Abstract:

Based on the monthly temperature and precipitation data of 53 observational stations in the Northeast China and NCEP/NCAR reanalysis data of monthly geopotential height data and monthly sea surface temperature data reconstructed by NOAA during 1961-2012, a comparison was made between the two 30-year climatic normal of meteorological elements as well as 500 hPa geopotential height and sea surface temperature field. The influence to climatic operation by the change of climatic normal condition was analyzed. The results suggest that for most part of the Northeast China, the climate in the new climatic normal condition is wetter and warmer than that in the old climatic normal condition; the global 500 hPa geopotential height and sea surface temperature values during the new climatic normal condition are all slightly higher than that in the old climatic normal condition; winter temperature rise in the Northeast China is largely caused by weakening intensity of East Asia trough and Siberian high; higher intensity of West Pacific subtropical high and Okhotsk blocking high, among others, is the major factor responsible for higher precipitation in most months in this region; reduced intensity of northeast cold vertex is the main reason that less precipitation occurs in June in this region; the reduction of precipitation in September and October may be associated with the change of sea surface temperature; variation in climatic normal condition produces effects on climatic operation such as climatic variation operation, climatic evaluation and climatic prediction, necessitating for example reevaluation of ENSO and warm winter event as well as reanalysis of extreme events, and may affect the trend and order of magnitude.

Key words: climatic average, difference, warm winter, ENSO, climate change operation