Atmospheric Remote Sensing Laboratory (PARSL)
A mobile atmospheric observation facility developed and operated by PNNL, PARSL provides measurements of atmospheric radiation, aerosols, and clouds for short duration field experimentsTSI Model 3563 Integrating NephelometerThe Pacific Northwest National Laboratory (PNNL) Atmospheric Remote Sensing Laboratory (PARSL) is a mobile laboratory for studying the interaction of clouds and aerosol with solar and terrestrial radiation. PARSL is intended for use in short-term field experiments designed to study issues related to climate, weather prediction, and air quality. PARSL instruments include solar shortwave and infrared radiometers, standard meteorological instruments, and remote sensing instruments for determining vertical profiles of cloud properties. For measuring cloud properties, the key instruments are two millimeter cloud radars and a cloud/aerosol depolarization lidar.
PARSL includes two millimeter cloud radars operating at 35 GHz and 94 GHz which correspond to wavelengths of 8 mm and 3 mm respectively. These radars are sensitive to cloud droplets unlike typical weather radars that operate at significantly lower frequencies. The radars can be used to provide vertical profiles of cloud properties including water content and cloud droplet sizes. The lidar also provides vertical profiles of cloud properties but it is much more sensitive to small particles than the radar. Consequently, the lidar is unable to see through optically thick clouds but it can see tenuous clouds with small droplets that the radar cannot. The lidar's sensitivity to small particles also allows it detect profiles of aerosol properties.
PARSL has participated in three field experiments. IMPROVE I and II (Improvement of Microphysical Parameterizations through Observational Verification Experiments I and II) were in collaboration with the University of Washington. IMPROVE I was held during February 2001 in Pacific Beach, Washington while IMPROVE II was held in December 2001 in Sisters Oregon. In July 2002, PARSL was deployed in Everglades City, Florida for the CRYSTAL-FACE experiment, a major, multi-agency experiment designed to study the microphysical properties of cirrus. In September 2004, PARSL will deployed in northern Alaska as part of the Mixed-Phase Arctic Cloud Experiment (M-PACE), an experiment sponsored by the DOE Atmospheric Radiation Measurement (ARM) program.
Key PARSL instruments include two millimeter cloud radars (operating at 94 and 35 GHz) and a multi-channel lidar. The figure above (top) shows a cirrus layer observed by the 94 GHz radar during CRYSTAL-FACE. The figure above (bottom) shows an aerosol layer and an overlying cloud layer observed by the lidar, also during CRYSTAL-FACE.
PARSL Instruments
Solar Radiation
Broadband hemispheric: Eppley PSPs (up- and down-looking)
Broadband diffuse: Eppley Black and White
Broadband direct: Eppley NIP
Narrow band direct/diffuse/total
Multi-filter rotating shadowband radiometer (Provides aerosol optical depth)
Terrestrial Infrared Radiation
Broadband hemispheric: Eppley PIRs (up- and down-looking)
8-12 micron window: Heinmann IR Thermometer (cloud properties)
Solar Tracking
Up-looking radiometers are mounted on a Kipp and Zonen solar tracker.
Integrated column water vapor and liquid
Two-channel (23, 35 GHz) Radiometrics microwave radiometer
Vertical distribution of clouds and aerosol
Vaisala 25K Ceilometer provides cloud base information up to a maximum altitude of 7 km. This maximum is generally achievable for night operation, with daytime ranges of approximately 4 km.
An eyesafe, dual-polarization lidar operating at 532 nm. Provides cloud base and vertical structure for optically thin clouds. Aerosol structure is also observable. The instrument can be deployed in a vertical only or scanning mode. An ultraviolet channel is being implemented.
Millimeter-wavelength radars, one operating at 94 GHz and one at 35 GHz. These radars provide vertical cloud distributions but are not sensitive to very small cloud particles.
Surface Meteorology
Standard sensors for measurements of pressure, temperature, relative humidity, wind speed, and wind direction.
Vertical Meteorological Profiles
A Vaisala Digicora III balloon sounding base station equipped with GPS and Loran-C tracking.
