CAPE - A link amid thermodynamics and microphysics for the occurrence of severe thunderstorms

Lkkj & bl 'kks/k&i= dk mÌs’; dksydkrk ¼22°32¢] 88°20¢½ esa ekulwu iwoZ _rq ¼vizSy&ebZ½ ds nkSjku xtZ ds lkFk vkus okys Hkh"k.k rwQkuksa dh mRifÙk vkSj fodkl esa lgk;d es?k dh lw{e HkkSfrdh; izfØ;kvksa dh tk¡p djuk gSA bl v/;;u ls ;g irk pyk gS fd dksydkrk esa ekulwu&iwoZ _rq ds nkSjku xtZ ds lkFk vkus okys Hkh"k.k rwQkuksa ds nkSjku rkixfrdh;] xfrdh;] es?k dh lw{e HkkSfrdh vkSj fctyh pdeus dks J`a[kykc) djus esa laoguh; miyC/k foHko ÅtkZ ¼lh- ,- ih- bZ-½ lgk;d gSA bl v/;;u ls izkIr gq, ifj.kkeksa ls ;g irk pyk gS fd dksydkrk esa laoguh; miyC/k foHko ÅtkZ 1000 twYl izfr fd- xzk- ds Hkhrj izcy ikbZ xbZ tks eqDr laogu Lrj ¼,y- ,Q- lh-½ ls Åij fu/kkZfjr nkc Lrjksa ds Hkhrj ikbZ xbZ vkSj ok;q dh viMªk¶V xfr ds ln`’k eku fu"izHkkoh mRIykodrk Lrj ¼,y- ,u- ch-½ esa yxHkx 30 - 50 eh-@ lsdsaM ik, x,A bl v/;;u ls ;g Hkh irk pyk gS fd 5 fe- eh- rd ds O;kl ds vkdkj dh c¡wns fLFkj jg ldrh gS ftlds ckn vkdkj c<+us ds dkj.k cw¡nsa VwV tkrh gSaA tc cw¡n dh f=T;k 2-5 fe- eh- ls 3 fe- eh- dh ifjf/k esa gksrh gS rc cw¡nksa dk VwVuk 'kq: gks tkrk gS vkSj 3 fe- eh- ls 5 fe- eh- dh ifjf/k esa cw¡nksa ds VwVus dh laHkkouk vf/kd gksrh gS D;ksfd bl fLFkfr esa cw¡nksa ds yxkrkj VwVus dh dkj.k mudk thoudky cgqr NksVk gks tkrk gSA The aim of the present paper is to view the cloud microphysical processes entailed in the genesis and the development of the severe thunderstorms of pre-monsoon season (April - May) over Kolkata (22°32', 88°20'). The study shows that Convective Available Potential Energy (CAPE) is instrumental in establishing a linkage among thermodynamics, dynamics, cloud microphysics, and lightning during severe thunderstorm of pre monsoon season over Kolkata. The results of the present study reveal that for the thunderstorms reported over Kolkata, CAPE are found to be predominantly within 1000 joules per kgs within the prescribed pressure levels above the Level of Free Convection (LFC) and the corresponding values of the updraft speeds of the air are found to be nearly 30 - 50 m/s at the Level of Neutral Buoyancy (LNB). The study also depicts that the drops may grow up to the size of 5mm in diameter stably, beyond which, they tend to breakup due to the large drop instability. The breakup or splitting is observed to initiate when the drop radius is within the range of 2.5mm to 3mm and the breakup is most likely within the range of 3mm to 5mm because at this stage the lifetime of the drops are short due to the spontaneous breakup.

Global in-situ cloud phase observations during the airborne Atmospheric Tomography mission and A-LIFE field experiment

&lt;p&gt;Clouds are an important contributor to the uncertainty of future climate predictions, partly because cloud microphysical processes are still not fully understood. Interhemispheric observations, providing a dataset to investigate these cloud microphysical processes, are surprisingly rare - in particular observations using the same instrumentation on a global scale.&lt;/p&gt;&lt;p&gt;Between 2016 and 2018, the ATom (Atmospheric Tomography; 2016-2018) mission and the A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics; 2017) field experiment performed extensive airborne in-situ measurements of aerosol and cloud microphysical properties in the atmosphere up to approx. 13km altitude on a global scale. Profiling of the remote atmosphere over the Pacific and Atlantic Oceans from about 80&amp;#176;N to 86&amp;#176;S during ATom and systematic sampling of the region in the Mediterranean during A-LIFE provides a combined dataset of nearly 60h of measurements inside clouds.&lt;/p&gt;&lt;p&gt;We developed a novel cloudindicator algorithm, which utilizes measurements of a second-generation Cloud, Aerosol and Precipitation Spectrometer (CAPS, Droplet Measurement Technologies), relative humidity and temperature. It automatically detects clouds and classifies them according to their cloud phase.&lt;/p&gt;&lt;p&gt;In this study we present the novel cloudindicator algorithm and the combined dataset of ATom and A-LIFE global scale in-situ cloud observations. Furthermore, we show results of the cloud phase analysis of the extensive dataset.&lt;/p&gt;

Stable isotopes in precipitation and water vapor simulated by isotope-incorporated NICAM

&lt;p&gt;The stable water isotopes (SWIs) (&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;D) are used as an indicator of the intensity of the atmospheric hydrological cycle due to their large variability in time and space. Although data about vapor isotope ratio with high frequency and high resolution are now available by satellite observations and spectroscopic analyses, there is some room for discussion on the variability of isotope ratios in vapor and precipitation related to cloud microphysical processes.&lt;/p&gt;&lt;p&gt;Here, we incorporated SWI tracer into the latest version of a global cloud system resolving model (the Nonhydrostatic Icosahedral Atmospheric Model (NICAM)), iso-NICAM, and investigated the contribution of cloud microphysical processes to the variability of isotope ratios in precipitation and vapor. One of the merits used NICAM is that its physical process can cover from low spatial resolution to high spatial resolution. We conducted two mode simulations (GCM and CRM). The GCM mode simulation is based on the Arakawa-Schubert scheme as convective parameterization and a large-scale condensation scheme as the cloud physical process. In contrast, the CRM mode simulation is based on the a single-moment bulk cloud microphysics scheme with 6 water categories as cloud microphysical scheme, convective parameterization scheme was not used. These simulations are set to about 223 km of horizontal mesh resolution and 78 vertical layers. We conducted an AMIP-type climate experiment for one year from 1979.&lt;/p&gt;&lt;p&gt;The simulated precipitation &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O showed the latitude effect pattern (high &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O in low latitude region, low &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O in high latitude region), but those values in the CRM mode was slightly lower than that in the GCM mode . The simulated precipitation &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O in the CRM mode was lower in high altitude or inland regions compared with those in the GCM mode . Besides, the precipitation d-excess in the CRM mode shows large spatial variability compared with the GCM mode. Although the low spatial resolution was set in this study, these simulations indicated cloud microphysical processes are important for understanding the variability of isotope physics. We will conduct these simulations with finer spatial resolution and a more extended simulation period.&lt;/p&gt;

Analysis of variability in divergence and turn-over induced by three idealized convective systems with a 3D cloud resolving model

The sensitivity of upper tropospheric and lower stratospheric convective outflows and related divergence fields is analysed using an ensemble of cloud resolving model (CM1) simulations in LES-mode including various physically manipulated simulations for three different convective systems initialized with an idealized trigger. The main goal of this study is to assess to what extend the divergence field depends on cloud microphysical processes, the mode of convection and on the processes of convective momentum transport and moist static energy redistribution. We find that latent heat release (representing the microphysical uncertainty) plays an essential role by explaining much of magnitude of the divergence field that will be formed. Convective organisation explains another important fraction of the variability in the divergence field that is formed by a convective system and behaves non-linearly, likely partly via condensation and subsequent (re-)evaporation/sublimation. The detrainment of stratospheric air also shows large sensitivity among the experiments.

Different effects of latent heat in planetary boundary layer and cloud microphysical processes on Typhoon 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.

Characterization and first results from LACIS-T: a moist-air wind tunnel to study aerosol–cloud–turbulence interactions

The interactions between turbulence and cloud microphysical processes have been investigated primarily through numerical simulation and field measurements over the last 10 years. However, only in the laboratory we can be confident in our knowledge of initial and boundary conditions and are able to measure under statistically stationary and repeatable conditions. In the scope of this paper, we present a unique turbulent moist-air wind tunnel, called the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T) which has been developed at TROPOS in order to study cloud physical processes in general and interactions between turbulence and cloud microphysical processes in particular. The investigations take place under well-defined and reproducible turbulent and thermodynamic conditions covering the temperature range of warm, mixed-phase and cold clouds (25∘C>T>-40∘C). The continuous-flow design of the facility allows for the investigation of processes occurring on small temporal (up to a few seconds) and spatial scales (micrometer to meter scale) and with a Lagrangian perspective. The here-presented experimental studies using LACIS-T are accompanied and complemented by computational fluid dynamics (CFD) simulations which help us to design experiments as well as to interpret experimental results. In this paper, we will present the fundamental operating principle of LACIS-T, the numerical model, and results concerning the thermodynamic and flow conditions prevailing inside the wind tunnel, combining both characterization measurements and numerical simulations. Finally, the first results are depicted from deliquescence and hygroscopic growth as well as droplet activation and growth experiments. We observe clear indications of the effect of turbulence on the investigated microphysical processes.

A numerical study of dust particle effects on cloud microphysical processes and hail/precipitation impacts

&lt;p&gt;The effects of natural aerosols on microphysical processes in clouds are quite important for their development and evolution and still pose some unresolved questions on the impact they have in the atmosphere and climate. The processes where they interfere, can lead to an uncertainty in the intensity of precipitation and the hydrometeor species as well as the temporal and spatial extent of the affected areas. Apart from the scientific interest of such studies, the outcome highly affects applications and early warning systems associated to water management, &amp;#160;food security and agriculture.&lt;/p&gt;&lt;p&gt;For the needs of the study, the state of the art atmospheric modeling system RAMS-ICLAMS was used to investigate the effects of desert dust concentrations on microphysical processes in clouds. The model is able to run in very high resolutions in order to resolve cloud processes explicitly. Extreme case studies were selected, simulated and the model performance was evaluated showing satisfactory results. Sensitivity tests were performed in order to quantify the direct, indirect and semi-direct impact of CCN and IN concentrations. These tests showed notable effects on the cloud microphysical processes, as well as on hydrometeors. This further enhances the need for a more accurate description of aerosol feedbacks in regional and climate atmospheric models.&lt;/p&gt;