Long-term variation of characteristics of local land atmosphere coupling over TP and the possible influence of Southern Asian Monsoon

This study investigates the long-term variations of local land atmosphere coupling (LoCo) over Tibetan Plateau (TP) by applying a mixing diagram to the observational data at six stations over TP and ERA5 and the possible influence of Southern Asian monsoon. The result indicates that the monthly-mean daily variation in T_2m, q_2m, H_sfc, and LE_sfc at Nyingchi, Nagqu, Nam Co, Qomolangma, Ngari, and Muztagata in ERA5 are close to those in observational data. Comparison of mixing diagram analysis using the monthly-mean variables of ERA5 and the observational data indicates ERA5 could provide reliable information of LoCo at six stations. The relationships between H_sfc and daytime PBLH, and the variations of LCL deficit at six stations are different due to the differences in the soil states. The long-term variations in the PBL energy budgets, mean daytime PBLH, and LCL deficits at 31^◦N and 90^◦E show clear annual variations and have a close relationship between Southern Asian monsoon. The possible influence of the Southern Asian monsoon is also discussed in terms of the relationship between the Webster-Yang index and the PBL energy budgets, mean PBLH and mean LCL over TP.