Skip to Main Content
Land Breeze and Thermals: A Scale Threshold to Distinguish Their EffectsAuthor(s): Yongqiang Liu
Source: Advance in Atmospheric Sciences 22(6): 889-902
Publication Series: Miscellaneous Publication
PDF: View PDF (1.06 MB)
DescriptionLand breeze is a type of mesoscale circulation developed due to thermal forcing over a heterogeneous landscape. It can contribute to atmospheric dynamic and hydrologic processes through affecting heat and water fluxes on the land-atmosphere interface and generating shallow convective precipitation. If the scale of the landscape heterogeneity is smaller than a certain size, however, the resulting land breeze becomes weak and becomes mixed up with other thermal convections like thermals. This study seeks to identify a scale threshold to distinguish the effects between land breeze and thermals. Two-dimensional simulations were performed with the Regional Atmospheric Modeling System (RAMS) to simulate thermals and land breeze. Their horizontal scale features were analyzed using the wavelet transform. The thermals developed over a homogeneous landscape under dry or wet conditions have an initial scale of 2-5 km during their early stage of development. The scale jumps to 10-15 km when condensation occurs. The solution of an analytical model indicates that the reduced degree of atmospheric instability clue to the release of condensation potential heat could be one of the contributing factors for the increase in scale. The land breeze, on the other hand, has a major scale identical to the size of the landscape heterogeneity throughout various stages of development. The results suggest that the effects of land breeze can be clearly distinguished from those of thermals only if the size of the landscape heterogeneity is larger than the scale threshold of about 5 km for dry atmospheric processes or about 15 km for moist ones.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationLiu, Yongqiang. 2005. Land Breeze and Thermals: A Scale Threshold to Distinguish Their Effects. Advance in Atmospheric Sciences 22(6): 889-902
Keywordsland breeze, thermals, horizontal scale, large-eddy simulation, wavelet transform
- Soil physical properties regulate lethal heating during burning of woody residues
- Numerical simulations of island effects on airflow and weather during the summer over the island of Oahu
- Landscape ecology: what is the state of science?
XML: View XML