Prof. Dr. T. Weidinger (Uni Budapest): Measurement and modeling of energy budget components and trace gases fluxes between atmosphere and different types of ecosystems of Hungary

Abstract:

After a presentation of the brief history and the present status of micrometeorological research activities in Hungary our field measurement programs, instrumentation and flux calculation methodology are presented. The research group consists of people from the Hungarian Meteorological Service and different universities, who work in close international cooperation. Field experiments using the gradient and the profile methods have been started 17 years ago. First, the daily and annual variations of deposition velocities and fluxes of ozone, nitrogen oxides and sulfur dioxide were investigated above grassland and spruce forest. Based on this measured data set an ozone deposition model for Hungary was also developed and tested. Measurement and modeling of deposition processes of nitrogen compounds, first of all that of ammonia were investigated in Hortobágy puszta in the frame of the EU4-GRAMINAE program (1999-2002). Ammonia bi-directional flux shows net deposition in annual time scale. Net emission of ammonia was detected daytime, during the vegetation period when the stomata are open. Measurements and model calculations suggest, ammonia is emitted mostly through stomata since the soil emission is limited below the soil pH 8, where all of ammonia exists in the form of ammonium ion. The effect of high nitrogen load (application of mineral fertilizer) was also investigated. High ammonia emission was detected daytime for few weeks of application of fertilizer. Continuous energy, water, carbon and nitrogen budget measurements have been carried out in the frame of the EU5 GREENGRASS and EU6 NitroEurope projects in the central part of the country (Bugac puszta) above a semi-natural grassland, since 2002. One of the main aim of these investigations was to reduce the large uncertainties in CO2, N2O and CH4-fluxes within the atmosphere and grassland under different climate conditions. Meteorological data were collected on the basis of 30 minute average. The eddy- covariance system used for calculation of momentum, CO2, sensible and latent heat fluxes consisted of a sonic anemometer and a Li-Cor 7500 open path CO2/H2O infrared gas analyzer. Nitrous oxide and methane emissions are also measured using static soil chambers. Profile measurements of ozone and nitrogen oxides (NO, NOx) and dynamic chamber measurements for nitric oxide have been started in 2006. Nitric oxide and nitrous oxide soil emissions amount approximately 10% of the total (wet and dry) deposition of nitrogen compounds. In the last part of the presentation the development of a new Hungarian reference climate network is illustrated, to detect the possible effects of future climate change, consists of both regular standard measurement program for climate stations and soil, radiation as well as energy budget measurements.

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