Seasonal Variation in Turbulent Fluxes over Tibetan Plateau and Its Surrounding Areas: Research Note

The Tibetan field observatories, which are constructed in a project of the Japan International Co-operation Agency in 2007, provide an opportunity to establish four observation sites equipped with same sensors on and around Tibetan plateau for better understanding the monsoon climate features over the Tibetan plateau. By using same analyzing technique, the present paper examines the seasonal and diurnal variations in (I) radiation components, (2) turbulent momentum, heat, water vapor, and CO2 fluxes, and (3) soil temperature, moisture, and heat flux of the four homogenous sites (BJ at Bu-Jong (Naqu), DL at Da-Li, LZ at Lin-Zhi, and WJ at Wen-Jiang) on and around the Tibetan Plateau, in 2008. Seasonal variation in the sensible heat flux at the BJ site indicate that the sensible heat flux was stronger thereat compared with other sites in spring (March to May). After the monsoon had set, sensible heat flux decreased in all four sites. On the other hand, the seasonal variations in latent heat flux suggest that the latent heat flux increases rapidly with the water content in the soil that rises from March to June at the LZ, DL, and WJ sites. An annual cyclic pattern of CO2 flux at sites DL and WJ was obvious. Finally, At the sparsely vegetated BJ site the seasonal variation in CO2 flux was small due to the limited CO2 absorption in summer and its subsequent limited release in other seasons; and at the very grassy LZ site, the CO2 absorption responds to seasonal march of monsoon. Energy partitioning dramatically responds to the onset of monsoon at the BJ site.