摘要：Thirty-five surveys were conducted across the Gulf of Finland from 2006 to 2013 to studythe characteristics and variability of the two pycnoclines in this stratified estuary. Easterlywinds caused a shallower position of the upper pycnocline near the southern coast and thedeeper pycnocline along the northern coast. Westerly winds had an opposite effect. Surfacingof the upper pycnocline (upwelling) was observed several times while the upper mixedlayer was deeper than 40 m in the case of downwelling. The deeper pycnocline weakenedand deepened significantly during the southwesterly wind bursts while it was observed atshallower depths than 50 m several times during the periods of easterly winds. The upperpycnocline was on average 3 m shallower near the southern coast while the deeper pycnoclinewas leveled. The inclination of the upper pycnocline corresponding to the averagelocal wind forcing agrees well with the general cyclonic circulation of the upper layerin the Gulf of Finland and the water exchange estimates between the gulf and the BalticProper. An average seasonal inclination of the pycnoclines showed high inter-annual variabilitydepending on the prevailing wind forcing. Easterly winds caused stronger verticalstratification and horizontal gradients across the gulf while in the case of westerly winds,horizontal and vertical gradients were weaker.
