A warmer Arctic Ocean leads to more snowfall further south, according to the new model

An increasingly warmer, ice-free Arctic Ocean has led to higher humidity at higher latitudes in recent decades. This moisture is carried south by cyclonic weather systems where it falls as snow, affecting the global hydrological cycle and many Earth systems that depend on it (Illustration: Tomonori Sato). Credit: Tomonori Sato

A new model explains that water evaporating from the Arctic Ocean due to global warming is carried south and can lead to increased snowfall in northern Eurasia in late autumn and early winter. This information will enable more accurate predictions of severe weather events.

The increase in air temperature due to global warming melts glaciers and ice caps. Seemingly paradoxically, snow cover in some areas of northern Eurasia has increased in recent decades. However, snow is a form of water; global warming increases the amount of moisture in the atmosphere, and therefore the amount and likelihood of rain and snow. Understanding exactly where moisture comes from, how it’s produced and how it’s transported south is important for better predicting extreme weather conditions and climate change.

Hokkaido University environmental scientist Tomonori Sato and his team have developed a new tagged moisture transport model that is based on the “55-year Japanese reanalysis data set,” an accurate reanalysis of historical meteorological data world over the past 55 years. The team used this material to keep their model calibrated over much longer distances than hitherto possible and were thus able to shed light on the mechanism of moisture transport particularly over the vast landmasses of Siberia.

A standard technique for analyzing moisture transport is the “labeled moisture transport model”. This is a computer modeling technique that tracks where hypothetical blocks of atmospheric moisture form, how they are moved, and where they precipitate due to local weather conditions. But computer models become increasingly inaccurate the further they get from the ocean. In particular, this makes quantitative forecasting difficult. Thus, these methods have not been able to satisfactorily explain snowfall in northern Eurasia.

The results of the study, published in the journal npj Science of climate and atmosphere show that the evaporation of water from the Arctic Ocean has increased over the past four decades and that the greatest changes have occurred in the Barents and Kara seas north of West Siberia, as well as in the Chukchi and East Siberian seas a north of eastern Siberia, between October and December. At this time of year, the Arctic Ocean is still warm and the ice-free area is still large.

Importantly, this development coincides with the area where sea ice retreat was strongest over the time period of the study. Furthermore, the quantitative model shows that evaporation and snowfall are particularly strong during certain weather events such as cyclonic systems that absorb unusually large amounts of moisture and carry it south into Siberia, thereby also highlighting detailed and specific mechanistic insights into weather dynamics. of the region.

Since the Arctic Ocean is twice as sensitive to rapid warming as the global average, evaporation and resulting changes to the hydrological cycle over northern Eurasia will become even more pronounced in the years to come.

The researchers say that because snowfall often delays the downstream effects of the abnormal weather events that cause it, ‘knowledge of the stored precursor signal as a snowpack anomaly should help improve seasonal predictions of abnormal weather conditions, for example the potential for heat waves to increase fire risk in boreal forests.”

This study therefore provides a key element to understand the mechanism of this weather system and others that are affected by it, and therefore to make better predictions of severe events that could cause damage to people and infrastructure.

More information:
Tomonori Sato et al, Enhanced Arctic Moisture Transport to Siberia in Autumn Revealed by Tagged Moisture Transport Model Experiment, npj Science of climate and atmosphere (2022). DOI: 10.1038/s41612-022-00310-1

Provided by Hokkaido University

Citation: A warmer Arctic Ocean leads to more snowfall further south, according to new model (2022, Nov. 24) retrieved Nov. 24, 2022, from https://phys.org/news/2022-11-warmer-arctic-ocean- snowfall-south .html

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