Central California Ozone Study (CCOS) - Desert Research Institute

CCOS Field Operations Plan (DRAFT) Version 2: 5/31/00
periods, probably five-minute averages. The one-hour database is dictated by the practice of the
distrcts to report hourly data. The supplemental CCOS data will be also collected and reported at
the shorter averaging time. Integrated data, such as from the VOC canister collection and the
carbonyl cartridge collection will be reported separately.
2.5 CCOS Ground-Based Aloft Air Quality and Meteorological Measurements
Meteorological soundings will be used to obtain information on temperature, relative
humidity, and wind at various levels of the atmosphere above ground level. Radiosondes releases
during IOPs will provide in situ measurements of pressure, temperature, humidity, and wind
speed and direction at various altitudes above ground. These balloons will also carry an
ozonsonde that will provide a vertical profile of ozone. Two types of remote sounding, radar
wind profilers and Doppler acoustic sounders, will provide continuous measurements of upperair
winds during the entire four-month CCOS measurement period (6/1/00 to 9/30/00). Table
2.5-1 provides a summary of the aloft meteorological measurements that are currently being
made by local agencies and that will be made by during CCOS by the Environmental
Technology Laboratory (ETL, Boulder, CO) and Air Resources Laboratory (ARL, Idaho Falls,
ID) of the National Oceanic and Atmospheric Administration (NOAA), Sonoma Technology,
Inc. (STI), and T&B systems. Figures 2.5-1 and 2.5-2 show the locations of the upper-air
meteorological measurement sites.
2.5.1 Continuous Upper-Air Meteorological Measurements
Radar Wind Profilers (RWP) provide sequential horizontal and vertical wind components
in data assimilation and model comparison on a sub-hour time scale. RWPs generally acquire
measurements within 100 to 150 m thick layers between ~0.150 and 3 km AGL with a minimum
vertical resolution of 60 meters. A radio-acoustic sounding system (RASS) are used to quantify
virtual temperature to elevations of ~1 km AGL (up to 2 km AGL in ideal conditions), but this is
insufficient altitude to characterize the daytime mixed layers of 2–3 km AGL often observed in
much of the study area. Acoustic Sounders (Sodars), like RWPs, also acquire continuous
measurements of winds aloft. Sodars have better vertical resolution (~30 m layers from ~50 to
600 m AGL) but less vertical range (750 m AGL maximum). Sodars are most applicable in
locations with lower-level structure, such as that found in marine layers, in channeling through
canyons and passes, and in nighttime radiation inversions.
Radar profilers, doppler sodars, and RASS are used at most sites because they acquire
hourly average wind speed, wind direction, and temperature by remote sensing without constant
operator intervention. Sodars are collocated with profilers at several locations because they
provide greater vertical resolution in the first 100 m agl. Several radar profilers are being
installed to acquire a multi-year database, and one of the important functions of the
CCOS/CRPAQS supplements to this network is to relate these relatively sparse measurements
tothe detailed meteorological patterns determined during CCOS. The ARB operates two
profilers (with RASS) in the San Joaquin Valley, and the San Joaquin Unified APCD and
Sacramento Metropolitan AQMD operate one profiler/RASS each as part of their PAMS
monitoring program. Military facilities with operational profilers include Travis AFB,
Vandenberg AFB, and the Naval Post Graduate School in Monterey. Because these profilers are
Chapter 2: FIELD MEASUREMENTS 2-35