Recently, the research group led by Professor Tian Pengfei from the Key Laboratory of Semi Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, has published research findings entitled Mechanisms Linking Arctic and East Pacific Oscillations to Compound Heat Wave–Wildfire Events in India in the international journal Journal of Climate.
Integrating temperature datasets from the India Meteorological Department, MODIS fire observations, ERA5 reanalysis datasets and SeasFire data, the research team systematically analyzed the spatiotemporal variations and driving mechanisms of compound heat wave wildfire events across India from 2003 to 2022.
The study finds that compound heat wave wildfire events in India predominantly occur in March and April and show an overall increasing trend over the past two decades. The negative phase Arctic Oscillation in April and the negative phase East Pacific Oscillation in March can both modulate large scale Northern Hemisphere circulations. They generate anomalous anticyclones and subsidence over India, amplifying solar radiation and surface warming. Meanwhile, they reduce precipitation and soil moisture, aggravate drought and fire danger, and thereby raise the probability of concurrent heat wave and wildfire occurrences. Linear Baroclinic Model (LBM) experiments further verify the downstream impacts of regional anomalies over Greenland and Alaska on atmospheric circulations over India.
Figure 1. Physical mechanisms of compound heat wave wildfire events in India modulated by the Arctic Oscillation and East Pacific Oscillation
The research further indicates that under the April negative phase Arctic Oscillation and March negative phase East Pacific Oscillation scenarios, population exposure to compound events in India increases by approximately 100 million person days and 171 million person days respectively. Such increases are mainly driven by rising frequency of compound events.
This study establishes a cross scale interaction framework: mid high latitude teleconnection anomalies → intensified Indian anticyclones → regional warming and drying → synchronized rise in heat wave and wildfire occurrences. It reveals month dependent modulation of compound events by different teleconnection modes, and provides scientific support for sub seasonal prediction and risk early warning of compound extreme events across South Asia.
This research was supported by the Ministry of Education Program for Breakthroughs in Basic and Interdisciplinary Disciplines, the Fundamental Research Funds for the Central Universities, and the Second Comprehensive Scientific Expedition to the Qinghai Xizang Plateau. The High Performance Computing Center of Lanzhou University provided computing platforms and resources for this work.
Article link: https://doi.org/10.1175/JCLI-D-26-0021.1
Written by: Yu Zeren
Figures by: Yu Zeren
Edited by: Zhai Minhan
