Editorial Type:
Article
Article Type:
Research Article

The “Triple Point” on 24 May 2002 during IHOP. Part I: Airborne Doppler and LASE Analyses of the Frontal Boundaries and Convection Initiation

Roger M. Wakimoto Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California

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Hanne V. Murphey Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California

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Edward V. Browell NASA Langley Research Center, Hampton, Virginia

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Syed Ismail NASA Langley Research Center, Hampton, Virginia

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Print Publication:
01 Jan 2006
DOI:
https://doi.org/10.1175/MWR3066.1
Page(s):
231–250
Restricted access

Abstract

An analysis of the initiation of deep convection near the triple point between a cold front and dryline is presented. High-spatial-resolution Doppler wind syntheses combined with vertical cross sections of mixing ratio (q) and aerosol scattering ratio retrieved from a lidar flying over the triple point provide an unprecedented view of the initiation process. The Doppler wind synthesis revealed variability along the dryline similar to the precipitation core/gap structure documented for oceanic cold fronts. Vertical cross sections through the dryline suggest a density current–like structure with the hot and dry air being forced up and over the moist air. Double thin lines associated with moisture gradients were also resolved. The vertical profile of retrieved q, approximately perpendicular to the dryline, showed a pronounced jump in the depth of the moisture layer across the triple point. Analyses of dropsonde data show the existence of virtual potential temperature (θV ) gradients across the cold front and the dryline. Although the vertical velocity was strong at the triple point, deep convection initiated ∼50 km to the east. The location where convection first developed was characterized by a prominent aerosol and moisture plume, reduced static stability, and the largest potential instability. An internal gravity wave may have provided the lift to initiate convection.

* Currrent affiliation: Earth Observing Laboratory, NCAR, Boulder, Colorado

Corresponding author address: Roger M. Wakimoto, NCAR/EOL, P.O. Box 3000, Boulder, CO 80307. Email: wakimoto@ucar.edu

Abstract

An analysis of the initiation of deep convection near the triple point between a cold front and dryline is presented. High-spatial-resolution Doppler wind syntheses combined with vertical cross sections of mixing ratio (q) and aerosol scattering ratio retrieved from a lidar flying over the triple point provide an unprecedented view of the initiation process. The Doppler wind synthesis revealed variability along the dryline similar to the precipitation core/gap structure documented for oceanic cold fronts. Vertical cross sections through the dryline suggest a density current–like structure with the hot and dry air being forced up and over the moist air. Double thin lines associated with moisture gradients were also resolved. The vertical profile of retrieved q, approximately perpendicular to the dryline, showed a pronounced jump in the depth of the moisture layer across the triple point. Analyses of dropsonde data show the existence of virtual potential temperature (θV ) gradients across the cold front and the dryline. Although the vertical velocity was strong at the triple point, deep convection initiated ∼50 km to the east. The location where convection first developed was characterized by a prominent aerosol and moisture plume, reduced static stability, and the largest potential instability. An internal gravity wave may have provided the lift to initiate convection.

* Currrent affiliation: Earth Observing Laboratory, NCAR, Boulder, Colorado

Corresponding author address: Roger M. Wakimoto, NCAR/EOL, P.O. Box 3000, Boulder, CO 80307. Email: wakimoto@ucar.edu

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