Radiative forcing of the tropical thick anvil evaluated by combining TRMM with atmospheric radiative transfer model
Radiative forcing of the tropical thick anvil evaluated by combining TRMM with atmospheric radiative transfer model
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TRMM与大气辐射传输模型相结合评估热带厚砧辐射强迫
DOI：
10.1002/asl.746
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发表时间：
2017
影响因子：
3
通讯作者：
Zhu Jiachen
中科院分区：
文献类型：
--
作者：
Yang Yuanjian;Fu Yunfei;Qin Fang;Zhu Jiachen
砧云的存在显著影响热带平均辐射收支，增加气候模式模拟的不确定性。利用1998 - 2007年热带测雨使命任务（TRMM）降水雷达（PR）和可见光和红外扫描仪（VIRS）观测资料，分析了热带地区（20°S-20°N）厚砧顶、厚砧底、厚砧发生率、云有效半径（CER）和云光学厚度（COD）的气候学平均分布特征。利用圣巴巴拉DISORT大气辐射传输模式（SBDART）模拟了短波（0.2 ~ 4 μm）和长波（4 ~ 50 μm）厚砧辐射强迫，即短波辐射强迫（SRF）和长波辐射强迫（LRF）及其在不同高度的净效应。结果表明，厚砧在陆地上的顶底比在海洋上的高，CER较小，COD较厚。在大气层顶（TOA），厚砧的净辐射效应是正变暖，这意味着地气系统获得厚砧强迫的能量。在地表，厚铁砧的净辐射效应在陆面为正增温，在洋面为负降温。在一般情况下，砧SRF，LRF和净效应随不同的地理位置，也提出了很大的陆地-海洋的差异，由于不同的砧表面加热和地形所迫使的属性。所有较强的砧座SRF、LRF和净效应的空间分布与砧座比例较高的地区，如亚洲季风区、热带辐合带（ITCZ）、南太平洋辐合带（SPCZ）、热带非洲、中美洲和南美洲，都有很好的匹配。此外，本文的工作还证明了利用SBDART模式结合卫星观测资料定量计算大尺度云的网格单元SRF和LRF是一种有效的方法。
The presences of anvil clouds significantly affect the tropical mean radiation budget and increase the uncertainty of climate model simulations. In this study, the climatological mean distributions of thick anvil parameters, such as top, bottom, occurrence, cloud effective radius (CER) and cloud optical depth (COD) in the tropics (20°S–20°N) are investigated by Tropical Rainfall Measuring Mission's (TRMM) precipitation radar (PR) and visible and infrared scanner (VIRS) from 1998 to 2007. The thick anvil radiative forcing at shortwave (0.2 ∼ 4 µm) and longwave (4 ∼ 50 µm) length, i.e. Shortwave radiative forcing (SRF) and Longwave radiative forcing (LRF) and their net effects at different altitudes are simulated with Santa Barbara DISORT Atmospheric Radiative Transfer Model (SBDART). The results show that thick anvils present higher top/bottom, smaller CER, and thicker COD over land than those over ocean. At the top of atmosphere (TOA), net radiative effects of thick anvils are positive warming, which means the earth‐atmosphere system obtains energy forced by thick anvils. At earth surface, net radiative effects of thick anvils are positive warming at land surface and negative cooling at ocean surface, respectively. In general, anvil SRF, LRF and net effects vary with different geographical locations and also present large land–ocean differences in the tropics, due to different anvil properties forced by the surface heating and topography. All spatial patterns of stronger anvil SRF, LRF and net effects are well matched with the places where exist higher fractions of anvils, such as Asian monsoon zone, the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), tropical Africa, Mid‐America and South America. In addition, the present work provides an evidence that it is an effective approach to calculate quantitatively the grid‐cell SRF and LRF of cloud at a large scale by using the SBDART model with inputs from satellite observations.