nasa-gesdisc/es-publications-researchareas huggingface dataset:
Surface albedo and reflectance: Review of definitions, angular and spectral effects, and intercomparison of major data sources in support of advanced solar irradiance modeling over the Americas (2019)

This study defines albedo and reflectance in the context of solar applications. It examines the main sources of surface albedo data that can be used to help solar irradiance modeling efforts, such as undertaken by the National Renewable Energy Laboratory (NREL) over the Americas, for instance, per the National Solar Radiation Database (NSRDB). The MODIS-based albedo database, as used as input to derive historical time series of solar irradiance in the current version of the NSRDB, is compared to other sources of global gridded data over the Americas in general and some specific areas in particular. The particular role of snow cover is analyzed. It is found that, in the current MODIS-based NSRDB implementation, snow-impacted areas have been assigned a too high albedo in general because of the lack of consideration for the antagonistic effect of surface roughness, among other factors. Other albedo databases, such as CMSAF, MINES-ParisTech or the ERA5 reanalysis, do not display such high albedos at latitudes above 40N. The gap-free and snow-free MODIS MCD43GF product is found affected by a long-term downward trend over some areas and out-of-phase seasonal effects over other areas, in comparison with MERRA-2 reanalysis data in particular. Comparisons with actual albedo measurements at the arid Desert Rock site in Nevada also show that albedo data derived from land surface models are affected by systematic bias. Five albedo databases are intercompared for the area around Ivanpah Playa, California, which has great importance in both remote sensing and solar applications. Various aspects of the proper usage of albedo data in solar radiation modeling are discussed, regarding calculations of both the backscattering process and reflections on a tilted surface: spatial resolution, temporal resolution, angular effects, and spectral effects. An important distinction is made between the use of albedo data at 4 km resolution for backscattering calculations and at 10 m resolution for transposition calculations to tilted planes, which might additionally require spectral information for monofacial or bifacial PV applications. It is shown that the tilted calculations usually performed in solar resource assessments are far from realistic in the case of most large-scale PV applications, for which a more suitable methodological approach is described. For such needs, the limitations of the current sources of high-resolution reflectance data are discussed. The impact of surface albedo estimation errors on the estimation of backscattered irradiance over snowy areas is evaluated. It is found non-negligible, and even large under cloudy conditions.

Research areas: Sun-Earth Interactions, Energy Production/Use
An overview of climate change in Iran: facts and statistics (2019)

The climate change fact is intensive among the Middle East countries and especially Iran. Among the Middle East countries, Iran will experience an increase of 2.6 C in mean temperatures and a 35% decline in precipitation in the next decades. In vice versa, Iran by total greenhouse gas (GHG) emissions nearly to 616,741 million tons of CO2 is the first responsible country to climate change in the Middle East, and seventh in the world. The high-level contribution of Iran to emissions of GHG depends on a significant production of oil, gas, and rapid urbanization. The present study aimed to reveal an overview of climate change facts and statistics in Iran.

Research areas: Atmospheric/Ocean Indicators, Greenhouse Gases, Habitat Conversion/Fragmentation
Impact of dust storm on phytoplankton bloom over the Arabian Sea: a case study during March 2012 (2019)

Dust storms affect the primary productivity of the ocean by providing necessary micronutrients to the surface layer. One such dust storm during March 2012 led to a substantial reduction in visibility and enhancement in aerosol optical depth (AOD) up to ~ 0.8 (AOD increased from 0.1 to 0.9) over the Arabian Sea. We explored the possible effects and mechanisms through which this particular dust storm could impact the oceans primary productivity (phytoplankton concentration), using satellite-borne remote sensors and reanalysis model data (20032016). The climatological analyses revealed anomalous March 2012 in terms of dust deposition and enhancement in phytoplankton concentration in the month of March during 20032016 over this region. The studied dust storm accounts for increase in the daily average surface dust deposition rate from ~ 3 to ~53 mg m2 day1, which is followed by a significant enhancement in the chlorophyll-a (Chl_a) concentration (~ 2 to ~9 mg m3). We show strong association between a dust storm and an event of anomalously high biological production (with a 4-day forward lag) in the Arabian Sea. We suggest that the increase in biological production results from the superposition of two complementary processes (deposition of atmospheric nutrients and deepening of the mixed layer due to dust-induced sea surface temperature cooling) that enhance nutrient availability in the euphotic layer.

Research areas: Water Quality
Giant kelp forests at critical light thresholds show compromised ecological resilience to environmental and biological drivers (2019)

Replacement of kelp and fucoid forests by low biomass turfing communities or urchin barrens has been identified in temperate marine ecosystems worldwide. Variation in the mechanisms of decline (e.g., urchin grazing, temperature stress) and apparent driving stressors (e.g., overfishing, sedimentation, global warming) has greatly limited the development of generalized management strategies. Thresholds of urchin density and thermal tolerance for habitat-forming seaweeds are increasingly well established, yet thresholds of turbidity are rarely considered. Given the universal requirement for light in aquatic macrophytes, estimation of photosynthetically active radiation (PAR) limits may help underpin frameworks for better management of terrestrial stressors. Here I have examined spatial and temporal variability of PAR in forests of the giant kelp Macrocystis pyrifera across a gradient of exposure to land-derived sediments. Exposure to excess suspended sediments pushed PAR below critical thresholds for net sporophyte growth (<1.0 mol m2 day1), affecting giant kelp densities, but also impacting a range of ecological metrics including: fucoid density; laminarian density; beta diversity metrics; subcanopy composition; and urchin density. While kelps and fucoids responded to similar light thresholds, kelps appear to be vulnerable to physical disruption by sediments whereas fucoids are tolerant of physical disruption mechanisms, but vulnerable to declining light availability. Light thresholds of 1.0 mol m2 day1 may be a useful target for management of stressors affecting water clarity (e.g., sedimentation, eutrophication), with universal applicability across diverse groups of aquatic photoautotrophs.

Research areas: Ecosystems
Aerosol and cloud droplet characteristics over Ganges Valley during break phase of monsoon: A case study (2019)

Unique airborne observations made 330 km south of Mt. Everest during the Cloud-Aerosol Interaction Precipitation Enhancement EXperiment (CAIPEEX) 2014 are presented in this case study. These observations provide the vertical profile and elemental composition of aerosols from single particle analysis during the break period. An aerosol dome was also documented from the horizontal transect across the Varanasi city. The boundary layer was dominated by light scattering fine mode aerosols mainly a mixture of dust and pollution. The individual particle characterization revealed complex mixing states within the same aerosol aggregate. Externally mixed aerosols were present at the cloud bases. Elemental composition of aerosol particles collected from free atmosphere contained signatures of aged pollution with heavy metals, carbonaceous particles and radioactive elements. Cloud processed aerosols were also noted in the neighborhood of deep convective clouds. Shallow and deep cumulus clouds developing in the haze layer revealed distinct dropsize distributions. Shallow cumulus clouds embedded in the haze layer showed narrow droplet size distribution and were narrower than the ones observed for premonsoon conditions. Deep cumulus tops in the neighborhood of rapidly developing convection showed broad, bimodal droplet size distribution attributing to droplet evaporation and entrainment effects. Aerosol sampling near these cloud tops showed aggregates of particles that are internally mixed.

Research areas: Environmental Impacts
Northerly wind trends along the Portuguese marine coast since 1950 (2019)

Wind is a marine coastal factor that is little understood but has a strong interaction with biological productivity. In this study, northerly wind trends in three regions of the Portuguese coast (Northwestern: NW, Southwestern: SW, and Southern: S) were analyzed. Two datasets with long-term (ICOADS: 19602010) and short-term data (Satellite: 19892010) were used to complement one another. The study revealed the northerly wind yearly data to be non-stationary and highly variable between years. Overall, the northerly wind intensity increased throughout the 1960s regardless of the area and dataset. Between 1960 and 2010, the northerly wind increased at a linear rate of 0.24, 0.09, and 0.15 m s-1 per decade in the NW, SW, and S coastal regions, respectively. The rate was higher in recent decades (19882009), with the wind intensity increasing by 0.4, 0.3, and 0.3 ms-1 per decade in the NW, SW, and S regions, respectively. Analyses of the sudden shifts showed significant increases in northerly wind intensities after 2003, 2004, and 1998 in the NW, SW, and S coast, respectively. Exceptions were found for autumn (September for short-term data), when a decrease in northerly winds was observed in recent decades, regardless of the area, and for summer, when no changes in wind trends were recorded in the NW and SW. The long-term data also showed a major increase in northerly winds in winter (January and February), which is the recruitment season for many small and medium-sized pelagic fish. The increase in the intensity of the northerly winds over the past two decades and the past half-century occurred at a higher rate than was estimated by the IPCC for the next century.

Research areas: Ecosystems
Moonlight enhances growth in larval fish (2019)

Moonlight mediates trophic interactions and shapes the evolution of life-history strategies for nocturnal organisms. Reproductive cycles and important life-history transitions for many marine organisms coincide with moon phases, but few studies consider the effects of moonlight on pelagic larvae at sea. We evaluated effects of moonlight on growth of pelagic larvae of a temperate reef fish using master chronologies of larval growth constructed from age-independent daily increment widths recorded in otoliths of 321 individuals. We found that daily growth rates of fish larvae were enhanced by lunar illumination after controlling for the positive influence of temperature and the negative influence of cloud cover. Collectively, these results indicate that moonlight enhances growth rates of larval fish. This pattern is likely the result of moonlight's combined effects on foraging efficiency and suppression of diel migrations of mesopelagic predators, and has the potential to drive evolution of marine life histories.

Research areas: Ecosystems
Long Term Assessment of Aerosol Radiative Forcing over Selected Sites of East Africa (2018)

Atmospheric aerosols have contributed to radiative forcing through direct and indirect mechanisms. Aerosol effects are important in computing radiative forcing estimates for the past, current and future climate. In this study, a comprehensive assessment of regional aerosol radiative forcing, Optical Properties of Aerosol and Clouds (OPAC) model (wavelength range of 0.25 - 4.0 m) over selected sites in East Africa was done. Aerosol optical properties constituted the inputs of a Radiative Transfer Model (RTM). Op-tical properties investigated included Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA) and Asymmetry Parameter (AP). Aerosol Radiative Forcing (ARF) during the study period at the surface (SFC), top of the atmosphere (TOA) and the atmosphere (ATM) was estimated to be -18.4  1.4 Wm-2, +1.1  0.3 Wm-2 and +19.5  2.5 Wm-2, respectively. This corresponds to an increment in net atmospheric forcing at a heating rate of about 0.55  0.05 K/day (0.41  0.03 to 0.78  0.03 K/day) in the lower troposphere. The study points out the significant role played by atmospheric aerosols in climate modification over the area of study. It is recommended that a further assessment be done in view of uncertainties that may impact on the findings and which were not within the scope of this research.

Research areas: Atmospheric/Ocean Indicators
Range Extensions of the Whitespotted Boxfish, Ostracion meleagris Shaw, 1796, in the East and West Coasts of the Baja California Peninsula, Mexico (2019)

The Whitespotted boxfish Ostracion meleagris Shaw, 1796 is a reef resident distributed along the Indo Pacific, but at the Baja California Peninsula, Mexico, this fish has been reported only in the southern region, with a northern limit at 24.2N inside the Gulf of California. Here we document the presence of O. meleagris in 17 sites along the central gulf, with an extreme record at Tortuga Island (27.445N, almost 400 km north of its accepted range), and also in two locations of the western Baja California Peninsula (Alijos Rocks and Puerto San Carlos, at 24N). These findings represent more examples of a recently observed trend in which several species of tropical fish have expanded their distribution range towards the inner Gulf of California and in the Pacific side of the peninsula, as a possible response to the reported warming that occurs in the region.

Research areas: Ecosystems, Atmospheric/Ocean Indicators
Changes in Vertical Distribution and Column Content of NO2 under the Influence of Sudden Stratospheric Warmings (2018)

Characteristic features of changes in the vertical distribution and column content of NO2, total ozone, and stratospheric temperature have been revealed as a result of major sudden stratospheric warmings (SSWs). Strong negative anomalies of column NO2, total ozone and stratospheric temperature are caused by the displacement of the stratospheric circumpolar vortex aside from the pole. Strong positive anomalies of column NO2 and total ozone are observed more frequently under SSWs accompanied by splitting of the stratospheric circumpolar vortex and are caused by the transport of stratospheric air from the low latitudes. Major SSWs can lead to significant changes in the vertical profile of NO2. The changes in different stratospheric layers can be opposite to each other when the edge of the polar vortex is over a site of ground-based observations.

Research areas: Air Quality
Temporal and spatial variations of NO2 over Saudi Arabia and identification of major hotspot areas during 2005-2014 by using satellite data. (2018)

The present study was designed to analyze the concentration of tropospheric NO 2 over
Saudi Arabia for a decade from 2005-2014 based on observations from satellite borne Ozone
Monitoring Instrument (OMI). The spatial analysis has identified two hotspots: Jeddah and Riyadh.
The result of temporal analysis shows increase of 1.45%, 3.15% and 3.10% per year over Saudi
Arabia, Jeddah and Riyadh respectively. The Linear Regression analysis and Analysis of Variance
(ANOVA) have been performed to analyze the relationship between meteorological parameters,
seasons, years and concentration of NO 2 . The results show that temperature and NO 2 are moderately
correlated whereas wind and humidity give negative correlation. The major causes of elevated NO 2
over the hotspots are road traffic and the fossil fuel combustion for electrical power generation.

Research areas: Air Quality, Energy Production/Use
Standard or local solar spectrum Implications for solar technologies studies in the Atacama desert (2018)

Knowledge of the solar spectrum is essential for the design and study of numerous technologies. Due to the area considered, the harsh conditions and the difficulty for accessing to some zones, information and measurement on local parameters and spectral resource are scarce. This fact, along with the special atmospheric conditions prevailing in Atacama Desert, has led to increasing interest on the part of the solar industry to ascertain the spectral variation respect to that of other places around the world. Considering the standard spectrum for a typical air mass as 1.5, the evaluation of PV module behaviour or device calibration under real conditions can generate a source of uncertainty where spectra may differ. This preliminary paper aims to study the influence of using the standard or local spectra in photovoltaic technologies in Atacama Desert, in order to highlight the necessity for a long-term ground-based measurement campaign. For that purpose, a first approach to the spatio-temporal average of solar spectrum in the Atacama Desert from satellite databases is estimated. Then, local spectra are compared against the Reference Spectra in order to show the differences in studies on solar energy applications. Long-term satellite database information is used to average the atmospheric parameters, such as Aerosol Optical Depth, Ozone, Precipitable Water Vapour, Albedo and Relative Humidity, for the entire Atacama Desert area and is then used to obtain the mean Global tilted Irradiance and Direct plus Circumsolar Irradiance solar spectrum. Finally, to study the influence that the shape of the local spectrum has on the performance of the different solar technologies, the photo-current density of two different solar cell types were studied under Atacama and standard conditions. The results indicate that there are considerable differences with the ASTM G173-03 reference spectra for short wavelengths, especially in the UV spectral range, which is 55% points higher than the reference, which influences in the performance of the solar technologies.

Research areas: Sun-Earth Interactions, Energy Production/Use
Passive microwave response associated with two main earthquakes in Tibetan Plateau, China (2018)

The thermal anomalies associated with earthquakes using satellite infrared data are being studied in different parts of the world for more than three decades. The thermal anomalies have emerged as one of the potential earthquake precursor. However, often cloud cover obstructs detection of the thermal anomalies. Compared to infrared, passive microwave sensors provide information about the thermal radiations under any weather conditions. In the present study, we have carried out detailed analysis of brightness temperature data derived from the Defense Meteorological Space Program (DMSP) Special Sensor Microwave/Imager (SSM/I) to determine thermal anomalies associated with the 1997 Manyi and 2001 Kokoxili earthquakes. Brightness temperature data for 13 years period from 1996 to 2008 observed from F13 satellite were considered to avoid difference in the sensor sensitivity. Based on 9 years background data that ignoring data for the years in which strong earthquake occurred, we computed Index of Microwave Radiation Anomaly (IMRA) over the Manyi-Yushu Fault (MYF) and Kun Lun Fault (KLF) zones, Tibetan Plateau. Our results indicate that the microwave brightness temperature at 19.35 GHz has higher sensitivity to the seismic anomalies in comparison to the other higher frequency channels. The IMRA with multi-region, multi-frequency, and multi-parameter variation were analyzed to validate our results. In addition, variation of different parameters (microwave brightness temperature, near surface air temperature and carbon monoxide-CO) observed for Kokoxili earthquake shows the transfer process of thermal anomalies from the focal region to the atmosphere during the preparation and occurrence of earthquake. Passive microwave satellite data combined with other surface and atmospheric parameters provide better understanding of physical mechanism of thermal anomalies associated with earthquakes.

Research areas: Earthquakes
Light absorption properties of brown carbon over the southeastern Tibetan Plateau (2018)

We present a study of the light-absorbing properties of water-soluble brown carbon (WS-BrC) and methanol-soluble brown carbon (MeS-BrC) at a remote site (Lulang, 3326m above sea level) in the southeastern Tibetan Plateau during the period 20152016. The light absorption coefficients at 365nm (babs365) of WS-BrC and MeS-BrC were the highest during winter and the lowest during monsoon season. MeS-BrC absorbs about 1.5 times higher at 365nm compared to WS-BrC. The absorption at 550nm appears lower compared to that of 365nm for WS-BrC and MeS-BrC, respectively. Higher average value of the absorption Angstrom exponent (AAE, 365550nm) was obtained for MeS-BrC (8.2) than that for WS-BrC (6.9). The values of the mass absorption cross section at 365nm (MAC365) indicated that BrC in winter absorbs UVvisible light more efficiently than in monsoon. The results confirm the importance of BrC in contributing to light-absorbing aerosols in this region. The understanding of the light absorption properties of BrC is of great importance, especially in modeling studies for the climate effects and transport of BrC in the Tibetan Plateau.

Research areas: Validation
Large-Scale Sea Turtle Mortality Events in El Salvador Attributed to Paralytic Shellfish Toxin-Producing Algae Blooms (2018)

In late October and early November 2013 and 2017, hundreds of sea turtles were found dead along the Pacific coastline of El Salvador. The dead turtles were in good body condition and did not have any injuries or other major anomalies. In order to determine the role of paralytic shellfish toxins (PSTs) in this mass mortality, tissue samples, including blood, flipper, liver, kidney, stomach and intestinal contents, of dead green turtles (Chelonia mydas) and olive ridley turtles (Lepidochelys olivacea) were analyzed for PSTs using a radioactive receptor binding assay, enzyme-linked immunosorbent assay, and high performance liquid chromatography. Highest values of PSTs were detected in enteric contents in the 2013 event (730.41 g STX eq 100 g-1) and in gastric contents during the 2017 event (1616.5 g STX eq 100 g-1). During these events, intense chlorophyllA and fluorescence line height anomalies suggestive of algal blooms were identified off the coast of El Salvador. In the 2017 event, Pyrodinium bahamense was observed in samples of gastrointestinal contents from affected sea turtles. Seawater from the region where dead sea turtles were found was also analyzed, but saxitoxin-producing species were found in low abundance (5400 cell/ in 2013 and 672 cell/L in 2017). Although threshold levels of toxicity in sea turtle species are not well-characterized, our evidence suggests that these large events were the result of PST-producing algal blooms and that these blooms are a major cause of sea turtle mortality in this region.

Research areas: Ecosystems