In this paper the contribution of turbulence into the electrification of thunderstorms, snowstorms, and dust storms is investigated for the first time. A model of large‐scale electric field ...generation in a weakly conducting medium, containing two types of particles charging by collisions, is used. Thunderstorm and snowstorm electrification are considered in detail in this paper; dust storm electrification is also considered, despite being substantially different from the two other cases, to demonstrate the universality of the proposed method. A comparison of the results with the experimental data for thunderstorms, blizzards, and dust storms is carried out. It is found that the situation is notably different for inductive and noninductive charge separations. For inductive charge separation there is a range of thunderstorm and snowstorm parameters (conductivity and the particle radii being the most important factors) for which the electric field grows exponentially with time. This effect can make the inductive mechanism dominant near the breakdown field in turbulent zones of thunderclouds. For noninductive (or triboelectric) charge separation caused by intense velocity fluctuations, the electric field strength grows only linearly with time. The most substantial effect of turbulence on noninductive charging is expected to occur in snowstorms and dust storms, whereas noninductive turbulent charging has a little impact on the thunderstorm electrification.
Key Points
A method for estimating the contribution of turbulence in electrification processes in weakly conducting media is proposed
The large‐scale electric field dynamics due to the turbulence is notably different for inductive and noninductive charging
The proposed method is used to estimate the role of turbulence in thunderstorm, snowstorm, and dust storm electrification
The assumption of nighttime ozone chemical equilibrium (NOCE) is widely employed for retrieving the Ox-HOx components in the mesopause from rocket and satellite measurements. In this work, the ...recently developed analytical criterion of determining the NOCE boundary is used (i) to study the connection of this boundary with O and H spatiotemporal variability based on 3D modeling of chemical transport and (ii) to retrieve and analyze the spatiotemporal evolution of the NOCE boundary in 2002–2021 from the SABER/TIMED dataset. It was revealed, first, that the NOCE boundary reproduces well the transition zone dividing deep and weak photochemical oscillations of O and H caused by the diurnal variations of solar radiation. Second, the NOCE boundary is sensitive to sporadic abrupt changes in the middle-atmosphere dynamics, in particular due to powerful sudden stratospheric warmings leading to the events of an elevated (up to ∼ 80 km) stratopause, which took place in January–March 2004, 2006, 2009, 2010, 2012, 2013, 2018, and 2019. Third, the space–time evolution of this characteristic expressed via pressure altitude contains a clear signal of an 11-year solar cycle in the 55∘ S–55∘ N range. In particular, the mean annual NOCE boundary averaged in this range of latitudes anticorrelates well with the F10.7 index with the coefficient of −0.95. Moreover, it shows a weak linear trend of 56.2±42.2 m per decade.
Ground-based microwave radiometers are increasingly used in operational meteorology and nowcasting. These instruments continuously measure the spectra of downwelling atmospheric radiation in the ...range 20–60 GHz used for the retrieval of tropospheric temperature and water vapor profiles. Spectroscopic uncertainty is an important part of the retrieval error budget, as it leads to systematic bias. In this study, we analyze the difference between observed and simulated microwave spectra obtained from more than four years of microwave and radiosonde observations over Nizhny Novgorod (56.2° N, 44° E). We focus on zenith-measured and elevation-scanning data in clear-sky conditions. The simulated spectra are calculated by a radiative transfer model with the use of radiosonde profiles and different absorption models, corresponding to the latest spectroscopy research. In the case of zenith-measurements, we found a systematic bias (up to ~2 K) of simulated spectra at 51–54 GHz. The sign of bias depends on the absorption model. A thorough investigation of the error budget points to a spectroscopic nature of the observed differences. The dependence of the results on the elevation angle and absorption model can be explained by the basic properties of radiative transfer and by cloud contamination at elevation angles.
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.
A modified derivation of the criterion of nighttime ozone chemical equilibrium (NOCE) in the mesopause region is presented. According to 3D model calculations, the improved criterion reproduces the ...lower boundary of the equilibrium much better than its earlier version. Processing of the SABER/TIMED data of 2021 has shown that the modified criterion elevates the NOCE boundary by ∼ 0.1–1.7 km, depending on latitude and season. The proposed method of determining the condition of chemical equilibrium can be used to analyse the equilibrium of many trace gases in the stratosphere and troposphere important for different practical applications.
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