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DCS cloud-precipitation properties derived from aircraft-surface-satellite observations during the MC3E IOP

 
Poster PDF

Authors

Xiquan Dong — University of Arizona
Ning Zhou — University of North Dakota
Baike Xi — University of Arizona
Tony Grainger — University of North Dakota
Zhe Feng — Pacific Northwest National Laboratory
Patrick Minnis — NASA - Langley Research Center
Mandana Khaiyer — Science Systems and Applications, Inc. (SSAI)
Scott Giangrande — Brookhaven National Laboratory
Tami Fairless — Pacific Northwest National Laboratory

Category

Cloud Properties

Description

The aircraft flight trajectory (black line and red points) with collocated NEXRAD radar reflectivity and classified three components (red-Convective core, green-stratiform region, and yellow-AC) on the May 20 case. The cloud microphysical properties measured by the UND citation research aircraft three sensors (red-CDP, 1-49 µm; blue-2DC, 15-3,000 µm; and black-HVPS, 200-30,000 µm).
The Midlatitude Continental Convective Clouds Experiment (MC3E) was a very successful field campaign with 15 convective cases observed by the University of North Dakota (UND) aircraft and surface-satellite sensors. There are at least six deep convective systems (DCS) (April 25 and 27, May 5/10, 20, and 23–24), including the classic DCS case on May 20, which has drawn much attention for scientists to study its structure and properties from observational and modeling points of view. This research team is providing the following results for ASR/ARM community: classified DCS components (convective cores [CC], stratiform rain [SR], anvil clouds [AC]) and their corresponding vertical structures and velocities from surface radar measurements, aircraft in situ measured and GOES satellite-retrieved cloud macrophysical and microphysical properties. These results will provide ground truth for modelers to validate and improve their simulated DCS properties.

Through an integrative analysis of the data sets, we have the following preliminary results for the May 20 case. The frontal squall line system originally located southwest of the ARM Southern Great Plains (SGP) Central Facility (CF), advanced over the CF around 0:00 UTC, maturing later. The convective cores started to pass over the CF around 9:00 UTC, and heavy precipitation occurred during 10:30–11:00 UTC with a significant change in cloud properties before and after the heavy precipitation. Before precipitation, there were large graupel and ice particles with strong vertical motion in the convective cores. After that, a stratiform region developed with two distinguished layers: ice and water particles above and below the melting band, respectively. The UND Citation flew spirally up and down over the CF, mostly within 30 km of the CF during the period 13:00–17:00 UTC. Four vertical profiles above the melting band (~ 4 km) were measured by the UND aircraft. When the plane flew upward from 4 to 8 km, the effective radius of the ice particles decreased from 1000 μm to 300 μm as determined from the two-dimensional cloud probe (2DC) sensor with bins ranging from 15 to 3000 μm. At the 8-km level, the high-volume precipitation spectrometer (HVPS), with bins covering the range from 300 - 30,000 μm, measured effective radii that were the same as the 2DC measurements (~ 300 μm). But at 4 km, they were as great as 4000 μm, indicating that the HVPS detected many very large ice particles/rain drops near the melting band that were missed by the 2DC probe. The GOES-retrieved effective radius, optical depth and ice water path (IWP) over the DCS convective cores are ~80 μm, 100, and 2000 gm-2, respectively. The satellite generally retrieves ice particle sizes representative of the top portion of the cloud (~ 12 km for May 20).