ON THE PROBLEM OF ESTIMATION OF THE CRITICAL POLLUTION CHARACTERISTICS FROM LOW AND HIGH SOURCES IN PBL

It is suggested an approach for complex estimation of dynamical and pollutant characteristics around sources in planetary boundary layer (PBL). The cases of pollution are systematically classified in groups and it is separately analyzed the conditions causing maximal / critical pollution

Graupel mixing ratio forecast from a cloud resolving numerical weather prediction model as a tool for lightning activity prediction

Graupel mixing ratio over Bulgaria for the warm half year of 2021 based on the AROME-BG numerical weather prediction (NWP) model, is evaluated and connected lightning data detected by the ATDnet lightning location network. Lightning data and forecasted graupel mixing ratios were considered on resolutions of 5×5 km and 10×10 km with flash rate for one and three hours, as well on a daily base using upscaling neighborhood method. Two daily model runs are considered – at 06 and 18 UTC. Commonly used skillscores in meteorological forecasts are used as evaluation metrics – probability of detection (POD), false alarm rate (F), proportion correct index (PC), and frequency bias index (FBI). Lightning probability forecast (based on graupel mixing ratio) is evaluated at diurnal, monthly, and spatial bases. Results show that graupel mixing ratio taken from the cloud resolving NWP model AROME-BG could be used as a tool to forecast lightning probability with a relatively high performance. Decreases of forecast spatial resolution and time frequency lead to improvement of forecast probability of detection (POD) and frequency bias index (FBI) and to a slight deterioration of its false alarm rate (F) and its percent correct (PC), and the impact of forecast time frequency is more pronounced

14 th Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes -2-6

Abstract: The basic characteristics in several types stable/neutral PBL turbulent regimes are determined on the basis of applied oriented complex method. The significant influence of free-flow stability effects is demonstrated. In particular the results can be used for parameterization of dynamic and diffusion processes in PBL under such conditions