Vol. 109, No. 2 * Pages 71–142 * April - June 2005

Diagnostic applications of the energy balance equation for vegetated surface (VSEBE) are briefly summarized. We tested whether VSEBE can be successfully applied for estimating surface soil moisture content (q) in the growing season using agroclimatological observations. The analysis is performed using data set of the Agrometeorological Observatory of the University of Debrecen collected in the period 1974–1986.
In the study, the process-based VSEBE model is described in detail. It is shown that VSEBE is not suitable for estimating instantaneous values of q, since the applicability of the model is fairly limited and the scattering of the estimates is relatively large. It is also shown that monthly mean values of q can be estimated with acceptable accuracy applying VSEBE for a long time period. The results obtained can be useful for estimating climate characteristics of agrometeorological stations.

The probability forecasts of precipitation (PoP) are of great interest in numerical weather forecasting. Besides the model errors and the ensemble spread insufficiencies, the quality of these PoP forecasts is strongly affected by the problem of representativity: while the original forecasts are valid on the scale of a gridbox, we want to verify them with observations of local stations. These inconsistencies can be treated by the so-called upscaling and downscaling methods. This paper presents a new approach for downscaling PoP forecasts with the combination of the esemble prediction system (EPS) and the representativity conditions explored by conditional error statistics of the observations with respect to forecasts.
Regarding the probability density functions (PDF) of the observations respect to the different forecast values, we found that there is only a very small difference between two or three years seasonal PDF-s as long as the model environment was consistent, and the geographical variability of the PDF-s is also not significant between areas – like Central Europe and Northern Hemisphere.
The new downscaling method in general delivered better verification statistics than the operational one. The best results could have been obtained for winter, while the least improvement was attained for summer. While the old probabilities were underconfident for most of the cases, the new probabilities showed some overconfidency. In general, there is no significant improvement in the resolution, but as an important result there is no deterioration at all. The greatest improvement was gained for the Brier skill score, especially for the thresholds of 1 mm and 5 mm. Regarding ROC curves, higher hit rates were also present, mainly for bigger thresholds. In addition strong similarities were found between the results for JJA and MAM, and also in the case of DJF and SON, which can probably be explained by local scale convection.

The paper is a review of the general features of lightning records produced by the System d’Alerte Foudre par Interferometrie Radio-electrique (SAFIR) lightning detection system used in Hungary over the recent 5 years. The intra-cloud (IC) and cloud-to-ground (CG) lightnings were distinguished. Lots of information was generated with the help of this system. The electrical parameters were collected and processed. The time and spatial distributions of the lightnings and different type of lightning characteristics were computed. As the first discharges appear in the early time of the forming of a cumulonimbus cloud, the application of data generated by the lightning detection system is a good tool in the every day meteorological short range forecasting. Understanding of the lightning physics leads to the more effective meteorological and industrial application.

Monthly mean daily values of global (G) and ultraviolet (UV) solar radiation incident upon a horizontal surface at Cairo urban area during two different periods (1969–1973 and 1993–1997) are presented, analyzed, and compared. The effect of urbanization processes on the solar radiation components is investigated and discussed. It was found that the total amount of the two radiation components, G and UV, received at the urban area of Cairo during the period 1969–1973 highly exceeds the total amount received during the period 1993–1997 for all months of the year. The mean relative reduction of Gand UV reached 17.4% and 27.4%, respectively. A significant correlation between G and UV radiation has been found, and the recommended correlation equation has been stated to estimate the values of UV radiation which is difficult to measure at any site in the zone of Lower Egypt. Also, a comparative study of the two radiation components, G and UV, at urban (Cairo) and rural (Bahtim) areas during the period 1993–1997 revealed, that the urban area always has values of G and UV radiation distinctly lower than values found in rural area for all months of the year. Urban-rural mean reduction of G and UV reached 7.0% and 17.9%, respectively. The ratio of the ultraviolet to global radiation (UV/G) are calculated and compared with other sites in the Arabian Peninsula. The effect of atmospheric dust on the measured solar radiation components is also investigated and discussed.