SRES A1B情景下未来宁夏玉米生育期气候资源变化分析

Analysis of climate resource changes during maize growth period inNingxia under SRES A1B scenario

  • 摘要: 玉米是宁夏的三大粮食作物之一, 其种植分布广泛, 中部干旱带和南部山区基本属于雨养玉米区, 气候条件对当地的玉米生产影响很大。观测到的气候变化已经对当地农业造成不利影响, 未来SRES A2和B2情景下宁夏地区的气候变化研究也有一定成果。由于气候变化引发宁夏的气温和降水出现异常, 为分析未来中等排放情景下气候变化可能对当地玉米生产造成的影响, 本文利用订正后的英国Hadley气候中心区域气候模式PRECIS模拟的情景数据, 分析了SRES A1B情景下宁夏未来2020s、2050s和2080s时段相对于气候基准时段(1961-1990年)的玉米生育期(4-9月)平均气温、最高气温、最低气温、≥10 ℃有效积温和降水的变化, 具体方法为先分析气候基准时段宁夏的气候要素分布并与实际状况进行比较, 再将未来3个时段的气象要素与气候基准时段求差值(其中降水用距平百分率表示), 分析未来玉米生育期的气候变化。结果表明: 平均、最高和最低气温以及≥10 ℃有效积温的模拟值普遍低于实际值, 且具有相似的北高南低的空间分布状态, 而降水的模拟值在大范围区域内高于实测值, 亦呈现出相似的南高北低分布状态, 总体来讲模拟值可以较合理地反映出宁夏的实际状况。相对于气候基准时段, 未来各气象要素总体表现为增加, 且增幅随时间推移而加大; 未来最高气温在宁夏南部增加剧烈, 平均气温、最低气温和≥10 ℃有效积温在宁夏北部增加较多, 降水则呈现北增南减的分布。在未来3个时段, 最高气温和降水分别为增量最大和波动最大的气象要素, 出现极端高温天气和发生干旱或洪涝等异常气候事件的可能性增大。总体上看, 未来气温升高对宁夏北部灌区的玉米生产有一定促进作用, 尤其是≥10 ℃有效积温的增加可以提供更充足的热量; 而南部山区气温增加虽然对玉米生产有利, 但是未来降水的减少将会给雨养玉米造成不利影响, 应当采取合理的应对措施。

     

    Abstract: Maize is one of the three main food crops in Ningxia and is widely cultivated in central arid and south mountain zones; where maize is mainly cultivated under rain-fed conditions and with significant influence of climatic conditions. Climate change has adversely affected local agricultural production in Ningxia and several other studies have reported even further adversities under SRES A2 and B2 scenarios. Also climate change has reportedly led to temperature and precipitation anomalies in Ningxia. This study therefore analyzed the impact of future climate change on maize production under moderate emission scenario. The analysis was based on revised data of the PRECIS regional climate model simulation under SRES A1B scenario. The data included changes in average temperature, maximum temperature, minimum temperature, ≥10 ℃ effective accumulated temperature and precipitation for the periods from April to September of 2011-2040 (for the 2020s), 2041-2070 (for the 2050s), 2071-2100 (for the 2080s) and 1961-1990 (the baseline period of climate). In the first step, the study analyzed the distribution of climatic factors in Ningxia for the baseline period and compared that with observed data for the same period. This was followed by distribution and variation analysis of 5 climatic factors for the 2020s, 2050s and 2080s under A1B scenario. These future values minus those of the baseline period yielded the changes in the climatic factors, where precipitation was specifically expressed in anomaly percent. In the final step, climate change during maize growth period was discussed for the future scenarios. The results showed that simulated average temperature, maximum temperature, minimum temperature and ≥10 ℃ effective accumulated temperature were generally lower than the observation values. However, the simulated distributions were similar to the actual situation; i.e., temperatures were high in the north and low in the south. Also while simulated precipitations for relatively large regions were higher than observation values, the simulated and observed precipitation distributions were similar. Overall, the simulated climatic factors reflected the observed conditions in Ningxia. Average temperature, maximum temperature, minimum temperature, ≥10 ℃ effective accumulated temperature and precipitation for the 2020s, 2050s and 2080s were higher than those of the baseline period and the gaps also widened with time. In south Ningxia, maximum temperature intensely increased while average temperature, minimum temperature and ≥10 ℃ effective accumulated temperature more or less increased in north Ningxia under the scenario simulations. Also precipitation increased in the north and decreased in the south of Ningxia under the scenario simulations. The future scenario analysis showed that maximum temperature and precipitation respectively increased and fluctuated with high likelihoods of extreme hot weathers, droughts and floods. Climate change in the future scenario facilitated maize production in the north irrigation zone of Ningxia, especially increase in ≥10 ℃ effective accumulated temperature provided additional heat for higher maize production. In the south mountain zone of Ningxia, however, limited precipitation negatively affected rain-fed production of maize despite any positive effect of increased temperature on maize production. This paper put forward and discussed appropriate countermeasures for crops production in the rain-fed condition.

     

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