1.1 Climate and extreme events, possible scenarios

Leading researcher: Sándor Szalai (HMS, Budapest)
Collaborators: Borbála Gálos (predoc, UWH, Faculty of Forestry, Institute for Environmantal and Earth Sceinces), Ilona Krüzselyi (PhD student, UWH, Faculty of Forestry, Institute for Environmantal and Earth Sceinces)

Results: Probability and severity of summer droughts in Hungary has been analysed using the regional climate model REMO. Dry events have been defined according to the temperature- and precipitation anomalies from the climate period 1961-90. For the period 1961-2000 the model results have been validated with observed data. For the periods 2001- 2050 and 2051 – 2100 the climatic trends have been analysed using three IPCC scenario simulations (B1, A1B, A2). The results show that the probability of dry events will be higher in the second half of the 21st century (Figure 1). In scenarios A1B and A2 every second year a summer drought may happen, the number of consecutive dry periods may increase. For 2051-2100 the severity of dry events may increase significantly in all scenarios compared to the reference period (1951-2000). From the analysed scenarios, B1 has the lowest future greenhouse gas emission rates, so that also the smallest changes are projected for the second half of the 21st century.

1.2. Interrelationship vegetation – climate

Leading researcher: Dr. Péter Vig
Collaborators: Áron Drüszler, Attila Eredics

To become acquainted with the reactions of the stands given to the change of the climatic conditions in the first phase we uncovered the components and correlations of the energy balance of a chosen stand. For this purpose, we utilized the measuring results of the test station functioning since 1996 in the compartment Sopron 171G; the instruments were modernized in 2006.
The exposition of the change of the meteorological parameters in space and time is based on the following draft:
1. Radiation budget (Áron Drüszler)
1.1. With the assistance of radiation-measuring sensors placed in 30 m height the daily and seasonal process of the individual components of the radiation balance appearing on the top surface of the stand as active surface, with special attention to the albedo and radiation.
1.2. The daily and yearly process of the absorption of the two types of radiation utilizing the data of the sensors measuring the global radiation functioning above and below the top surface as well as the photo-synthetically active radiation.
2. Heat budget (Attila Eredics)
2.1. Temperature of the leaf surface and the generated daily and seasonal changes of temperature lamination above and within the stand.
2.2. Uncovering of the lamination of the virtual temperature computed with the assistance of the moisture content data measured parallel with the temperature.
2.3. Description of the seasonal process of the soil temperature (0-100 cm).

1.3 Feedback of forest cover on the regional climate

Leading researcher: Prof. Dr. Csaba Mátyás (UWH, Faculty of Forestry, Institute for Environmantal and Earth Sceinces)
Collaborator: Borbála Gálos (predoc UWH, Faculty of Forestry, Institute for Environmantal and Earth Sceinces)

Results: Forest distribution in Hungary has been determined based on the Corine2000 Land Cover database and the gridded forest distribution dataset of the National Forest Service. Comparing these two databases, large differences can be detected in the forested area, especially on the Hungarian lowland that result from different data collection methods.
Reference forest cover. The Corine2000 database has been selected and included into REMO as reference land cover. For each land cover type, physical vegetation properties (e.g. leaf area index, background albedo, surface roughness length) have been determined and aggregated over the model grid.
Potential forest cover. For the 50 forest regions, the afforestation plan of the Research Institute (Führer et al. 2005) suggests to increase forest cover on marginal agricultural land (Figure 2). This means a 7% increase (6.5% deciduous and 0.5% coniferous) of the present 20% share of forests until the 2030s. A method has been developed to build in these land use changes into REMO. The potential increase of deciduous and coniferous forests has been allocated to all gridboxes (Figure 2) and the new, expected land cover parameters have been calculated. Due to the planned afforestation, leaf area index and roughness length increased, whereas surface albedo decreased compared to the reference land cover. A plan for the model simulations as well as for the analysis of the results has been prepared.