Temperature Trend-altitude Relationship In China Under The Background Of Global Warming

The global climate change has become a highlight of the world. Except for the mean temperature, there’s been a sensible rise in the maximum temperature and minimum temperature in many parts of the world. The change of maximum temperature is not correspondent to the minimum temperature, result in the change of diurnal temperature range. The current researches about temperature trend concentrated on the characteristics of horizontal distribution in China. But there are a little researches accounted-for impacts of elevation on warming trend. For the last two years, more scientists have an emphasis on the impacts of climate in the third dimension. This paper has an emphasis on demonstrating the spatial features of the temperature trend, exploring whether its relation with altitude is significant. The main conclusions are follows: 1. Analysis on the mean temperature trend-altitude relationship in ChinaThe relationship between altitude and temperature trend is: the temperature trend decreasing with altitude below 200 m while increasing from 200 to 2000 m, and a weak positive temperature trend-altitude relation is found over 2000 m.Based on daily air temperature data from 745 stations in China, present study investigates the regional characteristics of temperature trend and the dependence of temperature changes on the altitude during the period of 1963-2012. There is a consistent warming trend throughout the country except for the southwest China where a cooling trend is identified. Compared with other seasons, the warming trend is most pronounced in highland regions in winter. In summer, the temperature has no obvious increasing trend in north China, while the warming trend is found in south China.The relationship between altitude and temperature trend is further investigated by dividing China into three subregions according to the altitude: below 200 m, 200-2000 m, and above 2000 m. Although there is no simple linear relationship between elevation and warming trend on national scale, the temperature trend-altitude relation is different among the three regions. The temperature trend decreases with altitude below 200 m while increases from 200 to 2000 m, and a weak positive temperature trend-altitude relation is found over 2000 m. The magnitudes of decreases from 200 to 2000 m are one order lower than the increases below 200 m. Low-altitude stations appear to be influenced more by anthropogenic aerosols. High-altitude stations are mostly located in flat terrain and sparsely populated region. Therefore, temperature trends change with elevations. 2. Analysis on the maximum temperature, minimum temperature and diurnal temperature range trend-altitude relationship in ChinaThe maximum, minimum temperature and diurnal temperature range trend increase with altitude, except for spring. The correlation coefficients between maximum temperature trend and altitude are the best.Based on daily maximum and minimum temperature data from 740 homogenized surface stations, present study investigates the regional characteristics of temperature trend and the dependence of maximum, minimum temperature and diurnal temperature range changes on the altitude during the period of 1963-2012. It is found that the magnitude of minimum temperature increase is larger than the maximum temperature with the significant warming area at high altitude such as the Northeast, Inner Mongol and the Tibet region, and they all have increased remarkably. The maximum temperature and minimum temperature have a significant increase after the 1980 s. But before 1980 s, they have an obvious decrease at low altitude and have a feeble downward trend at high altitude. 3. Effect of the temperature tendency rate change on altitude at different decadesThe amplitudes of maximum and minimum temperature have inconsistency.Based on daily maximum and minimum temperature data from 740 homogenized surface stations, analyze the relationship between temperature tendency rate of maximum temperature, minimum temperature and diurnal temperature range and altitude at different decades during the period of 1963-2012. The amplitudes of maximum and minimum temperature have inconsistency: they exhibit increasing trends in the 1990 s with the significant change at low altitudes, while they change minimal in the 1980s; at high altitudes above 2000 m, magnitudes of their changes are weak before the 1990 s while larger in recent ten years. The seasonal variability of diurnal temperature range is great over 2000m: decrease in summer while increase in winter. Before the 1990 s, there is no significant variation between maximum, minimum temperature and altitude. However, their trend almost decrease then increase with altitude in the last twenty years. Additionally, the respond to climate in highland areas is more sensitive than that in the lowland areas.