基于CLDAS土壤相对湿度的云南农业干旱监测

Agricultural Drought Monitoring in Yunnan Based on CLDAS Soil Relative Moisture

选取2016-2020年云南37个土壤水分观测站逐日0-10cm土层相对湿度观测数据和逐日降水、气温观测资料,采用线性插值法,将CLDAS格点数据插值到观测站点上,用于与站点观测数据对比分析。利用回归订正法对插值后的CLDAS土壤相对湿度产品进行订正。采用相对误差、平均偏差、相关系数、标准差和均方根误差统计指标,定量评估CLDAS土壤相对湿度在云南的适用性。结果表明:云南土壤水分观测站相对湿度数据观测有效率不高,选用陆面融合数据开展农业干旱监测十分必要;云南地区近80%的CLDAS土壤相对湿度与土壤水分观测站观测值的相对误差绝对值<30%,数据可信度高;在干旱发生频率高的云南中部地区,CLDAS土壤相对湿度与土壤水分观测站观测值的相关系数均在0.8以上,平均偏差小于10%。从农业干旱监测效果来看,基于CLDAS土壤相对湿度的干旱监测指标能很好地描述由气温和降水异常导致的土壤墒情变化,当日降水量接近或超过5.0mm时,能快速响应轻旱站点数的减少;当连续有效降水发生后,监测指标可反映中等及以上等级农业干旱的缓解。综合来看,CLDAS土壤相对湿度在云南农业干旱监测的适用性好。

Based on the observation quality analyzing of daily soil relative humidity data in Yunnan from 2016 to 2020,0−10cm CLDAS soil relative humidity data was introduced and its applicability was analyzed.The results showed that the observation efficiency of relative humidity data in Yunnan soil water observation station was not high,so it was necessary to use land surface fusion data to monitor agricultural drought.The absolute error between the relative humidity of nearly 80%of CLDAS soil in Yunnan region and the observed values of soil moisture observation stations is less than 30%,indicating high data reliability.In the central region of Yunnan,where drought occurs frequently,the correlation coefficient between the soil relative humidity of CLDAS and the observed values of soil moisture observation stations is above 0.8,and the average deviation is less than 10%.From the perspective of agricultural drought monitoring effectiveness,the drought monitoring index based on CLDAS soil relative humidity can well describe the changes in soil moisture caused by abnormal temperature and precipitation.When the daily rainfall is close to or exceeds 5.0mm,it can quickly respond to the decrease in the number of light drought stations;When continuous effective precipitation occurs,the monitoring index can reflect the relief of agricultural drought of medium and above grade.In summary,CLDAS soil relative humidity is suitable for agricultural drought monitoring in Yunnan province.