Extended Abstract (96K)9.3
Advection, Edge, and Oasis Effects On Spatial Moisture and Flux Fields From Lidar, Thermal Imagers and Tower-Based Sensors
Daniel I. Cooper, LANL, Los Alamos, NM; and W. Eichinger, L. E. Hipps, M. Y. Leclerc, C. Neale, J. Prueger, and S. Bawazir
Relatively narrow forest stands such as the riparian Tamarisk bordering the Rio Grande are subject to dry air advection from the adjacent semi-desert environment. The transport of warm dry air into the canopy has a profound effect upon the spatial properties of the moisture field and associated latent energy flux. The Los Alamos National Laboratories' scanning Raman lidar was used in conjunction with an array of point sensors and an airborne thermal scanner to measure the three dimensional moisture and thermal fields over the Tamarisk canopy. These measurements were used to quantify how the micrometeorological scalar and gradient moisture fields are modified by intensive advection. The analysis from the micrometeorological measurements showed that the warm dry advected air had a clear effect on the moisture field and internal boundary layer structure. The spatial extent and intensity of the perturbation was dependent upon the wind direction, turbulence intensity and local stability of the microscale canopy-atmosphere system. The leading edge of the Tamarisk was directly effected by advection up to 300 m into the 500 m wide field, showing substantially larger gradients when compared to the non-advected fields. Further, the transition from advection-effected to marginally-effected conditions was relatively sharp and small. The coordination of surface and airborne remote sensing with in-situ instruments allows for the understanding of complex vegetation-atmospheric processes such as advection and evapotranspiration. These studies indicate that the micrometeorological and hydrological behavior of riparian Tamarisk requires an understanding not only of the local ambient surface-atmospheric conditions but also of the larger-scale interactions with the surrounding environments.
Session 9, Turbulence and Dispersion in Canopies Part 2
Thursday, 23 May 2002, 1:30 PM-4:00 PM
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