Research On Temperature Difference Of Urban-Rural Areas In Different Climates In Central-Eastern China

The paper mainly investigated the differences of temperature change(?Turban-rural)caused by urbanization in the mid-eastern China(including:Beij ing-Tianjin-Hebei region(jjj),Huanghuai region(hh)and Yangtze River Delta(yrd))from 1981 to 2014,by using the meteorological data of 424 meteorological stations and satellite reanalysis datasets.We found that the ?Turban-rural is basically positive,and there is a significant day-and-night difference in?Turban-rural between the northern areas(jjj)and the southern areas(yrd):the ?Turban-rural of yrd is stronger than the ?Turban-rural of jjj at daytime,and is most noticeable in summer;on the contrary,the ?Turban-rural of jjj is stronger than the ?Turban-rural of yrd at night,and is most noticeable in winter;the characteristics of the ?Turban-ural of hh is between the two above regions.Meanwhile,the ?Turban-rural of jjj is stronger at nighttime than at daytime,but the ?Turban-rural of yrd is stronger at daytime than at nighttime.the ?Turban-rural of hh is slightly stronger at night than at daytime.The results indicate that the scale of the urban is not the main cause of the day-and-night difference in ?Turban-rural between the north and the south.However,there is a significant positive correlation between ?Turban-rural and ATd urban-rural(the difference of the surface temperature between urban and rural areas),the northern areas(jjj)has the strongest response at night.Therefore,we try to explain its potential physical mechanism combining with the atmospheric heat sources(sinks)Q1,water vapor sinks Q2 and the other elements,and we found that the Q1 may be a better physical indicator to characterize the day-and-night difference in?Turban-rural,the results showed that:(1)During the daytime,the Q1 in south is larger than in north both in rural areas and urban areas.The northern and southern urban underlying surface types are similar(Q2 is basically the same),while the surface evaporation in the southern rural is intense,which makes the slowly warming up of the surface air temperature.The above results in a larger ?Tuban-rural in the southern areas than in the northern areas,and is most noticeable in summer;(2)During the nighttime,The absolute value of the negative value of Q1 in northern rural is larger than that in the southern rural and larger than that in the northern urban.That is,the colling effect of sensible heat in the northern rural is significantly stronger than that in the southern rural and stronger than that in the northern urban.Meanwhile,the Q,is basically the same both in the northern urban and the southern urban.The above results in a larger ?Turban-rural in the northern areas than in the southern areas.During the winter nights,the colling efifect of sensible heat in the northern urban is significantly weaker than that in the southern urban and weaker than that in the northern rural,resulting in a larger ?Turban-rural in the northern areas than in the southern areas,and is most noticeable in winter;(3)The northern areas are mainly effected by the sensible heat.The difference of the sensible heat absorption between urban and rural at daytime is smaller than the difference of the sensible heat emission between urban and rural at nighttime,so the ?Turban-rural of north is stronger at nighttime than at daytime;The influence of latent heat of precipitation in the southern areas is more significant,and the difference between day and night of Q1(Q2)in urban and rural areas is not significant.In the southern rural areas,surface evapotranspiration during the daytime is large,so the ?Turban-rural of south is stronger at daytime than at nighttime.The study show that the daytime ?Turban-rural is stronger in high temperature and humid areas,while the nighttime ?Turban-rural is stronger in low temperature and dry areas.