Seasonal variability of radiation tide in Gulf of Riga

Abstract

Abstract. Diurnal oscillations of water level in Gulf of Riga are considered. It was found that there is distinct daily pattern of diurnal oscillations in certain seasons. The role of sea breeze, gravitational tides and atmospheric pressure gradient are analysed. The interference of the first two effects provide the dominant role in diurnal oscillations. The effect of gravitational tides is described both with sole tidal forcing and also in real case with atmospheric forcing and stratification. The yearly variation of the declination of the Sun and stratification leads to seasonal intensification of gravitational tides in Gulf of Riga. Correlation between gravitational tide of the Sun with its radiation caused wind effects appears to be main driver of oscillations in Gulf of Riga. Daily variation of wind is primary source of S1 tidal component with a water level maximum at 18:00 UTC in Gulf of Riga. Effect of solar radiation influences also K1 and P1 tidal components which are examined, too.

Modeled surface salinity and satellite data as proxy for Secchi depth and watercolor of the Gulf of Riga

“…according EMODNET2020; meteorology -ERA5; initial and boundary conditions from Copernicus Marine environmental monitoring service (CMEMS); river discharge of 15 major rivers and 1 channel draining into the Gulf of Riga derived from E-HYPE product according to empirical calibration of the operational model setup for the Gulf of Riga. Monthly means of the reanalysis are provided[9]. Sea surface layer salinity (0-2m) during 1998-2018 had been used in the study.…”