1 / 12

Blowing Snow Observations during ASCII

Blowing Snow Observations during ASCII. David Kristovich Prairie Research Institute University of Illinois. Related Goals in Proposal and Supplemental Request. To examine PBL turbulence as a mechanism of orographic precipitation growth

dyllis
Download Presentation

Blowing Snow Observations during ASCII

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Blowing Snow Observations during ASCII David Kristovich Prairie Research Institute University of Illinois Related Goals in Proposal and Supplemental Request • To examine PBL turbulence as a mechanism of • orographic precipitation growth • to examine the terrain surface as a source of ice crystals and • orographic cloud glaciation, through blowing snow and/or ice • multiplication • Better characterization of hydrometeors using superior probes at the mountain crest site • Dedicated King Air flights

  2. Blowing Snow Observations during ASCII ? Horizontal transport, surface snow loss, change in snowpack characteristics Modified from Chung, Y.-C., S. Bélair, J. Mailhot, 2011: Blowing Snow on Arctic Sea Ice: Results from an Improved Sea Ice–Snow–Blowing Snow Coupled System. J. Hydrometeor, 12, 678–689.

  3. Blowing Snow Observations during ASCII • Objectives for ASCII • Understand vertical distribution of lofted ice particles throughout the mechanically-mixed BL • Understand BL structure, esp. vertical motions (fluxes?) http://stoneroads.blogspot.com/2010_05_01_archive.html • Mountains & Plains • Refine observational techniques using relatively new facilities http://impressions.v-infinity.net/2005_02_01_archive.html

  4. Blowing Snow Observations during ASCII • Issues and Questions • Are snow crystals transported vertically far enough to be important to snow growth? • Entirely possible in mountainous regions • Possible in some circumstances over plains Geerts, B., Q. Miao, Y. Yang, 2011: Boundary Layer Turbulence and Orographic Precipitation Growth in Cold Clouds: Evidence from Profiling Airborne Radar Data. J. Atmos. Sci., 68, 2344–2365.

  5. Blowing Snow Observations during ASCII • Issues and Questions • Are snow crystals transported vertically far enough to be important to snow growth? • Entirely possible in mountainous regions • Possible in some circumstances over plains http://lidar.ssec.wisc.edu/experiments/lakeice/highlights.htm http://www.panoramio.com/photo/47539031

  6. Blowing Snow Observations during ASCII • Issues and Questions • Are snow crystals transported vertically far enough to be important to snow growth? • Entirely possible in orographic systems • Possible in some circumstances • Are snow crystals transported vertically far enough to be observed? • WCR • Somewhat strong side lobes (17-19 dB lower than main lobe); least impact nadir antenna • Ground clutter 50 m to 200-300 m (Sam Haimov) • Check w/ non-blowing, non-snowing flight • 100 nanosec, 7.5 m sampling, 400 gates (3 km max) • along-flight sampling ≈ 5 m • surface effects on velocity field. BL motions?

  7. Blowing Snow Observations during ASCII • Issues and Questions • Are snow crystals transported vertically far enough to be important to snow growth? • Entirely possible in orographic systems • Possible in some circumstances • Are snow crystals transported vertically far enough to be observed? • WCR - nadir • WCL - nadir • very high vertical resol. (3.75 m? Wang et al. 2009) • Information on snow profile. BL depth? • Return power, linear depolarization ratio

  8. Blowing Snow Observations during ASCII • Issues and Questions • Are snow crystals transported vertically far enough to be important to snow growth? • Entirely possible in orographic systems • Possible in some circumstances • Are snow crystals transported vertically far enough to be observed? • WCR - nadir • WCL - nadir • UWKA in situ obs • Surface obs • Battle Pass (Bart) • SPEC Cloud Particle Imager (Paul Lawson)

  9. Blowing Snow IOPs • Two 3-4 hr long flights, one under optimal blowing snow conditions, the other under packed snow. In both cases, clear sky (non-precipitating clouds OK) • Flight plan: single flight under VFR conditions • single pattern takes ~ 45 min • 3 complete patterns can be flown on a single flight, or parts of the pattern can be flown repeatedly • both flights should track the same waypoints • No RSE case (seeding activities irrelevant) • Case calling controlled by ASCII • Required weather conditions • clear sky (non-precipitating clouds OK) – VFR conditions • blowing snow flight: • fresh snow on the ground, cold, very windy • high humidity, possibly some orographic cloud over the SM • no-blowing-snow flight: • weak wind and/or snow surface crusting • Leg 1 of the blowing snow flight pattern can be flown as an alternate to the aerosol race tracks in a dual-flight IOP • GAUS soundings: two soundings per IOP, launched early and late into the flight • Battle Town site fully operational • NO DOW operations

  10. Blowing Snow IOPs • Two 3-4 hr long flights, one under optimal blowing snow conditions, the other under packed snow. In both cases, clear sky (non-precipitating clouds OK) • Flight plan: single flight under VFR conditions • single pattern takes ~ 45 min • 3 complete patterns can be flown on a single flight, or parts of the pattern can be flown repeatedly • both flights should track the same waypoints • No RSE case (seeding activities irrelevant) • Case calling controlled by ASCII • Required weather conditions • clear sky (non-precipitating clouds OK) – VFR conditions • blowing snow flight: • fresh snow on the ground, cold, very windy • high humidity, possibly some orographic cloud over the SM • no-blowing-snow flight: • weak wind and/or snow surface crusting • Leg 1 of the blowing snow flight pattern can be flown as an alternate to the aerosol race tracks in a dual-flight IOP • GAUS soundings: two soundings per IOP, launched early and late into the flight • Battle Town site fully operational • NO DOW operations -20°C Baggaley, D. G., J. M. Hanesiak, 2005: An Empirical Blowing Snow Forecast Technique for the Canadian Arctic and the Prairie Provinces. Wea. Forecasting, 20, 51–62.

  11. Blowing Snow IOPs • Two 3-4 hr long flights, one under optimal blowing snow conditions, the other under packed snow. In both cases, clear sky (non-precipitating clouds OK) • Flight plan: single flight under VFR conditions • single pattern takes ~ 45 min • 3 complete patterns can be flown on a single flight, or parts of the pattern can be flown repeatedly • both flights should track the same waypoints • No RSE case (seeding activities irrelevant) • Case calling controlled by ASCII • Required weather conditions • clear sky (non-precipitating clouds OK) – VFR conditions • blowing snow flight: • fresh snow on the ground, cold, very windy • high humidity, possibly some orographic cloud over the SM • no-blowing-snow flight: • weak wind and/or snow surface crusting • Leg 1 of the blowing snow flight pattern can be flown as an alternate to the aerosol race tracks in a dual-flight IOP • GAUS soundings: two soundings per IOP, launched early and late into the flight • Battle Town site fully operational • NO DOW operations

More Related