Difference in the Interdecadal Variability of Spring and Summer Sensible Heat Flux over Northwest China

The present study investigates the difference in interdecadal variability of the spring and summer sensible heat fluxes over Northwest China by using station observations from 1960 to 2000. It was found that the spring sensible heat flux over Northwest China was greater during the period from the late 1970s to the 1990s than during the period from the 1960s to the mid-1970s. The summer sensible heat flux was smaller in the late 1980s through the 1990s than it was in the 1970s through the early 1980s. Both the spring and summer land-air temperature differences over Northwest China displayed an obvious interdecadal increase in the late 1970s. Both the spring and summer surface wind speeds experienced an obvious interdecadal weakening in the late 1970s. The change in the surface wind speed played a more important role in the interdecadal variations in sensible heat flux during the summer, whereas the change in the land-air temperature difference was more important for the interdecadal variations in sensible heat flux in the spring. This difference was related to seasonal changes in the mean land-air temperature difference and the surface wind speed. Further analysis indicated that the increase in the spring land surface temperature in Northwest China was related to an increase in surface net radiation.

Difference in the Interdecadal Variability of Spring and Summer Sensible Heat Flux over Northwest China

The present study investigates the difference between the interdecadal variability of spring and summer sensible heat flux over Northwest China by using station observational data for the period 1960-2000. It is found that spring sensible heat flux over Northwest China is larger in the late 1970s through 1990s than in the 1960s through mid-1970s, while summer sensible heat flux is smaller in the late 1980s through 1990s than in the 1970s through early 1980s. Both the spring and summer land-air temperature difference over Northwest China displays an obvious interdecadal increase in the late 1970s. Both the spring and summer surface wind speed experiences an obvious interdecadal weakening in the late 1970s. The surface wind speed change plays a more important role for interdecadal variations in sensible heat flux in summer, whereas the land-air temperature difference change is more important for those in spring. This difference is related to seasonal changes in the mean land-air temperature difference and surface wind speed. Further analysis indicates that the increase in spring land surface temperature in Northwest China is related to the increase in surface net radiation.