DISTRIBUTION AND VARIATION FEATURES OF SOIL HUMIDITY ANOMALY IN HUAIHE RIVER BASIN AND ITS RELATIONSHIP WITH CLIMATIC ANOMALY

With rotated empirical orthogonal function (REOF) analysis technique, the mainly anomalous spatial features of soil humidity in the 0-50 cm layer of Huaihe River basin and its relationship with precipitation and air temperature in different periods were specially analyzed by using the observed data including dekad averaged soil moisture data, precipitation and air temperature data in the east of China from 1990 to 2000. The results indicate that in the springtime the 30 cm soil layer can be treated as a boundary. From 0 cm layer to 30 cm layer, the first rotated loading vector field in every layer reflects the anomalous soil humidity pattern in the Huaihe river basin, named the pattern structure as "Huaihe river pattern". While from 30 cm layer to 50 cm layer, the second rotated loading vector field in every layer is also quite similar to "Huaihe river pattern". In summer and autumn, the "Huaihe river pattern" is still remarkable but the feature is less prominently than that in spring. It is also found soil moisture anomaly of this pattern in every layer has notable duration and a prominent period of nearly forty dekads. Furthermore, positive (negative) correlation between soil moisture and precipitation (air temperature) during prophase and the same period can be found. Also, negative (positive) correlation between soil moisture and the precipitation (air temperature) of nearly half a year later can by noted.