Sea Surface Salinity Retrievals from Aquarius Using Neural Networks

Even though the Sea Surface Salinity (SSS) retrieved from Aquarius are generally very close to in-situ measurements, the level of similarity varies with the region and with the circumstances of the observations (wind speed, sea surface temperature, etc.). SSS is currently retrieved from the brightness temperatures measured by Aquarius and applying the current theoretical model for the propagation and emission of the natural thermal radiation. In this contribution we consider an alternative retrieval approach based on a Neural Network (NN) with the goal of improving the subsets of Aquarius SSS data that are in poorer agreement within-situ measurements. The subset considered here are the SSS retrieved at latitudes higher than 30 . The output of the NN approach are compared against in-situ measurements using four statistical metrics (correlation coefficient, bias, RMSD and 5% trimmed range). The output of the NN and the nominal Aquarius SSS are compared against SSS values from in-situ measurements and from ocean models. From these comparisons it appears that the output of the NN matches the in-situ measurements better than the nominal Aquarius SSS

Localization of L-Band RFI Sources from SMAP Data

RFI (Radio-Frequency Interference) in the 1400-1427 MHz band degrades the quality of measurements made by satellite missions such as SMAP (Soil Moisture Active/Passive), Aquarius and SMOS (Soil Moisture and Ocean Salinity). A technique is presented here to estimate the location on the ground of RFI sources using SMAP measurements. The results of this technique have been validated against data derived by other means

Return of Floodplain Connectivity and Concurrent Macroinvertebrate Community Response Following Wetland Restoration in Western Kentucky

Wetlands improve the quality of our nation’s streams, rivers, and lakes, and they support a diverse assemblage of plant and animal species. The U.S. Department of Agriculture Natural Resources Conservation Service (USDA-NRCS) is responsible for administering the Wetland Reserve Program (WRP), a multi-billion-dollar effort to restore wetlands throughout the nation. Each year, WRP enrolls thousands of acres of private farmland into conservation easements with the goal of improving water quality and creating wildlife habitat. Hydrological modification structures, such as levee breaks, ditch plugs, or shallow water areas are constructed on easements to create wetlands by improving water retention and returning floodplain connectivity to adjacent rivers. The main objectives of my study were to assess the efficacy of these hydrological modifications and to quantify macroinvertebrate diversity, abundance, and secondary production on easements enrolled in WRP. My study sites included restoration easements of various ages as well as mature bottomland forests, which represent pre-disturbance “reference” wetlands, and low-quality, drained wetlands. A combination of pressure transducers, LiDAR, and drone imagery was used to determine wetland extent and hydroperiod on each easement. Macroinvertebrates were collected monthly from each wetland with stovepipe cores and dip-net sweeps. The results of my study indicate that hydrological modification structures allow easement wetlands to capture and retain floodwaters throughout the year. Insects accounted for 12.6% of the total abundance in degraded wetlands and increased to 26.5% in WRP easements and to 65.5% in reference wetlands. There was no statistical difference in annual production (g DM/m2), abundance, or biomass, diversity between wetland types. However, we found a wide range of annual production (850 to 7,746 mg DM/m2) and relative abundance of emergent taxa (\u3c20% to \u3e80%) among individual wetlands. Non-insect taxa were important to total biomass, and total Mollusk biomass decreased from 63% in degraded wetlands to 2.3% in reference wetlands. The frequency, intensity, and duration of inundation at each site were the primary variables influencing invertebrate community structure. Because new easements are permanently enrolled, there is tremendous potential to quantify the physical and biological changes for years or decades following enrollment. Understanding how these easements respond to restoration will provide opportunities for adaptive management, which can play a critical role in the protection, restoration, and creation of imperiled wetland ecosystems

L-Band RFI in Japan

In recent years, three instruments have been launched into orbit with the aim of producing global maps of sea surface salinity and soil moisture using the 1400-1427 MHz band: SMOS, Aquarius and SMAP. Although this frequency band is allocated to passive measurements only, RFI (Radio-Frequency Interference) is present in the data of all three missions. On a global scale, the three sensors have observed approximately the same distribution of RFI. Japan is an important exception that has implications for the design of RFI detection algorithms. RFI in Japan is caused by a large number of emitters belonging to the same system (TV receivers) and for this reason some traditional RFI detection strategies detect little to no RFI over Japan. The study of this case has led to an improvement of the approach to detect RFI in Aquarius data

Using Anthropometric Indicators for Mexicans in the United States and Mexico to Understand the Selection of Migrants and the Hispanic Paradox

Anthropometric measures including height provide an indication of childhood health that allows exploration of relationships between early life circumstances and adult health. Height can also be used to provide some indication of how early life health is related to selection of migrants and the Hispanic paradox in the United States. This article joins information on persons of Mexican nativity ages 50 and older in the United States collected in the National Health and Nutrition Examination Survey IV (NHANES IV 1999-2002) with a national sample of persons of the same age living in Mexico from the Mexican Health and Aging Survey (MHAS 2001) to examine relationships between height, education, migration, and late-life health. Mexican immigrants to the United States are selected for greater height and a high school, rather than higher or lower, education. Return migrants from the United States to Mexico are shorter than those who stay. Height is related to a number of indicators of adult health. Results support a role for selection in the Hispanic paradox and demonstrate the importance of education and childhood health as determinants of late-life health in both Mexico and the United States

Emissivity of Frozen Regions Retrieved from Aquarius Measurements

The land emissivity model used in the Aquarius data processing has been updated for the latest data release (V5.0). In order to improve the estimates of the brightness temperatures of frozen regions, the new model uses values of surface emissivity that have been estimated from the Aquarius measurements averaged over the entire duration of the mission. The retrieved emissivities depend on the geographic location, but they depend only marginally on time, temperature and snow cover

Recent Advances in SMAP RFI Processing

The measurements made by the Soil Moisture Active/Passive (SMAP) mission are affected by the presence of Radio Frequency Interference (RFI) in the protected 1400-1427 MHz band. In SMAP data processing, the main protection against RFI is a sophisticated RFI detection algorithm which flags sub-samples in time and frequency that are contaminated by RFI and removes them before estimating the brightness temperature. This contribution presents two additional approaches that have been developed to address the RFI concern in SMAP. The first consists in locating sources of RFI; once located, it becomes possible to report RFI sources to spectrum management authorities, which can lead to less RFI being experienced by SMAP in the future. The second is a new RFI detection method that is based on detecting outliers in the spatial distribution of measured antenna temperatures