Airborne lidar observations of the transition zone between the convective boundary layer and free atmosphere during the International H2O Project (IHOP) in 2002

Jeffrey S. Grabon, Kenneth James Davis, Christoph Kiemle, Gerhard Ehret

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Airborne, light detection and ranging (lidar) backscatter observations of the convective boundary layer from the International H2O Project (IHOP) in 2002 are analysed to study the structure of the transition zone; the backscatter gradient between the convective boundary layer and free atmosphere. A new mathematical algorithm is developed and used to extract high-resolution (15 m) transition-zone boundaries from 6,500 km (flight legs) of airborne observations. The cospectra of transition-zone boundaries and its thickness indicate that thickness changes occur from boundaries moving in opposite directions (vertically) at small wavelengths (<1 km), while at longer wavelengths (>1 km) both boundaries move coherently, with the lower boundary changing altitude more rapidly. Daily probability distributions of the transition-zone thickness are positively skewed with a mode of 60 m. The structure of the transition zone shows no dependence on the "overall" Richardson number, unlike the entrainment zone. This study provides the first quantitative characterization of the structure of the instantaneous transition zone, a contribution towards an improved understanding of convective boundary-layer entrainment.

Original languageEnglish (US)
Pages (from-to)61-83
Number of pages23
JournalBoundary-Layer Meteorology
Volume134
Issue number1
DOIs
StatePublished - Jan 1 2010

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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