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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Active microwave measurement of soil water content

Measurements of radar backscatter from bare soil at 4.7, 5.9, and 7.1 GHz for incident angles of 0-70 deg have been analyzed to determine sensitivity to soil moisture. Because the effective depth of penetration of the radar signal is only about one skin depth, the observed signals were correlated with the moisture in a skin depth as characterized by the attenuation coefficient (reciprocal of skin depth). Since the attenuation coefficient is a monotonically increasing function of moisture density, it may also be used as a measure of moisture content over the distance involved, which varies with frequency and moisture content. The measurements show an approximately linear increase in scattering with attenuation coefficient of the soil at angles within 10 deg of vertical and all frequencies. At 4.7 GHz this increase continues relatively large out to 70 deg incidence, but by 7.1 GHz the sensitivity is much less even at 20 deg and practically gone at 50 deg.

Ulaby, F. T.↗
NASA NTRS2003

Using Remote Sensing Platforms to Estimate Near-Surface Soil Properties

Evaluation of near-surface soil properties via remote sensing (RS) could facilitate soil survey mapping, erosion prediction, fertilization regimes, and allocation of agrochemicals. The objective of this study was to evaluate the relationship between soil spectral signature and near surface soil properties in conventionally managed row crop systems. High resolution RS data were acquired over bare fields in the Coastal Plain, Appalachian Plateau, and Ridge and Valley provinces of Alabama using the Airborne Terrestrial Applications Sensor (ATLAS) multispectral scanner. Soils ranged from sandy Kandiudults to fine textured Rhodudults. Surface soil samples (0-1 cm) were collected from 163 sampling points for soil water content, soil organic carbon (SOC), particle size distribution (PSD), and citrate dithionite extractable iron (Fed) content. Surface roughness, soil water content, and crusting were also measured at sampling. Results showed RS data acquired from lands with less than 4 % surface soil water content best approximated near-surface soil properties at the Coastal Plain site where loamy sand textured surfaces were predominant. Utilizing a combination of band ratios in stepwise regression, Fed (r2 = 0.61), SOC (r2 = 0.36), sand (r2 = 0.52), and clay (r2 = 0.76) were related to RS data at the Coastal Plain site. In contrast, the more clayey Ridge and Valley soils had r-squares of 0.50, 0.36, 0.17, and 0.57. for Fed, SOC, sand and clay, respectively. Use of estimated eEmissivity did not generally improve estimates of near-surface soil attributes.

Sullivan, D. G.↗
DOE OSTI2021

Active layer thickness as a function of soil water content

Active layer thickness (ALT) is a critical metric for monitoring permafrost. How soil moisture influences ALT depends on two competing hypotheses: (a) increased soil moisture increases the latent heat of fusion for thaw, resulting in shallower active layers, and (b) increased soil moisture increases soil thermal conductivity, resulting in deeper active layers. To investigate their relative influence on thaw depth, we analyzed the Field Measurements of Soil Moisture and Active Layer Thickness (SMALT) in Alaska and Canada dataset, consisting of thousands of measurements of thaw depth and soil moisture collected at dozens of sites across Alaska and Canada as part of NASA’s Arctic Boreal Vulnerability Experiment (ABoVE). As bulk volumetric water content (VWC) integrated over the entire active layer increases, ALT decreases, supporting the latent heat hypothesis. However, as VWC in the top 12 cm of soil increases, ALT increases, supporting the thermal conductivity hypothesis. Regional temperature variations determine the baseline thaw depth while precipitation may influence the sensitivity of ALT to changes in VWC. Soil latent heat dominates over thermal conductivity in determining ALT, and the effect of bulk VWC on ALT appears consistent across sites.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) from the Dominican Republic, February 2013 - August 2017.

Daily data that has been processed to monthly. Data represents near-surface soil moisture (depth of 0-10 cm) at a latitude of 19.76 N, and longitude -70.57 E. Data was downloaded from the PBO soil moisture data network and is publicly available. Data from this site is referenced as Dominican Republic (1) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1982

CONSERVB: A numerical method to compute soil water content and temperature profiles under a bare surface

A comprehensive, yet fairly simple model of water disposition in a bare soil profile under the sequential impact of rain storms and other atmospheric influences, as they occur from hour to hour is presented. This model is intended mostly to support field studies of soil moisture dynamics by our current team, to serve as a background for the microwave measurements, and, eventually, to serve as a point of departure for soil moisture predictions for estimates based in part upon airborne measurements. The main distinction of the current model is that it accounts not only for the moisture flow in the soil-atmosphere system, but also for the energy flow and, hence, calculates system temperatures. Also, the model is of a dynamic nature, capable of supporting any required degree of resolution in time and space. Much critical testing of the sample is needed before the complexities of the hydrology of a vegetated surface can be related meaningfully to microwave observations.

Vanbavel, C. H. M.↗
DOE OSTI2020

Soil Water Content (m3 m-3) located in the Dominican Republic , February 2013 - December 2016

Daily data that has been processed to monthly. Data represents near-surface soil moisture (depth of 0-10 cm) at a latitude of 17.90 N, and longitude -71.67 E. Data was downloaded from the PBO soil moisture data network and is publicly available. Data from this site is referenced as Dominican Republic (2) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1975

Soil water content and evaporation determined by thermal parameters obtained from ground-based and remote measurements

A procedure is presented for calculating 24-hour totals of evaporation from wet and drying soils. Its application requires a knowledge of the daily solar radiation, the maximum and minimum, air temperatures, moist surface albedo, and maximum and minimum surface temperatures. Tests of the technique on a bare field of Avondale loam at Phoenix, Arizona showed it to be independent of season.

Reginato, R.↗
DOE OSTI2022

Characterizing soil water content variability across spatial scales from optimized high-resolution distributed temperature sensing technique

Fiber-optic Distributed Temperature Sensing, when combined with the Single-probe Heat-pulse technique can measure soil moisture (θ) across spatial scales. The key limitation of this system is in obtaining the relationship between soil thermal conductivity (λ) and θ for a specific field. Using the Department of Energy Atmospheric Radiation Measurement (ARM) site, this study tested a new methodology to account for the spatial variability in the λ-θ relationship using a Gaussian processes model. The resulting accurate θ measurements (RMSE = 0.03 m 3 m –3 ) were used to characterize the spatial variability of θ across scales and to develop an empirical equation that can correct for the changes in the θ spatial variability observed at different spatial resolutions. In addition, the number of required samples to accurately characterize θ and its variability over scales ranging from 5 m and 350 m were estimated. Finally, these findings provide key information to scale soil moisture from centimeters to hundreds of meters for process understanding.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) from Australia, November 2007 - May 2009

Hourly data processed to monthly. Data collected from Eddy Covariance Flux Tower at near-surface (0-10 cm). Site located at latitude -13.08 deg N, longitude 131.12 deg E. Data was downloaded from the FluxNet soil moisture data network and is publicly available. Data from this site located at, referenced as Australia (3) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) from Australia, August 2001 - December 2014

Hourly data processed to monthly. Data collected from Eddy Covariance Flux Tower at near-surface (0-10 cm). Site located at latitude -12.49 deg N, longitude 131.15 deg E. Data was downloaded from the FluxNet soil moisture data network and is publicly available. Data from this site is referenced as Australia (4) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) from Guyaflux site, French Guiana, January 2007 - December 2014

Daily data processed to monthly. Data was collected from Eddy Covariance Flux Tower at the near-surface (0-10 cm). Site located at latitude 5.28 deg N, longitude -52.92 deg E. Data was downloaded from the FluxNet soil moisture data network and is publicly available. Data from this site is referenced as French Guiana (2) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) located in Santarem, Brazil K67, July 2000 - February 2004

Hourly data processed to monthly. Data collected from Eddy Covariance Flux Tower at the near-surface (0-10 cm). Site located at a latitude -3.02 deg N, longitude -54.97 deg E. Data was downloaded from the FluxNet soil moisture data network and is publicly available. Data from this site is referenced as Brazil (3) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3), October 2011 - May 2017

Hourly data processed to monthly. Data collected from Cosmic Neutron Probes at variable depth averaging 15 cm that was interpolated to near-surface (0-10 cm). Site located at latitude 0.28 deg N, longitude 36.87 deg E. Data was downloaded from the The COsmic-ray Soil Moisture Observing System (COSMOS) soil moisture data network and is publicly available. Data was made available by the COsmic-ray Soil Moisture Observing SysteM (COSMOS). Data from this site is referenced as Kenya in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) from Australia, June 2011 - December 2016

Hourly data processed to monthly. Data collected from Cosmic Neutron Probes at variable depth averaging 38 cm that was interpolated to near-surface (0-10 cm). Site located at latitude -14.16 deg N, longitude 131.39 deg E. Data was downloaded from the The COsmic-ray Soil Moisture Observing System (COSMOS) soil moisture data network and is publicly available. Data from this site located at, referenced as Australia (2) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Plant physiology, shrub size, thaw depth and soil water content, Seward Peninsula, Alaska, 2023

Stomatal response to changing irradiance measurements (m curves), CO2 response (ACi) and light response (AQ) curves on common tussock tundra shrub, graminoid and forb species. Data were collected in July 2023 from three sites on the Seward Peninsula, Kougarok Mile 64, Teller Mile 27 and Council. Measurements were made with LI-COR LI-6800 gas exchange systems on 18 species. For samples from Teller and Kougarok, thaw depth, soil moisture content and dGPS locations are also provided for most samples. Canopy height and canopy diameter are provided for shrubs measured at the Teller site. The data package files include data files, metadata files and the complete instrument output for all gas exchange measurements in .csv format, and a pdf describing the experimental protocols. See the related data package NGA508 for foliar trait data (leaf mass per area, leaf nitrogen concentration).The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a 15-year research effort (2012-2027) to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research.The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska.Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Soil Water Content (m3 m-3) from Australia, May 2014 - March 2017

Hourly data processed to monthly. Data collected from Cosmic Neutron Probes at variable depth averaging 28 cm that was interpolated to near-surface (0-10 cm). Site located at latitude -17.12 deg N, longitude 145.63 deg E. Data was downloaded from COSMOS data portal and is publicly available. Data from this site is referenced as Australia (1) in Table 1 and Figure 4 of Solander et al., 2020, The pan-tropical soil moisture response to El Nino, Hydrol. Earth Syst. Sci., in press.

54 ENVIRONMENTAL SCIENCES↗