The recent warm and sunny weather has significantly impacted sea surface temperatures along the Estonian coast, leading to the development of marine heatwaves in the Baltic Sea. Satellite images reveal that a substantial portion of the Baltic Sea is currently experiencing these unusual temperature increases. In the coming days, air temperatures are expected to rise to 31 degrees Celsius, with summery weather predicted to last until the first week of June.
Rivo Uiboupin, an associate professor at Tallinn University of Technology specializing in remote sensing methods for investigating sea surface temperature, explained that marine heatwaves are rare and extreme conditions where water temperatures are significantly higher than the long-term average for at least five days. "Most people think of heatwaves in the summer. However, a heatwave can also occur in the spring or even in the winter when the water temperature is significantly higher than the long-term average for that time of year," he said.
He noted that the current marine heatwave, while surprising, aligns with the data from measuring stations in Sõrve, which show sea temperatures at 16 degrees Celsius—remarkably high for May. The heatwave has affected the main Estonian islands and extended to Sweden and further south, covering about 100,000 square kilometers, roughly a quarter of the Baltic Sea area. In some areas, such as the west coast of Saaremaa, sea temperatures have been up to five degrees warmer than normal, exceeding 16 degrees.
Professor Uiboupin mentioned that the Baltic Sea typically experiences three to four marine heatwaves annually, each lasting 15 to 20 days. The current weather forecast suggests that the marine heatwave will continue due to the ongoing warm weather. However, stronger northeasterly and easterly winds offshore could slow its further development by bringing colder water from deeper layers to the surface along the Estonian coast.
The frequency, duration, and magnitude of marine heatwaves in the Baltic Sea have increased in recent decades. To better understand their potential impact on the marine ecosystem and the blue economy, scientists at Tallinn University of Technology (TalTech) have developed a climate service to monitor sea surface temperature and marine heatwaves. This system uses an autonomous data processing model to calculate sea surface temperatures from satellite images and compare them with long-term averages to identify the most affected areas.
This week saw the highest sea temperatures in 30 years, but the marine heatwave that began on May 12 is now subsiding. According to Uiboupin, the marine heatwave is receding, though temperatures on land are expected to reach up to 31 degrees in the coming days. "It's not very usual for the end of May to be close to or even over 30 degrees, as expected in the coming days, but it's not unusual either," said forecaster Helve Meitern.
The warm summery weather is anticipated to last until June 6 or 7. The heat will likely make the sea swimmable in shallower bays by next weekend, with water temperatures expected to reach the 20s. In the meantime, the capital will experience slightly cooler conditions.
More: https://news.err.ee/1609352178/marine-heatwaves-develop-along-estonian-coast
