Satellite based study on the role of Cloud Condensation Nuclei (CCN) and atmospheric thermodynamics in warm cloud evolution

IF 4.4 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research Pub Date : 2025-09-01 DOI:10.1016/j.atmosres.2025.108452

Subin Jose , Sijo Joseph , N.B. Lakshmi

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引用次数: 0

Abstract

The study presents observational evidence for the impact of Cloud Condensation Nuclei (CCN) concentration and atmospheric thermodynamic conditions on the diffusion growth and collision-coalescence processes in warm cloud evolution. We used multi-band optical data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (NPP) satellite (2013–2018) to identify the convective cloud clusters and examine the warm cloud evolution under different thermodynamic and pollution conditions based on cloud top temperature (T) - cloud drop effective radius (r_e) relationships. Analysis revealed that diffusion growth is predominant under polluted and stable (Estimated Inversion Strength (EIS) > 1 K) atmospheric conditions. In the unstable regime (EIS < 1 K), relative dispersion (ϵ) reaches its maximum (∼0.39) at a CCN concentration of around 1000 cm⁻³ and supersaturation remains higher at lower CCN concentrations and decreases rapidly beyond ∼1000 cm⁻³ which marks the transitional point between the aerosol-limited and updraft-limited regimes. However in the stable regime (EIS > 1 K), ϵ remains relatively low (between 0.10 and 0.25) with low supersaturation. In unstable conditions the estimated cloud top entrainment index (ECTEI) is found to be −5.6 ± 1.5 indicating more favourable conditions for entrainment, while in stable conditions ECTEI is found to be −2 ± 3.3 reflecting entrainment suppression. Although the Twomey effect is found to be predominant under stable atmospheric conditions, a nonlinear relationship exists between droplet growth and CCN concentration. In the aerosol limited regime, an increase in growth rate ranging from ∼0.0026

μ

m/s to 0.0032

μ

m/s is observed while at high CCN concentrations (above ∼1000 cm⁻³) growth rates decreases to 0.0025

μ

m/s. These observations can help refine aerosol–cloud interaction (ACI) parameterizations in climate models, thereby reducing uncertainties in the estimation of aerosol effective radiative forcing under a warming climate.

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基于卫星的云凝结核（CCN）和大气热力学在暖云演化中的作用研究

本研究提供了云凝结核（CCN）浓度和大气热力学条件对暖云演化中扩散生长和碰撞合并过程影响的观测证据。基于云顶温度(T) -云降有效半径（re）关系，利用2013-2018年中国国家极轨合作伙伴关系（NPP）卫星上搭载的可见光红外成像辐射计套件（VIIRS）的多波段光学数据，对对流云团进行了识别，并对不同热力和污染条件下的暖云演化进行了研究。分析表明，在污染和稳定的（估计逆温强度（EIS） > 1k）大气条件下，扩散生长占主导地位。在不稳定状态下（EIS < 1k），相对弥散（λ）在CCN浓度约为1000 cm−3时达到最大值（~ 0.39），在CCN浓度较低时过饱和度仍然较高，超过~ 1000 cm−3后迅速降低，这标志着气溶胶限制和上升气流限制之间的过渡点。然而，在稳定状态下（EIS > 1k），过饱和度低，λ保持相对较低（在0.10和0.25之间）。在不稳定条件下，估计的云顶夹带指数（ECTEI）为- 5.6±1.5，表明夹带条件更有利，而在稳定条件下，ECTEI为- 2±3.3，反映了夹带抑制。虽然在稳定的大气条件下，Twomey效应占主导地位，但液滴生长与CCN浓度之间存在非线性关系。在气溶胶限制条件下，观察到生长速率的增加范围从~ 0.0026 μm/s到0.0032 μm/s，而在高CCN浓度（高于~ 1000 cm−3）下，生长速率降低到0.0025 μm/s。这些观测有助于改进气候模式中的气溶胶-云相互作用（ACI）参数化，从而减少气候变暖条件下气溶胶有效辐射强迫估算的不确定性。

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来源期刊

Atmospheric Research 地学-气象与大气科学

CiteScore

9.40

自引率

10.90%

发文量

460

审稿时长

47 days

期刊介绍： The journal publishes scientific papers (research papers, review articles, letters and notes) dealing with the part of the atmosphere where meteorological events occur. Attention is given to all processes extending from the earth surface to the tropopause, but special emphasis continues to be devoted to the physics of clouds, mesoscale meteorology and air pollution, i.e. atmospheric aerosols; microphysical processes; cloud dynamics and thermodynamics; numerical simulation, climatology, climate change and weather modification.