Anti-heat island circulations and low-level jets on a sea gulf

作者：Savijarvi H I^*

来源：Tellus - Series A: Dynamic Meteorology and Oceanography , 2011, 63(5): 1007-1013.

DOI：10.1111/j.1600-0870.2011.00531.x

A two-dimensional fine-scale atmospheric model was set across an idealized 80-km-wide east-west sea gulf at 60 degrees N ('Gulf of Finland'). During a moderate south-easterly basic flow in overcast early summer conditions, a robust low-level jet (LLJ) is formed, with diverging and relatively strong afternoon surface easterlies blowing along the cool gulf. The LLJ is caused primarily by inertial oscillation in space-time due to the large difference in roughness and stability over the land and the sea, but the surface easterlies are also enhanced by an anti-heat island circulation triggered by the slant basic flow across the cool sea gulf. The dynamics and details of the anti-heat island circulation are discussed. With warmer waters the primary LLJ relaxes and the anti-heat island circulation ceases while the enhanced vertical mixing still maintains strong surface winds over the warm sea, but with reduced cross-isobar angles. Sunny conditions enhance convection over land and may induce sea breezes. These may reinforce the LLJ and the associated surface easterlies over the sea.

• 出版日期2011-10