黔南布依族苗族自治州1961—2015年日照时数变化特征分析

Analysis of changing characteristics of sunshine duration in Qiannan Bouyei and Miao Autonomous Prefecture from 1961 to 2015

关键词:  日照时数  时空变化  突变特征  周期变化

Key words:  sunshine duration  temporal and spatial changes  mutation characteristics  periodic variation

摘要:

日照时数是表征气候变化的重要气象要素，探究日照时数的变化，对农业生产具有重要意义。利用1961—2015年黔南州11个气象站点的日照时数数据，使用线性回归、气候距平、滑动平均、Mann-Kendall突变检验、小波分析对四季和年日照时数时空变化趋势进行分析，结果表明：（1）全年及四季日照时数都呈减少趋势。其中，年、春季日照时数发生突变性减少，夏、秋、冬季未发生明显突变；（2）州内年日照时数总体呈现“西南多东北少”，春季呈“西多东少”，夏季呈“西南和北部多、中部和东部少”，秋季呈“南多北少”的格局，冬季日照时数空间分布与年际相似；（3）通过小波分析发现，在29 a时间尺度上年日照时数大体经历了“多—少—多—少—多”的循环交替。研究结果可为该州气候预测和农业发展提供数据支撑。

Abstract:

Background, aim, and scope Sunshine duration is an important meteorological element that characterizes climate change. It is not only an important reflection of solar radiation intensity, but also an important parameter for measuring sunshine intensity. Changes in its abundance not only affect the radiation balance and water cycle process, but also restricts vegetation and ecological patterns. Qiannan Bouyei and Miao Autonomous Prefecture (hereinafter denoted as Qiannan Prefecture) is located in the southern part of Guizhou Province and has a subtropical monsoon humid climate. It is one of the areas with the best ecological environmental preservation in the province. Analyzing the sunshine duration in this area is of great significance for regional climate prediction, environmental protection, and sustainable development. Therefore, we processed the meteorological data of Qiannan Prefecture over the years, analyzed the spatiotemporal variation characteristics of sunshine duration, and explored the relationship between sunshine duration and precipitation, average temperature, average wind speed, and relative humidity in different seasons. Materials and methods The sunshine duration data from 11 meteorological stations in Qiannan Prefecture from 1961 to 2015 were analyzed using methods such as linear trend analysis, anomaly analysis, 5-year moving average, Mann-Kendall mutation test, Pearson correlation and wavelet analysis. Results (1) The sunshine duration in Qiannan Prefecture showed a significant decreasing trend in year, spring, summer and winter, and the climate tendency rate are −45.34, −9.79, −20.37 and −8.19 h·(10a)⁻¹, respectively. The sunshine duration in autumn decreased at a rate of 7.06 h·(10a)⁻¹. (2) The spatial distribution of sunshine duration throughout the year and four seasons has strong similarity. The sunshine duration throughout the year and winter decrease from southwest to northeast, with more sunshine hours in the west and less in the east in spring, more in the southwest and north in summer, less in the middle and east, and more in the south and less in the north in autumn. (3) The annual sunshine duration and spring sunshine duration decreased abruptly in 1989 and 1978, respectively, with no obvious sudden changes in summer and winter, and no sudden changes in autumn. (4) The wavelet analysis signal is relatively strong on the time scale of 29 a. From 1965 to 2013, the sunshine duration generally experienced a cycle of more-less-more-less-more. (5) The spatial distribution of annual sunshine duration and seasonal sunshine duration in most areas of the state differed greatly, but they all showed a decreasing trend. Discussion (1) The duration of sunshine has a strong negative correlation with precipitation. The correlation between precipitation and sunshine duration in summer and autumn has passed the significance test at the 0.01 level, indicating a highly significant negative correlation. This is because increased precipitation leads to reduced atmospheric visibility, resulting in reductions in the amount of solar radiation received at the surface and sunshine duration. (2) Sunshine duration is positively correlated with average temperature, indicating that as temperature increases, the duration of sunshine also increases. Except for autumn, the correlation between sunshine duration and temperature in spring, summer, and winter all showed highly significant positive correlation. This is because sunshine duration is one of the main factors that reflects the intensity of solar radiation. The stronger the solar radiation, the longer the sunshine time, and the higher the surface temperature. (3) The correlation coefficients between average wind speed and sunshine duration in spring, summer, autumn, and winter are 0.577, 0.321, 0.096, and 0.392, respectively. Sunshine duration and wind speed had a highly significant positive correlation in spring and winter and a significant positive correlation in summer. This is because wind speed is one of the main factors influencing air movement. The greater the wind speed, the less likely it is for clouds, water vapor, aerosols, and other pollutants in the air are to gather, the higher the visibility of atmosphere and sunshine duration increase significantly. (4) Except for winter, the correlations between sunshine duration and relative humidity in spring, summer, and autumn all passed the significance test at the 0.01 level, indicating a highly significant negative correlation. This is because as relative humidity increases, the amount of water vapor in the air increases, resulting in a decrease in atmospheric transparency and thus a decrease in sunshine duration. In addition, water vapor in the air attenuates atmospheric radiation through absorption, scattering, and reflection, thereby affecting sunshine duration. Conclusions This study provides important fundamental data for climate change research by analyzing changes in sunshine duration in Qiannan Prefecture from 1961 to 2015, and also highlighting the profound impact of sunshine variation on agricultural production. Recommendations and perspectives Using long-term meteorological data to explore regional climate change trends is of great significance for understanding the formation and change patterns of regional climate and for rational agricultural production layout. The next step will be to analyze the future trend changes in meteorological factors, aiming to achieve high-quality development of agriculture in this region.