Jože Rakovec

Object-Based Analysis of Satellite-Derived Precipitation Systems over the Low- and Midlatitude Pacific Ocean

Abstract The Method for Object-based Diagnostic Evaluation (MODE) developed by Davis et al. is implemented and extended to characterize the temporal behavior of objects and to perform a diagnostic analysis on the spatial distribution and properties of precipitation systems over the equatorial Pacific Ocean. The analysis is performed on two satellite-derived datasets [Tropical Rainfall Measuring Mission (TRMM) 3B42 and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN)]. A sensitivity analysis showed that temporal convolution produces an unwanted “spillover” effect and that a large spatial convolution radius produces too much smoothing, which results in unrealistically large objects. The analysis showed that the largest and most long-lived precipitation systems in the tropical Pacific are typically located in the western part. A good ability to track precipitation systems in the tropical Pacific was demonstrated: movement of precipitation systems in the IT...

Simulation of soil- and air-microclimate modifications using soil heating with warm water

Abstract In the present paper microclimate modifications are evaluated. Thermal conditions in soil and in the air above it are simulated by a model using soil heating with warm water (22°C) through pipes at a depth of 0.70 m. The results showed marked soil and less expressed air warming, which are most expressed in the spring months.

Climate Projections for the Sava River Basin

Presented are climate change projections for the Sava river basin that follow from the ensemble of 16 combinations of the global climate models (GCM) and regional climate models (RCM). RCMs are normally configured to offer the optimal results for the region as a whole. Thus, they may have in some specific smaller domains also some systematic bias. Such eventual bias can be corrected by comparing the simulated values in smaller domain with measured values in that domain. That was done for the Sava river basin for precipitation amount and temperature for the twenty-first century and the results are presented for summer and winter conditions for two future standard climatological periods: 2011–2040 and 2071–2100 and compared with the reference period 1971–2000. In general, temperature is expected to increase over the basin area in all seasons, but the most pronounced increase can be observed for summer and winter. Precipitation is expected to decrease significantly in summer, whereas less pronounced decrease is expected in spring and autumn. Winter precipitation is expected to increase, especially in the northwestern part of the basin.

Vertical radar reflectivity profiles in Slovenia

SummaryRadar reflectivity from hydrometeors is used for the estimation of the precipitation rate at ground level. If the vertical reflectivity profile is taken into account, the estimate can be improved considerably. In the first part of the article some theoretical explanations are given for the two most pronounced characteristic of the vertical radar reflectivity profile from clouds. In general, the observed values decrease with height in the upper part of the radar echo due to the growth of precipitation particles by collision and coalescence. The effect of the bright band, especially in more stratiform types of precipitation, adds a significant strong peak to the profile, at the approximate height of the 0 °C isotherm. These explanations, although being simplified, also provide a quantitative explanation of the two characteristics mentioned previously. Averaged seasonal characteristics of vertical profiles in Slovenia are used as the climatological basis for the construction of an idealised profile for correcting the precipitation estimate. For individual cases, and also after averaging, a maximum in the profiles can clearly be detected. This maximum is much sharper if the profiles are normalised. When looking at time changes, it is shown that most of the changes in radar reflectivity, on average, occur during a roughly 6-hour time-lag between the two measurements. With greater time-lags, the differences are smaller on average. This is caused by the local natural evolution of the precipitation field and indicates that a 6-hour to 12-hour accumulating and averaging of data could diminish much of the error due to the time variation in radar estimated precipitation.