nasa-gesdisc/es-publications-researchareas huggingface dataset:
Bacterial and archaeal biogeography of the deep chlorophyll maximum in the South Pacific Gyre (2015)

We used 16S rRNA gene tag pyrosequencing to examine the biogeography of bacterial and archaeal community composition in the deep chlorophyll maximum (DCM) of the South Pacific Gyre (SPG), the largest and most oligotrophic region of the world ocean. Dominant DCM bacterial taxa, including Prochlorococcus, SAR11, SAR406, and SAR86, were present at each sampled site in similar proportions, although the sites are separated by thousands of kilometers and up to 100 m in water depth. Marine Group II (MGII) and MGIII Euryarcheota dominated the archaeal assemblages of the DCM at these sites. Bray-Curtis indices show that assemblage composition of these sites is >70% similar for Bacteria and >80% similar for Archaea. Despite these similarities, communities of the central SPG, the western SPG margin, and the southern SPG margin are distinguishable from each other. Comparison of our bacterial results to samples from the DCM of the North Pacific Gyre (NPG) and the relatively nutrient- and chlorophyll-rich Equatorial Pacific (EQP) shows that DCM bacterial assemblage composition is >50% similar throughout all 3 regions. Nonetheless, the SPG, NPG, and EQP assemblages are statistically distinct from each other (ANOSIM, p = 0.001), with the communities of the 2 gyres resembling each other more closely than either resembles the EQP community (which lives geographically between them). Variation in assemblage composition correlates with sea-surface chlorophyll concentration (r2 = 0.71, p < 0.003). This study demonstrates that the DCM horizons of different oceanic regions harbor statistically distinct communities that are consistent within regions for thousands of kilometers.

Research areas: Ecosystems
Space technology applied to patagonian glaciers and their behavior as environmental indicators (2022)

This study contemplates a multi-temporal analysis with satellite images and meteorological data from a group of glaciers called Glaciares Escondidos, located to the southwest of the Southern Patagonian Ice Field. Made up of the Dickson, Cubo and Frias glaciers, it has suffered a marked retreat of its fronts that has accelerated in the last 10 years. The Dickson and Frias glaciers were originally fed by a single ice stream and used to act as natural dams, preventing the flow of water between Lake Frias and Lake Dickson. Due to the loss of mass and the retreat of its fronts, the waters that traveled more than 250 km, completely crossing the arid plain of Patagonia to empty into the Atlantic Ocean, today they do it towards the Pacific Ocean sailing the waters of the Chilean fjords that flow towards the west. Formations of proglacial lakes, an increase in the speed of retreat and a high speed of ice flow are observed, which were estimated with multi-temporal measurements and the offset tracking technique with radar images. Likewise, analyzes of mass balances on these three glaciers of the last 20 years are presented, using the geodesic method.

Research areas: Cryospheric Indicators
Adaptations toward Climate Risk: Challenges and Opportunities of the Upland Farmers in Ifugao, Philippines (2021)

There has been an increasing concern over the threats posed by climate change to the conservation of UNESCO World Heritage Sites and Globally Important Agricultural Heritage Systems (GIAHS). However, the Ifugao Rice Terraces (IRT) have received limited attention with respect to climate change, considering it is one of the provinces in the Philippines highly at risk to temperature change, projected rainfall change, and combined climate and weather-related risks. It is therefore necessary to assess how the community perceives climate change and how they can cope up with these impacts. This study aimed to explore farmers perceptions, adaptation strategies, and barriers to climate change in the community of Batad Rice Terraces. A total of 114 out of 197 households, three focused group discussions, and five interviews with key stakeholders, including government officials and community leaders, were conducted in 2017 and 2018. The result showed that farmers have already observed the negative impacts of changing weather patterns, particularly in their agricultural production. The most common impacts observed were low rice yield, drought, and drying of rice plants due to unpredictable rainfall patterns and temperature increase. The top three most important adaptation strategies in the face of climate variability are all water-related. This shows that strong local government support is recommended to repair and maintain irrigation canals within the terraces. The salient climate change barriers identified by the farmers were access to climate information, inadequate farm labor, and lack of access to agricultural extension.

Research areas: Agriculture
Seasonal trend analysis of carbon dioxide across latitudes of Africa, Europe and Asia (2020)

Carbon-driven emissions are on the rise and much work remains to be done to benchmark seasonal carbon increase and ensure its prompt reduction. There is a great need of new methods for validating seasonal trends of carbon dioxide (CO2). We obtained CO2, temperature and normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra satellite from 2003 to 2008 over Africa (Nigeria, Mauritania, Congo, Sudan), Europe (France, Finland, Turkey, Ukraine), and Asia (China, Mongolia, India, Afghanistan). For the first time, seasonal index analysis was used to validate vegetation index. The seasonality in carbon dioxide was determined dividing the monthly average by the annual mean. Additionally, the percentage difference correlation of the NDVI and CO2 relationship was calculated to investigate the underlying influence of both parameters and validate the seasonal change resulting from the solar activity cycle. By grouping years based on solar activity maximum (2003-2004), intermediate (2005-2006) and very low activity (2007-2008), the results expanded the physical interpretation that seasonal fluctuation of NDVI corresponds to the terrestrial sink of regional CO2, mostly occurring during equinoctial months. Our results demonstrate that seasonal variation of CO2 depends on geographic latitude and the solar activity cycle. This result is essential in studying the future trend relationship between NDVI and CO2.

Research areas: Greenhouse Gases, Land Surface/Agriculture Indicators
Deepsea fluxes of barium and lithogenic trace elements in the subtropical northeast Atlantic (2017)

Total particle flux, Barium and lithogenic trace element fluxes were measured at the mooring Kiel 276 (33N, 22W) in the deepsea of the subtropical Northeast Atlantic. The particulate material was collected between 2002 and 2008 with a sediment trap in 2000m depth and analyzed with ICP-OES/-MS to determine its geochemical composition. The particle flux is controlled by primary production, lithogenic particle inputs via atmospheric transport and the migration of the Azores Front. We used refractory trace elements (eg. Ti, Zr, and the rare earth elements) to demonstrate the changes in flux and composition of the material due to lithogenic inputs. Shortly after periods of high dust load and enhanced primary production an increase in lithogenic trace element fluxes occurred. Especially the formation of aggregates with biogenic matter seems to have a major impact on the downwards transport of lithogenic particles. The observation of particulate Ba is of great interest since it is known as a proxy for past and present primary production. Ba fluxes ranging between 0.02mgm2d1 and 1.21mgm2d1 with biogenic proportions up to 97%. The fluxes of particulate Barium in the water column are mainly attributed to the strength of primary production.

Research areas: Ecosystems
Comparison of TMPA-3B42 Versions 6 and 7 Precipitation Products with Gauge-Based Data over India for the Southwest Monsoon Period (2015)

The upgraded version 7 (V7) of the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) products is available to the user community. In this paper, two successive versions of the TMPA-3B42 research monitoring product, version 6 (V6) and V7, at the daily scale are evaluated over India during the southwest monsoon with gauge-based data for a 13-yr (19982010) period. Over typical monsoon rainfall zones, biases are improved by 5%10% in V7 over the regions of higher rainfall like the west coast, northeastern, and central India. A similar reduced bias is seen in V7 over the rain-shadow region located in southeastern India. In terms of correlation, anomaly correlation, and RMSE, a marginal improvement is seen in V7. Additionally, in all-India summer monsoon rainfall amounts, mean, interannual values, and standard deviation show an overall improvement in V7. Different skill metrics over typical subregions within India show an improvement of the monsoon rainfall representation in V7. Rainfall frequency in different categories also indicates an overall improvement in V7 across all scales and subregions. Over central India regions associated with the monsoon transients, the sign of the bias has changed toward a positive bias. Even if the bias in the frequency of the occurrence of light rain has improved in V7, the values still show a large difference compared to observations. Though both V6 and V7 are able to represent the anomalous dry/wet regions during contrasting monsoon years, V7 shows some improvement in amplitude of those anomalies over V6. In general, V7 has considerably improved over V6 and will continue to be in demand from various sectors of observed rainfall data users.

Research areas: Validation
New atmospheric composition observations in the Karakorum region: Influence of local emissions and large-scale circulation during a summer field campaign (2014)

In this work we provide an overview of short lived climate forcers (SLCFs) and carbon dioxide variability in the Karakorum, by presenting results deriving from a field campaign carried out at Askole (3015 m a.s.l., Pakistan Northern Areas), by Baltoro glacier. By using an innovative embedded and transportable system, continuous measurements of aerosol particle number concentration (Np, 1571  2670 cm3), surface ozone (O3, 31.7  10.4 nmol/mol), carbon dioxide (CO2, 394.3  6.9 mol/mol) and meteorological parameters have been performed from August 20th to November 10th 2012. The domestic combustion from the Askole village emerged as a possible systematic source of contamination in the valley, with short-lasting pollution events probably related to domestic cooking activities characterized by high values of Np (6066  5903 cm3). By excluding these local contamination events, mountain thermal wind regime dominated the diurnal variability of Np, O3 and CO2. In comparison to night-time, we observed higher Np (+354 cm3) and O3 (+7 nmol/mol) but lower CO2 (8 mol/mol) in air-masses coming from the lower valley during the central part of the day. Part of the day-to-day atmospheric composition variability can be also ascribed to synoptic circulation variability, as observed by using HYSPLIT 5-day back-trajectories.

Research areas: Air Quality
Uncertainty and variability in satellite-based water vapor column, aerosol optical depth and Angstrom exponent, and its effect on radiative transfer simulations in the Iberian Peninsula (2014)

The water vapor column product from the MODIS instrument onboard the Terra satellite is compared with ground-based measurements at six Spanish locations (AERONET stations) in the Iberian Peninsula. In addition, aerosol optical depth (AOD) at 443 nm and at 675 nm retrievals from the MISR instrument onboard the Terra satellite is also compared with ground-based measurements at the same locations to determine their uncertainties. Remote sensing data of water vapor and aerosol optical properties are averaged each month to obtain climatology tables and to characterize atmospheric properties at nine locations in the Iberian Peninsula. These tables are used as input in a radiative transfer model to calculate total shortwave (SW) and ultraviolet erythemal (UVER) irradiance at the nine locations. SW and UVER simulations are recalculated considering the uncertainties and the climatological variability of the input datasets. AOD uncertainty provides changes lower than 6% in most cases for both SW and UVER simulations. The propagation of water vapor uncertainty causes variations in SW simulations less than 4% for solar zenith angles below 75.

Research areas: Validation
Dust-storm dynamics over Sistan region, Iran: Seasonality, transport characteristics and affected areas (2015)

The present work examines the seasonality, dust-plume altitudinal variation and affected areas for dust storms originated from the Sistan region, southeastern Iran during the summer (JuneSeptember) months of the period 20012012 synthesizing local meteorological records, satellite observations (TOMS, OMI, METEOSAT, MODIS) and HYSPLIT forward trajectories. Dust-storm days (356 in total) are associated with visibility below 1 km at Zabol, Iran meteorological station with higher frequency and intensity in June and July. Monthly-mean composite maps of TOMS and OMI AI show high (>33.5) values over Sistan and nearby downwind areas. HYSPLIT forward-trajectory analysis at 500 m for air masses originated from Sistan on the dust-storm days shows that they usually follow an anti-clockwise transport direction at elevations usually below 2 km, initially moving southwards and then shifting to east-northeast when they are approaching the Arabian Sea coast. This is the result of the influence of the local topography and formation of thermal low-pressure systems over the arid lands. It is found that in few cases the dust storms from Sistan affect central/south Arabian Sea and India, while they control the aerosol loading over northernmost Arabian Sea. The Infrared Difference Dust Index (IDDI) images, which represent brightness temperature reduction due to dust presence over land, are used at specific periods of persistent dust storms over Sistan, confirming the main pathways of the dust plumes and illustrating the importance of the region as one of the most active dust sources in southwest Asia.

Research areas: Air Quality
Examination of water budget using satellite products over Australia (2014)

Large-scale water balance in the Australian continent is examined over an 8-year period (20032010) with three commonly used satellite based water cycle components: precipitation (P) from the Tropical Rainfall Measuring Mission (TRMM), evapotranspiration (ET) from the Moderate Resolution Imaging Spectroradiometer (MODIS), and terrestrial water storage change (S) from the Gravity Recovery and Climate Experiment (GRACE). First we evaluate the water balance using the three products over areas with limited annual streamflow to eliminate the influence of runoff in the analysis. We observe more frequent and better closure and consistency in the water balance from the three components over the central part of Western Australia, where low precipitation, high elevation and low relief exist. The data are more coherent at seasonal and annual scales compared to the monthly scale. Application of the three products in Lake Eyre Basin (an internal drainage system) suggests a maximum 6.2 mm/year groundwater inflow to the basin, which is consistent with the regional groundwater flow direction in the area. This result also indicates that the absolute integrated error of the combination of three products should be smaller than 6.2 mm/year, which is about 2.1% of annual precipitation in the basin. If this relative error is assumed for the whole continent, water balance calculation using the three products over the whole Australian continent results in 144.7  11.3 mm/year estimated total runoff to the surrounding oceans during the study period. We found that this estimate is comparable to the estimates of 50150 mm/year from the Australian Bureau of Meteorology and National Water Commission.

Research areas: Land Surface/Agriculture Indicators
A comparison of Microtops II and satellite ozone measurements in the period 20012011 (2013)

Daily average total ozone Microtops measurements obtained during several campaigns conducted from 2001 to 2011 at latitudes from 31 to 68N and in different seasons are compared with satellite observations. The Microtops ozone is derived using different wavelength combinations (Channel I, 305.5/312.5 nm; Channel II, 312.5/320 nm; and Channel III, 305.5/312.5/320 nm). Satellite data from TOMS, OMI, GOME, and GOME-2 are used in the comparison. The three Microtops channels show a high correlation with the satellite retrievals. Channel I shows the best results and produces a mean bias deviation (MBD) less than 2.14% with respect to TOMS, OMI and GOME. The MBD increases to 3% in the comparison against GOME-2, due to the small number of available data. In addition, the total ozone content provided by Channel I displays the more stable behavior during the ten-year period. The Channel III total ozone shows MBD values smaller than those observed for Channel I. However the Channels II and III present a larger variability and show a larger spread of the data. Consequently, Channel I appears as the best option for long term measurements with Microtops.

Research areas: Validation
Long-term changes in the radiative effects of aerosols and clouds in a mid-latitude region (19852010) (2013)

As clouds and aerosols are the main sources of uncertainty in the determination of the energy balance of the Earth, there is a growing interest in the evaluation of their radiative effects. Hence, in this work, long-term data of shortwave radiation from 13 locations over Spain (South-Western Europe) are used to investigate, for the first time, the radiative effects of clouds and aerosols in the period 19852010. In particular, monthly radiation data from ground-based observations and radiative transfer simulations fed with reanalysis data of ozone, water vapour and surface albedo, are used to evaluate the cloud and aerosol radiative effect (CARE). Annual values of the CARE become less negative from Northern to Southern stations. For instance, the annual CARE values for Bilbao (North), Valladolid (Centre), and Murcia (South) are  82,  46, and  42 Wm 2, respectively. CARE averages exhibit a clear seasonal pattern with the strongest contribution during spring and summer months. Particularly in these seasons, there is a very high correlation between CARE values and sunshine duration, number of cloud-free days, and temperature. Additionally, a significant decrease of the radiative effects of the clouds and aerosols is observed over Spain in the last 26 years. Overall, the linear trend of the mean annual CARE series over Spain is statistically significant with positive sign, 3.1 Wm 2 per decade. The significant trend values at individual stations range between 2.9 and 5.2 Wm 2 per decade. Seasonal trends in summer and spring are larger than in autumn and winter. Finally, the radiative effects of water vapour and ozone were also evaluated showing an annual mean over Spain of about  10 Wm 2 and  1 Wm 2, respectively. However, no significant trends were observed for these two variables between 1985 and 2010.

Research areas: Sun-Earth Interactions
Monthly distribution of diurnal total column ozone based on the 2011 satellite data in Peninsular Malaysia (2013)

Ozone (O3) is a radiatively active trace gas, and naturally present in our atmosphere, that plays a prominent role in atmosphere heating rates due to its good capability to absorb the infrared radiation. O3 occurs both naturally in the Earths upper atmosphere and at the ground level. As we breathe the air on Earth, O3 causes damage to the lung tissue and plants as it is an injurious pollutant; it is a major constituent of smog. The atmospheric O3 observations can only be made on global and continental scales by remote sensing instruments situated in the space. The satellite-borne sensor, namely the Atmospheric Infrared Sounder (AIRS) included on the EOS Aqua satellite, was employed to investigate the spatial and temporal variations of diurnal total column Ozone burden over Peninsular Malaysia for the year 2011. The analysis of O3 above five dispersed stations in the study area shows the seasonal variation in the O3 fluctuated considerably observed between NEM and SWM seasons. The mean and the standard deviation of monthly O3 was 244.7  26.8 DU for the entire period, and O3 values strongly correlated with weather conditions. The highest O3 values occurred over industrial and congested urban zones (271.5 DU) on May at Johor. The lowest O3 values were observed during NEM in the pristine coastal environment on December at Kuantan (217 DU; at 3.45N, 103.20E). The O3 has an inverse relationship with the rain and positive with temperature. The monthly O3 maps were obtained from the NASA-operated Giovanni portal (http://disc.sci.gsfc.nasa.gov/giovanni). The AIRS data and the satellite measurements are able to measure the increase of the atmosphere O3 concentrations over different areas.

Research areas: Air Quality, Environmental Impacts
Spatio-temporal distribution of absorbing aerosols over Pakistan retrieved from OMI onboard Aura satellite (2015)

The observations of aerosol index (AI) deduced from Ozone Monitoring Instrument (OMI) with spatial resolution of 0.25x0.25 have been analyzed over Pakistan from December 2004 to November 2008. Significant spatiotemporal variabilities in AI values were observed with higher values in southern parts and lower values in northern parts of Pakistan. The mean annual AI in Southern and Northern Pakistan have been found to be 1.2200.250 and 1.0880.280, respectively with an overall mean of 1.1550.257 over the entire country. The monthly spatially averaged values of AI show a clear maximum in the month of May (1.5390.499), one of the two months having highest dust storm activity in the region, and minimum value in the month of December (0.8510.134), having lowest dust storm activity. We have also examined the effect of precipitation on AI values and have found that inverse correlation exists between AI and accumulated precipitation, particularly in the months of July, August and September with corresponding R2 values of 0.24, 0.25 and 0.33 respectively.

Research areas: Air Quality
A study of tropospheric NO2 variability over Pakistan using OMI data (2014)

In this study we present an analysis of spatiotemporal variability of monthly averaged Vertical Tropospheric Columns (VTCs) of NO2 over Pakistan using OMI (ozone monitoring instrument) dataset from December 2004 to November 2008. The results have shown significant spatial and temporal variability of NO2 column values over the study region. Four NO2 hotspots and a high density corridor were identified within the study region. The main sources of NO2 emissions in these areas were also investigated. During the study period, an average value of NO2 was observed to be 1.102  0.081  1015 molecules/cm2, with an increasing trend of 3.29% per year. Twin cities of Islamabad/Rawalpindi, Lahore, Dera Ghazi Khan and Karachi have shown positive trends of 44.10%, 23.48%, 31.40%, and 32.32% per year respectively. Karachi has shown the highest and the lowest mean monthly average values of 11.33  1015 molecules/cm2 and 0.98  1015 molecules/cm2 respectively. Air mass trajectories for hotspot regions have been used to track possible longrange transport of NO2.

Research areas: Air Quality