定量评估东亚地区植被对大气变率的反馈

Quantitative Assessment of Vegetation Feedback to Atmospheric Variability over East Asia

利用统计方法分析了东亚地区植被与大气变率之间的相互关系,并利用平衡反馈分析法(EFA)定量评估了植被对大气的反馈程度。研究发现植被与温度和降水均有明显的相关性,在中高纬度地区植被与温度呈明显的同期正相关,植被与降水存在负相关关系。而在中低纬地区植被与降水呈同期正相关,植被与气温呈负相关关系。前期中高纬度植被增加后,会导致后期异常升温。这是由于前期植被覆盖度增加后会遮挡地表积雪,导致地表积雪覆盖度减少,反射率减少,地表吸收更多的太阳辐射,导致异常升温。超前的降水对植被的影响在中低纬度十分明显,这是由于中低纬度地区年平均温度较高,降水是制约植被生长的主要因素。当植被超前降水一个月时,中低纬度地区植被与降水呈正相关,其原因是植被增加会导致局地水汽辐合,蒸发/蒸腾增加,导致降水增加。植被对温度的反馈系数在大兴安岭、贝加尔湖等地区,反馈系数为正,为1~2℃·(0.1FPAR)^(-1),中国南部地区温度反馈系数也为正,但反馈较小,为0.2~1℃·(0.1FPAR)^(-1)。植被对降水的反馈系数噪音较多,在我国华北地区为正的反馈,反馈系数约为1.5cm·mon^(-1)·(0.1FPAR)^(-1)。

This paper employs statistical methods to analyze the relationship between vegetation and climatology variables.Additionally,it quantitatively assesses vegetation feedback over East Asia using the equilibrium feedback assessment(EFA)method.The study reveals a significant correlation between vegetation and climate variables,including temperature and precipitation.In middle and high latitudes,positive feedback is observed between vegetation and temperature,while negative feedback is identified between vegetation and precipitation.In middle and low latitudes,positive feedback is observed between vegetation and precipitation,while negative feedback is identified between vegetation and temperature.In high latitudes,the positive vegetation anomaly tends to reduce the albedo by shading effect,leading to increased energy absorption and warming air during winter and spring.The analysis highlights that in low latitudes,the correlation between leading vegetation and precipitation is highly sensitive.It is mainly because the high year-round temperature in this area leads to the vegetation being dominated by precipitation signals.The study also finds a positive correlation between leading vegetation and precipitation in low latitudes.The increased vegetation stimulates moisture convergence and enhances evapotranspiration,resulting in more precipitation.The vegetation feedback parameter for temperature is positive in regions around the Da Hinggan Mountains and Baikal Lake,predominantly covered by evergreen needle-leaf forests.The feedback parameter in this area is approximately 1 to 2℃·(0.1FPAR)^(-1).The positive feedback parameter is identified in the southern part of China,ranging from 0.2 to 1℃·(0.1FPAR)^(-1).Regarding precipitation,the feedback parameter exhibits significant noise,making it challenging to distinguish signals except for the positive signal around the North China Plain.In the North China Plain,the feedback parameter for precipitation is approximately 1.5 cm·mon^(-1)·(0.1FPAR)^(-1).