Quantifying the impact of basin dynamics on the regional sea level rise in the Black Sea

Abstract

Abstract. Satellite altimetry measurements show that the magnitude of the Black Sea sea level trends is spatially uneven. While the basin-mean sea level rise from 1993 to 2014 was about 3.15 mm yr −1 , the local rates of sea level rise varied from 1.5-2.5 mm yr −1 in the central part to 3.5-3.8 mm yr −1 at the basin periphery and over the northwestern shelf and to 5 mm yr −1 in the southeastern part of the sea. We show that the observed spatial differences in the dynamic sea level (anomaly relative to the basin-mean) are caused by changes in the large-and mesoscale dynamics of the Black Sea. First, a long-term intensification of the cyclonic wind curl over the Black Sea, observed in 1993-2014, strengthened divergence in the center of the basin and led to the rise of the sea level in coastal and shelf areas and a lowering in the basin's interior. Second, an extension of the Batumi anticyclone to the west resulted in ∼ 1.2 mm yr −1 higher rates of sea level rise in the southeastern part of the sea. Further, we demonstrate that the large-scale dynamic sea level variability in the Black Sea can be successfully reconstructed using the wind curl obtained from an atmospheric reanalysis. This allows for the correction of historical tide gauge records for dynamic effects in order to derive more accurate estimates of the basin-mean sea level change in the past, prior to the satellite altimetry era.

Study of the Process of the Black Sea Upper Layer Mixing in the Zone of the Rim Current Activity in Winter Based on the Drifters Data

“…The obtained results can characterize the mixing processes for the entire sea, since in January -March a single cyclonic circulation of water masses is observed [5]. This cyclonic circulation of the upper layer is determined by the surface wind stress curl, the main contribution to which is made by monsoon and orographic effects [16][17][18].…”

“…In the Rim Current northern branch, where the seasonal thermocline upper boundary was located at about 40 m depth, the variation of thermocline and CIL location depths significantly depended on the fluctuations of the surface current. The comparison of average velocity values for December [16][17][18][19][20][21][22][23][24][25][26][27][28]2012 showed that the surface current velocity (V = 0.26 m·s -1 ) was about two times higher than the geostrophic one (V g = 0.14 m·s -1 ). Apparently, this can explain an insignificant correlation of geostrophic velocity with the depth of the seasonal thermocline upper boundary.…”

Study of the Process of the Black Sea Upper Layer Mixing in the Zone of the Rim Current Activity in Winter Based on the Drifters Data

“…Полученные результаты могут характеризовать процессы перемешивания для всего моря, поскольку в январемарте наблюдается единое циклоническое вращение водных масс [5]. Эта циклоническая циркуляция верхнего слоя определяется завихренностью касательного напряжения трения приземного ветра, основной вклад в которую дают муссонный и орографический эффекты [16][17][18]. Вообще преобладающее в северной части моря в течение года направление ветра (северное и северо-восточное) формирует циклоническую циркуляцию вод [9], а межгодовая и синоптическая изменчивость циркуляции атмосферы в регионе Черного моря регулирует повторяемость и силу ветра различных румбов в его западной части [2,9].…”

Recent Sea Level Changes in the Black Sea From Satellite Gravity and Altimeter Mesurements

“…According to Avsar et al (2015), the rate of rise was 3.2 mm/year with analysis of altimetry data between January 1993 and December 2014. Changes in the budget of water (water balance) are considering as the main reason for the basin-averaged sea level changes in the Black Sea (Ginzburg et al, 2013;Kubryakov et al, 2017;Stanev et al, 2000;Volkov and Landerer, 2015;Yildiz et al, 2011). For example, Ginzburg et al (2013) concluded that the sea level change in 1993-2002 was well correlated with variability of the Danube discharge.…”