Between June 26 th and August 29 th of 2007, nine field campaigns were carried out in Virginia and Maryland as part of the CALIPSO And Twilight Zone (CATZ) experiment. The field work was conducted on an alternating basis between the two daytime ground tracks closest to the NASA Goddard Space Flight Center with four taking place in Virginia and five based on the eastern shore of Maryland.
Cimel sun photometers were positioned and operated within 150m of the CALIPSO ground track during satellite overpass. The number of Cimels deployed ranged from 3 to 11, and were generally run from early morning (to acquire low sun almucantars) until late afternoon. After the morning almucantars were completed, the Cimels were placed in the ‘Oneill mode’ which is configured to take direct sun measurements every 3 minutes instead of the standard interval of 15 minutes. During the hour before and after overpass, the Cimels were placed in ‘BCLSun’ mode which takes AOD measurements at the highest temporal resolution (1-min interval), and principal plane measurements were also initiated just before and after overpass, as well as periodically throughout the day whenever sky conditions were most suitable (cloud-free in the measurement viewpath).
In addition to the mobile Cimels, a permanent Cimel and Micropulse Lidar (MPL) were situated near Strasburg, PA ( 39.932 N,76.198W) close to the point where the CALIPSO day and night tracks intersected and these were operated continuously for the duration of the experiment. For several of the campaigns these measurements were supplemented by a mobile MPL (operated on the day track), as well as airborne lidar including the High Spectral Resolution Lidar (HSRL) [Chris Hostetler] and/or a Raman Airborne Spectroscopic Lidar (RASL) [Dave Whiteman]. The initial campaigns also included a small network of Microtops handheld sun photometers deployed around the mobile MPL location in order to evaluate the spatial homogeneity of the aerosol.