engleski

Interaction of a sea breeze and a moist convection over the northeastern Adriatic coast: an analysis of the sensitivity experiments using the high-resolution mesoscale model

The study investigates the sensitivity of the high-resolution mesoscale atmospheric model in the model reproduction of the combined large-scale wind and thermally induced local wind (i.e. sea breeze) on the moist convection development. The area of the interest is Istria, the largest peninsula in the north-eastern Adriatic. The three chosen cases were simulated by the Weather and Research Forecasting (WRF-ARW) model at three (nested) model domains, where the innermost domain involved 1.5 km horizontal grid spacing. The sensitivity tests were accomplished by modifying: (i) the model setup, (ii) the sea surface temperature (SST) distribution and (iii) the model topography. The first set of the simulations (over the 3 summer 1.5-day periods) were carried out through the modification of the model setup, varying microphysics and the boundary layer parameterizations. The SST distribution has two representations in the model: a weakly time-varying SST field (every 6 h) from the ECMWF skin temperature analysis and a varying SST field provided by hourly geostationary satellite data. The same events were simulated with the modified topography where the mountain heights in Istria were reduced to 30% of the initial height. A comprehensive set of the numerical experiments was statistically analyzed in a several ways: by the standard statistical measures, the image moment analysis approach and the spectral method. The results of the each model setup were compared with available measurements, which were provided by the standard station and radar measurements and each of these approaches showed optimal combination of the model schemes. The SST variations revealed the effect on the boundary layer and on the evolution of the turbulent fluxes, sea breeze cells and cumulonimbus clouds. The modified topography exposed variations in the origin, timing and the amount of the convective activity as well as on the sea breeze evolution and its dimensions.

sea/land breeze; deep convection; spectral method; the image moment analysis; SST; modified topography

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