Submitted to: Agricultural and Forest Meteorology Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/24/2002
Publication Date: N/A
Technical Abstract: 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 Laboratory's 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 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 were dependent upon the wind direction, turbulence intensity and local stability of the micro-scale canopy-atmosphere system. The leading edge of the Tamarisk was directly affected by the 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.