25-Year analysis of tropical cirrus clouds: insights from ground and space-based LIDAR observations

IF 4.5 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research Pub Date : 2025-04-14 DOI:10.1016/j.atmosres.2025.108158

P. Riya Mol , M. Venkat Ratnam , C. Sudheesh

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引用次数: 0

Abstract

In this study, we used a two-and-a-half-decade dataset (1998–2023) of cirrus cloud properties obtained from a ground-based LIDAR located at the National Atmospheric Research Laboratory (NARL), Gadanki (13.5°N, 79.2°E), India. The percentage occurrence of cirrus clouds during the observational period is 42 %, and the most probable altitude is around 14.2 km. Significant seasonal variability in cirrus clouds is observed, with the highest frequency (74 %) during the monsoon season and the lowest (31 %) in winter. A detailed analysis was conducted on cirrus macro-physical, thermodynamic, and optical properties. Additionally, we investigated the long-term trends of the Tropical Tropopause Layer (TTL) to better understand its relationship with cirrus cloud properties. We observed a significant increasing trend in TTL thickness (0.003 ± 0.0005 km year⁻¹) and Cold point Tropopause Height (CPH) (0.003 ± 0.0003 km year⁻¹) while cirrus base (−0.003 ± 0.001 km year⁻¹), top (−0.005 ± 0.001 km year⁻¹), and geometrical thickness (−0.01 ± 0.0005 km year⁻¹) showed a decreasing trend over the observational period. We also analysed long-term trends of sub-visible, thin and thick cirrus clouds. A significant decreasing trend was found in the mid-cloud altitudes of sub-visible (−0.003 ± 0.001 km year⁻¹), thin (−0.006 ± 0.0009 km year⁻¹), and thick cirrus (−0.008 ± 0.0009 km year⁻¹) clouds, along with an increasing trend in mid-cloud altitude temperatures (0.035 ± 0.008 km year⁻¹_, 0.03 ± 0.007 km year⁻¹_, 0.05 ± 0.009 km year⁻¹) over the last 25 years. Additionally, a significant decreasing trend was noted in the geometrical thickness of sub-visible cirrus clouds and in the optical thickness of thin and thick cirrus clouds. The ground-based climatology obtained from the NARL lidar was compared with 18 years (2006–2023) of data obtained from the Cloud-Aerosol LIDAR with Orthogonal Polarization (CALIOP) satellite. Both datasets generally exhibit good agreement but differ in the magnitudes of several cirrus cloud properties, an important factor for understanding the radiative impacts of these cirrus clouds.

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热带卷云的25年分析：来自地面和天基激光雷达观测的见解

在这项研究中，我们使用了位于印度Gadanki（13.5°N, 79.2°E）的国家大气研究实验室（NARL）的地面激光雷达获得的25年半的卷云特性数据集（1998-2023）。在观测期间，卷云的发生率为42%，最可能的高度在14.2 km左右。观察到卷云的显著季节性变化，季风季节的频率最高（74%），冬季的频率最低（31%）。对卷云的宏观物理、热力学和光学性质进行了详细分析。此外，我们研究了热带对流层顶层（TTL）的长期趋势，以更好地了解其与卷云性质的关系。TTL厚度（0.003±0.0005 km - 1）和冷点对流层顶高度（CPH）（0.003±0.0003 km - 1）呈显著增加趋势，而卷云底部（−0.003±0.001 km - 1）、顶部（−0.005±0.001 km - 1）和几何厚度（−0.01±0.0005 km - 1）呈下降趋势。我们还分析了不可见、薄卷云和厚卷云的长期趋势。近25年来，亚可见光云（−0.003±0.001 km年−1）、薄云（−0.006±0.0009 km年−1）和厚云（−0.008±0.0009 km年−1）的云中高度呈显著下降趋势，云中高度温度（−1年0.035±0.008 km、−1年0.03±0.007 km、−1年0.05±0.009 km年−1）呈上升趋势。此外，亚可见光卷云的几何厚度以及薄卷云和厚卷云的光学厚度都有显著的减小趋势。将NARL激光雷达获得的地面气候学数据与CALIOP（正交偏振云-气溶胶激光雷达）卫星18年（2006-2023年）的数据进行了比较。这两个数据集总体上表现出很好的一致性，但在一些卷云特性的量级上有所不同，这是理解这些卷云的辐射影响的一个重要因素。

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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.