Surface Layer Stability Transition Research Maximum Time Delay from Sunrise/Non-Ideal Conditions: 2001 June Case Study

Report No. ARL-TR-2823
Authors: Gail-Tirrell Vaucher and Manny Bustillos
Date/Pages: May 2003; 60 pages
Abstract: Near surface target acquisition and EO propagation significantly improve during the Surface Layer Stability Transition (SLST). Thus, this research expands Army Chief of Staff Shinseki?s vision from ?to see first? to, ?to see better.? The SLST is also the starting and ending points for the atmospheric convection growth phase, an important factor in chemical warfare modeling. In 2001, the Meteorological-sensors Integration Team of the Army Research Laboratory conducted the second of three field tests with the primary purpose of characterizing, modeling and exploiting repeatable patterns in the lower portion of the atmospheric boundary layer. The repeatable patterns investigated were the morning Stability Transitions (ST) or Neutral Events (NE). The 2001 June 20?22 test dates were selected based on a forecasted maximum time interval between the local Sunrise and an Ideal case NE. Two other field tests addressed the minimum Sunrise-to-NE time interval (March and September). These Tests are documented separately. The SLST Research pursued two measurement and analysis methods: Eulerian (Tower data) and quasi-Lagrangian (Rawinsonde data). The June results were as unexpected as the atypical Monsoon weather conditions observed. Excellent examples of Extended and Multiple STs were quantified by the data. A ST lasting at least 26 minutes surprised scientists by occurring well before sunrise and the morning twilight. The cumulative findings over this 2001 Solstice time period have expanded the documented character of a desert stable-neutral-unstable morning transition. The information in this report is a useful building block in support of the primary goal.
Distribution: Approved for public release
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Last Update / Reviewed: May 1, 2003