nasa-gesdisc/es-publications-researchareas huggingface dataset:
Organic carbon inputs to the sea bottom of the Mallorca continental slope (2015)

To assess the origin and degradation state of the organic particles sinking towards the sea bottom of the Mallorca continental slope, the major inorganic and organic components of the total mass flux and its biochemical composition (in terms of protein, carbohydrate, lipid and phytopigment contents) have been analysed. Two instrumented lines were deployed at the western (Soller station, Balearic sub-basin) and southern (Cabrera station, Algerian sub-basin) slopes of Mallorca Island, 900m depth from November 2009 to January 2011. The two locations are characterized by putatively different environmental settings. Settled material at Soller station has higher lithogenic contents when compared with the Cabrera one. Such difference can be explained by the synergistic presence in the Soller station of large inputs of resuspended material due to the mesoscale variability of the Balearic current and the impact of bottom trapped waves. On the other hand, at the Cabrera station sinking particles are characterized by OM and opal percentages higher than those recorded at the Soller station. This result points out that organic particles reaching the sea floor at the Cabrera station have a pre-eminent pelagic origin. Based on analyses of the C and N stable isotopes of the sinking material, our results also highlight that, overall, the OM reaching the sea floor at the Mallorca slope is mostly of marine origin. In general, the OM settled at the Soller station has a higher nutritional value than that at the Cabrera one. Such a difference, occurring across a relatively reduced spatial scale, let us hypothesizing that the nutritionally richer particles descending in the Cabrera station are exposed to a less energetic environment than that in the Soller setting. This would lead to higher settling velocity of particles in the Soller setting which in turn would result in lower degradation rates of particles during their descent towards the sea bottom.

Research areas: Ecosystems
Variability of satellite-derived sea surface height anomaly, and its relationship with Bigeye tuna (Thunnus obesus) catch in the Eastern Indian Ocean (2015)

We analyzed the variability of sea surface height anomaly (SSHA), and its relationship with Bigeye tuna catch in the eastern Indian Ocean (EIO) off of Java Island (Indonesia). Both time series of SSHA and Bigeye tuna HR show dominant signals corresponding to the annual and inter-annual variability. During the southeast monsoon the wind blows along southern coast of Java and produces coastal upwelling. This causes sea level to drop due to an offshore Ekman transport, and thermocline becomes shallower. During El Nino and Indian Ocean Dipole (IOD) positive phase, upwelling is more intense and a large cold eddy forms in the EIO off Java. Generally, Bigeye tuna HR tends to increase during upwelling seasons and becomes even higher during El Nino and the positive phase of the IOD. The increased Bigeye tuna HR during the southeast monsoon, El Nino and the IOD positive phase can be attributed to the shallower thermocline depth and the enhancement of biological productivity due to development of eddies and strong upwelling in the EIO. The spatial distribution of SSHA indicates that Bigeye tuna catches are abundant in the frontal regions between cold and warm eddies.

Research areas: Agriculture, Atmospheric/Ocean Indicators, Ecosystems
UV Irradiance Enhancements by Scattering of Solar Radiation from Clouds (2015)

Scattering of solar radiation by clouds can reduce or enhance solar global irradiance compared to cloudless-sky irradiance at the Earths surface. Cloud effects to global irradiance can be described by Cloud Modification Factors (CMF). Depending on strength and duration, irradiance enhancements affect the energy balance of the surface and gain of solar power for electric energy generation. In the ultraviolet region, they increase the risk for damage to living organisms. Wavelength-dependent CMFs have been shown to reach 1.5 even in the UV-B region at low altitudes. Ground-based solar radiation measurements in the high Andes region at altitudes up to 5917 m a.s.l showed cloud-induced irradiance enhancements. While UV-A enhancements were explained by cloud scattering, both radiation scattering from clouds and Negative Ozone Anomalies (NOA) have been discussed to have caused short-time enhancement of UV-B irradiance. Based on scenarios using published CMF and additional spectroradiometric measurements at a low-altitude site, the contribution of cloud scattering to the UV-B irradiance enhancement in the Andes region has been estimated. The range of UV index estimates converted from measured UV-B and UV-A irradiance and modeled cloudless-sky ratios UV-B/erythemal UV is compatible with an earlier estimate of an extreme UV index value of 43 derived for the high Andes.

Research areas: Public Health, Sun-Earth Interactions
Use of multitemporal satellite images to find some evidence for glacier changes in the Haft-Khan glacier, Iran (2015)

Present paper reports on the Haft-Khan glacier clean-ice area change between 1955 and 2010 based on several high to medium spatial resolution satellite images. Present glacier is heavily covered by debris (referred as supra-glacial debris cover). Because of these covers, mapping the actual glacier area with reasonable accuracy is impossible. Therefore, the changes of clean-ice regions have been detected as a good evidence for glacier change. For the detection of these changes, nine high to medium spatial resolution satellite images were selected. Although these images are the best available satellite images in Haft-Khan Glacier (to avoid any misclassification), but the possible changes in perennial snow fields cannot be separated from the clean-ice area changes. It means that some of the obtained changes may also be related to the changes in perennial snow fields not the absolute change of clean-ice regions. The object-oriented classification approach has been used to estimate the clean-ice glaciated areas. Object-oriented classification method takes into account the shapes of the features along with their spectral patterns. In the last decades, advantages in computer technologies have led to the development of object-based image analysis; an image classification technique that can be seen as an alternative to the common pixel-based image analysis and manual digitization. Results revealed that debris-free areas of Haft-Khan glacier shrank since 2010 with an overall area reduction of about 58  5 %. Although the general trend is clean-ice area reduction, some limited area gain has been observed over the period of 20032010. During the 19922000, the maximum reduction in the clean-ice area was observed (0.13  0.009 km2 a1). However, during the 20032010, the areas of clean-ice regions have steadily increased. Fractional snow cover (FSC) change during the last 34 years (19792013) revealed that precipitation during the accumulation period (from November to May of the following year) decreased significantly, reducing the snowfall contribution to mean balance. This is the main reason for the clean-ice area shrinkage in the Haft-Khan glacier.

Research areas: Cryospheric Indicators
Time series analyses reveal environmental and fisheries controls on Atlantic horse mackerel (Trachurus trachurus) catch rates (2015)

Time-series models (Dynamic factorial analyses and; Min/max autocorrelation factor analysis) were used to explore the relative influences of environmental variables and fishing pressure of trawl, seine and artisanal fleets on catch rates on Trachurus trachurus in ICES IXa sub-divisions (IXaCN-North coast; IXa- CS-South coast; IXaS-Algarve, South coast, Algarve). Fishing effort influenced catch rates in all areas with a 2 year lag and fishing pressure for each area was related to specific fleet sectors effort. In IXaCN, winter upwelling (spawning peak) and both summer northerly wind and wind magnitude (outside of the spawning peak) were strongly correlated with catch rates. In IXaCS summer/autumn westerly winds were related with catch rates. Northerly winds in spring, upwelling and SST (winter and autumn) were related with catch rates in IXaS-Algarve. For species with a long spawning season such as horse mackerel, seasonal analyses at broad regional scales can detract from a better understanding of variability in short term sub-stock catch rates. Favorable environmental conditions, even during seasons with low spawning activity can positively affect catch rates. Ignoring the role of regional oceanographic features on the spatial distribution of the sub-stocks when analysing variability in catch rates can lead to poor inferences about the productivity of the populations.

Research areas: Agriculture, Atmospheric/Ocean Indicators
Spatiotemporal variability in dust observed over the Sinkiang and Inner Mongolia regions of Northern China (2015)

This study presents a detailed analysis of the spatiotemporal variability in dust observed over Sinkiang and Inner Mongolia in Northern China from 2005 to 2008. The relationships between airborne dust (observed by OMIAI and MODISAOD), the normalized difference vegetation index (NDVI), monthly total precipitation (MTP) and surface wind speed (SWS) are investigated. The results show that the spatial distribution of airborne dust distinctly decreases from west to east across Northern China; this pattern is opposite to that of the NDVI and MTP. Both Sinkiang and Inner Mongolia experience high amounts of airborne dust in spring, with the highest values in April. The two regions also had different dust variabilities. In Sinkiang, three major dust regions were identified, with airborne dust mainly distributed in regions with NDVI values between 0 and 0.1, SWS values between 2 and 5m/s, and a MTP of less than 5mm. In addition, the temporal variation in airborne dust exhibits both positive and negative correlations with the NDVI, MTP and SWS. However, over Inner Mongolia, five highdust regions were confirmed, with airborne dust generally distributed in the areas with NDVI values between 0 and 0.4, SWS values between 3 and 6m/s, and a MTP of less than 10mm. The time series of airborne dust is negatively correlated with the NDVI and MTP but strongly and positively correlated with the SWS. In addition, the temporal pattern of the AOD in Sinkiang is essentially controlled by dust activity, whereas it may be influenced by anthropogenic emissions in Inner Mongolia. Overall, the spatiotemporal variabilities in dust over Sinkiang and Inner Mongolia are not identical, although both regions are important sources of dust in East Asia.

Research areas: Air Quality
Spatiotemporal coherence of mean and extreme aerosol particle events over eastern North America as observed from satellite (2015)

Quantifying spatiotemporal scales of coherence and variability of aerosol particle properties provides (i) metrics for evaluating observational data sets and model simulations, (ii) inferences regarding dominant causes of variability, and (iii) information that is necessary to determine their climate forcing and air quality impacts. Accordingly, analyses of columnar aerosol optical depth (AOD) and Angstrom exponent (AE) from the MODerate resolution Imaging Spectroradiometer (MODIS) on the Aqua and Terra satellites, and AErosol RObotic NETwork (AERONET) stations are used to evaluate the spatially averaged (Level-3) MODIS products, and to characterize the spatiotemporal scales of variability (and coherence) of aerosol particles over eastern North America (20002013). Results show a high degree of consistency in AOD retrievals from the different data sets but larger discrepancies in AE estimates, highest mean AOD and lowest day-to-day variability during the summer, and largest scales of spatial coherence in summer and fall. Consistent with the scales of spatial coherence from MODIS data, in both data sets power spectra indicate AOD variability is manifest primarily on synoptic and annual time scales. Conversely, AE variability in MODIS data is primarily focused on seasonal, semiannual, and annual time scales, and there is an additional mode of AE variability at 30 days in the AERONET measurements. The frequency of co-occurrence of extreme AOD values (>local 90th percentile) decreases to below 50% at 150 km from a central grid cell, but is above that expected by random chance over almost all of eastern North America, indicating supra-regional scale extreme events.

Research areas: Air Quality
A dual-tracer approach to estimate upwelling velocity in coastal Southern California (2015)

The distribution of the cosmogenic radionuclide 7Be (t1/2=53d) in the surface ocean has previously been used to estimate upwelling velocity in the open ocean. However, the loss of 7Be to particle export has limited this approach in high particle density environments like the continental margins. In this study, we combine a mass balance of 7Be with a 234Th budget in the surface ocean to constrain the loss of 7Be to particle sinking at the San Pedro Ocean Time-series (SPOT) in the inner Southern California Bight during spring 2013. Upwelling velocities (all in m d1) determined from the 7Be mass balance were observed to increase from 0.50.6 in January to 2.51.3 in May, then decrease to 1.20.5 in June. These results agree within uncertainty with upwelling velocities derived from the monthly Bakun Upwelling Index, which ranged from 0.1 to 2.8 m d1, supporting the pressure-field-based approach. Evidence from a heat budget and the nutrient distribution over the course of the study supports that the upwelling signal at SPOT (20 km offshore) is not transported from coastal upwelling near shore, but instead is dominantly a local signal, likely driven by wind-stress curl.

Research areas: Atmospheric/Ocean Indicators
Validation of modeled daily erythemal exposure along tropical and subtropical shipping routes by ship-based and satellite-based measurements (2015)

AbstractThe Personal ERythemal EXposure (PEREX) model for seafarers working on decks of vessels has been developed to be used for retrospective estimates of personal occupational erythemal exposure in dependence of work profile, time period, and sea route. Extremely high UV index values up to 22 and daily erythemal exposure up to 89 standard erythemal dose have been derived from ship-based measurements in tropical oceans. Worldwide climatological maps of daily solar erythemal exposure derived from 10 year (20042013) hourly grid point radiative transfer model calculations for both cloudless sky and cloudy sky serve as the database of PEREX. The PEREX database is compared with ship-based measurements taken along four routes of merchant vessels, continuous UV radiation measurements taken on the research vessel Meteor on its mainly tropical and subtropical routes for 2 years, daily cloudless-sky erythemal exposure derived from 10 min LibRadtran radiative transfer model calculations, and 2 years of satellite-based erythemal exposure data of the Ozone Monitoring Instrument on the Aura satellite along the ship routes. Systematic differences between PEREX model data, ship-based data, and satellite-based daily erythemal exposure for all-sky conditions are only 1 to 3%, while short-term variations of cloudiness result in standard deviations of differences around 30%. Measured ratios between cloudless-sky erythemal radiation at vertical to horizontal incidence decrease with decreasing solar zenith angle, while clouds flatten their diurnal course.

Research areas: Public Health
Vortex dynamics in the southeastern Baltic Sea from satellite radar data (2015)

The analysis of radar satellite images shows that vortex dipoles are a typical element of the water circulation in the southeastern part of the Baltic Sea. The wide range of spatial dimensions of observed vortices (from approximately 2 to 25 km) corresponds to mesoscale and submesoscale vortex formations (signifying whether the diameter is respectively larger or smaller than the baroclinic Rossby radius of deformation, equal to 56 km). Vortex dipoles typical for different areas and their spatial characteristics are considered. These areas were the Hel Spit, the Taran Cape, the central part of the Gulf of Gdansk and the area northward of the Gulf. It is shown that the mesoscale vortex dipoles and the associated jets condition horizontal water exchange in an area comparable with the size of the considered water area. The differences in the appearance of the cyclonic and anticyclonic components of vortex dipoles revealed in satellite radar images are discussed.

Research areas: Atmospheric/Ocean Indicators
Variability in aerosol optical properties and radiative forcing over Gorongosa (18.97oS, 34.35oE) in Mozambique (2015)

This paper reports the observational results of aerosol optical, microphysical and radiative characteristics for the time measured over Gorongosa (18.97oS, 34.35oE, 30 m asl) in Mozambique using a ground-based AERONET sun-sky radiometer. In the present study, the data recorded during the period JulyDecember, 2012 have been used and particular attention was paid to show how aerosol loading evolves during the biomass burning season (spring) including pre- and post-months. The results reveal that the monthly mean aerosol optical depth (AOD) at 500 nm was high (low) with 0.64  0.34 (0.20  0.06) in September (November), while the Angstrom Exponent (AE) (440870) decreased, except September (1.56  0.26) due to increase in the fine-mode aerosol concentration produced from biomass burning. The volume size distribution (VSD) has bimodal lognormal structure and has fine-mode (coarse) maximum at a radius of 0.15 m (3.0 m) in September (December). The single scattering albedo (SSA) decreases with wavelength from July to October and almost stable in November and December. The imaginary (Im) refractive index (RI) showed a strong evidence of black carbon aerosol origin during the biomass burning months. Aerosol radiative forcing (ARF) computed from SBDART model shows large negative values at the surface (89.22 W m2) and at the top (22.36 W m2), with a higher value of atmospheric forcing (+66.87 W m2) resulting in average tropospheric heating rate of 1.88 K day1 for the study period. Further, the comparison shows good agreement between the ARFs at the top and bottom of the atmosphere derived from AERONET to SBDART.

Research areas: Atmospheric/Ocean Indicators
UV and global irradiance measurements and analysis during the Marsaxlokk (Malta) campaign (2015)

Abstract. A solar radiation measurement campaign was performed in the south-eastern village of Marsaxlokk (3550' N; 1433' E; 10 m a.s.l), Malta, between 15 May and 15 October 2012. Erythemal solar radiation data (from a UVB-1 pyranometer), and total horizontal solar radiation (global and diffuse components) from two CM21 pyranometer were recorded. A comparison of atmospheric compounds from ground measurements and satellites shows that TOC (total ozone column) data from the Ozone Monitoring Instrument OMI, TOMS and DOAS algorithms correlate well with ground-based recorded data. The water vapour column and the aerosol optical depth at 550 nm show a significant correlation at the confidence level of 99 %. Parametric models for evaluating the solar UV erythemal (UVER), global (G) and diffuse (D) horizontal irradiances are calibrated, from which aerosol effects on solar irradiance are evaluated using the Aerosol Modification Factor (AMF). The AMFUVER values are lower than AMFG, indicating a greater aerosol effect on UVER than on global solar irradiance. In this campaign, several dust event trajectories are identified by means of the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and by synoptic conditions for characterizing desert dust events. Hence, changes in the UV index due to atmospheric aerosols are described.

Research areas: Public Health, Sun-Earth Interactions
Using remote sensing to monitor the influence of river discharge on watershed outlets and adjacent coral Reefs: Magdalena River and Rosario Islands, Colombia (2015)

Worldwide, coral reef ecosystems are being increasingly threatened by sediments loads from river discharges, which in turn are influenced by changing rainfall patterns due to climate change and by growing human activity in their watersheds. In this case study, we explored the applicability of using remote sensing (RS) technology to estimate and monitor the relationship between water quality at the coral reefs around the Rosario Islands, in the Caribbean Sea, and the rainfall patterns in the Magdalena River watershed. From the Moderate Resolution Imaging Spectroradiometer (MODIS), this study used the water surface reflectance product (MOD09GQ) to estimate water surface reflectance as a proxy for sediment concentration and the land cover product (MCD12Q1 V51) to characterize land cover of the watershed. Rainfall was estimated by using the 3B43 V7 product from the Tropical Rainforest Measuring Mission (TRMM). For the first trimester of each year, we investigated the inter-annual temporal variation in water surface reflectance at the Rosario Islands and at the three main mouths of the Magdalena River watershed. No increasing or decreasing trends of water surface reflectance were detected for any of the sites for the study period 20012014 (p>0.05) but significant correlations were detected among the trends of each site at the watershed mouths (r=0.570.90, p<0.05) and between them and the inter-annual variation in rainfall on the watershed (r=0.630.67, p<0.05). Those trimesters with above-normal water surface reflectance at the mouths and above-normal rainfall at the watershed coincided with La Nina conditions while the opposite was the case during El Nino conditions. Although, a preliminary analysis of inter-annual land cover trends found only cropland cover in the watershed to be significantly correlated with water surface reflectance at two of the watershed mouths (r=0.58 and 0.63, p<0.05), the validation analysis draw only a 40.7% of accuracy in this land cover classification. This requires further analysis to confirm the impact of the cropland on the water quality at the watershed outlets. Spatial analysis with MOD09GQ imagery detected the overpass of river plumes from Barbacoas Bay over the Rosario Islands waters.

Research areas: Water Quality
Urban-Induced Mechanisms for an Extreme Rainfall Event in Beijing China: A Satellite Perspective (2015)

Using 1 km satellite remote sensing observations, this paper examines the clouds, aerosols, water vapor and surface skin temperature over Beijing to understand the possible urban system contributions to the extreme rainfall event on 21 July 2012 (i.e., 721 event). Remote sensing measurements, with the advantage of high spatial resolution and coverage, reveal three key urban-related mechanisms: (a) the urban heat island effect (UHI) resulted in strong surface convection and high level cloud cover over Beijing; (b) urban aerosol amount peaked before the rainfall, which seeded the clouds and invigorated precipitation; and (c) urban tall buildings provided additional lift for the air mass and provided heat at the underlying boundary to keep the rainfall system alive for a long duration precipitation  (>10 hours). With the existing rainfall system moving from the northwest and abundant water vapor was transported from the southeast into Beijing, the urban canyon-lifting, aerosol, and UHI effects all enhanced this extreme rainfall event. This work proves that urban system is responsible, at least partly, for urban rainfall extremes and thus should be considered for urban extreme rainfall prediction in the future.

Research areas: Heat, Atmospheric/Ocean Indicators