William E. Nichols

Evaluation of the evaporative fraction for parameterization of the surface energy balance

The evaporative fraction is a ratio of latent heat flux to the sum of latent and sensible heat fluxes. It has been used to characterize the energy partition over land surfaces and has potential for inferring daily energy balance information based on midday remote sensing measurements. The HAPEX-MOBILHY program SAMER system provided surface energy balance data over a range of agricultural crops and soil types. Data from this large-scale field experiment was analyzed to study the behavior and daylight stability of the evaporative fraction in both ideal and general meteorological conditions. Strong linear relations were found to exist between the midday evaporative fraction and the daylight evaporative fraction. Statistical tests, however, rejected the hypothesis that the two quantities were equal. Relations between the evaporative fraction and surface soil moisture as well as soil moisture over the complete root zone were explored, but no correlation was identified.

Pushbroom microwave radiometer results from HAPEX-MOBILHY

Abstract The NASA C-130 remote sensing aircraft was in Toulouse, France from 25 May through 4 July 1986, for participation in the HAPEX-MOBILHY program. Spectral and radiometric data were collected by C-130 borne sensors in the visible, infrared, and microwave wavelengths. These data provided information on the spatial and temporal variations of surface parameters such as vegetation indices, surface temperature, and surface soil moisture. The Pushbroom Microwave Radiometer (PBMR) was used to collect passive microwave brightness temperature data. This four-beam sensor operates at the 21-cm wavelength, providing cross-track coverage approximately 1.2 times the aircraft altitude. Observed brightness temperatures for the period were high, ranging from above 240 K about 290 K. Brightness temperature images appeared to correspond well to spatial and temporal soil moisture variation. Previous research has demonstrated that an approximately linear relationship exists between the surface emissivity and surface soil moisture. For these data, however, regression analysis did not indicate a strong linear relationship (r2=0.32 and r2=0.42 respectively) because of the limited range of soil moisture conditions encountered and the small number of ground measurements. When results from wetter soil conditions encountered in another experiment were included, the regression improved dramatically. Based on similar research with the PBMR and an understanding of the ground data collection program, this result was examined to produce recommendations for improvements to future passive microwave research and data collection programs. Examples of surface soil moisture maps generated with PBMR data are presented which appear to be representative of the actual soil moisture conditions.

Geographic and Operational Site Parameters List (GOSPL) for the 2004 Composite Analysis

This report briefly describes each of the key data fields, including the source(s) of data, and provides the resulting inputs to be used for the 2004 Composite Analysis. A master spreadsheet termed the Geographic and Operational Site Parameters List (GOSPL) was assembled to facilitate the generation of keyword input files containing general information on each waste site, its operational/disposal history, and its environmental settings (past, current, and future).

User Instructions for the Systems Assessment Capability, Rev. 1, Computer Codes Volume 3: Utility Codes

This document contains detailed user instructions for a suite of utility codes developed for Rev. 1 of the Systems Assessment Capability. The suite of computer codes for Rev. 1 of Systems Assessment Capability performs many functions.

User Instructions for the Systems Assessment Capability, Rev. 0, Computer Codes Volume 1: Inventory, Release, and Transport Modules

One activity of the Department of Energys Groundwater/Vadose Zone Integration Project is an assessment of cumulative impacts from Hanford Site wastes on the subsurface environment and the Columbia River. Through the application of a system assessment capability (SAC), decisions for each cleanup and disposal action will be able to take into account the composite effect of other cleanup and disposal actions. The SAC has developed a suite of computer programs to simulate the migration of contaminants (analytes) present on the Hanford Site and to assess the potential impacts of the analytes, including dose to humans, socio-cultural impacts, economic impacts, and ecological impacts. The general approach to handling uncertainty in the SAC computer codes is a Monte Carlo approach. Conceptually, one generates a value for every stochastic parameter in the code (the entire sequence of modules from inventory through transport and impacts) and then executes the simulation, obtaining an output value, or result. This document provides user instructions for the SAC codes that handle inventory tracking, release of contaminants to the environment, and transport of contaminants through the unsaturated zone, saturated zone, and the Columbia River.

The evaporative fraction as a measure of surface energy partitioning

The evaporative fraction is a ratio that expresses the proportion of turbulent flux energy over land surfaces devoted to evaporation and transpiration (evapotranspiration). It has been used to characterize the energy partition over land surfaces and has potential for inferring daily energy balance information based on mid-day remote sensing measurements. The HAPEX-MOBILHY programs SAMER system provided surface energy balance data over a range of agricultural crops and soil types. The databases from this large-scale field experiment was analyzed for the purpose of studying the behavior and daylight stability of the evaporative fraction in both ideal and general meteorological conditions. Strong linear relations were found to exist between the mid-day evaporative fraction and the daylight mean evaporative fraction. Statistical tests however rejected the hypothesis that the two quantities were equal. The relations between the evaporative fraction and the surface soil moisture as well as soil moisture in the complete vegetation root zone were also explored.