Skills of Thunderstorm Prediction by Convective Indices over a Metropolitan Area: Comparison of Microwave and Radiosonde Data

Abstract

In this work, we compare the values of 15 convective indices obtained from radiosonde and microwave temperature and water vapor profiles simultaneously measured over Nizhny Novgorod (56.2°N, 44°E) during 5 convective seasons of 2014–2018. A good or moderate correlation (with coefficients of ~0.7–0.85) is found for most indices. We assess the thunderstorm prediction skills with a lead time of 12 h for each radiosonde and microwave index. It is revealed that the effectiveness of thunderstorm prediction by microwave indices is much better than by radiosonde ones. Moreover, a good correlation between radiosonde and microwave values of a certain index does not necessarily correspond to similar prediction skills. Eight indices (Showalter Index, Maximum Unstable Convective Available Potential Energy (CAPE), Total Totals index, TQ index, Jefferson Index, S index, K index, and Thompson index) are regarded to be the best predictors from both the true skill statistics (TSS) maximum and Heidke skill score (HSS) maximum points of view. In the case of radiosonde data, the best indices are the Jefferson Index, K index, S index, and Thompson index. Only TSS and HSS maxima for these indices are close to the microwave ones, whereas the prediction skills of other radiosonde indices are essentially worse than in the case of microwave data. The analysis suggests that the main possible reason of this discrepancy is an unexpectedly low quality of radiosonde data.

Continuous monitoring of boundary layer height over Nizhny Novgorod

“…The first reason is the presence of a systematic difference between the microwave and radiosonde temperature profiles, which, apparently, is the result of a smoothing error of the RPG-HATPRO retrieval procedure [13] . The second reason is the presence of a systematic difference between the water vapor profiles, which was revealed in the study of the accuracy of the thunderstorm events prediction over Nizhny Novgorod using the atmosphere convective indices [14] .…”

The estimation of seasonal variation of retrieval error in tropospheric temperature microwave profiling

“…Thus we compiled the dataset of simultaneous microwave and radiosonde measurements. The dataset is well described in [10,11]. In brief the microwave profiles are averaged over 12-min intervals (6 min before and after a radiosonde launch).…”

Long-Term Observations of Microwave Brightness Temperatures over a Metropolitan Area: Comparison of Radiometric Data and Spectra Simulated with the Use of Radiosonde Measurements

“…The analysis of specific events led to the conclusion that microwave indices and some primary microwave data (in particular, the standard deviation of brightness temperature at 22 GHz) could be considered as a useful tool for ultra-short-term forecasting of thunderstorms, showers, wind shear and others. Another research [18] assessed the thunderstorm prediction skills over a metropolis for different radiosonde and microwave indices and revealed the better effectiveness of microwave data.…”