2024. február 29. csütörtök
IDŐJÁRÁS - angol nyelvű folyóirat
Climatic threats determining future adaptive forest management – a case study of Zala County
Borbála Gálos, Ernő Führer, Kornél Czimber, Krisztina Gulyás, András Bidló, Andreas Hänsler, Daniela Jacob, and Csaba Mátyás
idojaras.2015.4.1 (p. 425–)
 PDF (4145 KB)   |   Abstract

Research of future climate tendencies is a precondition for appropriate climate change adaptation strategies in forestry and agriculture. The aim of this paper is to investigate the expected probability and magnitude of threatening climate conditions that are of primary importance in terms of forest management. Until 2100, precipitation and temperature results of an ensemble of 12 regional climate model simulations as well as derived indicators (e.g., Forestry Aridity Index and Ellenberg’s climate quotient) have been analyzed for the A1B emission scenario. For the case study area in Southwest Hungary (Zala County), projections indicate an increasing tendency of warming and drying of summers towards the end of the 21st century. In the period 2071–2100, decrease of summer precipitation sum may exceed 25% compared to 1981–2010. Both extreme droughts and heavy precipitation events are expected to be more frequent. Consequently, the already observed climate change impacts and damages in forestry are very likely to occur with higher probability and severity. Including these results, a GIS-based “Agroclimate” decision support system is under development that contains a coherent data chain from climate change simulations, through impact assessments to adaptation support in order to provide quantified information on the possible yield potential and production risk for sustainable forest management.

A new hail size forecasting technique by using numerical modeling of hailstorms: A case study in Hungary
Kálmán Csirmaz
idojaras.2015.4.2 (p. 443–)
 PDF (6188 KB)   |   Abstract

A new forecasting method for maximum size of hail stones is presented in this paper by using the outputs of a high-resolution, non-hydrostatic numerical weather prediction model (NWP). The method was tested applying simulations of a real case supercell storm producing damaging hail with the Weather, Research and Forecasting (WRF) model. Numerical simulations were made with two distinct horizontal resolutions, 2 km and 100 m, applying nesting technique to assess the effect of the resolution on the storm microphysical properties and the maximum size of the hail stones on the surface. The WRF was able to simulate the main observed characteristics of the supercell on both resolutions. However, the numerical simulation with finer resolution gave better agreement with the radar observation and the observed maximum hail size on the surface. It was found that the horizontal resolution has significant influence on the magnitude and evolution of the microphysical processes in the storm. The numerical simulation with finer resolution produced not only significantly larger maximum mixing ratios of graupel/hail than the 2 km one did, but the volume integrated content of graupel/hail particles in the storm was also larger in the case of finer resolution. This difference can be attributed to the stronger updraft in the case of 100 m resolution.  The analysis of various production shows that graupel/hail particles were mainly formed by the heterogeneous freezing of supercooled rain drops and by the freezing of rain drops due to the collision with cloud ice in the midlevels (between 3 and 8 km). Subsequent accretion of graupel/hail particles occurred by the collision with cloud and rain water. Larger graupel/hail content aloft in the case of finer simulation resulted in larger surface mixing ratios which directly led to larger maximum hail sizes on the ground.

Examining the probable length in days of wet and dry spells in Khuzestan province
Seyed Hossein Mirmousavi
idojaras.2015.4.3 (p. 475–)
 PDF (1599 KB)   |   Abstract

This study evaluated the probable length in days of dry and wet spells in Khuzestan province using daily rainfall data from 11 synoptic stations during the period 1990–2012. Transfer matrix calculations and model tests were performed using Matlab software. For interpolation maps, kriging in ARC GIS 10.2 software was used. Results indicated that the probability of dry days occurring in Khuzestan province increases from the south to the north. The highest probabilities of a two-day dry spell were 15% in the north and 12% in the northeast of the province. The probability of a 3-day dry spell in the north and northeast was 10%. Moving to the south and southwest of the province, the probability decreases, amounting to 6% in the southwest. Results of calculations of return periods of wet and dry days showed the probability of the dry-days return period increases from the north to the south. An investigation of the role of general circulation in the creation of wet and dry periods showed that 4 patterns are effective in their production.

Mann–Kendall trend analysis of surface air temperatures and rainfall in Iraq
El-Sayed M. Robaa and Zhian Al-Barazanji
idojaras.2015.4.4 (p. 493–)
 PDF (1337 KB)   |   Abstract

In this study, trends of the seasonal and annual maximum (Tmax), minimum (Tmin), and mean (T) air temperatures, as well as rainfall amounts (Ra) time series were investigated for eleven stations in Iraq for the period 1972–2011 (40 years). Four statistical tests including homogeneity, Mann–Kendall (MK), Sen's slope estimator and linear regression were used for the analysis. The results revealed that annual mean of Tmax, Tmin, and T time series showed statistically significant increasing trends over 81.8, 100, and 100% of the stations at the 0.001 level and they experienced an increase of 0.50, 0.67, and 0.58 °C/decade, respectively; while the annual rainfall has shown decreasing trends at 90.9% of the stations and it experienced a decrease of –20.50 mm/decade. Seasonally, the highest increase of Tmax, Tmin, and T values have been found over the extreme south of the country during summer at the rates of 1.47, 1.06, and 1.16 °C/decade, respectively, while the highest decrease of Ra values has been found in the northern part of the country during winter at the rate of –36.35 mm/decade.

Continentality in Europe according to various resolution regional climate models with A1B scenario in the 21st century
Beáta Szabó-Takács, Aleš Farda, Pavel Zahradníček, and Petr Štěpánek
idojaras.2015.4.5 (p. 515–)
 PDF (4453 KB)   |   Abstract

The purpose of our research is to simulate the influence of the thermal properties of land surface on the Central European climate in the 21st century. The simulation is carried out with calculation of Gorczynsky and Conrad continentality indexes, respectively, as a function of annual temperature range. Seven different ENSEMBLES models (ARPÈGE, CNRM, DMI, ITCP, KNMI, MPI, and SMHI) with various resolutions perform the space difference of continentality between seven European regions with IPCC A1B emission scenario for two time slices: 2021–2050 and 2071–2100. Beside these models, ALADIN-Climate/CZ simulation is implemented in finer resolution and smaller CECILIA domain taking into consideration only the central European area. The bias correction of models is implemented using the European Climate Assessment and Dataset (ECA&D). The largest influence to the spread among the simulation results is due to the chosen global climate models (GCMs). The resolution differences do not play dominant role in the variance of the results against the domain size. There are not significant differences between the Gorczynsky and Conrad index values. The largest change in the climate type tendency is simulated in the Scandinavian region by the Gorczynsky approach. In central Europe, the climate becomes continental only according to CNRM result which correlates with its underestimation of precipitation and overestimation of temperature. The simulated continentality indexes and the predicted changes are presented here.

Estimation of solar and wind energy potential in the Hernád Valley
Károly Tar, Andrea Kircsi Bíróné, Blanka Bartók, Sándor Szegedi, István Lázár, Róbert Vass, Attila Bai, and Tamás Tóth
idojaras.2015.4.6 (p. 537–)
 PDF (2727 KB)   |   Abstract

This paper focuses on the climatic conditions of the Hernád Valley with the purpose of exploring on what level the utilization of wind and solar energy is advanced or detained in the micro-region. For determination of wind and solar energy potential, an automatic weather station was mounted in the Hungarian section of the Hernád Valley located on a small hill 500 meters west from the settlement of Hidasnémeti.
Available long-term surface global radiation data do not represent our study area on regional scale. For this reason, daily global radiation datasets of the nearest weather station, the airport of Kosice has been used for the analyses. Diurnal and annual variation and spatial pattern of global radiation have been examined by combination of statistical analyses and geo-information/GIS methods.
Other important aim of the research is to describe the spatial characteristics of the wind energy potential related to orography in the Hernád Valley. Diurnal courses of different statistical parameters and the spatial pattern of wind speeds has been investigated on the base of our measured data. Since these data are not continuous, relationships between the diurnal average wind speeds of Kosice and Hidasnémeti were examined also. An attempt has been made to complete our diurnal average wind speed database by linear regression.
Finally, the social and economic conditions regarding solar and wind energy utilization are mentioned shortly in the paper.

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