The Turbulence Characteristics of the Atmospheric Surface Layer on the North Slope of Mt. Everest Region in the Spring of 2005

Abstract

Turbulence measurements at 3 m performed at the base camp of Mt. Everest during the spring of 2005 were used to study the atmospheric turbulent characteristics under conditions of down-slope ambient wind (katabatic wind). The cases where large-scale forcing resulted in a down-slope ambient wind were considered. Firstly, the normalized standard deviations of wind speed (u and v components) were larger than those reported in the literature. Then the (co)spectral characteristics of turbulence under near neutral stratification were described depending on the prevailing wind; case A-southerly with wind speed larger than 6 m s À1 during daytime, case B-southerly with wind speed less than 6 m s À1 and case C-northerly wind. The analysis of the averaged spectra and co-spectra revealed that low frequency perturbations had a large influence on the variance of u and w wind components, and also altered the co-spectra of momentum and sensible heat flux under near neutral stratification. The features of spectral shape and power were di¤erent from the previous ones under ideal flat and homogeneous conditions. The possible cause of these features is due to strong down-valley flow induced by (normal) glacier wind.

Similarities and differences of aerosol optical properties between southern and northern sides of the Himalayas

“…Everest. Southwesterly winds near the surface prevail during the monsoon season, while in other seasons northeasterly winds prevail (Ma et al, 2011;Li et al, 2012). EVK2-CNR station in Nepal (Table 1, Fig.…”

A 3-year dataset of sensible and latent heat fluxes from the Tibetan Plateau, derived using eddy covariance measurements

“…It is complicated and problematic using variance (σ 2 ) to explain C EB . Furthermore, the glacial wind and mountain-valley wind effect (Sun et al 2007;Li et al 2012) at Qomolangma have important consequences for the non-closure of the surface energy balance during the daytime. The advection produced by glacial and mountain-valley winds leads to a large residuum at the Qomolangma site.…”

Land-atmosphere interactions and their relationships to the Asian monsoon in the Tibetan plateau

“…Furthermore, AVHRR band 1 and band 2 are broad bands which contain several strong water vapour absorption zones and this will reduce AVHRR retrieval accuracy. In comparison with estimate results from AVHRR and MODIS data, it can be seen their spatial patterns are consistent on the same day but the MODIS results are greater than the AVHRR results (3)(4)(5). The reason is that the shortwave solar radiation or the net radiation flux at 13:00 is greater than those at 15:00 which is validated by the in-situ measurements (for instance, Lhasa station).…”

“…Accordingly, surface albedo declines together with atmospheric water vapour content increasing from spring to autumn. The surface flux estimation results show that the spatial distribution of net radiation flux, sensible heat flux, latent heat flux and soil heat flux in the study area corresponds well with that of the surface parameters (NDVI, Pv and surface albedo) (3)(4)(5). In the eastern part with relatively higher vegetation cover, the net radiation flux and the latent heat flux are much higher while the sensible heat flux is much lower.…”

“…This method will be investigated to derive LST from AVHRR data. (3)(4)(5)(6)(7)(8)(9) Where 4 T and 5 T are brightness temperature of band 4 and band 5 for AVHRR; W is water vapour content and ε is average emissivity of band 4 and band 5.…”