Anomaly Variation of Vegetation and Its Influencing Factors in Mainland China During ENSO Period

Abstract

Considering the noncore region influenced by El Niño-Southern Oscillation (ENSO) events, China is hardly investigated in terms of the vegetation variation during the ENSO period.Therefore, this study focused on increasing knowledge of vegetation growth and variation during the ENSO period.The novelty of this paper is introduced the moving window correlation analysis method to determine the thresholds of vegetation response to sea surface temperature anomaly (SSTa) and southern oscillation index (SOI) and analyze the main reasons for such variations.China was divided into seven areas based on different weather conditions, and the variations in vegetation growth in various areas during the ENSO period were analyzed. The response of vegetation to ENSO events in China was analyzed from the perspectives of precipitable water vapor (PWV), temperature, and precipitation, thereby revealing the interplay of multi-factors on vegetation growth.The main conclusions include (1) a positive vegetation response to El Niño exists all over China with thresholds of SSTa ≥ 1.87°C and SOI ≤ -3.27hPa, whereas a negative response of vegetation variation to La Niña exists with thresholds of SSTa ≤ -1.05°C and SOI ≥ 1.7hPa; (2) the correlations (p <; 0.05) of PWV to normalized difference vegetation index (NDVI) (PWV-NDVI), temperature-NDVI, and precipitation-NDVI reached 0.84, 0.86, and 0.68, respectively, and PWV, temperature, and precipitation were negatively/positively abnormal during El Niño/La Niña periods; (3) in coastal areas of Southeast China, correlations between NDVI and PWV/temperature/ precipitation are poor and the opposite anomalies of PWV/temperature/ precipitation existed when compared to other areas of China.

Keywords

• ENSO
• anomaly variation of vegetation
• influencing factors
• mainland China