Determining the Regime Shift of the Baltic Sea Ice Seasons during 1982–2016

Abstract

The distributions of ice season characteristics in the Baltic Sea during 1982-2016 were studied. A shift in the ice season regime was observed in 2006-2007. Ice season characteristics before and after the shift were determined in the northern and southern regions of the Baltic Sea, and the contributions of these areas to the shift regime were evaluated. To study changes in ice conditions, satellite data on the daily ice concentration over the Baltic Sea provided by the Copernicus Marine Environment Monitoring Service were used. The ice cover extent and number of ice days were calculated. The maximal ice extent event of the ice season shifted from the beginning of March to the end of January in 2007. The average ice concentration over the Baltic Sea was 18% and 10% before and after the shift, respectively. On average, 32 and 19 ice days occurred before and after the shift, respectively. The average ice concentration in the northern Baltic was 54% before and 34% after the shift, and the concentration in the southern Baltic was 8% before and 7% after the shift. The determined shift of the ice season characteristics indicated that extensive ice cover does not last long during the after-shift seasons. Sažetak Proučavale su se karakteristike rasporeda ledene sezone na Baltičkome moru od godine 1982. do 2016. Promjena u režimu ledene sezone uočena je 2006. i 2007. godine. Karakteristike ledene sezone prije izmjene i nakon nje određene su u sjevernim i južnim regijama Baltičkoga mora te su evaluirani doprinosi ovih prostora na promjenu režima. Da bismo proučili promjene u uvjetima leda, satelitski podatci o koncentraciji leda nad Batičkim morem, korišteni su podatci koje je priskrbila Copernicus nadzorna služba za pomorski okoliš. Izračunata je debljina sniježnoga pokrivača i broj ledenih dana. Maksimalan razmjer ledenoga događaja, ledene sezone, pomakao se od početka ožujka do kraja siječnja 2007. Prosječna koncentracija nad Baltičkim morem bila je 18 %, a 10 % prije promjene i nakon nje, redoslijedom navođenja. Prosječno 32 i 19 ledenih dana dogodilo se prije promjene i nakon nje prema redoslijedu navođenja. Prosječna koncentracija leda na sjevernome Baltiku bila je 8 % prije, a 7 % nakon promjene, a koncentracija na južnome Baltiku bila je 8 % prije, a 7 % nakon promjene. Određena promjena karakteristika ledene sezone pokazuje da sniježni pokrivač ne traje dugo tijekom sezona nakon promjene. KEY WORDSBaltic Sea climate ice season ice concentration climatic regime regime shift ice days KLJUČNE RIJEČI klima Baltičkoga mora ledena sezona koncentracija leda klimatski režim promjena režima ledeni dani

Effects of sea ice and wind speed on phytoplankton spring bloom in central and southern Baltic Sea

“…When the temperature decreases again, the ice cover expands. The formation and closure of ice-free openings is a common phenomena in the Gulf of Finland [47][48][49].…”

Effects of sea ice and wind speed on Phytoplankton spring bloom in Central and Southern Baltic Sea

“…It also affects underwater light conditions by limiting the amount of light transmitted through the surface and modifying water mixing and nutrient circulation under the ice [11]. 49 The Baltic Sea ice season lasts 5-7 months between November to May. During a mild winter, ice occurs only in the Bothnian Bay and the easternmost Gulf of Finland, but during a cold winter the whole Baltic Sea is covered with ice [12].…”