Različiti utjecaji latentne topline u planetarnom graničnom sloju i mikrofizičkih procesa u oblacima na tajfun Sarika (2016)

Three simulation experiments were conducted on Typhoon (TC) “Sarika” (2016) using the WRF model, different effects of the latent heat in planetary boundary layer and cloud microphysical process on the TC were investigated. The control experiment well simulated the changes in TC track and intensity. The latent heat in planetary boundary layer or cloud microphysics process can affect the TC track and moving speed. Latent heat affects the TC strength by affecting the TC structure. Compared with the CTL experiment, both the NBL experiment and the NMP experiment show weakening in dynamics and thermodynamics characteristics of TC. Without the effect of latent heat, the TC cannot develop upwards and thus weakens in its intensity and reduces in precipitation; this weakening effect appears to be more obvious in the case of closing the latent heat in planetary boundary layer. The latent heat in planetary boundary layer mainly influences the generation and development of TC during the beginning stage, whereas the latent heat in cloud microphysical process is conducive to the strengthen and maintenance of TC in the mature stage. The latent heat energy of the cloud microphysical process in the TC core region is an order of magnitude larger than the surface enthalpy. But the latent heat release of cloud microphysical processes is not the most critical factor for TC enhancement, while the energy transfer of boundary layer processes is more important.Kako bi se ispitali različiti utjecaji latentne topline u planetarnom graničnom sloju i mikrofizičkih procesa u oblacima, WRF modelom su provedena tri eksperimenta za tajfun (TC) “Sarika” (2016). Kontrolnim eksperimentom dobro su simulirane promjene intenziteta i putanja TC-a. Latentna toplina u planetarnom graničnom sloju te mikrofizički procesi u oblacima mogu utjecati na putanju TC i na brzinu njegovog gibanja. Latentna toplina utječe na jačinu TC-a putem promjene strukture TC-a. U usporedbi s CTL eksperimentom i NBL i NMP eksperiment ukazuju na slabljenje dinamike i termodinamičkih svojstava TC-a. Bez utjecaja latentne topline TC se ne može vertikalno razvijati i stoga mu intenzitet slabi, a količina oborine se reducira; to slabljenje je očitije u slučaju kada je latentna toplina ograničena na planetarni granični sloj. Latentna toplina u planetarnom graničnom sloju uglavnom utječe na stvaranje i razvoj TC-a u početnoj fazi, dok latentna toplina vezana za mikrofizičke procese u oblaku pogoduje jačanju i održavanju njegove zrele faze. Latentna toplina mikrofizičkih procesa u oblakcima u jezgri TC-a je za red veličine veća od prizemne entalpije. Međutim, oslobađanje latentne topline pri mikrofizičkim procesima u oblacima nije najvažnije za jačanje TC-a, već je za njegovo jačanje važniji transfer energije u procesima planetarnog graničnog sloja.

Simulation of the Impacts of Urbanization on Winter Meteorological Fields over the Pearl River Delta Region

The influences of urbanization on weather in Guangdong Province, China, were studied using the Weather Research and Forecasting model from 31 December 2009 through 3 January 2010. Model outputs were compared with extensive monitoring of meteorological data to examine the simulation ability. Model results between tests (with and without land-use change) show that the urbanization had major effects on meteorological fields across nearly the entire Pearl River Delta region and particularly in urban areas. Studied fields (wind speed, temperature, precipitation, and sensible and latent heat fluxes) were affected by the urbanization of the PRD region. The major influences occurred in urban areas, where wind speeds decreased greatly, while the daytime surface upward sensible heat flux clearly increased. Unlike the sensible heat flux, the latent heat flux had a nonmonotonic increase or decrease. As a consequence of the two heat fluxes, 2-m temperature varied with location and time. Change of precipitation was complex. The main rain band became more concentrated, while precipitation decreased upwind of the urban area and increased downwind

Substituent effects and mechanism elucidation of enantioselective sulfoxidation catalyzed by vanadium Schiff base complexes

The effects of substituents of the Schiff base ligands on oxo-vanadium-catalyzed enantioselective sulfoxidation were first systematically studied, and a rational mechanism of enantioselective sulfoxidation based on our experimental data and the reported data is proposed

Thermodynamic studies on mechanism of chiral resolution by liquid chromatography

Chiral recognition is an important part of molecular recognition. Studies of mechanistic aspects of chiral resolution by liquid chromatography are helpful to optimize chromatographic conditions, to design novel chiral stationary phases and to understand chiral recogniton mechanisms. In this paper, the methodologies for deriving corresponding thermodynamic parameters in the chiral resolution processes by linear or nonlinear chromatography are reviewed. The meaning of correlative parameters is explained. The applications of these parameters in the studies of mechanistic aspects of retentions and chiral resolutions by liquid chromatography are expatiated, and corresponding research prospects are put forward

Numerical Simulation of the Effect of Cloud Condensation Nuclei Concentration on the Microphysical Processes in Typhoon Usagi

The Weather Research and Forecasting model version 3.2.1 with the Lin microphysics scheme was used herein to simulate super typhoon Usagi, which occurred in 2013. To investigate the effect of the concentration of cloud condensation nuclei (CCN) on the development of typhoon Usagi, a control simulation was performed with a CCN concentration of 100 cm−3, together with two sensitivity tests: C10 and C1000, having CCN concentrations of 10 cm−3 and 1000 cm−3, respectively. The path, intensity, precipitation, microphysical processes, and the release of latent heat resulting from the typhoon in all three simulations were analyzed to show that an increase in CCN concentration leads to decreases in intensity and precipitation, an increase of the cloudless area in the eye of the typhoon, a more disordered cloud system, and less latent heat released through microphysical processes, especially the automatic conversion of cloud water into rainwater. Overall, an increase in CCN concentration reduces the total latent heat released during the typhoon suggesting that typhoon modification by aerosol injection may be optimized using numerical simulations to ensure the strongest release of latent heat within the typhoon

Investigation of the Air Pollution Event in Beijing-Tianjin-Hebei Region in December 2016 Using WRF-Chem

The online coupled weather research and forecasting model with chemistry (WRF-Chem) was used to investigate an air pollution event during December 2016 in Beijing-Tianjin-Hebei urban agglomeration. Evaluation indicates that WRF-Chem captured the main weather conditions and pollutant distribution in this event. The primary meteorological drivers of air pollution formation were stationary atmospheric flows in both vertical and horizontal directions. High relative humidity and a strong temperature inversion accelerated event formation. In the shallow temperature inversion layer, aerosol particles were strongly confined near the surface, producing high surface contaminant concentrations. In addition, based on a normal experiment, three sensitivity experiments were constructed by adding hypothetical terrain (HT) of 400, 300, and 200 meters, over the region 115°E, 38.8°N to 117.54°E, 38.8°N. The results indicate that pollutants were diffused and transported below 400 meters, and the pollutant amounts concentrated south of the HT because of the HT blocking effect. Nevertheless, because there were less total contaminants north of the HT in the normal run, there was a slight decrease in pollutants north of the HT. There were some increases in pollution north of the HT because of local emissions, which were obstructed by the HT. The higher the HT, the stronger the blocking effect

Climate Impacts of the Biomass Burning in Indochina on Atmospheric Conditions over Southern China

Substantial biomass burning (BB) activities in Indochina during March and April of each year generate aerosols that are transported via westerly winds to southern China. These BB aerosols have both radiative (direct and semi-direct) and indirect effects on the climate. This study evaluates impacts of BB in Indochina during April 2013 on atmospheric conditions in southern China using WRF-Chem sensitivity simulations. We show that the atmosphere becomes drier and hotter under the aerosol radiative effect in southern China, while the changes linked to the indirect effect are opposite. The former (the latter) rises (reduces) surface temperature 0.13°C (0.19°C) and decrease (increase) water vapor mixing ratios 0.23 g kg⁻¹ (0.40 g kg⁻¹) at 700 hPa. Atmospheric responses to aerosols in turn affect aerosol dissipation. Specifically, BB aerosols absorb solar radiation and heat the local atmosphere, which inhibits the formation of clouds (reducing low-level cloud about 7%) related to the aerosol semi-direct effect. Less cloud enhances surface solar radiation flux and temperature. Otherwise, northeasterly winds linked to radiative effect suppress water vapor transport. In this case, precipitation reduces 1.09 mm day⁻¹, diminishing wet removal and westward transport of aerosols. Under the indirect effect, greater cloud coverage is formed, which reduces surface solar radiation flux and increases local latent heat release. This extra heating promotes air convection and diffusion of pollution. Regional mean precipitation increases 0.49 mm d⁻¹, facilitating wet pollution removal. Under indirect effect, aerosol extinction coefficient reduces 0.011 km⁻¹ at 2-km height over southern China. However, it increases around 0.002 km⁻¹ at 3-km height over southernmost China related to radiative effect. Therefore, atmospheric changes linked to indirect effect play a greater role in removing pollutants from the atmosphere than radiative effect over southern China