loading page

Orbital Forcing Strongly Influences the Poleward Shift of the Spring Himalayan Jet During the Past Millennium
  • Uday Kunwar Thapa,
  • Samantha Stevenson,
  • Madhavan Midhun
Uday Kunwar Thapa
University of California Santa Barbara

Corresponding Author:[email protected]

Author Profile
Samantha Stevenson
University of California, Santa Barbara
Author Profile
Madhavan Midhun
Cochin University of Science and Technology
Author Profile


The latitudinal position of the subtropical jet over the Himalayas (Himalayan jet latitude or HJL) controls the region’s climate during winter and spring by guiding moisture-delivering storms. Here we use the Community Earth System Model-Last Millennium Ensemble to diagnose forced trends in HJL during the past millennium. During 850-1849, there is a weak equatorward trend in winter HJL. In contrast, the spring HJL has a relatively larger poleward trend, and increases in both variance and frequency of poleward/equatorward excursions. We demonstrate changes in orbital precession reduced the thermal gradient between tropical and subtropical Asia, shifting the spring HJL poleward. During 1850-2005, the spring HJL exhibits no trend due to compensating influences from orbital and anthropogenic greenhouse gas forcings. These findings suggest it is essential climate models properly simulate the effects of and potential interactions between orbital forcing and anthropogenic factors to accurately project Himalayan jet variability and associated storm tracks.
16 Feb 2022Published in Geophysical Research Letters volume 49 issue 3. 10.1029/2021GL095955