8a, but for the latent heat flux at 1400 LT averaged over every five-day period of the 1992 season. The dashed line represents the reference V–S simulation (simulation S0), the solid line is the simulation after V–S calibration with airborne NDVI data (simulation S1), and the dash–dot line is the simulation after V–S calibration with satellite NDVI data (simulation S2).
Svat monitor series#
Time series of simulated and measured hourly latent heat flux on the CES during a 10-day period of the growing season (Day of Year 262–271). Precipitation (mm) measured at the CES, CWS, and SS sites during HAPEX-Sahel 1992.įig. 6a but for SS and over grass–shrub subsite (solid line). The dotted line is the reference V–S simulation (simulation S0), the solid line is the simulation after V–S calibration with airborne shortwave data (simulation S1), the dash–dot line is the simulation after V–S calibration with satellite shortwave data (simulation S2). (b) Comparison of LAI time profiles measured over grassland (dashed line) with simulations of the V–S model on CWS.
(a) Comparison of LAI time-profiles measured over grassland (asterisk) with simulations of the V–S model on CES. The dashed line is the NDVI resulting from the reference V–S simulation (simulation S0), (solid line) is the NDVI after calibration of the V–S model with the AVHRR data (simulation S2). The dashed line is the NDVI resulting from the reference V–S simulation (simulation S0), solid line is the NDVI after calibration of the V–S model with airborne NDVI data (simulation S1).Ĭomparison of NDVI time-profile generated with the SAIL model and simulated LAI, with AVHRR unmixed NDVI (asterisk) on the CWS grassland site. The outlined arrow represents the meteorological forcing (air temperature, relative humidity, wind speed, solar radiation, and precipitation).Ĭomparison of NDVI time-profile generated with the SAIL model and simulated LAI with airborne measurements (asterisk) over the CES grassland. The dashed-line arrow shows how radiative properties are derived from model variables.
The thin arrow represents some of the model links. The state variables are the carbon contents in the shoots and the roots, and the water content of the soil. The large bold arrow indicates carbon, water, and energy fluxes. The grassland NDVI is significantly higher than the mixed-pixel NDVI, whereas the millet NDVI is lower.Ĭoupled vegetation growth and energy–water budget models (V–S). The dotted line represents the NDVI over the mixed pixel, before cloud screening. NDVI profiles of the pure grassland (cross) and pure millet (circle) components resulting from the unmixing process of the AVHRR signal. (b) NDVI profiles of the grassland component obtained from unmixing of the AVHRR signal on CES (solid), on CWS (dashed), and SS (dash–dot). (a) NDVI profile of the grassland component obtained for airborne NDVI on CES (solid line) and on CWS (dashed line), Also shown is SS (dash–dot line), which represents NDVI profile of the grass–shrub components.
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