Role of El Nino-Southern Oscillation (ENSO) & Indian Ocean Dipole (IOD) Events on the Spatiotemporal Variability of NDVI in Southern Indian Region

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

pure and applied geophysics Pub Date : 2025-06-14 DOI:10.1007/s00024-025-03733-y

Aarthi Deivanayagam, Ranjit Kumar Sarangi

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Abstract

The El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are the crucial phenomena that occasionally cause impactful consequences on the land surface. The influence of ENSO and IOD phases on vegetation condition variability has been evaluated in this study over southern Indian region cover Kerala and Tamilnadu states by using the Normalized Difference vegetation Index (NDVI). The study carried out using NOAA Sea Surface Temperature data (ERSST.v5) along with Landsat 4–5 Thematic Mapper (TM) and Landsat-8 Operational Land Imager (OLI) datasets to derive the NDVI images. The intensive physical occurrences of ENSO discerned 2017 as El Nino year with a Sea Surface Temperature (SST) anomaly of 2.13 °C and 2015 as La Nina year with an SST anomaly of -1.82 °C. The positive phase (pIOD) and negative phase (nIOD) stipulated as the year 2010 with an SST anomaly of 1.77 °C, the year 2007 with an SST anomaly of − 1.87 °C, respectively. The NDVI results show that the study region experienced extreme drought during El Nino and nIOD, where it mostly discerned with less range of NDVI (~ 0.5 to − 0.2). The computed correlation analysis proclaimed the least dependency with a satisfying significance p-value ranging from 0.005 to 0.244 between SST and NDVI anomalies, during both the cases of ENSO and IOD. The change detection signified that 17.13% (7341.83 km²) of dense vegetation coverage diminished with the concern of ENSO and 3.42% (1467.31 km²) of dense vegetation expanded from nIOD to pIOD. It reveals that El Nino and nIOD lead to stronger impact on vegetation in this specific study region especially in southern Tamil Nadu compared to southern Kerala and the impacts of these climatic teleconnections differ with various geographical locations. The far off process also affects the Indian vegetation condition, which is proven as a true concept over the southern Indian region with the variations in NDVI parameter and its seasonality as the novelty of this study.

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厄尔尼诺-南方涛动（ENSO）和印度洋偶极子（IOD）事件对南印度地区NDVI时空变化的影响

厄尔尼诺-南方涛动（ENSO）和印度洋偶极子（IOD）是偶尔对陆地表面造成影响的关键现象。本文利用归一化植被指数（NDVI）评价了ENSO期和IOD期对印度南部喀拉拉邦和泰米尔纳德邦植被条件变率的影响。该研究使用了NOAA海洋表面温度数据（ERSST.v5）以及Landsat 4-5专题成像仪（TM）和Landsat-8业务陆地成像仪（OLI）数据集来获得NDVI图像。ENSO的强物理事件识别2017年为厄尔尼诺年，海温异常为2.13°C， 2015年为拉尼娜年，海温异常为-1.82°C。正相（pIOD）和负相（nIOD）分别为2010年和2007年，海温异常分别为1.77°C和- 1.87°C。NDVI结果表明，研究区在El Nino和nIOD期间经历了极端干旱，且NDVI变化幅度较小（~ 0.5 ~−0.2）。计算的相关分析表明，在ENSO和IOD情况下，海温与NDVI异常的相关性最小，显著性p值在0.005 ~ 0.244之间。变化检测结果表明，随着ENSO的影响，17.13% （7341.83 km2）的植被覆盖度减少，3.42% （1467.31 km2）的植被覆盖度从nIOD扩展到pIOD。结果表明，与喀拉拉邦南部相比，厄尔尼诺和nIOD对该特定研究区域的植被影响更大，特别是在泰米尔纳德邦南部，这些气候遥相关的影响因地理位置的不同而不同。远距过程对印度植被状况也有影响，在印度南部地区证明了这一概念是正确的，NDVI参数的变化及其季节性是本研究的新颖之处。

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来源期刊

pure and applied geophysics 地学-地球化学与地球物理

CiteScore

4.20

自引率

5.00%

发文量

240

审稿时长

9.8 months

期刊介绍： pure and applied geophysics (pageoph), a continuation of the journal "Geofisica pura e applicata", publishes original scientific contributions in the fields of solid Earth, atmospheric and oceanic sciences. Regular and special issues feature thought-provoking reports on active areas of current research and state-of-the-art surveys. Long running journal, founded in 1939 as Geofisica pura e applicata Publishes peer-reviewed original scientific contributions and state-of-the-art surveys in solid earth and atmospheric sciences Features thought-provoking reports on active areas of current research and is a major source for publications on tsunami research Coverage extends to research topics in oceanic sciences See Instructions for Authors on the right hand side.