymbiont specificity influence the relative ecological dominance and genetic diversification of coral endosymbionts in the genus Symbiodinium (2010)

Aim This study examines the importance of geographic proximity, host life history and regional and local differences in environment (temperature and water clarity) in driving the ecological and evolutionary processes underpinning the global patterns of diversity and distribution of symbiotic dinoflagellates. By comparing and contrasting coralalgal symbioses from isolated regions with differing environmental conditions, we may assess the potential of coral communities to respond to significant changes in climate. Location Indian Ocean. Methods Community assemblages of obligate symbiotic invertebrates were sampled at numerous sites from two regions, the north-eastern Indian Ocean (Andaman Sea, western Thailand) and the western Indian Ocean (Zanzibar, Tanzania). Molecular genetic methods, including denaturing gradient gel electrophoresis analysis of the ribosomal internal transcribed spacers, DNA sequencing and microsatellite genotyping, were used to characterize the species diversity and evolutionary relationships of symbiotic dinoflagellates (genus Symbiodinium). Hostsymbiont specificity, geographic isolation and local and regional environmental factors were evaluated in terms of their importance in governing the distribution and prevalence of certain symbiont taxa. Results Host-generalist symbionts (C3u and D1-4, formerly D1a now designated Symbiodinium trenchi) frequently occurred alone and sometimes together in hosts with horizontal modes of symbiont acquisition. However, the majority of Symbiodinium diversity consisted of apparently host-specific species. Clade C Symbiodinium were diverse and dominated host assemblages from sites sampled in the western Indian Ocean, a pattern analogous to symbiont communities on the Great Barrier Reef with similar environmental conditions. Clade D Symbiodinium were diverse and occurred frequently in hosts from the north-eastern Indian Ocean, especially at inshore locations, where temperatures are warmer, water turbidity is high and large tidal exchanges commonly expose coral populations to aerial desiccation. Main conclusions Regional and local differences in cnidarianalgal combinations indicate that these symbioses are ecologically and evolutionarily responsive and can thrive under various environmental conditions. The high temperatures and turbid conditions of the north-eastern Indian Ocean partly explain the ecological success of Clade D Symbiodinium relative to Clade C. Phylogenetic, ecological and population genetic data further indicate that Clade D has undergone an adaptive radiation, especially in regions around Southeast Asia, during the Pleistocene.

Research areas: Ecosystems
Long-range transport of dust aerosols over the Arabian Sea and Indian region  A case study using satellite data and ground-based measurements (2010)

The present study addresses an intense dust storm event over the Persian Gulf and the Arabian Sea (AS) region and its transport over the Indian subcontinent using multi-satellite observations and ground-based measurements. A time series of Indian geostationary satellite KALPANA-1 Very High Resolution Radiometer (VHRR) together with ground observations are used to analyze the temporal variation of the dust event that occurred from 19 to 24 February 2008 with the strongest intensity on 22 February. The Ozone Monitoring Instrument (OMI) Aerosol Index (AI) is also examined to provide an independent assessment of dust presence and plume location. During the dust event drastic increase in Terra/Aqua MODIS AOD550 (>1.0) and AURA-OMI-AI is observed. Vertically-resolved attenuated backscatter during daytime and nighttime from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is also used as an additional tool to monitor the dust vertical distribution. The main dust layer is observed to be situated between 3 and 5km in altitude, while the CALIPSO observations on vertical profile of aerosols are in qualitative agreement with values of MODIS-AOD550 and OMI-AI. Ground-based measurements show significant reduction in solar irradiance on the dust-laden day (22 February 2008) over Hyderabad, while sun photometer derived AODs from six AERONET sites in south Asia verify the presence of dust and its transport from west to east.

Research areas: Air Quality
Latitudinal distribution of Trichodesmium spp. and N2 fixation in the Atlantic Ocean (2010)

Abstract. We have determined the latitudinal distribution of Trichodesmium spp. abundance and community N2 fixation in the Atlantic Ocean along a meridional transect from ca. 30 N to 30 S in NovemberDecember 2007 and AprilMay 2008. The observations from both cruises were highly consistent in terms of absolute magnitude and latitudinal distribution, showing a strong association between Trichodesmium abundance and community N2 fixation. The highest Trichodesmium abundances (mean = 220 trichomes L1,) and community N2 fixation rates (mean = 60 mol m2 d1) occurred in the Equatorial region between 5 S15 N. In the South Atlantic gyre, Trichodesmium abundance was very low (ca. 1 trichome L1) but N2 fixation was always measurable, averaging 3 and 10 mol m2 d1 in 2007 and 2008, respectively. We suggest that N2 fixation in the South Atlantic was sustained by other, presumably unicellular, diazotrophs. Comparing these distributions with the geographical pattern in atmospheric dust deposition points to iron supply as the main factor determining the large scale latitudinal variability of Trichodesmium spp. abundance and N2 fixation in the Atlantic Ocean. We observed a marked South to North decrease in surface phosphate concentration, which argues against a role for phosphorus availability in controlling the large scale distribution of N2 fixation. Scaling up from all our measurements (42 stations) results in conservative estimates for total N2 fixation of 6 TgN yr1 in the North Atlantic (040 N) and ~1.2 TgN yr1 in the South Atlantic (040 S).

Research areas: Ecosystems