Frequent heat waves have been recorded in the European continent and Northeast Asia lately and researchers in a new study have uncovered the reason behind this phenomenon. According to the study, deep snow cover in the Arctic region is an intensifier of heatwaves.
"Internal atmosphere-land interactions in Eurasia are believed to be an important factor in triggering abnormal summer temperatures. However, the exact reasons for such interactions causing heatwaves remain largely unclear," said Associate Professor Tomonori Sato of the research team.
Researchers, in the study published in the journal Scientific Reports, examined a large dataset derived from the "database for Policy Decision making for Future climate change".
It comprised data spanning over a 60-year period (from 1951 to 2010) which incorporated observed sea surface temperature, sea ice, and natural and anthropogenic forcing.
Researchers analyzed 6,000 patterns in the spatial distribution of summer temperatures in Eurasia and succeeded in dividing past summer temperature variations into two groups--one attributable to global warming and the other attributable to natural changes.
The former exhibited the rising temperatures in Eurasia since around 1990, while the latter showed the spatial distribution of low and high temperatures that correspond to the meandering of the westerlies.
The distribution shows a wave train-like structure - which demonstrates that when some regions experienced abnormally high temperatures, the surrounding areas were hit by abnormally low temperatures.
The researchers then discovered that when Western Russia had a deeper-than-usual snow cover in late winter and spring, the wave train-like distribution of temperatures appeared.
When deeper snow accumulation occurs, more moisture retains in the soil after snowmelt. The soil moisture then prevents the summer temperature from rising, which is a likely cause for making the westerlies meander, thus causing the surrounding regions to experience high temperatures.