Numerical simulations of sea and land breezes at high latitudes

Abstract

Few investigations of sea/land breezes (SB/LB) at high latitudes have been reported in themeteorological literature. However, internal reports at some Norwegian institutions, summarisedrecently by Grønaås and Sandvik, show that SB/LBs, in combination with terrain-drivencirculations, are frequent along the coast of Norway and Spitsbergen. In this paper, numericalsimulations of SB/LBs for latitudes between 50° and 80° N have been made for spring andsummer with a mesoscale non-hydrostatic model in order to study the characteristics of highlatitude SB/LBs. The results show that in spring, the latitudinal variation of the extent andstrength of the SB is large, and no SB seems to develop north of 70°N. The LB is active at alllatitudes and increases in strength and duration with increasing latitudes. In summer it is foundthat the character of the SB changes from a classical SB at 50°N to a monsoon kind of a SBat the highest latitudes with small diurnal variations. The northward decrease in the extent andstrength of the SB is small. The results are found to be in accord with observations. The highlatitude SB in summer is further studied by simulations on a circular island at 78°N. A relativelystrong SB develops which persists during the night with a stronger circulation the next day. Inthis way, what we have called a monsoon low SB establishes over the island. The influence ofan snow/ice cover and mountains has been investigated. It is indicated from both simulationsand observations that monsoon lows might be present at peninsulas and islands at latitudesdown to at least 60°N.