Extended Abstract (264K)4.3
LIDAR APPLICATIONS IN ATMOSPHERIC DYNAMICS: MEASUREMETNS OF WIND, MOISTURE AND BOUNDARY LAYER EVOLOUTION.
Belay B. Demoz, NASA/GSFC, Greenbelt, MD; and D. Whiteman, B. Gentry, G. Schwemmer, K. Evans, P. Di Girolamo, and J. Comer
Variability in the convective boundary layer moisture, wind and temperature fields and their importance in the forecasting and understanding of storms have been discussed in the literature. These variations have been reported in relation to frontal zones, stationary boundaries and during horizontal convective rolls (see Weckwerth et al. 1996 for a discussion and references). While all three vary substantially in the convective boundary layer, moisture poses a particular challenge. Moisture or water vapor concentration (expressed as a mass mixing ratio, g kg-1), is conserved in all meteorological processes except condensation and evaporation. The water vapor mixing ratio often remains distinct across an air-mass boundary even when the temperature difference is indistinct. These properties make it an ideal choice in visualizing and understanding many of the atmosphere's dynamic features. However, it also presents a unique measurement challenge because water vapor content can vary by more than three orders of magnitude in the troposphere. Characterization of the 3D-distribution of water vapor is also difficult as water vapor observations can suffer from large sampling errors and substantial variability both in the vertical and horizontal.
This study presents ground-based measurements of wind, boundary layer structure and water vapor mixing ratio measurements observed by three co-located lidars and radar profilers. This presentation will focus on the evolution and variability of moisture and wind in the boundary layer and summarize ground-based measurements made during several interesting dynamic events (cold front, Bore-soliton-gravity waves, dryline). These data sets and analyses are unique in that they combine simultaneous measurements of wind, moisture and CBL structure to study the detailed thermal variability in and around clear air updrafts during these events. It will quantify the variation across and along a dryline, undulare bore and frontal convergence zones. The data presented here were collected primarily in the panhandle of Oklahoma as part of the International H2O Project (IHOP_2002), a field experiment that took place over the Southern Great Plains (SGP) of the United States from 13 May to 30 June 2002. But, data collected in north-central Oklahoma at the DOE-ARM site will also be used to illustrate some points.
Session 4, Results from IHOP_2002 and Mesoscale Studies using Lidar
Tuesday, 11 January 2005, 1:30 PM-3:15 PM
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