Length of growing season is modulated by Northern Hemisphere jet stream variability

Title: Length of growing season is modulated by Northern Hemisphere jet stream variability

Authors: Amy R. Hudson, William K. Smith, David J. P. Moore, Valerie Trouet

Journal: International Journal of Climatology

URL: https://doi.org/10.1002/joc.7553

Atmospheric circulations, such as the jet stream, can influence the climate at the land’s surface. However, it is unclear how plants respond to that influence, especially as resources limiting plant growth vary throughout the growing season. Here, we examined the seasonal impacts of jet stream position on the length of the growing season across the Northern Hemisphere. Global satellite products of the growing season derived from greenness measures were paired with Northern Hemisphere jet stream indices which were based on the latitude of maximum westerly wind speed in the tropopause. 

For a third of the Northern Hemisphere landmass, the length of the growing season was modulated by jet stream position in the spring and fall. In spring, a northern jet stream, which typically corresponded to warmer temperatures at the land surface, led to an earlier start of the growing season and a longer growing season, especially in cold systems north of the typical jet stream latitude. Surprisingly, in fall, a northern jet stream led to shorter growing seasons for most systems. These findings suggest that corresponding warming may lower the water available to plants in this season when water is critical for sustained growth. Southern jet stream positions typically corresponded with similar but opposite effects as northern anomalies, with some regional anomalies. Croplands were mixed in their growing season response to the jet stream, reflecting the impact of land-use and management on growing season length.

As we continue to observe the jet stream response to global warming, it is important to consider cascading effects of jet stream variability on the length of the growing season, with big implications for land management and global food security.