The Numerical Simulation Of Different Response Of Temperature Variation In The Asian Mid-latitude Arid Area To Two Global Warming During The Past 100 Years

The asian mid-latitude arid area is the northernmost arid region of the world, across the westerlies and the monsoon climate zone from west to east, with prominent and difference obviously climatic feature, has unique response to global climate change.Research showed that the world had experienced two significant climate warming periods over 100 years, which occurred from the 1920’s to 1940’s and after the 1980’s.The area showed obvious response to the second global warming period,but scarcely any response to the first.The reason is unknown until now.In regard to the problem, firstly, the characteristics of air temperature variation in the asian mid-latitude arid area was studied using the CRU data and the main circulation factors that affects the temperature change were selected. Then for the limitations of CRU only including finite meteorological elements of the surface, the global monthly three-dimensional grid data with 102 years were produced by using numerical simulation.lt has 261evels from the surface to 50hpa, with 2.8125°×2.8125°grid spacing,including complete meteorological elements, which made up for the short-time series and low resolution of the existing data and built a data foundationfor the research of climate change in asian mid-latitude arid area. Then the northern hemisphere polar vortex, the eurasian circulation and the western pacific subtropical high that affects the temperature change of the asian mid-latitude arid area were scientific studied using these data. And their variant characteristicsand affected relation with the temperature change of the asian mid-latitude arid area in two global warming periods were preliminary revealed. Finally, the characteristics and differences that responding to the east-central equatorial pacific SSTA of the temperature in the asian mid-latitude arid area in two global warming periodswere studied from the view point of the air-seainteraction using numericalsimulation. Themainresults are asfollows:1. The CRU data showed, like the global warming, although the temperatures in the asian mid-latitude arid area increased for 100 years,it didn’t obvious respond to the first global warming period except the monsoon influce marginal area.But for the second global warming, the temperature change of the asian mid-latitude arid area made a strong response.The northern hemisphere polar vortex, the eurasia circulation and the western pacific subtropical high were the main factor that affects temperature variation in the asian mid-latitude arid area.2. The gridded data with 102 years which builted by numerical simulation reconstructed successfully the trends and characteristics of temperature change of the asian mid-latitude arid arid during the two global warming periods.3.Analysized by the change of the northern hemisphere polar vortex and its impact, during the first global warming period, the center position of the northern hemisphere polar vortex and the main cold air bias in the eastern hemisphere,thereby suppressing the response of the temperatures of the asian mid-latitude arid area to the global warming.But during the second wide global warming period, the center position of the northern hemisphere polar vortex and the main cold air bias in the western hemisphere, which made the temperature changes of the asian mid-latitude arid area response significantly to global warming.4.The eurasian longitudinal and latitudinal circulation is one of the most direct circulation factor that affecte the climate change of the asian mid-latitude arid area. Research showed that, during the first global warming period,due to the polar vortex bias in the eastern hemisphere, the stronger eurasian meridional circulation and the more active stronger cold air,the temperature of the asian mid-latitude arid area made no obvious response to the first global warming inhibited by all these factors.While during the second global warming period, due to the polar vortex bias in the western hemisphere, the stronger eurasian zonal circulation,the inactive weaker cold air, the temperature change of the asian mid-latitude arid area responded obviously to the second global warming under all the factors,.5.The west pacific subtropical high is also one of the important circulation factor that affecte the climate change of the asian mid-latitude arid area.Results showed that, compared with that of the first global warming period,during the second global warming period, the area of the west pacific subtropical high was larger, the intensity was stronger, the location of the north boundary was more northerly and the western ridge point was more west.Therefore the west pacific subtropical high showed significantly warming effect on the asian mid-latitude arid area during the second warming period of the global, but no apparent effects on the area during the first global warming period except for the eastern asia.6. Numerical simulation showed that, when the SST of the central and eastern equatorial pacific was lower, the response that temperature variation of the asian mid-latitude arid area to the global climate change was not significant. But when the SST was higher, the response was sensitively, which indicates that high(EL) or low(La Nina) SST of the central and eastern equatorial pacific will affect the sensitivity of response of temperature change of the asian mid-latitude arid area to global climate change. The analysis of observed SST showed that, during the first global warming period,SST of the central and eastern equatorial pacific was low(active La Nina) and unfavourable forthe response to the global warming.While during the second warming period, the SST was higher,which the Elnino phenomenon was active.All of the factors were helpful for response to global warming in the asian mid-latitude arid area.In conclusion, results of this study are summarized as follow:during the first global warming process, because the northern hemisphere polar vortex was bias eastern hemisphere and the eurasian meridional circulation was stronger, the cold air was more activity and stronger.Although the west pacific subtropical high slightly enhanced, but the main effect area was in eastern asia, the SST of the central and eastern equatorial pacific was lower, all those factors inhibited the response to global warming. While during the second global warming period, Compared that of the first, the northern hemisphere polar vortex was bias the western hemisphere obviously,which led to stronger eurasian zonal circulation and weaker meridional circulation, weaker and inactive cold air.Additionaly, the western Pacific subtropical high had larger area, stronger intensity, more northerly north boundary, further westwestern ridge point. Also, the SST of the east-central equatorial pacific was higher(more active the Elnino phenomenon) which promoted the response of temperature of the asian mid-latitude arid area to the global warming.Under the combined effect of these factors, the temperature of the asian mid-latitude arid area made a significant response to the second global warming.