Using daily mean, maximum, and minimum surface air temperature （abbreviated as Tmean, Tmax, and Tmin, respectively） data from CN05.2 and the Met Office Hadley Centre observation data-sets for 1961-2012, the trends i...Using daily mean, maximum, and minimum surface air temperature （abbreviated as Tmean, Tmax, and Tmin, respectively） data from CN05.2 and the Met Office Hadley Centre observation data-sets for 1961-2012, the trends in day-to-day variability of Tmean, Tmax, and Tmin （abbreviated as DVTFmean, DVTTmax, and DVTTmin, respectively） are examined. It is revealed that the annual trends of DVTTmean, DVTTmax, and DVTTmin are all negative in Northeast China （NEC）, and more obvious in North China than in South China. Seasonal trends of DVTTmean are also negative in NEC, except in summer. For DVTTmax, trends are generally more obvious than DVTTmin in all seasons in NEC; moreover, trends in spring are obvious in both the north and the south, but trends in summer and winter are more obvious in the southern region than in the northern part. As far as DVTT-Fmin is concerned, except in autumn, seasonal trends are more obvious in the north than in other regions of the country.展开更多
The important effects of snow cover to ground thermal decades. In the most of previous research, the effects were usually regime has received much attention of scholars during the past few evaluated through the numeri...The important effects of snow cover to ground thermal decades. In the most of previous research, the effects were usually regime has received much attention of scholars during the past few evaluated through the numerical models and many important results are found. However, less examples and insufficient data based on field measurements are available to show natural cases. In the present work, a typical case study in Mohe and Beijicun meteorological stations, which both are located in the most northern tip of China, is given to show the effects of snow cover on the ground thermal regime. The spatial （the ground profile） and time series analysis in the extremely snowy winter of 2012-2013 in Heilongjiang Province are also performed by contrast with those in the winter of 2011-2012 based on the measured data collected by 63 meteorological stations, Our results illustrate the positive （warmer） effect of snow cover on the ground temperature （GT） on the daily basis, the highest difference between GT and daily mean air temperature （DGAT） is as high as 32.35℃. Moreover, by the lag time analysis method it is found that the response time of GT from 0 cm to 20 cm ground depth to the alternate change of snow depth has 10 days lag, while at 40 cm depth the response of DGAT is not significant. This result is different from the previous research by modeling, in which the resnonse denth of ground to the alteration of snow depth is far more than 40 cm.展开更多
基金supported by the National Natural Science Foundation of China[grant numbers 41421004 and 41630424]the Science and Technology Development Plan in Jilin Province of China[grant number 20130204053SF]
文摘Using daily mean, maximum, and minimum surface air temperature （abbreviated as Tmean, Tmax, and Tmin, respectively） data from CN05.2 and the Met Office Hadley Centre observation data-sets for 1961-2012, the trends in day-to-day variability of Tmean, Tmax, and Tmin （abbreviated as DVTFmean, DVTTmax, and DVTTmin, respectively） are examined. It is revealed that the annual trends of DVTTmean, DVTTmax, and DVTTmin are all negative in Northeast China （NEC）, and more obvious in North China than in South China. Seasonal trends of DVTTmean are also negative in NEC, except in summer. For DVTTmax, trends are generally more obvious than DVTTmin in all seasons in NEC; moreover, trends in spring are obvious in both the north and the south, but trends in summer and winter are more obvious in the southern region than in the northern part. As far as DVTT-Fmin is concerned, except in autumn, seasonal trends are more obvious in the north than in other regions of the country.
基金Under the auspices of National Natural Science Foundation of China(No.41471289,41301368)Natural Science Foundation of Jilin Province(No.20140101158JC)Foundation of State Key Laboratory of Remote Sensing Science(No.OFSLRSS201517)
文摘The important effects of snow cover to ground thermal decades. In the most of previous research, the effects were usually regime has received much attention of scholars during the past few evaluated through the numerical models and many important results are found. However, less examples and insufficient data based on field measurements are available to show natural cases. In the present work, a typical case study in Mohe and Beijicun meteorological stations, which both are located in the most northern tip of China, is given to show the effects of snow cover on the ground thermal regime. The spatial （the ground profile） and time series analysis in the extremely snowy winter of 2012-2013 in Heilongjiang Province are also performed by contrast with those in the winter of 2011-2012 based on the measured data collected by 63 meteorological stations, Our results illustrate the positive （warmer） effect of snow cover on the ground temperature （GT） on the daily basis, the highest difference between GT and daily mean air temperature （DGAT） is as high as 32.35℃. Moreover, by the lag time analysis method it is found that the response time of GT from 0 cm to 20 cm ground depth to the alternate change of snow depth has 10 days lag, while at 40 cm depth the response of DGAT is not significant. This result is different from the previous research by modeling, in which the resnonse denth of ground to the alteration of snow depth is far more than 40 cm.
