ANALYSIS OF METEOROLOGICAL AND AGRICULTURAL DROUGHTS IN SERBIA

Abstract: Drought represents a combined heat-precipitation extreme and has become an increasingly frequent phenomenon in recent years. In order to access the entire analysis of drought, it is necessary to include the analysis of several types of drought. In this paper, impacts of meteorological and agricultural drought were analyzed across the Standardized Precipitation Index (SPI) and Agricultural Rainfall Index (ARI) on the territory of Serbia for the period from 1980 to 2010. For both types of drought, year 2000 is notable as the year when most of the observed stations had the highest drought intensity. It was found that meteorological drought for year 2000 has a higher intensity in the central and southeastern parts of the country, as well as in the north. Of all the stations, the highest intensity of meteorological drought was observed at Loznica station in 1989. Agricultural drought in 2000 had the lowest intensity in western Serbia.   Key words: drought, meteorological drought, agricultural drought, Standardized Precipitation Index, Agricultural Rainfall Index, Serbia.

Multi-scenario and multi-model ensemble of regional climate change projections for the plain areas of the Pannonian Basin

This study is focusing on the projected temperature and precipitation changes in the plain areas of Serbia and Hungary. The simulated changes are calculated for two future time periods (namely, 2021‒2050 and 2069‒2098) on a monthly scale, and they are compared to the 1971‒2000 reference period. In order to estimate the uncertainties deriving from different sources, 10 RCM simulations driven by different GCMs, and three RCP scenarios (RCP2.6, RCP4.5, and RCP8.5) were taken into account. According to the obtained results, higher temperature values are likely to occur in the future, and warmer conditions tend to occur if greater radiative forcing change is assumed. In the case of precipitation, larger variability emerges, but for July, a clear decreasing trend is projected, especially in the case of RCP8.5; while from October to June an increase is projected by most of the RCM simulations. Rainfall variability index shows that the number of dry years will be 5–20 from 30-year time series in the mid-century, and slightly less in the late-century. Extreme dry conditions will tend to occur in 2–12 years overall during 30-year future time periods in the northern plain subregions, and somewhat more frequently in the southern subregions (i.e., in Serbia). The obtained results do not show substantial differences depending on the RCP scenarios, since the scenario plays a less important role in the overall uncertainty of climatic projections compared to the model physics and parameterizations or the internal climatic variability

How To Measure Oscillator’s Short-Term Stability Using Frequency Counter

In this paper a few methods of how to use frequency counter in time-domain frequency stability analysis are described. Three implemented methods are presented. As an experiment, a comparison of the realized methods in the Technical Test Center (TOC) and the “references” obtained in the Directorate of Measures and Precious Metals (DMDM) in Belgrade are accomplished. The measurement uncertainty estimation for time interval measurement with one frequency counter is presented as well

EFEKTI UTICAJA MODELA SOLARNE RADIJACIJE NA PRORAČUN REFERENTNE EVAPOTRANSPIRACIJE

The crop evapotranspiration has the great effect on defining and planning of water resources. The estimation of evapotranspiration depends on various climatic parameters. In this study, the analysis of the effect of solar radiation (Rs) on daily reference evapotranspiration (ET0) was conducted. The FAO-56 Penman-Monteith method (FAO-56 PM) was used for the estimation of ET0 in Serbia at eight meteorological stations for the period 1980-2010. The Rs was estimated using the ten one-parameter global solar radiation models. The ET0 with Almorox and Hontoria model 1 had the smallest deviation related to the ET0 with Angstrőm-Prescott (AP) model, and ET0 with Toğrul et al. model 2 and Rietveld model had the greatest deviation from ET0 with AP model. Evapotranspiracija useva ima veliki uticaj na definisanje i planiranje vodnih resursa. Proračun evapotranspiracije zavisi od različitih klimatskih parametara. U ovom radu je sprovedena analiza uticaja solarne radijacije (Rs) na dnevne vrednosti referentne evapotranspiracije (ET0). Za proračun ET0 je korišćen FAO-56 Penman-Monteith metod (FAO-56 PM) u Srbiji za vremenski period 1980-2010. Rs je određen upotrebom deset jednoparametarskih globalnih solarnih radijacionih modela. ET0 dobijena korišćenjem Almorox and Hontoria model 1 za proračun Rs daje najmanja odstupanja u odnosu na ET0 sa Angstrőm-Prescott (AP) modelom a ET0 izračunanta uz pomoć Toğrul et al. model 2 i Rietveld modela daje najveća odstupanja od ET0 sa AP modelom

Estimation of reference evapotranspiration by Penman-Monteith (PM) method using meteorological data from fifteen CLIMWAT stations located in the Pannonian Basin

The Penman-Monteith (PM) method for estimation of reference evapotranspiration (ET0) uses numerous input data that are often missing in many regions. In such circumstances, temperature-based equations can be used for estimating ET0. The primary objective of this note was to compare the calibrated temperature-based ET0 approaches with the PM equation using meteorological data from fifteen CLIMWAT stations located in the Pannonian Basin. The most of these locations are classified as humid. Twelve temperature-based PM, Hargreaves and Thornthwaite equations were evaluated according to the standard PM method. The regionally calibrated Hargreaves equation (HT) gave the lowest RMSE at seven sites and the second lowest RMSE at three sites. New regionally calibrated Thornthwaite approach (TT) yielded the lowest RMSE three times and the second lowest RMSE seven times. These approaches resulted in the lowest average RMSE for all fifteen locations (0.28 and 0.30 mm day−1, respectively). The other temperature-based approaches significantly fall behind the HT and TT equations at most stations. The overall results show the advantage of the HT approach except for a few southeast stations where the TT approach is dominant. It can be concluded that the regionally calibrated temperature-based approaches (HT and TT) are the most suitable to estimate ET0 in the Pannonian Basin

Aszályindexek összehasonlító elemzése a Pannon-régió alföldi területeire

Számos koordinált kutatás kapcsolódik a globális éghajlati rendszer működésének pontosabb megértését célzó, átfogó nemzetközi programhoz, a WCRP-hez. Ezek egyike a PannEx (Ceg-lar et al., 2018): a WCRP részeként működő GEWEX keretében létrejött nemzetközi kezdeményezés, amelynek célja, hogy jobban megértsük a Pannon-medence térségének regionális éghajlati viszonyait alakító folyamatokat, valamint a felszín és a légkör között lejátszódó kölcsönhatásokat. A PannEx iránt érdeklődő, elsősorban régióbeli kutatóintézetekben, egyetemeken dolgozó résztvevők sokféle kutatási szakterületet fednek le, amelyeket öt vezértéma köré csoportosíthatunk: mezőgazdaság, levegőminőség, fenntartható fejlődés, vízgazdálkodás és oktatás. Az ezekkel a tárgykörökkel kapcsolatos legfontosabb megválaszolandó tudományos kérdéseket egy hosszabb összegző tanulmány (Lakatos et al., 2018) foglalja össze. A PannEx kezdeményezés tehát a Magyarországot teljes mértékben lefedő Kárpát-medence térségére fókuszál, és támogatja a nemzetközi együttműködéseket annak érdekében, hogy integrált megközelítéssel vizsgálhassuk a klímaváltozás, illetve az antropogén tevékenység környezeti hatásait, továbbá megfelelő tudományos alapot biztosítson az adaptációs stratégiák kidolgozásához. Jelen kutatásunk – amely a Pannon régió aszályainak és heves esőzéseinek elemzésére irányul (az elmúlt néhány évtizedet és a XXI. századot tekintve) – egy hivatalosan 2017. ősz végén kezdődött, két évre szóló szerb-magyar bilaterális kapcsolat keretében indult

Plasma Amino Acids in NAFLD Patients with Obesity Are Associated with Steatosis and Fibrosis: Results from the MAST4HEALTH Study

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) have been linked to changes in amino acid (AA) levels. The objective of the current study was to examine the relationship between MRI parameters that reflect inflammation and fibrosis and plasma AA concentrations in NAFLD patients. Plasma AA levels of 97 NAFLD patients from the MAST4HEALTH study were quantified with liquid chromatography. Medical, anthropometric and lifestyle characteristics were collected and biochemical parameters, as well as inflammatory and oxidative stress biomarkers, were measured. In total, subjects with a higher MRI-proton density fat fraction (MRI-PDFF) exhibited higher plasma AA levels compared to subjects with lower PDFF. The concentrations of BCAAs (p-Value: 0.03), AAAs (p-Value: 0.039), L-valine (p-Value: 0.029), L-tyrosine (p-Value: 0.039) and L-isoleucine (p-Value: 0.032) were found to be significantly higher in the higher PDFF group compared to lower group. Plasma AA levels varied according to MRI-PDFF. Significant associations were also demonstrated between AAs and MRI-PDFF and MRI-cT1, showing the potential utility of circulating AAs as diagnostic markers of NAFLD