Abstracts for the 5th International GAME Conf.

3-5 October 2001

Aichi Trade Center

Nagoya Japan

Time-Scale Structure of the Heat/Vapor Flux over the Tibetan Plateau revealed by

Asanuma, Jun (1), Sachiko, Aoki (2), Hayakawa, Norio (3), Kim, Joon (4), Taejun, Choi (4), Wang, Jiemin (6), Gao, Zhiqiu (7)

Turbulence measurements were made in the flat sparse grassland near Naqu city (31.22N, 91.54E, 4500m ASL ) over the central Tibetan Plateau during the summer of 1998. This field measurements is a cooperative work between Korean, Chinese and Japanese scientists as a part of the field campaigns during Intensive Observation Period of GAME (GEWEX Asian Monsoon Experiment), one of whose main purposes is to improve our understanding on the role of the Asian monsoon in the global energy and water cycle. Out of the acquired data, 9 daytime runs with the length of about 7 hours, were applied to an orthogonal wavelet transform to identify the scales relevant to the transfer of the sensible/latent heat and momentum between the landsurface and the atmosphere. Wavelet variances of the wind velocity components, temperature and specific humidity as well as wavelet covariances for sensible/latent heat flux and momentum flux, which are wavelet counterparts of the Fourier spectrum and cospectrum respectively, were constructed from the wavelet decomposition, and clearly show a so-called ``spectrum gap'' at the scale between 1 and few hours. However, it is also found that there is a significant portion of the sensible heat transfer, either positive or negative, at a scale larger than that with this spectrum gap, while the latent transfer is negligible at these larger scales. An inverse wavelet transfer of the larger scale components indicates that this sensible heat transfer at the scale larger than few hours is associated with a diurnal variation of the temperature. These results suggest that mesoscale phenomena, such as mountain and valley winds, can transfer a quite amount of the sensible heat and that this heat transfer cannot be captured by the flux measurements with the eddy correlation technique when its averaging time is less than or equal to 1 hour.

Submittal Information

Name : Date :
    Jun Asanuma
    28-May-01-16:05:00
Organization : Theme :
    Terrestrial Environment Research Center, Tsukuba Univ.
    Theme 2
Address : Presentation :
    Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577
    Poster or oral
Country : Abstract ID :
    Japan
    T2JA28May01160500
Phone : Fax :
    +81-298-53-6704
    +81-298-53-2530
E-mail :
    asanuma@erc2.suiri.tsukuba.ac.jp