Laura Thölix

SNORTEX (Snow Reflectance Transition Experiment): Remote sensing measurement of the dynamic properties of the boreal snow-forest in support to climate and weather forecast: Report of IOP-2008

Large discrepancies are observed between snow albedo in Numerical Weather Prediction (NWP) models and from satellite observations in the case of high vegetation. Knowledge of the Bidirectional Reflectance Distribution Function (BRDF) of snow-forest system is required to solve the problem. The 3-years SNORTEX (Snow Reflectance Transition Experiment) campaign acquires from 2008 in situ measurements of snow and forest properties in support to the development of modelling tools and to validate coarse resolution satellite products (POLDER, MODIS, MERIS, METOP). The measurement scheme and some first example results are presented from the Intensive Observing Period (IOP) of 2008, which can be decomposed into airborne and ground operations. Multi-temporal BRDF at a metric resolution were acquired from OSIRIS (airPOLDER) onboard a helicopter and from ground with FigiFiGo spectrogoniometer. The same helicopter embarked a pair of UV sensors, pyranometers and a wide-optics camera. Ground component includes exhaustive snow measurements.

The effects of driver data on the performance of the FinROSE chemistry transport model

In this paper we tested the performance of the FinROSE chemistry transport model for three different datasets from the European Centre for Medium-Range Weather Forecasts (ECMWF). Global middle atmospheric simulations from 1990 to 2005 were done using winds and temperatures from the ECMWF re-analysis (ERA) datasets, the ERA-40, the operational and the ERA-Interim. Analysis data was used in all simulations. The performance of the model for each dataset was analysed using the simulated stratospheric age-of-air and the ascent rate in the tropics. The ERA-40 data produced with a three-dimensional variational assimilation system (3D-Var) resulted in a too strong Brewer–Dobson circulation. The operational analysis produced with a four-dimensional variational assimilation system (4D-Var) gave somewhat improved results, and the new 4D-Var ERA-Interim re-analysis resulted in a much more realistic upward transport. Also the modelled ozone showed better agreement with observations when using the new re-analysis data.

UV measurements at Marambio and Ushuaia during 2000–2010

Kaisa Lakkala1,2, Alberto Redondas3, Outi Meinander1, Laura Thölix1, Britta Hamari1, Antonio Fernando Almansa3, Virgilio Carreno3, Guillermo Deferrari4,5, Hector Ochoa6, Germar Bernhard7, Ricardo Sanchez8, and Gerardus de Leeuw1 1Finnish Meteorological Institute, Climate Research, Helsinki, Finland 2Finnish Meteorological Institute, Arctic Research, Sodankylä, Finland 3Izaña Atmospheric Research Center, Agencia Estatal de Meteorología, Tenerife, Spain 4Centro Austral de Investigaciones Cientificas (CADIC/CONICET), Ushuaia, Argentina 5Universidad Nacional de Tierra del Fuefo, Ushuaia, Argentina 6Dirección Nacional del Antártico-Instituto Antártico Argentino, Buenos Aires, Argentina 7Biospherical Instruments, Inc., San Diego, U.S.A 8Servicio Meteorológico Nacional, Argentina Correspondence to: Kaisa Lakkala (kaisa.lakkala@fmi.fi)