Climate Characteristic of First and Last Frost Dates in Wuwei
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Abstract:
Aiming to adjust measures to local conditions, reasonably adjust planting structure and layout, and effectively utilize agricultural climate resources, based on the observation dates of first frost day and last frost day (the minimum ground temperature less than 0 ℃) of 4 meteorological stations in from 1961 to 2014 over Wuwei, the spatial and temporal variation characteristics of the dates of first and last frost days are analyzed systematically with the climate diagnosis analysis method. The results show that the spatial distribution of the first frost date is the earliest in mountain regions, earlier in desert regions, and the latest in oasis plains in Wuwei; that of the last frost date is the latest in mountain regions, later in deserts and the earliest in oasis plains, because of the influence of altitude, topography, and vegetation cover. First and the last frost dates have certain abnormality in various regions. The occurrence possibility of normal first and the last frost dates is about 60%, and that of the abnormal cases such as the earlier and early frost, later and late frost dates that may cause hazards on agricultural production is all about 20%. First frost date assumes a significantly delayed trend, and last frost date assumes a significantly early trend. Frost period assumes a significantly short trend, and the advanced magnitude of last frost date is greater than the delayed magnitude of first frost date. The time series of first and last frost dates have the quasiperiodic variation of 8 to 10 years and 9 to 11 years, respectively. First frost date and last frost date have a climate abrupt change in 1998 and in 1996, respectively.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.