Spatiotemporal Patterns and Trends of Precipitation and Their Correlations with Related Meteorological Factors by Two Sets of Reanalysis Data in China

Abstract. This paper investigates the spatial-temporal characteristics of the changes in precipitation for China and the influence of other meteorological factors on precipitation. Two reanalysis datasets at monthly scale, namely, the GLDAS2 phase 2 forcing data 0.5 × 0.5 (1948 ~ 2008) and National Centers for Environmental Prediction (NCEP) data were employed. The Mann-Kendall trend test identified the annual and seasonal changes in four meteorological factors for precipitation, air temperature, long wave radiation and surface pressure. Confidence levels of 95 % were taken as thresholds to classify the significance of positive and negative trends. The trend analysis was conducted in three storm zones (I-Eastern Monsoon Region, II-Northern Inland Region and III-Qinghai-Tibetan Plateau Region) specified by Wang (2002). The findings indicate:

1) Air temperature, specific humidity and downward long wave radiation, have strong correlation with precipitation, especially for the eastern monsoon region of China; while surface pressure has very weak correlation with precipitation.

2) Latent heat shows very strong correlation with precipitation throughout China except for a small, extremely arid area in north China where large portions of the area are deserts.

3) The correlation between the volumetric soil moisture with precipitation and latent heat are controlled by precipitation with the characteristics of high annual precipitation and high correlations.

4) For precipitation, an increasing tendency in precipitation for the southeastern monsoon region and a decreasing tendency for the northeastern monsoon region (the drier region) were observed.

5) Strong increasing tendencies for air temperature and downward long wave radiation, were observed in the northeastern monsoon region and the western area of Qinghai-Tibetan Plateau.

6) Due to changes in precipitation and air temperature and downward long wave radiation, the scarcity of water resources in northeastern monsoon region and flooding problems in southeastern monsoon region may become more severe.

7) The study shows that agricultural development in China may require a shift between northern and western areas to adapt to the shift in precipitation patterns.