A Study Of Air Temperature Correction And Its Response Due To LUCC Based On Remote Sensing And GIS

Global warming is an inarguable truth; therefore evaluating and forecasting the global and regional warming trends is often addressed in the scientific community. As one of the important factors which influence the homogeneity of the temperature measured by meteorological stations, urbanization has lead to regional Land Use and Land Cover Changes (LUCC). But the influence of urbanization is similar to that of greenhouse gases which are increasing gradually without mutation. Therefore the correction of temperature trends affecting homogeneity caused by urbanization is a difficult issue.Aiming at addressing this meaningful scientific problem, the academic methodology of this paper is that: In order to do temperature correction and to study the relationship between temperature and LUCC, we choose eighty meteorological stations in Anhui province, utilize the temporal and spatial characteristics of the air temperature, use the time series temperature data, multi-source remote sensing data, multi-period land-use data, a DEM, city population and economic data, then perform a temperature correction, get the background air temperature, and finally analyze the stations' underlying influence on the measured temperature.The conclusion is:①The regional climate of AnHui has a typical spatial distribution; with the Huaihe River, Yangtze River, Dabie mountainous areas, Jiangnan mountainous areas and natural regions as boundaries. It can be divided into six kinds of regional climate zones and eight subdivided regional climate zones.②There have been violent transformations between different land cover types. Arable land has suffered the greatest loss while urban land has made the greatest gains. The decrease in arable land is mainly due to conversion into urban land and forest land while the increased urban land cover mainly comes from rural construction and settlements. Although the temperature in urban land is high, it is so small that it has little contribution to the temperature increase. Therefore the increased forest and arable land cover is the main reason for the difference in temperature.③The trend of increasing temperature and heat-island intensity are different among districts and cities in Anhui Province. Urbanization mainly affects temperatures of cities which have more than 200,000 people; so the affects are most noticeable in the large and medium-sized cities, with steady trends apparent in medium-sized cities. But the small cities under 200,000 people are very small, therefore 200,000 people appears to be the population threshold for cities to show a heat island effect in the temperature data.④After analyzing the weather data station in small cities with populations between 100,000 and 200,000 by using an artificial neural network (ANN), we can draw a conclusion that the majority of stations in small cities as well as stations with a population bellow 100,000 show almost the same temperature tendency and intensity, with only three stations influenced greatly by urbanization.⑤The underlying local environment in urban stations has a great influence on a station's temperature observations, with a close relationship revealed among building, lawn and the intensity of the urban heat island. The influential distance is about three kilometers and it decreases dramatically as the distance increases. Bodies of water have further influence.The innovating points of this research are as follows:(1) This research is the first one to look at the effects of the regional variations in the temperature records, thus getting rid of correcting errors leaded by climate differences which result from regional conditions and taking over correcting difficulties resulting from missing metadata and simplifying the procedure.(2) Overcoming the disadvantages in research of heat island of big, moderate and small cities and systematic analysis is carried out in heat-land's characteristic especially in the analysis of moderate and small cities. We have determined a boundary of the heat-island effect in Anhui province, and provide a reference to define the urban stations from the rural ones.(3) We break through the traditional methods of considering the city population and other single data separately; We take both the city population and the meteorological stations'underlying land-use type into account, using ANN to separate the urban stations from the rural ones.(4) Among all the factors, the station underlying environment is a determining factor. Taking this into consideration, we do a certain buffer analysis based on observations, analyze LUCC's influence on temperature measured by meteorological stations, and finally get the range and the intensity of this influence.