The study, published in Atmospheric Research, was carried out by Ph.D. Student Victor Murphy and Dr. Assaf Hochman of the Institute of Earth Sciences at the Hebrew University of Jerusalem and Dr. Sigalit Berkovic of the Israel Institute for Biological Research. The researchers investigated how the Indian Ocean Dipole (IOD), a recurring pattern of warming and cooling across the tropical Indian Ocean, affects prolonged winter dry spells in the Levant, one of the world’s most water-stressed regions.
Persistent winter dry spells can last for weeks, threatening water supplies, agriculture, and ecosystems across Israel and neighboring countries. Yet forecasting these events has remained notoriously difficult.
By analyzing more than seven decades of climate observations and atmospheric data, the researchers discovered that positive phases of the Indian Ocean Dipole are linked to large-scale shifts in atmospheric circulation stretching from the Indian Ocean across Eurasia into the Eastern Mediterranean. These shifts favor stable high-pressure systems that suppress rainfall and increase the likelihood of prolonged winter dry spells. The study also found that conditions in the Indian Ocean during December are associated with an increased chance of especially long dry spells later in the winter, highlighting the potential for improved seasonal forecasting.
“When we think about drought in the Eastern Mediterranean, we rarely think about the Indian Ocean,” said Dr. Sigalit Berkovic. “Yet our research shows that what happens thousands of kilometers away can reshape the atmospheric circulation that determines whether our region experiences weeks without rain. This highlights just how interconnected Earth’s climate system really is.”
“Weather in the Mediterranean is not controlled only by local conditions,” said Dr. Assaf Hochman. “Our results show that changes in the tropical Indian Ocean can trigger atmospheric processes that ultimately shape winter rainfall in the Levant. Understanding these long-distance climate connections gives us valuable insight into predicting weather extremes months in advance.”
The findings arrive as international attention focuses on the possibility of an unusually strong El Niño event. While El Niño originates in the Pacific Ocean, the new research highlights that tropical climate variability extends far beyond the Pacific itself. The Indian Ocean also plays a critical role in shaping weather patterns across distant regions through atmospheric “teleconnections”—planet-scale links that transmit the effects of ocean temperature changes across continents.
Rather than focusing on El Niño alone, the study emphasizes that multiple tropical oceans contribute to seasonal climate variability and that incorporating Indian Ocean conditions into forecasting systems could improve predictions of drought risk and other weather extremes in the Eastern Mediterranean.
Beyond advancing climate science, the research could help governments, water authorities, and farmers prepare more effectively for prolonged winter dry periods, improving resilience in a region already facing increasing pressure from climate change.
