Abstract Convective clouds evolve through intensification, reorganization, and dissipation mechanisms within their 2–3-hr lifespan, dominating global high rain rate precipitation. Infrared heating and cooling (IRH/C) intricately influence these processes throughout their lifecycle. We have parameterized radiative IRH/C to evaluate their impact on vertical momentum within convective clouds. The temperature change within a convective cloud due to IRH/C has been parameterized by simultaneously solving line-by-line infrared radiative transfer, the heat advection diffusion equation, and the specific moist entropy equation. Then, the perturbations in vertical profiles of specific moist entropy, momentum, and vertical velocity have been calculated. The developed parameterization has been initialized using the ERA5 reanalysis on October 17, 2018, over Gadanki, India, and the HITRAN spectroscopic database. Our results showed a consistent decrease in the absorption coefficient at constant rates relative to pressure levels. Notably, maximum infrared heating occurred near the surface consistently across all times. A positive perturbation in moist entropy and a temperature increase, suggest the effects of IR heating and latent heat release during 10, 11, 14, and 15 UTC, indicating cloud growth. Additionally, the positive specific vertical momentum during the same period suggests updrafts within the cloud, consistent with cloud formation. In contrast, during 12 and 13 UTC, cloud dissipation is indicated by negative moist entropy and temperature changes, accompanied by downdrafts (negative specific momentum). This study emphasized the importance of IRH/C in the cloud’s cyclic dissipation, intensification, and hydrometeor redistribution. Research highlights <UnorderedList Mark="Bullet"> <ItemContent> The parameterization has been devised to assess the influence of infrared heating and cooling (IRH/C) on the evolution of convective clouds. </ItemContent> <ItemContent> The vertical distribution of infrared radiative properties within the atmosphere has been estimated using HITRAN spectroscopic parameters. </ItemContent> <ItemContent> IRH/C plays pivotal role in governing the vertical structure of clouds by regulating moist entropy and vertical momentum transfer. </ItemContent> <ItemContent> Moist entropy disturbances, either positive or negative, induced by IRH/C signify hydrometeor evaporation (growth) or melting (decay) within clouds. </ItemContent> <ItemContent> The impact of IRH/C extensively alters the vertical velocity, influencing the occurrence of updrafts or downdrafts and subsequently affecting hydrometeor dispersion within the cloud. </ItemContent> </UnorderedList>

Infrared heating/cooling-induced perturbation in vertical velocity inside convective clouds

期刊论文
发表日期：

2025年8月27日

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Subhrajit Rath,
Amit Kesarkar,
Kavita Patnaik,
Jyoti Bhate,
Govindan Kutty

摘要

Abstract

Convective clouds evolve through intensification, reorganization, and dissipation mechanisms within their 2–3-hr lifespan, dominating global high rain rate precipitation. Infrared heating and cooling (IRH/C) intricately influence these processes throughout their lifecycle. We have parameterized radiative IRH/C to evaluate their impact on vertical momentum within convective clouds. The temperature change within a convective cloud due to IRH/C has been parameterized by simultaneously solving line-by-line infrared radiative transfer, the heat advection diffusion equation, and the specific moist entropy equation. Then, the perturbations in vertical profiles of specific moist entropy, momentum, and vertical velocity have been calculated. The developed parameterization has been initialized using the ERA5 reanalysis on October 17, 2018, over Gadanki, India, and the HITRAN spectroscopic database. Our results showed a consistent decrease in the absorption coefficient at constant rates relative to pressure levels. Notably, maximum infrared heating occurred near the surface consistently across all times. A positive perturbation in moist entropy and a temperature increase, suggest the effects of IR heating and latent heat release during 10, 11, 14, and 15 UTC, indicating cloud growth. Additionally, the positive specific vertical momentum during the same period suggests updrafts within the cloud, consistent with cloud formation. In contrast, during 12 and 13 UTC, cloud dissipation is indicated by negative moist entropy and temperature changes, accompanied by downdrafts (negative specific momentum). This study emphasized the importance of IRH/C in the cloud’s cyclic dissipation, intensification, and hydrometeor redistribution.

Research highlights

The parameterization has been devised to assess the influence of infrared heating and cooling (IRH/C) on the evolution of convective clouds.

The vertical distribution of infrared radiative properties within the atmosphere has been estimated using HITRAN spectroscopic parameters.

IRH/C plays pivotal role in governing the vertical structure of clouds by regulating moist entropy and vertical momentum transfer.

Moist entropy disturbances, either positive or negative, induced by IRH/C signify hydrometeor evaporation (growth) or melting (decay) within clouds.

The impact of IRH/C extensively alters the vertical velocity, influencing the occurrence of updrafts or downdrafts and subsequently affecting hydrometeor dispersion within the cloud.