The aim of this paper is to study the wintertime physical properties of atmospheric aerosol particles on the basis of data observed at the K-puszta regional background station in Hungary. In Hungary wintertime smog episodes are linked to strong stable air (high pressure blocking events) with thermal inversion. These atmospheric conditions are frequently formed during winter months (November–February) due to the special geographical location of the country. The formation of smog events is highly probable in cases of thermal inversion periods sustaining for at least 4 days. We discuss in the paper the role of high-pressure blocking events in aerosol properties in terms of PM10 concentrations, aerosol size distributions, new particle formation and optical properties. We found that high-pressure blocking events have significant impacts on the size distribution and particle formation processes. At K-puszta the aerosol is in highly aged state with size distribution dominated by the accumulation mode. This is further supported by the optical properties, e.g., by high scattering Ångstrom exponent and by relatively weak absorption. The most significant effect of extreme episodes is manifested in the changes in PM10 concentrations and, consequently, in aerosol optical properties. The PM10 concentrations, scattering coefficients and absorption coefficients considerably increase to extreme values that are characteristic of a heavily polluted atmosphere rather than rural air. Our results indicate that in winter, the air quality at K-puszta is often influenced by regional air pollution as shown by spatial distribution of PM10 concentration. It is found that PM10 had almost the same concentration in regional background air and in different types of urban environments. The special meteorological conditions and the role of regional-scale transport can explain why local abatements in cities cannot lead to significant improvement of the air quality during smog events.
Összefoglalás. Az elmúlt évtizedekben a globális felmelegedés hatásai Európában, azon belül a Kárpát-medencében is nyilvánvalóvá váltak, s ez a hatás jelentős mértékű az energiaszektorra is. A kizárólag az időjárás által befolyásolt függő fűtési és hűtési energiaigényt leíró technikai klímaindexek alakulását mutatjuk be Magyarországon, nevezetesen a fűtési foknap (Heating Degree Days) és a hűtési foknap (Cooling Degree Days) paramétereket vizsgáljuk. A jelen klímát leginkább jellemző éves és havi normálértékek mellett a változásokat is elemezzük. A múlt század elejétől a fűtési foknapok egyértelmű csökkenése, míg a hűtési foknapok egyértelmű emelkedése figyelhető meg. Országos átlagban 314,6 foknappal [°C nap] csökkent a fűtési foknapok éves összege a lineáris trendmodell szerint 1901-től, míg ugyanerre az időszakra 79,4 ℃ nappal nőtt a hűtési foknap értéke. A legutóbbi három évtizedben, a legintenzívebb melegedés időszakában igen markánsak a változások, s ez a folyamat minden bizonnyal folytatódik a század végéig és azon túl is. Summary. In recent decades, the effects of global warming have become evident in Europe, including the Carpathian Basin, and this impact is significant for the energy sector. The most obvious impact of climate change in Hungary is the increase in extremes associated with high temperatures. Not only summer, but also winter and transition seasons show a warming trend, affecting all productive and service sectors. Rising temperatures could lead to shorter heating seasons and milder cold months, potentially reducing heating energy demand. However the heat waves have become more frequent and intense due to warming, leading to an increase in cooling energy demand. In the first part of this article, we present the evolution of heating degree-days from the beginning of the last century to the present day for the whole area of Hungary. The heating degree day is an indicator of the energy consumption for heating of buildings, which depends only on the weather. That is a temperature value, expressed in °Cday, which is proportional to the amount of energy required to heat the indoor environment to a given temperature on a given day, taking into account the daily minimum, maximum and mean temperature for a specific base temperature (15.5°Cday). Importantly, its value does not depend on the insulation of the buildings, economic indicators or the type of energy sources. Essentially, the colder the weather, the more the air temperature deviates from the base temperature of 15.5 degrees Celsius, the more energy is needed to heat the indoor environment and the higher the heating degree day value will be. In addition, we present the analysis of cooling degree days. The cooling degree day is derived in a similar way, following the logic of the heating degree day derivation. Therefore, the warmer the weather and the higher the air temperature is above the base temperature of 22°C, the more energy is needed to cool the indoor environment. Based on the results presented in the article, we can conclude that the annual as well as the monthly amounts of heating degree-days have decreased since the beginning of the last century, with the greatest decrease in mountainous areas and in Western Hungary. One of the few benefits of climate change is that less energy is needed to heat interiors, and this is particularly true for the last decades, when annual heating degree-day amounts were usually lower than normal. At the same time, as heating degree-days have decreased, as the heat waves have become more frequent and intense with warming, resulting in an increase in cooling degree-days. In Hungary, on average, the last 30 years have been characterised by the highest cooling degree-day values over the last century’s climate normal periods. On a national average, the annual amount of heating degree-days has decreased by 314.6°Cday according to the linear trend model since 1901, while the cooling degree-day value has increased by 79.4°Cday over the same period. During the period of most intense warming, the August weather-dependent cooling energy demand increased the most. Due to the urban heat island effect in the inner-city environment, cooling of buildings requires additional energy. The recent trends is likely to continue until the end of the century and beyond. Therefore important to monitor changes in climate parameters affecting energy security and to develop an effective strategy and action plans to address the climate risks for the energy sector.
The long-term trends of relative humidity and its relationship with the long-term change of temperature are some of the unsolved problems of climate research. In this paper, the results of the analysis of long-term changes (1961–2020) in relative humidity and temperature in Hungary are presented. Homogenized station data series were used to perform the analyses. While warming was significant in each season, a significant reduction of relative humidity was observed only in spring and summer. The seasonal variability in the dependence of the change of relative humidity on the change of temperature indicates that the change of temperature directly impacts the change of relative humidity in summer, and the enhancement of evaporation due to the increase of temperature may mitigate the impact of warming in other seasons. Homogenized datasets were used to study the daily variation of the long-term trend of relative humidity. Significant reduction was found at noon in each season, except for autumn. However, the reduction was more scattered during the night, depending on the season and/or the geographical location of the station. The relationship between the surface data and data observed by radio sounding (00 UTC and 12 UTC in time period of 2007–2018) was studied to predict the long-term trends of relative humidity in the lower, 100-m deep layer of planetary boundary layer from the trend of surface relative humidity. The results suggest that this prediction can be reasonable only if daytime trends are considered.
An unprecedented deadly and destructive EF4 tornado struck the Czech Republic across Břeclav and Hodonín districts on June 24, 2021. On this day, several supercells developed in Central Europe, however, in Austria and the Czech Republic region only one cell produced a tornado. For this reason, in addition to the macrosynoptic setup, it is also worth exploring the small-scale cell interactions that can lead to the formation of a devastating EF4 tornado. We use ECMWF analysis and forecast fields, sounding profiles, and radar measurements to examine the synoptic weather situation and convective processes. Moreover, to investigate the evolution and structure of convection, two Weather Research and Forecasting (WRF) model simulations were carried out at 1.5 km grid spacing with onemoment and two-moment microphysical parameterizations. WRF captures the overall spatial distribution and supercellular nature of thunderstorms, although discrepancies exist in the magnitude and spatial location of individual cells. The low-reflectivity region accompanying the thunderstorms is better represented by the one-moment microphysics scheme.
