Warmer Arctic Ocean leads to more snowfall further south, new model shows

Warmer Arctic Ocean leads to more snowfall further south, new model shows

An increasingly warm, ice-free Arctic Ocean has, in recent decades, led to more humidity in higher latitudes. This moisture is carried south by cyclonic weather systems where it precipitates as snow, influencing the global hydrological cycle and many Earth systems that depend on it (Illustration: Tomonori Sato). 1 credit

New model explains that water evaporating from the Arctic Ocean due to global warming is transported south and may lead to increased snowfall in northern Eurasia in late fall and at the beginning of winter. This information will allow for more accurate predictions of severe weather events.

Rising air temperatures due to global warming are melting glaciers and the polar ice caps. Seemingly paradoxically, snow cover in parts 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 where exactly moisture comes from, how it is produced and how it is transported south is relevant to better predict extreme weather and climate change.

Tomonori Sato, an environmental scientist at Hokkaido University, and his team have developed a new model of tagged moisture transport that relies on “the 55-year-old Japanese reanalysis dataset”, a careful reanalysis of historical global weather data over the past 55 years. The group used this material to keep their model calibrated over much longer distances than previously 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”. It is a computer modeling technique that tracks where hypothetical chunks of atmospheric moisture form, how they move, and where they precipitate due to local weather conditions. But computer models become increasingly inaccurate as distance from the ocean increases. In particular, this makes quantitative predictions difficult. Thus, these methods were unable to satisfactorily explain snowfall in northern Eurasia.

The results of the study, published in the journal npj Climate and atmospheric sciences show that water evaporation 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 Western Siberia, as well as in the Chukchi and East Siberian Seas north of East Siberia between October and December. At this time of year, the Arctic Ocean is still warm and the area not covered by ice is still significant.

Importantly, this development coincides with the area of ​​greatest sea ice retreat during the study period. In addition, the quantitative model shows that evaporation and snowfall are particularly strong during certain weather events such as cyclone systems absorbing unusually large amounts of moisture and carrying it south in Siberia, thus also highlighting evidence of detailed and specific mechanistic information on the meteorological dynamics of the Region.

With the Arctic Ocean being twice as sensitive to rapid warming as the global average, evaporation and subsequent changes in the hydrological cycle in northern Eurasia will become even more pronounced in coming years.

The researchers say that since snowfall often delays the down-stream effects of the freak weather events that cause it, “knowledge of the precursor signal stored as a snow cover anomaly should help improve seasonal forecasts of snow cover conditions.” abnormal weather conditions, for example, the potential for heat waves”. that increase the risk of fire in boreal forests.

This study therefore provides a key element for understanding the mechanism of this weather system as well as others that are influenced by it, and thus better predict serious events that could harm people and infrastructure.

More information:
Tomonori Sato et al, Enhanced arctic moisture transport to Siberia in autumn revealed by a marked moisture transport model experiment, npj Climate and atmospheric sciences (2022). DOI: 10.1038/s41612-022-00310-1

Provided by Hokkaido University

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

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