Department of Geography (Geoinformatics), University of Pune, Pune, Maharashtra, 41107, India.
Agriculture and Land Ecosystem Division (AED), Space Applications Centre, ISRO, Ahmedabad, Gujarat, 380015, India.
Environ Monit Assess. 2020 Apr 23;192(5):311. doi: 10.1007/s10661-020-08272-8.
Remote sensing data from Indian geostationary satellites (Kalapana-1, INSAT 3A) were used for the first time for early warning of agricultural drought and forewarning of crop vigour. An Early warning indicator (EWI) was developed from operational product of rainfall and reference evapotranspiration from observations of Kalpana-1 very high resolution radiometer (VHRR). The effectiveness of EWI was evaluated for the two drought years (2009 and 2012). The positive correlation (r = 0.66-0.68 for 2009 and r = 0.64-0.70 for 2012) between the EWI in the month of June-July and standardized precipitation index-1 (SPI-1) averaged over administrative unit (called district) indicates that EWI can be used successfully for drought early warning. Lag-response behaviour between EWI and crop vigour in terms of normalized difference vegetation index (NDVI) and LAI (leaf area index) over cropland was studied. Systematic patterns emerged for 30 days lag period between negative EWI and NDVI at both grid-scale (0.25°) and at district level. Linear relations were found between 10-day EWI and NDVI or LAI at 30 days lag during June-July period. Linear models were developed to forewarn crop vigour which was validated with realized NDVI from INSAT 3A charge-coupled device (CCD) observations within 95% accuracy. The EWI is recommended as potential indicator for early-season agricultural drought assessment and can be used for sub-district scale with finer scale rainfall and evaporation products from advanced next-generation geostationary meteorological satellites.
首次使用印度地球静止卫星（Kalapana-1、INSAT 3A）的遥感数据进行农业干旱预警和作物活力预警。从 Kalpana-1 甚高分辨率辐射计（VHRR）观测的降雨和参考蒸散量的业务产品中开发了早期预警指标（EWI）。评估了 EWI 在两个干旱年份（2009 年和 2012 年）的有效性。6 月至 7 月 EWI 与行政单位（称为区）平均标准化降水指数-1（SPI-1）之间的正相关（2009 年 r=0.66-0.68，2012 年 r=0.64-0.70）表明 EWI 可成功用于干旱预警。研究了 EWI 与作物活力之间在植被指数（NDVI）和叶面积指数（LAI）方面的滞后响应行为。在网格尺度（0.25°）和区一级，负 EWI 与 NDVI 之间出现了 30 天滞后的系统模式。在 6 月至 7 月期间，发现了 10 天 EWI 与 NDVI 或 LAI 之间的线性关系。建立了线性模型来预警作物活力，并用 INSAT 3A 电荷耦合器件（CCD）观测到的实际 NDVI 在 95%的精度内进行了验证。EWI 被推荐为早期农业干旱评估的潜在指标，并可用于具有更精细尺度降雨和蒸发产品的次区尺度的下一代先进地球静止气象卫星。
