Hajnalka Breuer

Climate change in Hungary during the twentieth century according to Feddema

Climate change in Hungary during the twentieth century is analyzed using Feddema’s original scheme suitable for global scale applications (F-GS) and Feddema’s fine-tuned scheme designed for Hungarian applications (F-HU). Input data of precipitation (P) and air temperature (T) are taken from the Climatic Research Unit (CRU) TS 1.2 database constructing P-T data referring to three 30-year periods (1901–1930, 1941–1970, 1971–2000) and two 50-year periods (1901–1950, 1951–2000). The method and data organizational effects are compared using these schemes and data sets. The results show that the evaluation of the climate change process depends much more on the methodological rather than on data organizational effects. Methodical fine-tuning effects considerably improved the spatial distribution, while the organization of data improved the insight into the dynamic of the processes. According to F-GS, there is no climate change on 76.7 % of Hungarian territory. According to F-HU, such areas amount to only 38.5 %. The main climate change process for F-GS is drying, while for F-HU drying and warming beside either drying or warming. For both models, the most climate change affected areas are characterized by higher altitudes, such as in the Mecsek and Villány Mountains (geographical region Transdanubia), in the Bükk Mountains (geographical region North Hungarian Mountains), and in the region of the so-called Danube Bend. The spatially most realistic climate description is obtained by using F-HU and the 30-year data sets. It is to be noted that Köppen’s, Holdridge’s, and Thornthwaite’s methods are less suitable than F-HU for representing the process of climate change in Hungary in the twentieth century.

Climate of Hungary in the twentieth century according to Feddema

Feddema’s (Physical Geography 26:442–466, 2005) bioclimatic classification scheme is applied to Hungary for the twentieth century using the Climatic Research Unit (CRU) data series. The method is tested in two modes. In the first, its original form is used which is suitable for global scale analysis. In the second, the criteria used in the method are slightly modified for mesoscale classification purposes. In both versions, potential evapotranspiration (PET) is calculated using McKenney and Rosenberg’s (Meteorol 64:81–110, 1993) formula. We showed that McKenney and Rosenberg’s formula could be applied to Hungary. According to Feddema’s global scale application, local climates of the three main geographical regions, the Great Hungarian Plain, the North Hungarian Mountains, and Transdanubia, can be distinguished. However, the spatial distribution pattern within the regions is poorly reproduced, if at all. According to Feddema’s mesoscale application, a picture of climatic subregions could be observed.

Sensitivity of WRF-simulated planetary boundary layer height to land cover and soil changes

Planetary boundary layer (PBL) height sensitivity to both so-called single and accumulated land cover and soil changes is investigated in shallow convection under cloud-free conditions to compare the effects. Single land cover type and soil changes are carried out to be able to unequivocally separate the cause and effect relationships. The Yonsei University scheme in the framework of the Weather Research Forecasting (WRF) mesoscale modeling system is used as a research tool. The area investigated lies in the Carpathian Basin, where anticyclonic weather type influence dominated on the five summer days chosen for simulations. Observation-based methods applied for validating diurnal PBL height courses manifest great deviations reaching 500–1300 m. The obtained deviations are somewhat smaller around midday and greater at night. They can originate either from the differences in the measuring principles or from the differences in the atmospheric profiles used. Concerning sensitivity analyses, we showed that PBL height differences caused by soil change are comparable with the PBL height differences caused by land cover change. The differences are much greater in the single than in the accumulated tests. Space averaged diurnal course difference around midday reaching a few tens of meters can be presumably treated as strongly significant. PBL height differences obtained in the sensitivity analyses are, at least in our case, smaller than those obtained by applying different observation based methods. The results may be utilized in PBL height diurnal course analyses.

The climate of Carpathian Region in the 20th century based on the original and modified Holdridge life zone system

The Holdridge life zone system has already been used a number of times for analysing the effects of climate change on vegetation. But a criticism against the method was formulated that it cannot interpret the ecotones (e.g. forest steppe). Thus, in this paper transitional life zones were also determined in the model. Then, both the original and modified life zone systems were applied for the climatic fields of database CRU TS 1.2. Life zone maps were defined in the Carpathian Region (43.5–50.5° N, 15.5–28° E) for each of five 20-year periods between 1901 and 2000. We estimated correctness of the result maps with another vegetation map using Cohen’s Kappa statistic. Finally, temporal changes in horizontal and vertical distribution of life zones were investigated. The coverage of boreal region decreased with 59.46% during the last century, while the warm temperate region became almost two and a half larger (257.36%). The mean centres of those life zones, which were not related to mountains, shifted northward during the investigation period. In case of the most abundant life zone types, the average distribution elevation increased. Using the modified model, the potential distribution of forest steppe could be also identified.

Assessment of projected climate change in the Carpathian Region using the Holdridge life zone system

In this paper, expected changes in the spatial and altitudinal distribution patterns of Holdridge life zone (HLZ) types are analysed to assess the possible ecological impacts of future climate change for the Carpathian Region, by using 11 bias-corrected regional climate model simulations of temperature and precipitation. The distribution patterns of HLZ types are characterized by the relative extent, the mean centre and the altitudinal range. According to the applied projections, the following conclusions can be drawn: (a) the altitudinal ranges are likely to expand in the future, (b) the lower and upper altitudinal limits as well as the altitudinal midpoints may move to higher altitudes, (c) a northward shift is expected for most HLZ types and (d) the magnitudes of these shifts can even be multiples of those observed in the last century. Related to the northward shifts, the HLZ types warm temperate thorn steppe and subtropical dry forest can also appear in the southern segment of the target area. However, a large uncertainty in the estimated changes of precipitation patterns was indicated by the following: (a) the expected change in the coverage of the HLZ type cool temperate steppe is extremely uncertain because there is no consensus among the projections even in terms of the sign of the change (high inter-model variability) and (b) a significant trend in the westward/eastward shift is simulated just for some HLZ types (high temporal variability). Finally, it is important to emphasize that the uncertainty of our results is further enhanced by the fact that some important aspects (e.g. seasonality of climate variables, direct CO2 effect, etc.) cannot be considered in the estimating process.

Soil-atmosphere relationships: The Hungarian perspective

Abstract This study discusses scientific contributions analyzing soil-atmosphere relationships. These studies deal with both the biogeophysical and biogeochemical aspects of this relationship, with biogeophysical aspects being in the majority. All of the studies refer either directly or indirectly to the fundamental importance of soil moisture content. Moisture has a basic influence on the spatiotemporal pattern of evapotranspiration, and so 1) on cloud formation and precipitation events by regulating the intensity of convection, and 2) on the trace-gas exchanges in the near-surface atmosphere. Hungarian modeling efforts have highlighted that soils in the Pannonian Basin have region-specific features. Consequently, shallow and deep convection processes are also, to some extent, region-specific, at least in terms of the diurnal change of the planetary boundary layer height and the spatial distribution of convective precipitation. The soil-dependent region-distinctiveness of these two phenomena has been recognized; at the same time the strength of the relationships has not yet been quantified.

A Sensitivity Study on the Soil Parameter-Boundary Layer Height Interrelationship

Simulations with the WRF model have been carried out with high resolution soil data to analyze its effect on planetary boundary layer (PBL) development. The default soil texture distribution of 5′ horizontal resolution has been replaced with a 30′′ one on the basis of the Digital Kreybig Soil Information System and Hungarian Agrogeological Database in Hungary. Soil parameter values determined from HUNSODA and MARTHA Hungarian soil databases were also compared. Comparison of PBL height simulations and measurements obtained by radiometer and windprofiler shows that the impact of soil parameter differences on PBL height evolution is not negligible. The latent heat flux and PBL height daytime courses show significant ( 𝑃 0 . 0 1 ) differences over more than 50% of the model domain covering the Carpathian basin.