Vertical variability of cloud hydrometeors in the stratiform region of mesoscale convective systems and bow echoes

Abstract During the Bow Echo and Mesoscale Convective Vortex Experiment, the NOAA P-3 research aircraft executed 17 spiral descents to the rear of convective lines to document the vertical variability of hydrometeors above, within, and below the stratiform melting layer. Ten spirals were behind line...

Full description

Saved in:
Bibliographic Details
Published in:Monthly weather review 2007-10, Vol.135 (10), p.3405-3428
Main Authors: MCFARQUHAR, Greg M, TIMLIN, Michael S, RAUBER, Robert M, JEWETT, Brian F, GRIM, Joseph A, JORGENSEN, David P
Format: Article
Language:English
Subjects:
Aggregation
Aircraft
Atoms & subatomic particles
Bowing
Clouds
Convective vortices
Cooling
Crystals
Data processing
Earth, ocean, space
Echoes
Evaporative cooling
Evolution
Exact sciences and technology
External geophysics
Heterogeneity
Hydrometeors
Ice
Isothermal layers
Melting
Mesoscale convective systems
Mesoscale phenomena
Mesoscale vortexes
Meteorology
Parameter modification
Particle size
Precipitation
Radar
Radar reflectivity
Reflectance
Relative humidity
Research aircraft
Saturation
Slopes
Storms
Sublimation
Superhigh frequencies
Temperature
Trends
Variability
Vertical profiles
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Abstract During the Bow Echo and Mesoscale Convective Vortex Experiment, the NOAA P-3 research aircraft executed 17 spiral descents to the rear of convective lines to document the vertical variability of hydrometeors above, within, and below the stratiform melting layer. Ten spirals were behind lines that exhibited bowing at some stage in their evolution. Although quick descents on some spirals forced sampling of different particle zones, clear trends with respect to temperature were seen. For 16 spirals, the ambient relative humidity with respect to ice was in the range of 100% ± 4% at temperatures between −10°C and the melting layer, but exhibited steady decreases below the melting layer to an average relative humidity with respect to water of 77% ± 15% at 9°C. In contrast, one spiral conducted on 29 June 2003 directly behind a developing bow echo had a relative humidity with respect to ice averaging 85% at heights above the 0°C level and relative humidity with respect to ice further decreased below the 0°C level to a minimum relative humidity with respect to water of 48% at 9°C. Vertical profiles of particle shapes, size distributions (SDs), total mass contents (TMC), number concentrations, and parameters of gamma distributions fit to SDs were computed using optical array probe data in conjunction with measurements of radar reflectivity from the P-3 X-band tail radar. For spirals with humidity at or near saturation above the melting layer, melting particles occurred through about 300 m of cloud depth between 0° and 2° or 3°C. Above the melting layer, number concentrations, dominated by smaller crystals, decreased at 19% ± 10% °C−1, faster than the 10% ± 7% °C−1 decrease of TMC dominated by larger particles. Increases in the numbers of crystals with a maximum dimension
ISSN:0027-0644
1520-0493
DOI:10.1175/MWR3444.1