To sum up, the conclusions about the characteristics of the sand-surface reflectivities of visible light channel and near infrared channel in the Tazhong region in the hinterland of the Taklimakan Desert in winter are as following:(1) On fine days, the sand-surface average reflectivities of visible light channel and near infrared channel in the Tazhong region are 25.8% and 28.6% respectively. It is roughly estimated that the atmosphere can reduce the reflectivities of these two channels for 5.2% and 7.5% respectively comparing with the RS data of NOAA satellite in the corresponding period.(2) On fine days, the reflectivities of visible light channel and near infrared channel have the following characteristics: 1. At all the positions of a dune, the reflectivity of near infrared channel is higher than that of visible light channel, and 4.3% higher in maximum on the sand-falling slope and the left wing of dune; 2. Among the different positions of a dune, the reflectivity change of visible light channel is low but that of near infrared channel is high, and the latter is about 5 times of the former: 3. The reflectivities of both visible light channel and near infrared channel on the south-facing slopes are slightly higher than that on the north-facing slopes.(3) The reflectivities of visible light channel and near infrared channel are the highest on cloudy days comparing with that on fine days and thin-cloudy days; from the fine days to the thin-cloudy days and cloudy days, the green values, reflectivity difference between the near infrared channel and visible light channel of dunes, and the maximum reflectivity difference of near infrared channel between the different dune positions are successively reduced; but the maximum reflectivity difference of visible light channel between the different dune positions are gradually increased.(4) On fine days, the dune reflectivities of visible light channel and near infrared channel are reduced with the increase of sun's altitude, but the negative correlation between the reflectivity of visible light channel and the sun's altitude is higher than that between the reflectivity of near infrared channel and the sun's altitude.(5) Frost on sand surface can increase the reflectivities of visible light channel and near infrared channel, and increase for 2.6% and 3.5% respectively compared with that without frost.
After analyzing the heat conditions in the years of serious reduction of cotton yield in the main cotton-growing areas of Xinjiang, it is found that the cold disasters, especially the delaying cold disasters, are the most serious meteorological disasters to the cotton production in Xinjiang.
In the paper, the three outstanding features of climate change in Xinjiang for the recent 40 years are identified. Their causes are discussed primarily from two aspects of natural change and factitious influence. Results are as follows: (1)The warming trend of winter mean temperature in northern and southern Xinjiang are resulted from the controlling of macroclimate regularities of winter warming in The Northern Hemisphere and the local influence of factitious factors, the former is more important than the latter. (2)The increasing trend of summer precipitation in southern Xinjiang may have little to do with the change of macroclimate background, but mainly have to do with human activities, especially with increasing of real evaporation in oasis area, which are result from both the area under cultivation (or oasis) enlarging continually in southern Xinjiang between the south foot of Tianshan Mountains and the north foot of Kunlun Mountains and the amount of drawing water from Tarim River increasing continually. Furthermore, the warming trend of summer in southern Xinjiang for the recent 40 years coinciding with The Northern Hemisphere also helps to increase evaporation intensity, to form the increasing trend of real evaporation amount, and results in the increase of summer precipitation. But this is less important than the increase of available evaporation water amount and evaporation area that result from the acreage under cultivation (or oasis) enlarging. (3)The variability of annual mean temperature in Tianshan Mountainous area is the greatest, which maybe have to do with that the annul difference of early or later of forming or smelting, thick or thin and cover extent of seasonal stable snow is largely in the area.
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