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Combined impact of summer heat waves and coastal upwelling in the Baltic Sea

Suursaar Ülo

Oceanologia

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2020

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No. 62 (4PA)

511--524

EN

Under warming climates, heat waves (HWs) have occurred in increasing intensity in Europe. Also, public interest towards HWs has considerably increased over the last decades. The paper discusses the manifestations of the summer 2014 HW and simultaneously occurring coastal upwelling (CU) events in the Gulf of Finland. Caused by an anticyclonic weather pattern and persisting easterly winds, CUs evolved along the southern coast of the Gulf in four episodes from June to August. Based on data from coastal weather stations, 115 days-long measurements with a Recording Doppler Current Profiler (RDCP) oceanographic complex and sea surface temperature (SST) satellite images, the partly opposing impacts of these events are analysed. Occurring on the background of a marine HW (up to 26°C), the CU-forced SST variations reached about 20 degrees. At the 10 m deep RDCP mooring location, a drop from 21.5 to 2.9°C occurred within 60 hours. Salinity varied between 3.6 and 6.2 and an along-shore coastal jet was observed; the statistically preferred westerly current frequently flowed against the wind. Locally, the cooling effect of the CUs occasionally mitigated the overheating effects by the HWs both in the sea and on the marine-land boundary. However, in the elongated channel-like Gulf of Finland, upwelling at one coast is usually paired with downwelling at the opposite coast, and simultaneously or subsequently occurring HWs and CUs effectively contribute to heat transfer from the atmosphere to the water mass. Rising extremes of HWs and rapid variations by CUs may put the ecosystems under increasing stress.

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Diurnal variability of water vapour in the Baltic Sea region according to NCEP-CFSR and BaltAn65+ reanalyses

Jakobsons E., Keernik H., Luhamaa A., Ohvril H.

Oceanologia

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2014

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No. 56 (2)

191--204

EN

Diurnal variations in water vapour in the Baltic Sea region are examined using BaltAn65+ and NCEP-CFSR reanalyses of summer (JJA) data for the period 1979-2005. A systematic difference between precipitable water (PW) diurnal variability above the land and the water is revealed. Above the land, PW diurnal variability has minimal values at 00 and 06 UTC, as in previous studies, whereas above the water, the minima are at 12 and 18 UTC. Diurnal variability in the vertical humidity profile is controlled by turbulent mixing and the diurnal behaviour of sea breezes. The impacts and proportions of diurnal variability of humidity are evaluated at different vertical levels.

3

Formy eoliczne w utworach plażowych na przykładzie wybrzeża Bałtyku między Mrzeżynem a Dźwirzynem

Kurowski L.

Przegląd Geologiczny

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2000

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Vol. 48, nr 10

917-923

PL

Wpływ czynnika eolicznego na modelowanie utworów klastycznych w środowisku plażowym jest znaczący, uzależniony głównie od jego siły, kierunku i czasu działania. Prędkość wiatrów, w czasie prowadzenia obserwacji, przy mocniejszych podmuchach dochodziła do 4" w skali Beauforta (5,3-7,4 m/s), a efektem ich działalności było powstanie wielu niewielkich, najczęściej nietrwałych form, których genezę można łączyć z akumulacyjną, bądź erozyjną (deflacja, korazja) działalnością wiatru. Najbardziej pospolitymi formami akumulacji piasku są różnego typu riplemarki eoliczne oraz zaspy piaszczyste. Genezę erozyjno-akumulacyjną przypisuje się śladom owiewania. Natomiast strukturami erozyjnymi są poziomy bruku deflacyjnego, nisze korazyjne w dużych klastach torfowych, a także formy nazwane w tej pracy "grzybkami piaszczystymi" i "rysunkami traw na piasku". Opisane formy, bez względu na to czy rozpoznamy je w osadach kopalnych, czy obserwujemy współcześnie, ze względu na swoje charakterystyczne cechy morfologiczne, strukturalne i teksturalne mogą być bardzo dobrymi wskaźnikami reżimu wiatrowego w badanym środowisku.

EN

The influence of an eolian factor on the modelling of clastic sediments in a beach environment is considerable and is determined mainly by its strength, direction and duration. The wind strength at the time of observations was reaching, at stronger gusts, 4 in the Beaufort wind scale (5.3-7.4 m/s) and, as a result of its work, numerous small - scale, usually undur able forms were created. Their origin may be explained in terms of accumulative or erosive (deflation, corrosion) wind action. The most typical forms of sand accumulation were eolian ripples of various types and sand - drifts. Erosional structures were represented by deflation pavement horizons, corrosion cavities in big peat clasts and by forms that were here referred to as "sand mushrooms" and "grass traces on sand". In the author s opinion wind - related crescent marks are oj'mixed erosional and accumulation origin. Describedforms, no matter if recognised in the stratigraphic record or as they occur at the present day, may be employed as used wind regime indicators in the analysed environment due to their characteristic morphological, textural and structural features.