The characteristics of the sensible heat and momentum transfer coefficients over the Gobi in Northwest China

Abstract

AbstractUtilizing the data of the intensive observation period (May–June 2000) of the Dunhuang land‐surface process field experiment supported by the ‘Atmosphere‐land Interactive Field Experiment over Arid Regions of Northwest China(NWC‐ALIEX)’, the bulk momentum transfer coefficient (Cd) and the bulk sensible heat transfer coefficient (Ch) between the surface and the atmosphere over the arid Gobi Desert region are determined using three different methods. The results indicate that these coefficients, especially the means, are the same order of magnitude. The influence of the building near the observational station on the results is significant. When the building effect exists, the diurnal variation of the atmospheric bulk transfer coefficients and the bulk Richardson number are irregular. After the building effect is eliminated through analysing the wind direction, the bulk Richardson number and the range of the typical values of the bulk transfer coefficients over the Gobi are obtained. The diurnal variations of the bulk transfer coefficients are smoother than that without the building affect. The bulk transfer coefficients are larger in the daytime than in the nighttime. It is also worth noting that the variations of the bulk transfer coefficients and the bulk Richardson number are just opposite in phase, and that the bulk transfer coefficient for sensible heat flux is more related to the bulk Richardson number than that for momentum flux. The results are more reasonable than that after removing the building effect. The relation between the bulk transfer coefficients is also discussed. Copyright © 2010 Royal Meteorological Society