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  • Open access
  • 14 Reads
Helical cyclogenesis in the Earth’s atmosphere and beyond

A unified basis is proposed to explain the formation of intense large-scale long-lived vortices in the planet atmospheres.

Back in the 1980s, two hypotheses appeared: the turbulent vortex dynamo theory (Moiseev et al. 1983) with possible application to describe the formation of hurricanes/typhoons in the tropical atmosphere, and the universal concept of helical cyclogenesis (Levich and Tsvetkov, 1985), covering the vortex generation processes in the tropical, middle, and polar latitudes of the Earth. The hypotheses were advanced independently and aimed at explaining the formation of intense large-scale long-lived atmospheric vortices due to the upscale energy cascade in helical atmospheric turbulence. Recently, a new contribution to the development of the turbulent vortex dynamo theory was made by Kopp et al. (GAFD, 2021), who substantiated the dynamo effect for a rotating stratified moist atmosphere and took into account the tilt of the planet's rotation axis. The latter allows the theory to be applicable for a specific planet, e.g., in the Solar System.

The substantiation of the dynamo effect in a real atmosphere has become possible after the discovery of vortical cloud deep convection ‒ Vortical Hot Towers (VHTs) in the tropical zone (Hendricks et al., 2004). The implementation of turbulent vortex dynamo in the Earth's tropical atmosphere, based on the key role of VHTs in the excitation and maintenance of large-scale helical-vortex instability, was shown in a series of collaborative Russian-American works (Levina and Montgomery, 2009‒2015), which were reviewed in (Levina, 2018).

In the present work, theoretical and numerical estimations for the effects of the turbulent vortex dynamo in the Earth’s and Jovian atmospheres are given and compared. Perspectives of research on helical cyclogenesis in the atmospheres of the Earth and planets-giants, Jupiter, Saturn, and Neptune are discussed. The work was supported by the research project “Monitoring” No. 01.20.0.2.00164.

  • Open access
  • 69 Reads
Impact of COVID -19 Lockdown on the Air Quality in the Kullu Valley of Northwestern Himalaya, India
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The outbreak of corona virus or COVID-19 pandemic has created a serious health concern worldwide. The world was forced to shut down. India witnessed nationwide lockdown from 25 March 2020 to 31 May 2020 in four different phases. Industries were shut and vehicle movement was restricted both in inter and intra state. In the present study, concentration of criteria pollutants, Surface ozone (O3,),Sulphur dioxide (SO2), Carbon monoxide (CO), Nitrogen Dioxide NO2 and Total Suspended Particles (TSP)were monitored in pre lockdown period (PLD) 1 January-24 March 2020 and during lockdown (LD) 25 March-31 May 2020 were analyzed. Total Suspended Particles (TSP) were monitored by gravimetric method using Respirable Dust Sampler (RDS), NO2 was measured using modified Jacob and Hochhesier method while sulphur dioxide, carbon monoxide and surface ozone were monitored using online gas analyzers manufactured by thermo fisher scientific at Mohal Kullu Valley of northwestern Himalaya which is a semi urban area.The results revealed reduction of 66.24%, 37.32%, 27.02 % and 16.67% in CO, TSP , NO2 and SO2 respectively during lockdown as compared to pre- lockdown while surface ozone (O3) showed an increase in concentration during lockdown period as compared to pre lockdown. The overall air quality improved during the lockdown period when compared to the pre lockdown period in the valley indicating how the air quality is affected by anthropogenic activities in the area.

  • Open access
  • 37 Reads
Comparison between 3DVAR and 3DEnVAR methods applied to SisPI for dense fog forecast

The objective of this research is to evaluate and compare the impact of the 3DVAR and 3DEnVAR methods on short-term and very short-term fog forecasting, applied to Short-range Forecast System (SisPI). The experiments were developed using the initialization of 00:00 UTC on December 30th and 31th, 2019, where there was a continuous event of dense fog recorded in the region of Havana, Artemisa and Mayabeque. The research combines data related to conventional observations contained in prepbufr format, radiance information from microwave sensors available in bufr format, and observations from the KBYX and KBMA radars that include measurements of radial velocities and reflectivity, something that constitutes a novelty at the national level in relation to fog investigations in the country. As a whole, domain-dependent covariance matrices (BECs) are used, generated with the inclusion of hydrometeors as additional control variables. Given the high degree of subjectivity inherent in the registration of fog and haze in the conventional stations of the study area, the binary analysis uses the data of the present time code with the visibility predicted by the model, which is obtained through an empirical algorithm. The results suggest that the 3DVAR method leads to improve the CSI values by only 1% and the correct detections by 2%. These discrete values respond to a limited modification of the background field as a consequence of an inadequate dispersion of the impact of the observations on the domain. 3DEnVAR generates a more realistic analysis field compared to 3DVAR and achieves a more efficient spread of the impact of observations over the domain. The CSI values manage to be up to 17% higher than the runs without assimilation and 11% at 3DVAR.

  • Open access
  • 45 Reads
The structure of blizzard transport and heat costs of sublimation of ice crystals in blizzards on the surface of the Elbrus Mountain glacier
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Wind transport of snow and sublimation of ice crystals during blizzards have a significant impact on the accumulation of snow on the surface of a mountain glacier and, consequently, on river runoff. Automated meteorological measurements were organized on the Garabashi glacier during the accumulation season in February 2022. For the first time for glaciers of the Central Caucasus, estimates of blizzard transport based on automated measurements with high time discreteness were performed and a numerical algorithm of the rate of crystal sublimation during blizzards was applied. It has been shown that the sublimation of crystals could be comparable with the sensible and latent heat fluxes. In addition, the process of sublimation in blizzards can significantly affect the total evaporation and, consequently, the mass balance of the mountain glacier. Therefore, for a reliable assessment of the thermal balance of the surface and the mass balance of a mountain glacier in the numerical models of weather and climate, it is necessary to consider the process of sublimation of ice crystals during blizzards with the development of appropriate parameterizations.

Also, the method of measuring of the vertical blizzard transport distribution using “blizzard traps” was tested. It has been shown that exponential decrease of the vertical distribution of the intensity of horizontal snow transport is typical for deflationary blizzards. At the same time, in cases of general blizzards, the effect of increasing wind speed with height prevails and cases of "inversion" vertical distribution occur.

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