Surface layer response to topographic solar shading in Antar

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TitleSurface layer response to topographic solar shading in Antarctica's dry valleysAbstractThe effects of topographic shading on local flow transitioning and atmospheric surface layer properties are investigated using observational data from the Miers Valley, one of the dry valleys of Antarctica. A unique data set was collected during a 9 day period in the summer of 2012 using an eddy covariance system and a sound detection and ranging that provided vertical profiles of wind and turbulence characteristics in the surface layer and the lower part of the boundary layer within the Miers Valley. This data set is ideal for investigating the dynamics of flow transitioning due to topographic shading, without the atmosphere experiencing complete darkness. The lack of atmospheric humidity, soil moisture, and surface vegetation in the dry valleys creates an atmosphere within which the microclimatic responses are amplified, and as a result, the valley atmosphere is extremely sensitive to solar radiation. The entire measured valley boundary layer (up to 250 m above ground level) feels the transition from an unstable to a stable stratification as the surface temperature drops by 10^circC in response to the topographic shading. Wavelet analysis reveals the dynamics of flow deceleration, stagnation, and oscillations as the flow transitions from an unstable to a stable boundary layer. The larger air mass (along valley) scales to the longer terrain fetch, and as the shade is cast over the valley, it retains some of the longer wavelengths of the flow. The cross-valley component influenced by the slopes is quicker to adjust to short-period oscillations and takes around three more hours before it couples with the oscillatory pattern of the along-valley flow. Key Points Effects of topographic shading on local flow transitioning in mountainous area Flow transitioning without atmosphere experiencing darkness Microclimate features of AntarcticaÅ› dry valley Copyright2013. American Geophysical Union. All Rights Reserved.AcknowledgementsThe authors would like to thank the technical staff at the Geography Department of the University of Canterbury for their assistance in the instrumentation setup. Also, the authors acknowledge Antarctica New Zealand and the United States Antarctic Program for their support. The authors would also like to thank the Antarctic K020 program operated under the research program of nzTABS in Waikato University, New Zealand. This research was also partially supported by the U. S. National Science Foundation under Grant ATM0938401. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

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1st AuthorKaturji, M.AuthorKaturji, M.Zawar-Reza, P.Zhong, S.Year2013JournalJournal of Geophysical Research AtmospheresVolume118Number22Pages12332-12344DOI10.1002/2013JD020530URLhttps://www.scopus.com/inward/recor.....e8b8d64a50031999e911637e2KeywordsAtmospheric temperatureAtmospheric thermodynamicsBoundary layersSoil moistureSunTurbulenceWavelet analysis, AntarcticaAtmospheric surface layersEddy covariancemicroclimatesodar, Landforms, boundary layerdata setmicroclimateshadingsolar radiationsurface layertopographic effectturbulence, AntarcticaEast AntarcticaMcMurdo Dry Valleys, rank5Author KeywordsAntarcticaatmospheric surface layereddy covariancemicroclimatesodarturbulence

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TypeArticleCitationKaturji, M., Zawar-Reza, P. and Zhong, S. (2013). Surface layer response to topographic solar shading in Antarctica's dry valleys. Journal of Geophysical Research Atmospheres, 118(22): 12332-12344 IdentifierKaturji2013Relevancerank5