未来RCP4.5情景下非洲地区主要气候要素时空演变特征

气候变化影响及其适应受到广泛关注。大量研究表明,受气候变化影响所造成的增温和降水减少已影响到非洲地区的农业生产和环境。本文利用HadGEM2区域气候模式输出的RCP4.5情景数据,基于时间序列分析及空间分析方法,对非洲大陆2010-2099年主要关键气候要素时空演变特征进行了预估,探讨了非洲大陆未来90年包括降水、辐射、平均气温、最高气温、最低气温等主要气候要素的时空变化格局。结果表明：各气候要素在不同时段的变化均表现出明显的地域分异差异： ① 相较于1970-1999年基准时段,未来3个时段(2020s、2050s、2080s)降水均增加,在2080s增至峰值,增加地区集中在20 °N附近的尼日尔、乍得、利比亚等国;最高增幅达4.5%;② 辐射增加区域分布在赤道地区和非洲大陆的南北两端,尤其是高海拔地区,如撒哈拉沙漠以北的阿特拉斯山脉附近,加丹加高原等地,最大增幅达0.04%;③ 未来90年非洲地区气温增加明显,包括平均气温、最高气温、最低气温,气温增幅由2020s、2050s、2080s依次递增,到2080s达到最大值,平均气温、最高气温、最低气温的最大增幅分别达到5、4.3和5.1 ℃。总体上,未来90年非洲大陆的气温较1970-1999年基准时段明显增多,但靠近海域的沿海地区增温较小,这是由于受到近海寒流的影响,起到了降温的作用。气温增幅过高也将不利于未来农业生产和地区安全。

Temporal-spatial Variation of Climate Factors in Africa under Representative Concentration Pathways Scenario 4.5

Impacts of climate change and adaptation are of key concern of scientific research. Vast research results indicated that agricultural production and environment in Africa have been affected a lot by increased temperature and decreased precipitation caused by climate change. This study used the output of regional climate model HadGEM2 under Representative Concentration Pathways Scenario 4.5 (RCP 4.5) to analyze the temporal and spatial evolution of major climate factors including precipitation, solar radiation, annual average temperature, maximum temperature and minimum temperature. Our results indicated that the variation of the five climate variables at different periods showed obvious regional differences. (1) Compared with the base period of 1970-1999, precipitation increased during the three future periods and reached peak value in 2080s. The area of precipitation increase is mainly located in the latitude of 20 degrees, such as Niger, Chad, Libya, etc. and the maximum increase is around 4.5%. (2) The area of increased solar radiation is mainly located in north and south ends of Africa continents, especially in high altitude area, i.e. Atlas mountain and Plus plateau and the maximum increase is 0.04%. (3) Over the next 90 years, the annual average temperature, maximum temperature and minimum temperature are all increasing and reach the maximum value by 2080s, increasing 5 ℃,4.3 ℃,5.1 ℃ at 2020s, 2050s, 2080s, respectively. The temperature is significantly increased compared with the base period of 1970-1999, but increased less in the coastal area due to the cold current. The high increase of temperature might play negative role in agriculture production and regional security.