scholarly journals Top‐of‐Atmosphere Radiation Budget and Cloud Radiative Effects over the Tibetan Plateau and Adjacent Monsoon Regions from CMIP6 simulations

2021 ◽  
Author(s):  
JianDong Li ◽  
ZhiAn Sun ◽  
YiMin Liu ◽  
QingLong You ◽  
GuoXing Chen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Radiation Budget ◽  
The Tibetan Plateau ◽  
Radiative Effects ◽  
Cloud Radiative Effects

scholarly journals Effects of Cloud Microphysics on the Vertical Structures of Cloud Radiative Effects over the Tibetan Plateau and the Arctic

2021 ◽  
Vol 13 (14) ◽  
pp. 2651
Author(s):  
Yafei Yan ◽  
Yimin Liu ◽  
Xiaolin Liu ◽  
Xiaocong Wang
Keyword(s):  
Tibetan Plateau ◽  
Cloud Microphysics ◽  
Mixed Phase ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
The Tibetan Plateau ◽  
Radiative Effects ◽  
Cloud Radiative Effects ◽  
Phase Water

The Tibetan Plateau (TP) and the Arctic are both cold, fragile, and sensitive to global warming. However, they have very different cloud radiative effects (CRE) and influences on the climate system. In this study, the effects of cloud microphysics on the vertical structures of CRE over the two regions are analyzed and compared by using CloudSat/CALIPSO satellite data and the Rapid Radiative Transfer Model. Results show there is a greater amount of cloud water particles with larger sizes over the TP than over the Arctic, and the supercooled water is found to be more prone to exist over the former than the latter, making shortwave and longwave CRE, as well as the net CRE, much stronger over the TP. Further investigations indicate that the vertical structures of CRE at high altitudes are primarily dominated by cloud ice water, while those at low altitudes are dominated by cloud liquid and mixed-phase water. The liquid and mixed-phase water results in a strong shallow heating (cooling) layer above the cooling (heating) layer in the shortwave (longwave) CRE profiles, respectively.

scholarly journals Black carbon-induced snow albedo reduction over the Tibetan Plateau: uncertainties from snow grain shape and aerosol–snow mixing state based on an updated SNICAR model

2018 ◽  
Vol 18 (15) ◽  
pp. 11507-11527 ◽  
Author(s):  
Cenlin He ◽  
Mark G. Flanner ◽  
Fei Chen ◽  
Michael Barlage ◽  
Kuo-Nan Liou ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Black Carbon ◽  
Grain Shape ◽  
Interactive Effect ◽  
The Tibetan Plateau ◽  
Mixing State ◽  
Radiative Effects ◽  
Snow Albedo ◽  
Internal Mixing ◽  
The Mean

Abstract. We implement a set of new parameterizations into the widely used Snow, Ice, and Aerosol Radiative (SNICAR) model to account for effects of snow grain shape (spherical vs. nonspherical) and black carbon (BC)–snow mixing state (external vs. internal). We find that nonspherical snow grains lead to higher pure albedo but weaker BC-induced albedo reductions relative to spherical snow grains, while BC–snow internal mixing significantly enhances albedo reductions relative to external mixing. The combination of snow nonsphericity and internal mixing suggests an important interactive effect on BC-induced albedo reduction. Comparisons with observations of clean and BC-contaminated snow albedo show that model simulations accounting for both snow nonsphericity and BC–snow internal mixing perform better than those using the common assumption of spherical snow grains and external mixing. We further apply the updated SNICAR model with comprehensive in situ measurements of BC concentrations in the Tibetan Plateau snowpack to quantify the present-day (2000–2015) BC-induced snow albedo effects from a regional and seasonal perspective. The BC concentrations show distinct and substantial sub-regional and seasonal variations, with higher values in the non-monsoon season and low altitudes. As a result, the BC-induced regional mean snow albedo reductions and surface radiative effects vary by up to an order of magnitude across different sub-regions and seasons, with values of 0.7–30.7 and 1.4–58.4 W m−2 for BC externally mixed with fresh and aged snow spheres, respectively. The BC radiative effects are further complicated by uncertainty in snow grain shape and BC–snow mixing state. BC–snow internal mixing enhances the mean albedo effects over the plateau by 30–60 % relative to external mixing, while nonspherical snow grains decrease the mean albedo effects by up to 31 % relative to spherical grains. Based on this study, extensive measurements and improved model characterization of snow grain shape and aerosol–snow mixing state are urgently needed in order to precisely evaluate BC–snow albedo effects.

scholarly journals An Improved Algorithm for the Detection of Cirrus Clouds in the Tibetan Plateau Using VIIRS and MODIS Data

2015 ◽  
Vol 32 (11) ◽  
pp. 2125-2129 ◽  
Author(s):  
L. Xia ◽  
F. Zhao ◽  
Y. Ma ◽  
Z. W. Sun ◽  
X. Y. Shen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Land Surface ◽  
Infrared Imaging ◽  
Global Radiation ◽  
Cirrus Clouds ◽  
Radiation Budget ◽  
Cirrus Cloud ◽  
The Tibetan Plateau ◽  
Test Algorithm ◽  
Improved Algorithm

AbstractCirrus clouds play an important role in the global radiation budget balance. However, the existing MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) cirrus cloud test algorithms struggle to provide accurate cirrus cloud information for the Tibetan Plateau region. In this study, the 1.38-μm cirrus cloud test was improved by adding 11-μm brightness temperature and a multiday average land surface temperature test. An algorithm sensitivity analysis indicated that the proposed algorithm lowered the threshold of the existing 1.38-μm algorithm to 0.005 in the winter and did not produce any observable misclassifications. Compared to the existing 1.38-μm cirrus test algorithm, the accuracy validation indicated that the improved algorithm detected 31.7% more cirrus clouds than the existing VIIRS 1.38-μm cirrus test and yielded 14% fewer misclassifications than the MODIS 1.38-μm cirrus test.

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