HR: 09:00h
AN: A11B-05    [PDF]
TI: In Situ Measurements of Microphysical and Radiative Properties of Cirrus and Anvil Clouds
AU: * Lawson, P
EM: plawson@specinc.com
AF: SPEC Incorporated, 3022 Sterling Circle Suite 200, Boulder, CO 80301 United States
AU: Baker, B
EM: brad@specinc.com
AF: SPEC Incorporated, 3022 Sterling Circle Suite 200, Boulder, CO 80301 United States
AU: Pilson, B
EM: bryan@specinc.com
AF: SPEC Incorporated, 3022 Sterling Circle Suite 200, Boulder, CO 80301 United States
AB: In situ microphysical and radiative properties of mid-latitude cirrus, anvil and tropical anvil clouds, based on research flights conducted with the SPEC Learjet, the NASA WB-57 and DC-8, and the University of North Dakota Citation research aircraft, are presented. The measurements were collected in Colorado, Utah, Oklahoma, Florida and Kwajalein. All of the research aircraft were equipped with a standard complement of microphysical sensors and optical probes, plus a cloud particle imager (CPI), which produces high-definition (2.3 micron pixel) digital images of ice particles. The CPI data provide improved measurements of particle shape and size, facilitating better calculations of radiative properties of cirrus and anvil clouds. Based on the measurements, average mid-latitude cirrus, and mid-latitude and tropical cirrus microphysical properties of particle size distribution, crystal habit, ice water content, extinction coefficient, effective radius and optical depth are derived. The data show a distinct difference between particle characteristics in mid-latitude cirrus and anvil clouds. In cirrus, the predominate crystal type (weighted by area or mass) is the bullet rosette, a polycrystalline structure typical of crystal formation at temperatures colder than -30 C. Conversely, although anvils occur at temperatures similar to cirrus, bullet rosettes are very rare in anvils. Instead crystal types in anvils are typical of those formed at temperatures warmer than - 30 C. There is also a notable difference in microphysical and radiative characteristics between mid-latitude, Florida, and tropical (Kwajalein) anvils. Tropical anvils are comprised mainly of single crystals, mostly irregular blocky-shapes. In mid-latitude and Florida anvils, there are more aggregates and often chains of small particles that may be formed as a result of the higher electric fields in continental clouds. The impact of crystal type on calculations of radiative transfer are also considered.
UR: http://www.specinc.com
DE: 0320 Cloud physics and chemistry
DE: 1610 Atmosphere (0315, 0325)
DE: 3359 Radiative processes
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting