Wind-induced sea level fluctuations at Yuzhnyi and Chornomorsk sea ports and evaluation of the possibility of their forecast

Abstract

The sea level of the Black Sea coastal area is subject to non-periodic wind-induced fluctuations. Such fluctuations affect economic activity of the sea ports, enterprises and businesses located within the coastal area while those may be flooded when the sea level rises and, on the contrary, there is a threat of vessels grounding in case of sea level fall. There are several big sea ports which are located at the north-western part of the Black Sea and affected by wind-induced fluctuations. Therefore, the study of these processes and development of methods allowing their forecast are of great practical interest and this fact proves the topicality of the conducted research.

The article's aim is to analyse wind-induced fluctuations within the water area of Yuzhnyi and Chornomorsk sea ports, identify statistical links between such fluctuations and wind characteristics / equations used for calculation of their values. The observations at Chornomorsk (2006-2013) and Yuzhnyi (2000-2011) stations show that within a year there are 1-2 upsurge-downsurge occurrences during an average month, however, the number of those increases up to 3-4 over the autumn-winter period. The average sea level rise at Chornomorsk station is equal to 34 cm, the average sea level fall – 38 cm, maximum values amount to 97 cm and 191 cm, respectively. The average sea level rise at Yuzhnyi station is equal to 30 cm, the average sea level fall – 34 cm, maximum values amount to 91 and 98 cm, respectively. The average duration of wind-induced fluctuations at both stations amount to 34-38 hours. In most cases the sea level rise is observed at Chornomosk station when winds blow from the South and the South-East, at Yuzhnyi station  – when those blow from the South, the South-East and the South-West. The sea level fall is observed at Chornomosk station when winds blow from the North-West and the West, at Yuzhnyi station – when those blow from the North, the North-West and the North-East. Both stations are characterized with effective directions of wind causing occurrence of upsurge-downsurges. Based on the regression analysis equations for calculation of the sea level rise and fall values associated with wind characteristics were defined. The initial value of the sea level and the sum of the wind projections on effective directions for previous 30 hours are used as arguments in the equations. The accuracy of equation-based calculation constitutes 60-90%. The article offers recommendations on the use of equations when forecasting wind-induced fluctuations.