温度植被干旱指数(TVDI)在农业干旱监测中的应用

准确及时地监测作物干旱情况可为应对作物受灾减产提供策略,进而降低经济损失。研究基于重建的归一化植被指数(NDVI)和地表温度(LST)数据构建旱地作物生育期内LST-NDVI特征空间,计算温度植被干旱指数(TVDI),结合研究区实地观测数据对TVDI指数进行定量验证。结果表明,构建的NDVI-T_s特征空间散点图符合三角形关系,与前人研究结果相符;旱地作物不同生育阶段TVDI与土壤湿度均呈负相关性,表明TVDI具备反映研究区土壤湿润条件的能力;2017年黑龙江旱地作物生育期内各时段均有干旱状况发生,其中西部地区干旱发生频率和范围整体大于东部地区;TVDI与土壤相对湿度干旱等级判对率一致性达到90%以上。综上所述,基于MODIS数据构建的TVDI指数可以反映黑龙江省旱地作物干旱情况,研究可为作物生育期多时段干旱监测的业务化运行及为黑龙江省制定抗旱减灾策略提供科学参考依据。

Temperature Vegetation Dryness Index and Its Application in Agricultural Drought Monitoring

Accurate and timely monitoring of crop drought conditions can provide strategies for responding to crop disasters and crop losses, and against financial loss. The study took Heilongjiang Province, a major agricultural province in China, as the research area. Based on the temperature vegetation dryness index (TVDI), with high sensitivity and precision, the study monitored the drought degree and spatial and temporal pattern in the growth period of dry crop. Savitzky-Golay (S-G) filter method was selected to remove normalized difference vegetation index (NDVI) and land surface temperature (LST) noise, then the TVDI was calculated from the re-created NDVI and LST data. Combined with local meteorological data and soil moisture data observed simultaneously in field, the TVDI was verified quantitatively. The results show that: NDVI-LST feature space established in this paper accords with triangular relationship, which is consistent with the previous research results. TVDI has significant negative correlation with surface soil moisture in different growth stages, and it shows that TVDI has the ability to reflect the dry and wet conditions of soil. Based on the TVDI drought classification grade results, drought occurs in each period of dry crop growth period in 2017, and the frequency and range of drought in western are higher than that in eastern Heilongjiang Province. At the beginning of sowing season, spring drought is more serious in the western part of Heilongjiang, especially in Qiqihar City. In early July, the influence of drought on the western part of Heilongjiang is alleviated,and the impact of the drought is gradually shrinking. The correctness rate of drought grade between TVDI and soil moisture is relatively high, and the consistency of the correctness rate basically reaches 90%. In conclusion, the TVDI index constructed based on MODIS data can reflect the agricultural drought in Heilongjiang Province. Our study can provide a basis for agricultural drought monitoring, as well as scientific reference for drought relief in Heilongjiang Province.