2.4
Nocturnal boundary layer evolution in Houston during the TEXAQSII campaign
Bridget M. Day, University of Houston, Houston, TX; and C. B. Clements and B. Rappenglueck
The evolution of the nocturnal boundary layer in Houston, TX was examined using high-temporal resolution tethersonde profiles taken during the TexAQS II field campaign. The measurements were made at the University of Houston campus, located approximately 4 km southeast of the downtown Houston central business district, and consisted of vertical profiles of potential temperature, water vapor mixing ratio, wind speed, wind direction, and ozone concentration up to a maximum height of 400 m AGL. Profiles were taken at approximately 30 min intervals throughout selected nights during Intensive Observational Periods (IOPs), including both the evening and morning transitional periods. Tethersonde experiments also were performed during a few additional morning break-up periods during the campaign.
Preliminary results from the night of Sept 7-8, 2006 showed that the stability during the evening transition period remained near neutral in the lowest 200 m AGL. Cooling occurred uniformly within this layer but stronger surface cooling appeared to be delayed; it ultimately began between 2130 – 2315 CDT and continued through 0430 CDT. In the early morning an elevated bluff-like structure developed in the virtual potential temperature profiles indicating neutral stability within the 50 - 100 m AGL level. Just before sunrise a neutral layer with constant potential temperature developed between the surface and 50 m AGL indicating mixing processes occurring near the surface. Further analyses will be presented for the additional morning transitional and overnight period profiles taken during the campaign.
Recorded presentationSession 2, Texas AQ2006 Field and Modeling Studies-II
Monday, 21 January 2008, 10:45 AM-11:45 AM, 230
Previous paper