nasa-gesdisc/es-publications-researchareas huggingface dataset:
Considering flood scaling property in multi-objective calibration of the SWAT model: a case study in Zijinguan watershed, Northern China (2023)

Adopting new technologies to calibrate hydrological models to produce good simulations for water resources or flood risk management is one of the important research topics in hydrology field. Incorporating hydrological signatures and concepts in hydrological model calibration becomes prevalent in recent years. A good realistic simulation of hydrological processes within the catchment is more significant than only achieving good performance at watershed outlet with single-statistical-objective function. This research adopts the concept of flood scaling property, which describes the statistical relationship between flood peak, its contributing areas and additional catchment attributes, to behave as one of the constraints under multi-objective model calibration framework. Several designed calibration scenarios are tested by employing the soil and water assessment tool hydrological model. In comparison with single-objective calibration scenarios, multi-objective calibration method is recommended to obtain both good simulation at catchment outlet and sub-basins reaches. The multi-objective calibration method assists in improving the model performance in terms of flow duration curve and also in reducing the bias of long-term runoff ratio. The proposed model calibration approach reflects the hydrological interaction of flood peaks across sub-basins and takes into account the catchment antecedent wetness and climatic condition for each flood event.

Research areas: Validation
Comparison of precipitation estimates between Version 7 3-hourly TRMM Multi-Satellite Precipitation Analysis (TMPA) near-real-time and research products (2015)

Over the years, blended methods that use multi-satellites and multi-sensors have been developed for estimating global precipitation and resulting products are widely used in applications. An example is the 3-hourly TRMM (Tropical Rainfall Measuring Mission) Multi-Satellite Precipitation Analysis (TMPA) that consists of two products: near-real-time (3B42RT) and research-grade (3B42). The former provides quick, less accurate estimates suitable for monitoring activities; the latter provides more accurate estimates more suitable for research. Both products have been widely used in research and applications. Nonetheless, to improve near-real-time applications, it is important to understand their difference. In this study, seasonal mean difference (MD), mean absolute difference (MAD), root mean square difference (RMSD), and their inter-annual variations in boreal (June, July and August or JJA) and austral (December, January and February or DJF) summers and in different rain regimes over two surface types are investigated on a large scale (50N50S) from 2000 and 2012. Over land, positive MD values (3B42RT N 3B42) dominate, especially in western China, western United States, northwest Asia and over some oceanic regions of light rain in both JJA and DJF. Over ocean, negative MD values (3B42RT b 3B42) prevail, except over regions of light rain. In general, relative (to 3B42) MD values increase with rain rate. Variation of the individual differences between the two products is small (large) over regions of heavy (light) rain. There is no significant inter-annual variation in the seasonal mean statistics. The difference between the two products is likely due to the algorithms and further investigations are needed.

Research areas: Validation
Comparative study of the tropospheric ozone derived from satellite data using different interpolation techniques (2015)

Tropospheric ozone (TO) has been derived from the Aura/Ozone Monitoring Instrument (OMI) and the Aura/Microwave Limb Sounder (MLS) over the Indian sub-continent region using a tropospheric ozone residual (TOR) technique. The TO was initially retrieved at a horizontal spatial resolution following that of the Aura/ MLS (300 km), which has a lower horizontal spatial resolution than that of the Aura/ OMI (25 km). To overcome the limitations imposed by data at a lower spatial resolution, we have introduced a 2D rectangular interpolation (RI) algorithm for effective resampling of data to higher horizontal spatial resolutions. The performance of this algorithm has been evaluated by comparison against existing standard techniques such as nearest neighbourhood (NN) and kriging interpolation as well as comparison against in situ ozonesonde observations. Gridded TO estimates were subsequently generated for the region of interest at 25, 50, and 100 km horizontal spatial resolutions for further study.

Research areas: Validation
Black carbon aerosols in urban central China (2015)

The first ever (to our knowledge), year-round measurements of Black Carbon (BC) aerosols in Hefei, an urban site of central China, from June 2012 to May 2013 are performed. The aim of this paper is to evaluate the black carbon in Hefei in terms of seasonal, monthly and diurnal variations, including their source identification. The annual mean BC mass concentration MBC is found to be 3.5 7 2.5 gm 3 in Hefei, while the aerosol optical depth shows a yearly average value of   0.6. The seasonality of MBC depicts minimum values in the summer, moderate levels in the spring and fall, and maximum in the winter. The monthly average values of MBC vary threefold, ranging from the lowest average value of 2.0 7 1.0 gm 3 in July to the highest 6.0 7 2.6 gm 3 during January. Diurnal variations exhibit two BC peaks, corresponding to the morning and evening rush hours. Higher median BC concentrations are observed during haze episodes compared with non-haze periods, although low MBC is sometimes observed for high visibility, which is probably indicative of the aerosol scattering dominating diminished visibility. Based on trajectory analyses, the haze BC pollutions are mostly classified into three types from local areas, long-range transport from the Yangtze Delta, and transport from the North China Plain. The median MBC values for haze groups attributed to biomass burning from MODIS wildfire maps are higher than related groups that are not, which is indicative of the significant enhancement of BC aerosols due to agricultural biomass burning. The study suggests that aerosol absorption contributes more to the observed haze episodes in fall compared to other seasons.

Research areas: Air Quality, Environmental Impacts
Assessment of long-term trends in chlorophyll-a and sea surface temperature in the Arabian Sea and their association with aerosols using remote sensing (2023)

Aerosols over the oceanic region significantly influence Earths energy budget and climate change. Therefore, this study examines the spatiotemporal patterns of MODIS retrieved aerosol optical depth, sea surface temperature, Chlorophyll-a, Sea-WiFS retrieved aerosol optical depth, and MERRA-2 model dust mass concentrations over the Arabian Sea (4o N26o N to 50o E 78o E) during the period 20022020. The effects of dust aerosols on phytoplankton blooms using the Mann-Kendall and Theil Sen-slope are also analyzed in this study. An increase in aerosol optical depth (AOD) was observed within the latitudes of (4o N26o N). The AOD shows an increasing trend at 13.4% per year over the Arabian Sea (AS). The highest value of Chl-a (~7 mgm 3) was observed along the coast of Pakistan, Iran, and Oman. Moreover, a negative correlation is found between AOD and sea surface temperature (SST) along the coast of Oman and Somalia, while a strong positive correlation (~0.99) is observed between AOD and Chlorophyll-a (Chl-a) along the coasts of Oman and Somalia.

Research areas: Ecosystems, Atmospheric/Ocean Indicators
Application of the WASP Model for Assessment of Aeration Impact on Water Quality of Porsuk River, Turkey (2022)

Porsuk Stream is the longest branch of the Sakarya Basin which originates from Murat Mountain and bypasses the provinces of Kutahya and Eskisehir. Based on recent increasing pollution concentrations reported in the literature, the main river is experiencing problems with decreased water quality. In this study, hydrodynamics and water quality parameters are simulated in the Porsuk River via the application of the Water Quality Analysis Simulation Program (WASP) using the available flow and meteorological data. After the validation of the hydrodynamics along the main river, water quality parameters are simulated using the eutrophication module. Simulation of dissolved oxygen concentrations pointed out hypoxia, especially at two locations; Kutahya-Reservoir1 and Alpu-Guroluk segments where dissolved oxygen values stayed well below the standard limits throughout the year. As a mitigation option, aeration applications at these two stations are proposed and the effects of aeration on the simulated parameters of dissolved oxygen, phosphorus and nitrate concentrations are investigated. Aeration at two segments has significantly improved the dissolved oxygen concentrations (from ~3 mg/l to >14 mg/l) whereas it has a more subtle effect on nitrate and phosphorus concentrations.

Research areas: Water Quality
An analysis of aerosol properties during a dust storm due to the TAUKTAE cyclone using remote sensing (2023)

Millions of people suffer from health problems due to poor air quality in regions of high particulate pollution. Therefore, this paper proposes for better understanding of the impact of dust storms on both short- and long-term environmental factors that can help in a preferable formulation of warning and prediction scenarios in arid regions. We evaluate the effect of dust storms on the optical properties of aerosols and meteorological parameters by employing both ground-based and satellite remote sensing approaches. For this, we use AERosol RObotic NETwork (AERONET), MODerate resolution Imaging Spectroradiometer (MODIS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), Ozone Monitoring Instrument (OMI), Suomi National Polar-orbiting Partnership (S-NPP), and Sentinel-5 Precursor (S5P) to retrieve aerosol optical properties from 15 May 2021 to 20 May 2021 over Karachi. At 550nm, the instantaneous maximum values of aerosol optical depth (AOD) are measured to be ~0.8, and 0.59 on 16 May 2021, and the lowest values of Angstrom Exponent (AE) are discovered to be ~0.2, and ~0.26 by Aqua-MODIS and AERONET respectively. Such observations are attributed to dust aerosols over Karachi; these values are more than those that might be expected on an ordinary day. We also found S5P and OMI retrieved ultraviolet aerosol index (UVAI) of about 1 and ~1.9 on 17 May 2021 respectively which indicate the presence of absorbing (dust) aerosols. Subtypes of aerosols derived by CALIPSO with vertical profile taken on 17 May 2021 segregate the widespread aerosol burden as contaminated dust particles over surrounding regions of Karachi (24.4830.59 N, 69.0170.56 E).

Research areas: Air Quality, Severe Storms
Aerosols heat up the Himalayan climate (2023)

The impact of aerosols, especially the absorbing aerosols, in the Himalayan region is important for climate. We closely examine ground-based high-quality observations of aerosol characteristics including radiative forcing from several locations in the Indo-Gangetic Plain (IGP), the Himalayan foothills and the Tibetan Plateau, relatively poorly studied regions with several sensitive ecosystems of global importance, as well as highly vulnerable large populations. This paper presents a state-of-the-art treatment of the warming that arises from these particles, using a combination of new measurements and modeling techniques. This is a first-time analysis of its kind, including ground-based observations, satellite data, and model simulations, which reveals that the aerosol radiative forcing efficiency (ARFE) in the atmosphere is clearly high over the IGP and the Himalayan foothills (80135 Wm2 per unit aerosol optical depth (AOD)), with values being greater at higher elevations. AOD is >0.30 and single scattering albedo (SSA) is 0.90 throughout the year over this region. The mean ARFE is 24 times higher here than over other polluted sites in South and East Asia, owing to higher AOD and aerosol absorption (i.e., lower SSA). Further, the observed annual mean aerosolinduced atmospheric heating rates (0.50.8 Kelvin/day), which are significantly higher than previously reported values for the region, imply that the aerosols alone could account for >50 % of the total warming (aerosols + greenhouse gases) of the lower atmosphere and surface over this region. We demonstrate that the current state-of-the-art models used in climate assessments significantly underestimate aerosol-induced heating, efficiency and warming over the Hindu Kush  Himalaya  Tibetan Plateau (HKHTP) region, indicating a need for a more realistic representation of aerosol properties, especially of black carbon and other aerosols. The significant, regionally coherent aerosolinduced warming that we observe in the high altitudes of the region, is a significant factor contributing to increasing air temperature, observed accelerated retreat of the glaciers, and changes in the hydrological cycle and precipitation patterns over this region. Thus, aerosols are heating up the Himalayan climate, and will remain a key factor driving climate change over the region.

Research areas: Atmospheric/Ocean Indicators
Variations in aerosol optical characteristics from SKYNET measurements in Beijing (2023)

Atmospheric aerosols have significant impacts on climate and environment, so the study on aerosol optical properties is of great scientific significance for climate change and atmospheric environment. The variations in column-integrated aerosol optical properties over Beijing were investigated from March 2016 to December 2019 based on the SKYNET data products. Higher values of AOD and AE found in summer indicate that it is important to pay more attention to fine particle pollution in summer. By fitting the AOD data of SKYNET with AERONET at same waveband, we found that monthly variations in aerosol optical depth estimated from SKYNET observation were mostly consistent with the AERONET data. Aerosols were divided into several modes according to optical characteristics, which deepen some insight into aerosol optical and radiative properties and revealed that the weak absorption aerosol dominated and contributed much to the radiation transport in Beijing. Data derived from the polarization lidar CALIPSO were combined with aerosol optical depth (AOD) from SKYNET and these results were consistent, which further identified the scientific of data. The random forest algorithm was used to interpolate the missing AOD500nm observations. The original results and the interpolation results were fitted with MODIS respectively, which proved that the random forest algorithm can supplement the missing results well. This work will be of great significance in addressing the impacts of aerosols on climate and environment, and will help reduce the uncertainty of the impacts of aerosols on the Earth's radiation budget. All work will provide scientific support for the prevention and control of specific pollution.

Research areas: Validation
What Is Polluting Delhis Air? A Review from 1990 to 2022 (2023)

Delhis annual average PM2.5 concentration in 202122 was 100 g/m320 times more than the WHO guideline of 5 g/m3. This is an improvement compared to the limited information available for the pre-CNG-conversion era (~30%), immediately before and after 2010 CWG (~28%), and the mid-2010s (~20%). These changes are a result of continuous technical and economic interventions interlaced with judicial engagement in various sectors. Still, Delhi is ranked the most polluted capital city in the world. Delhis air quality is a major social and political concern in India, often with questions regarding its severity and primary sources, and despite several studies on the topic, there is limited consensus on source contributions. This paper offers insight by reviewing the influence of Delhis urban growth since 1990 on pollution levels and sources and the evolution of technical, institutional, and legal measures to control emissions in the National Capital Region of Delhi.

Research areas: Habitat Conversion/Fragmentation, Air Quality
Winter phytoplankton size classes in the Northeastern Arabian Sea based on in-situ and remote sensing methods (2023)

Phytoplankton size classes (PSCs) are important in marine ecosystems because they organise the food chain and trophic pathways, which determine the overall biological environment. Based on three FORV Sagar Sampada cruises, the current study provides changes in PSCs in the Northeastern Arabian Sea (NEAS; north of 18 N) during different phases of the Northeast Monsoon [NEM (NovemberFebruary)]. During all three phases of NEM such as early (November), peak (December), and late (February), in-situ chlorophyll-a fractionation data revealed that nanoplankton (220 m) predominated, followed by microplankton (>20 m) and picoplankton (0.22.0 m). This was primarily because winter convective mixing in the NEAS maintains only a moderate level of nutrients in the surface mixed layer, which is more conducive to the dominance of nanoplankton. Brewin et al. (2012) and Sahay et al. (2017) have satellite-based PSC estimation algorithms; the former was developed for the entire Indian Ocean, while the latter is a modification of the former for the Noctiluca bloom-infested NEAS, with a claim that such blooms are typical of the NEM. When current in-situ PSCs data were compared to algorithm-based NEM data, Brewin et al. (2012) revealed a more realistic PSCs contribution pattern, especially in oceanic waters, with nanoplankton predominating except during early NEM. But the PSCs data from Sahay et al. (2017) showed a high degree of variation from the in-situ data, demonstrating the dominance of pico- and microplankton and a notably small contribution from the nano phytoplankton. The current study showed that Sahay et al. (2017) is inferior to Brewin et al. (2012) at quantifying PSCs in the NEAS without Noctiluca blooms, and provided evidence to show that Noctiluca blooms are not a typical feature of the region during the NEM.

Research areas: Ecosystems
A case study of weather impact on air pollution during the COVID-19 pandemic in South Africa (2023)

This study investigates climate, weather characteristics, and air pollution during the third COVID-19 wave in South Africa. During this time, a decrease in of SO2 and NO2 column mass was observed. The investigation displays a positive trend in for tropospheric Ozone (O3) mass mixing in winter over the last two decades with a fitted slope of 1.0005. Despite the negative trend for the daily changes (for all 12 months) of the total column mass density for PM2.5 during the year before the pandemic and two years after for pandemic years, they have slightly increased specifically during winter COVID-19 third wave time. The temporal seasonal yearly time changes (19612021) of different meteorological parameters such as surface temperature, low-level vertical pressure velocity, low-level relative humidity, and precipitation rate over South Africa show sharp changes from 2020 to 2021. This analysis indicates rather colder surface temperatures, smaller but positive low-level vertical velocity, slightly higher low-level relative humidity, and higher total country precipitation rate in the study area during the COVID-19 pandemic years. Weather chart analysis displays a very stable atmospheric condition during the third wave of COVID-19 peak time. This is correlated with the extension of the atmospheric ridge associated with a blocking high pressure, downward motion, positive vorticity, and rather weak winds specific in the north, west, and central areas causing atmospheric stability and possible accumulation of the atmospheric pollution corresponding to the higher COVID-19 cases during the South Africa third wave.

Research areas: Air Quality
Physical mechanisms affecting phytoplankton variability along the Chilean coast (2024)

Chile has high phytoplankton production due to being a classic example of an Eastern Boundary Upwelling System. Monthly averaged chlorophyll- (Chl) and physical parameters (sea surface temperature, precipitation rate, southerly and westerly winds) were studied off the Chilean coast from 2002 to 2018, in order to understand the primary production along this important ocean margin. The coastal margin was split into three zones and ten sub-sections. The Northern Zone had a low phytoplankton production with small seasonal variability, except in its north. This pattern is due to a narrow shelf, weak winds, lack of precipitation and relatively stable weather conditions driven by the Southeast Pacific Subtropical Anticyclone (SPSA). The Central Zone presented a seasonally varying production, with a high Chl concentration in summer and early spring. This is linked to the SPSA movement and sunlight reduction during the winter. A high Chl activity is seen in the Southern Zone despite this Zone being at the limits of the SPSA effect, leading to weak longshore winds only during the warm season. Overall, this study has demonstrated the importance of shelf width and the upwelling driven by the presence or absence of the SPSA for ocean primary production. Thus, the most productive region is from 35S to 45S owing to both variables being present.

Research areas: Ecosystems
First Report on the Reproductive Biology of the Redtail Scad Decapterus kurroides Bleeker, 1855 in Iligan Bay, Southern Philippines (2022)

This study provided the first report on the reproductive biology of the redtail scad, Decapterus kurroides. The reproductive activity of the redtail scad was assessed to characterize its sex ratio, spawning period, length at maturity, and fecundity. Meanwhile, remote sensing data on environmental variables were accessed from Giovanni online data system. Fish samples were collected monthly from October 2017 to September 2018 from both commercial and municipal landed catches. Male D. kurroides was found to have a larger size than the female in terms of mean total length and mean body weight, but it did not differ significantly from the female (t = 1.31, df = 1,348, p = 0.19). Collected male and female samples were mostly in the 15.00  18.00 cm size class. Overall sex ratio exhibited female dominance (1.2:1), which significantly deviated from the 1:1 ratio (x2 = 8.17, p = <0.05). As expected for tropical fish, spawning of D. kurroides occurred year-round, with peak spawning in December and minor spawning events in March and August, as reflected in the monthly percent occurrence of different gonad maturity stages and gonadosomatic index evolution. Among the environmental variables evaluated, sea surface temperature appeared to have more influence on the spawning of D. kurroides followed by chlorophyll-a concentration. Females matured at a length of 17.2 cm, while males matured at a length of 17.6 cm. Absolute fecundity ranged from 6,416 to 197,672 eggs per female with a mean of 61,733  3,955 and increased proportionally with gonad weight. Information from this study may be used to formulate effective management strategies for the resource.

Research areas: Ecosystems