Estimation of surface heat and moisture fluxes over a prairie grassland. 4. Impact of satellite remote sensing of slow canopy variables on performance of a hybrid biosphere model

Journal Article · Sat Mar 20 00:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JD01917· OSTI ID:6836845

Crosson, W L ^[1]; Smith, E A; Cooper, H J ^[2]

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1. Universities Space Research Association, Huntsville, AL (United States)
2. Florida State Univ., Tallahassee (United States)

The authors present the results of a series of numerical experiments using the Ex-BATS biosphere model, which is an adaptation of Dickinson's biosphere-atmosphere transfer scheme (BATS). These simulations are used to assess how the model performs when remotely sensed data are used to estimate three key canopy variables. These canopy variables, which effectively represent the slowly changing boundary conditions of a vegetated surface, consist of the total surface albedo, leaf area index, and the nondiurnally varying component of stomatal resistance, referred to as stressed stomatal resistance. The surface albedo is retrieved from NOAA-AVHRR (advanced very high resolution radiometer) channel 1 spectral reflectance information in conjunction with a directional reflectance model which accounts for the strong diurnal variations in surface reflectance. A 4-channel vegetation index also retrieved from AVHRR measurements is used to estimate the leaf area index. A similar index derived from high-resolution SPOT visible and near-infrared information has been used to describe the spatial variations in such indices which impact the retrieval of the leaf area index. Satellite retrieval of stomatal resistance is based on split-window skin temperatures from AVHRR channels 4 and 5 from the afternoon overpass ([approximately]1630 LT). It was found that although stomatal resistance has little correlation with the diurnal amplitude of skin temperature, it is closely related to the daily maximum of skin temperature. Numerical experiments have been conducted to examine model sensitivity to each of these canopy variables. The rms measurement-model flux differences in every numerical trial were within 6 W m[sup [minus]2] of the rms differences obtained for the simulations performed using measured albedo and leaf area index. Measured stomatal resistance values were obtained using an inversion form of the model. 35 refs., 16 figs., 1 tab.

• OSTI ID: 6836845
• Journal Information: Journal of Geophysical Research; (United States), Vol. 98:D3; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
54 ENVIRONMENTAL SCIENCES
BIOSPHERE
MATHEMATICAL MODELS
CANOPIES
REMOTE SENSING
RANGELANDS
MOISTURE
ALBEDO
BOUNDARY CONDITIONS
HEAT
HEAT FLUX
INFORMATION
LEAVES
NUMERICAL ANALYSIS
PERFORMANCE
PLANTS
RESOLUTION
SATELLITES
SENSITIVITY
SIMULATION
SPECTRAL REFLECTANCE
STOMATA
TRANSPIRATION
VARIATIONS
ECOSYSTEMS
ENERGY
MATHEMATICS
OPENINGS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
TERRESTRIAL ECOSYSTEMS
140100* - Solar Energy- Resources & Availability
540210 - Environment
Terrestrial- Basic Studies- (1990-)