Winds, waves and storm surges can inflict severe damage in coastal areas. In order to improve preparedness for such events, a better understanding of storm-induced coastal flooding episodes is necessary. To this end, this paper highlights the use of atmospheric downscaling techniques in order to improve wave and storm surge hindcasts. The downscaling techniques used here are based on existing European Centre for Medium-Range Weather Forecasts reanalyses (ERA-20C, ERA-40 and ERA-Interim). The results show that the 10 km resolution data forcing provided by a down-scaled atmospheric model gives a better wave and surge hind-cast compared to using data directly from the reanalysis. Furthermore, the analysis of the most extreme mid-latitude cyclones indicates that a four-dimensional blending approach improves the whole process, as it assimilates more small-scale processes in the initial conditions. Our approach has been successfully applied to ERA-20C (the 20th century reanalysis).

The present article is the first one of a couple of articles, related to the assessment of the human forecasts (forecast made by weather forecasters). In this article, we have performed an integral assessment of the human-derived extreme temperature forecasts during 2009-2014. It will give us a more general picture of the forecasts, their accuracy over the years of the period in consideration, and their change through the different months of the year. We will show how the accuracy of the forecasts increases in the assessing period, and also how human forecasts underestimate extreme temperatures. The integral assessment gives us a more clear view on the movement of the various errors in time, but it has a significant shortcoming - the spatial distribution of the information is lost. The spatial distribution would give us a valuable feedback, that could be used to correct the forecasts. It will be discussed in the second article, where an assessment by stations will be made.

Information about the hydro-meteorological parameters during the extreme sea storms is of significant importance for the sustainable development in the context of flood risk for the coastal areas. Usually there is a lack of sufficiently long history of instrumental measurements of the extreme winds, waves and storm surges. Simulation of historical storms is an important tool to evaluate the potential coastal hazards. In the absence of measured data hindcasts can satisfy the need for historical data. The wave and storm-surge regional numerical simulations have been carried out for the ten most severe storms over the Bulgarian coast of the Black Sea from the period 1972-2012. The ERA-Interim and ERA-40 reanalysis of wind at 10 m and mean sea level pressure have been downscaled with a high resolution atmospheric model ALADIN to the horizontal and time scales suitable for precise evaluation of hydro-meteorological parameters during the storms. The downscaled fields of wind and sea level pressure have been used as input for the wave and storm surge models.

code: AO6 Hindcast of extreme hydro-meteorological events along the Bulgarian Black Sea coast Anna Kortcheva, Vasko Galabov, Marieta Dimitrova, Andrey Bogatchev National Institute of Meteorology and Hydrology, Sofia, Bulgaria Corresponding author details: National Institute of Meteorology and Hydrology (NIMH), 66 Tzarigradsko shosse blvd, 1784 Sofia, Bulgaria; e-mail: Anna.Kortcheva@meteo.bg Keywords : Storms, coastal hazards, downscaling, numerical modelling, Earth Observations, Black Sea INTRODUCTION High waves and storm surge are linked to severe storms and represent major hazards for the coastlines. Knowledge of the extreme hydrometeorological parametrs during the storms is of significant importance for the sustainable development of a coastal zone. It is rare that there exists a sufficiently long term history of accurate measurements of extreme storm generated winds, waves and storm surges. Simulation of historical storm situations is a key tool in examining potential coastal hazards. Hindcasting is the application of the numerical model to estimate waves and storm surges conditions that occurred in the past. In the absence of measured data covering the whole Bulgarian coastline in old periods, storm surges and waves hindcasts can satisfy the need for historical data

The EC FP6 project CECILIA (http://www.cecilia-eu.org) aims at climate change impacts and vulnerability assessment in targeted areas of Central and Eastern Europe. Emphasis is given to regional climate change modeling at resolution of 10 km. The respective weather patterns influence local air quality. For its assessment EPA Models-3 (MM5, CMAQ, SMOKE) is used. The meteorological input is produced by the climatic version of ALADIN weather forecast system. TNO emission inventory for 2000 is exploited. The boundary conditions are extracted from 50-km runs over Europe made in Aristotle University of Thessaloniki, Greece. Calculations for the period 1991–2000 are performed, results presented.

The presented work is aiming at climate change impacts and vulnerability assessment in Bulgaria Climate change may affect exposures to air pollutants by affecting weather and thereby local and regional pollution concentrations Local weather patterns influence atmospheric chemical reactions and can also affect atmospheric transport and deposition processes. US EPA Models-3 System for a region with resolution of 10 km covering Bulgaria is exploited here The meteorological background is produced by the climatic version of ALADIN weather forecast system TNO emission inventory for 2000 is used The chemical boundary conditions are extracted from 50-km resolution runs over Europe made in Aristotle University of Thessaloniki, Greece Calculations for the period 1991-2000 are performed, results presented in a study For year 2000, some scenarios are run, results compared with measured data.

Intensive long-term meteorological modeling took place over an area covering Bulgaria with resolution of 10 km. The climatic version of the operational weather forecast model ALADIN was applied for simulating 3 time slices: 1960-2000, 2020-2050 and 2070-2100, following the IPCC scenario A1B. The differences of climatic fields for the 3 periods are presented and interpreted. The created met-data base is used to estimate the impact of climate changes on air quality, as well. A respective modeling System was created on the base of US EPA Models-3 tool (MM5, CMAQ and SMOKE). Calculations for the last 10 years of each time slice are performed. Grid technology in the frame of SEE-GRID-SCI project is used to perform this enormous volume of calculations as an application abbreviated to CCIAQ (Climate Change Impact on Air Quality). The results are presented and interpreted in the study

The presented work is aiming at climate change impacts and vulnerability assessment in Bulgaria. Climate change may affect exposures to air pollutants by affecting weather and thereby local and regional pollution concentrations, by affecting anthropogenic emissions (emission scenarios), by affecting natural sources of air pollutant emissions (biogenic VOCs) and by affecting many other processes. Local weather patterns (namely temperature, precipitation, clouds, atmospheric water vapor, wind speed, and wind direction) influence atmospheric chemical reactions; they can also affect atmospheric transport and deposition processes as well as the rate of pollutant export. US EPA Models-3 System (MM5, CMAQ and partly SMOKE) for a region with resolution of 10 km covering Bulgaria is exploited, here. The meteorological input is produced by the climatic version of ALADIN weather forecast system and TNO emission inventory for 2000 is used. The chemical boundary conditions are extracted from results of 50-km runs over Europe made in Aristotle University of Thessaloniki, Greece. Calculations for the period 1990-2000 are performed, results presented in the study. For year 2000, some scenarios are run, results compared with measuring data.