Characteristics of the atmospheric low-frequency oscillation on the drought process during the flood season (May to September) in eastern part of the northwest China are analyzed using the NCEP/NCAR reanalysis data and conventional surface precipitation data. Results show the low-frequency characteristics of the southward and eastward propagation in the middle and high latitudes, and the divergence airflow over eastern part of the northwest China during the drought. Drought event occurs during propagation of the low-frequency north wind and before convergence of the north and south airflows. The drought process mainly occurs in the negative phase of relative vorticity low-frequency oscillation and in the positive phase of the OLR low-frequency oscillation, i.e., in the period of relatively weak convection. A method based on the atmospheric Low-Frequency diagnosis was used to predict the meteorological drought event in eastern part of the northwest China. The forecast results are promising on the meteorological drought event during the flood season from 2010 to 2017.
In this paper, the variability characteristic and response to climate change of surface water resources, such as glacier,
snow, lake and runoff of rivers in northwest China are analyzed by meteorological, hydrological and remote sensing
data. The results show that the melting water has been increasing while glacier has been thinning and deteriorating along
with global warming. The runoff of rivers that rely primarily on precipitation as water resource has significantly
decreased. However the runoff of rivers originated from mountains shows significant increase as a result of increased
melting water, which dominates the water supply, in addition to increased rainfalls since 80s. The water level of most
lakes in Xinjiang has dramatically been rising and the areas are expanding because of increased rainfalls and melt water,
in contrast to trend of lowering water level and shrinking areas for lakes in Inner Mongolia and Tibetan Plateau.