Search

The Mediterranean, and particularly its Eastern basin, is a crossroad of air masses advected from Europe, Asia and Africa. Anthropogenic emissions from its megacities meet over the Eastern Mediterranean, with natural emissions from the Saharan and Middle East deserts, smoke from frequent forest fires, background marine and pollen particles emitted from ocean and vegetation, respectively. This mixture of natural aerosols and gaseous precursors (Short-Lived Climate Forcers—SLCFs in IPCC has short atmospheric residence times but strongly affects radiation and cloud formation, contributing the largest uncertainty to estimates and interpretations of the changing cloud and precipitation patterns across the basin. The SLCFs' global forcing is comparable in magnitude to that of the long-lived greenhouse gases; however, the local forcing by SLCFs can far exceed those of the long-lived gases, according to the Intergovernmental Panel on Climate Change (IPCC). Monitoring the spatiotemporal distribution of SLCFs using remote sensing techniques is important for understanding their properties along with aging processes and impacts on radiation, clouds, weather and climate. This article reviews the current state of scientific know-how on the properties and trends of SLCFs in the Eastern Mediterranean along with their regional interactions and impacts, depicted by ground- and space-based remote sensing techniques. [ABSTRACT FROM AUTHOR]

The Precision Solar SpectroRadiometer (PSR) is a new spectroradiometer developed at Physikalisch-Meteorologisches Observatorium Davos-World Radiation Center (PMOD-WRC), Davos, measuring Direct Solar Irradiance at the surface, in the 300-1020 nm spectral range at high temporal resolution. The purpose of this work is to investigate the instrument's potential of retrieving Integrated Water Vapor (IWV) using its spectral measurements. Two different approaches were developed in order to retrieve IWV, the first one using single channel/wavelength measurements, following a theoretical water vapor high absorption wavelength, and the second one using direct sun irradiance integrated at a certain spectral region. IWV results have been validated using a 2-year dataset, consisting of an AERONET sun- photometer Cimel CE318, a Global Positioning System (GPS), a Microwave Radiometer Profiler (MWP) and radiosonde retrievals recorded at Meteorological Observatorium Lindenberg, Germany. For the monochromatic approach, better agreement with retrievals from other methods/instruments was achieved using the 946 nm channel, while for the spectral approach using the 934-948 nm window. Compared to other instruments' retrievals, the monochromatic approach leads to mean relative differences up to 3.3 % with the coefficient of determination (R2) being in the region of 0.87-0.95, while for the spectral approach mean relative differences up to 0.7 % were recorded with R2 in the region of 0.96-0.98. Uncertainties related to IWV retrieval methods were investigated and found to be less than 0.28 cm for both methods. Absolute IWV deviations of differences between PSR and other instruments were determined the range of 0.08-0.30 cm and only in extreme cases would reach up to 15 %. [ABSTRACT FROM AUTHOR]