A. Tsikerdekis

Spatiotemporal variability and contribution of different aerosol types to the aerosol optical depth over the Eastern Mediterranean

This study characterizes the spatiotemporal variability and relative contribution of different types of aerosols to the Aerosol Optical Depth (AOD) over the Eastern Mediterranean as derived from MODIS Terra (3/2000-12/2012) and Aqua (7/2002-12/2012) satellite instruments. For this purpose, a 0.1° × 0.1° gridded MODIS dataset was compiled and validated against sunphotometric observations from the AErosol RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium sized cities, industrial zones, and power plant complexes, seasonal variabilities, and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is ~ 0.22 ± 0.19 with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic aerosols, transport of pollution and smoke from biomass burning in Central and Eastern Europe, and transport of dust from the Sahara Desert and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-aerosol-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different aerosol types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine mode natural aerosols over land and anthropogenic, dust and marine aerosols over the sea is examined. The relative contribution of the different aerosol types to the total AOD550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic aerosols, dust and fine mode natural aerosols account for ~ 51 %, ~ 34 % and ~ 15 % of the total AOD550 over land, while, anthropogenic aerosols, dust and marine aerosols account ~ 40 %, ~ 34 % and ~ 26 % of the total AOD550 over the sea, based on MODIS Terra and Aqua observations.

Climate change but not unemployment explains the changing suicidality in Thessaloniki Greece (2000-2012).

INTRODUCTION Recently there was a debate concerning the etiology behind attempts and completed suicides. The aim of the current study was to search for possible correlations between the rates of attempted and completed suicide and climate variables and regional unemployment per year in the county of Thessaloniki, Macedonia, northern Greece, for the years 2000-12. MATERIAL AND METHODS The regional rates of suicide and attempted suicide as well as regional unemployment were available from previous publications of the authors. The climate variables were calculated from the daily E-OBS gridded dataset which is based on observational data RESULTS Only the male suicide rates correlate significantly with high mean annual temperature but not with unemployment. The multiple linear regression analysis results suggest that temperature is the only variable that determines male suicides and explains 51% of their variance. Unemployment fails to contribute significantly to the model. There seems to be a seasonal distribution for attempts with mean rates being higher for the period from May to October and the rates clearly correlate with temperature. The highest mean rates were observed during May and August and the lowest during December and February. Multiple linear regression analysis suggests that temperature also determines the female attempts rate although the explained variable is significant but very low (3-5%) CONCLUSION Climate variables and specifically high temperature correlate both with suicide and attempted suicide rates but with a different way between males and females. The climate effect was stronger than the effect of unemployment.

A 3-D Evaluation of the MACC Reanalysis Dust Product Over Europe Using CALIOP/CALIPSO Satellite Observations

This work focuses on the evaluation of the MACC (Monitoring atmospheric composition and climate) reanalysis dust product over Europe. Europe receives significant amounts of dust on an annual basis primarily from the large neighboring area sources (Sahara Desert, Arabian Peninsula) and from smaller local sources. Dust affects a number of processes in the atmosphere modulating weather and climate and exerts an impact on human health and the economy. Hence, the ability of simulating adequately the amount of dust and its optical properties is essential. For the evaluation of the MACC reanalysis, pure dust satellite-based retrievals from CALIOP/CALIPSO are utilized for the period 2007–2012. Specifically, the CALIOP/CALIPSO data used here come from an optimized retrieval scheme that was originally developed within the framework of the LIVAS (Lidar Climatology of Vertical Aerosol Structure for Space-Based LIDAR Simulation Studies) project. The natural aerosol extinction coefficients from MACC and the dust optical depth patterns at 550 nm are validated against dust extinction coefficients and dust optical depth patterns at 532 nm from CALIOP/CALIPSO. Our results highlight the important role that space-based lidars may play in the improvement of the MACC aerosol product.

Evaluation of Regional Climate Model Surface Solar Radiation Patterns Over Europe Using Satellite-Based Observations and Radiative Transfer Calculations

The ability of RegCM4 regional climate model to simulate surface solar radiation (SSR) patterns over Europe is assessed through an evaluation of a decadal simulation against satellite-based observations from the Satellite Application Facility on Climate Monitoring (CM SAF). The model simulates adequately the SSR patterns over the region slightly overestimating SSR (bias of ~+2.5 % for the period 2000–2009). Cloud macrophysical and microphysical properties from RegCM4 such as cloud fractional cover (CFC), cloud optical thickness (COT) and cloud effective radius (Re) are evaluated against data from CM SAF. The same is done for aerosol optical properties such as aerosol optical depth (AOD), asymmetry factor (ASY), and single scattering albedo (SSA) using data from the MACv1 aerosol climatology, and other parameters, such as surface broadband albedo (ALB) using data from the CERES satellite sensors, and water vapor amount (WV) using data from the ERA-Interim reanalysis. The good agreement between RegCM4 and satellite-based SSR observations is a result of counterbalancing effects of these parameters. The contribution of each parameter to the RegCM4-CM SAF SSR deviations is estimated with the combined use of the aforementioned data and a radiative transfer model (SBDART). CFC, COT and AOD are the major determinants of these deviations.

An Assessment of Near Surface Ozone Over Europe from the Global CAMS Interim Reanalysis

ECMWF-Copernicus Atmospheric Monitoring Service (CAMS) interim reanalysis (CAMSiRA) provides global atmospheric composition fields at a horizontal resolution of ~80 km and 60 hybrid sigma-pressure levels from the surface up to 0.1 hPa which can be further used to serve as boundary conditions for regional air quality models over Europe and world-wide. Here we present an evaluation of near surface ozone reanalysis for the period 2003–2013 based on measurements at rural locations from the European Monitoring and Evaluation Program (EMEP) and the European Air Quality Database (AirBase). The CAMS interim reanalysis is also compared to a control run in order to assess the impact of assimilation on near surface ozone. The evaluation results are discussed in terms of the physical processes (transport and deposition) and the chemical processes (photochemical production and destruction) that control near surface ozone variability.