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Atmospheric Radiation Working Group (ARWG)

This document is a summary of the major problems in atmospheric radiation, together with recommendations for appropriate action, as evaluated by the U.S. Atmospheric Radiation Working Group (ARWG). 1 It is intended for information and possible use by atmospheric scientists, scientific committees, agencies engaged in the support of atmospheric research, and those who have the responsibility for planning future scientific programs.

The report summarizes the present status and outlines the major unsolved problems of the following five aspects of atmospheric radiation: 1) radiative transfer in realistic atmospheres, 2) radiative energy budgets, 3) radiative properties of atmosphere and surface, 4) radiative instruments and measurements, and 5) radiative interactions in dynamical systems. The final, and probably most important, section consists of recommendations for action that can be taken now to start filling the gaps in our knowledge of atmospheric radiation which are considered by the ARWG to be of highest priority. A list of members of the ARWG steering committee is included in the Appendix.

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Hiroyuki Kurokawa
and
Taishi Nakamoto

1. Introduction The limit of the planetary radiation (the so-called longwave radiation) of an ocean planet is determined by various mechanisms called “radiation limits.” These radiation limits are important when considering the formation of an ocean ( Abe and Matsui 1988 ) and when attempting to determining the habitable zone of exoplanets ( Kasting et al. 1993 ). The radiation limits are related to the inner edge of the habitable zone. The radiation limits (or runaway greenhouse effect) were

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Dominik Michel
,
Rolf Philipona
,
Christian Ruckstuhl
,
Roland Vogt
, and
Laurent Vuilleumier

1. Introduction Accurate net radiation flux measurements are indispensable for the determination of the surface energy budget. Net radiation, being an important part of the surface energy balance, forms together with the storage flux the available energy that is partitioned into the turbulent heat fluxes. The fact that, under ideal conditions, the available energy should equal the sum of turbulent heat fluxes—in general addressed as energy balance closure—makes the measured net radiation a

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Rosie Howard
and
Roland Stull

1. Introduction The surface radiation budget in snow-covered mountainous terrain is important in hydrology ( Fierz et al. 2003 ), snowmelt modeling ( Plüss and Ohmura 1997 ; Sicart et al. 2006 ), and glacier energy balance investigations ( Brock et al. 2010 ). Avalanche forecasting and safety studies ( McClung 2002a , b ; McClung and Schaerer 2006 ) show the significance of the radiation budget for a natural alpine snowpack. Ski racing takes place on manually prepared ski pistes. It has been

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S. M. S. Costa
and
K. P. Shine

article is intended to be a pedagogical discussion of one component of the KT97 figure [which was not updated in Trenberth et al. (2009) ], which is the amount of longwave radiation labeled “atmospheric window.” KT97 estimate this component to be 40 W m −2 compared to the total outgoing longwave radiation (OLR) of 235 W m −2 ; however, KT97 make clear that their estimate is “somewhat ad hoc” rather than the product of detailed calculations. The estimate was based on their calculation of the

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Vincent E. Larson
,
Kurt E. Kotenberg
, and
Norman B. Wood

participants can easily implement the same radiative formula. Second, LESs usually last 6 h or less, a period too short to heat or cool clear air significantly, thereby vitiating the advantage of accurate multiband radiative calculations for gaseous absorption. Third, an analytic longwave formula is computationally inexpensive. This is advantageous because considerable expense is associated with both LES and numerical radiation calculations. LES is expensive because it requires a small grid size (often

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Husi Letu
,
Run Ma
,
Takashi Y. Nakajima
,
Chong Shi
,
Makiko Hashimoto
,
Takashi M. Nagao
,
Anthony J. Baran
,
Teruyuki Nakajima
,
Jian Xu
,
Tianxing Wang
,
Gegen Tana
,
Sude Bilige
,
Huazhe Shang
,
Liangfu Chen
,
Dabin Ji
,
Yonghui Lei
,
Lesi Wei
,
Peng Zhang
,
Jun Li
,
Lei Li
,
Yu Zheng
,
Pradeep Khatri
, and
Jiancheng Shi

Surface downward solar radiation (SSR) is an essential driving force that significantly influences energy exchange between Earth’s surface and atmosphere ( Houborg et al. 2007 ; Wild 2009 ; Zhang et al. 2018 ; Liang et al. 2021 ; Wang et al. 2023 ). SSR can be divided into four compositions (SSRC) by wavelength that relate to different applications: shortwave radiation (SWR; 0.3–3.0 μ m), which quantifies the overall solar energy resources ( Gitelson et al. 2021 ), photosynthetically

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Kaicun Wang
and
Shunlin Liang

1. Introduction Surface net radiation R n is the sum of incident downward and upward shortwave and longwave radiation: where S ↓ and S ↑ are the surface downward and upward shortwave radiation, L ↓ and L ↑ are the surface downward and upward longwave radiation, α is surface albedo, and S n is surface net shortwave radiation. The downward components of R n are controlled by solar zenith angle (i.e., time of day, season, and latitude), cloud amount, atmospheric water vapor amount

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Evelyn Jäkel
,
Manfred Wendisch
,
Mario Blumthaler
,
Rainer Schmitt
, and
Ann R. Webb

1. Introduction Accurate atmospheric measurements of spectral ultraviolet (UV) radiation (290–400 nm) are challenging, in particular, in spatially inhomogeneous atmospheric and surface albedo conditions. The absorption of UV radiation due to the stratospheric ozone causes a strong decrease of the downward UV reaching the troposphere. It causes a sudden drop of the spectral radiation of several orders of magnitudes toward smaller wavelengths ( λ ), which is referred to as the atmospheric cutoff

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Bolei Yang
and
Zhe-Min Tan

.g., Nicholls and Montgomery 2013 ; Nicholls 2015 ). Three leading mechanisms have been postulated to explain how radiation can affect convective activity ( Fig. 1 ). First, the stratification could be changed by large-scale nocturnal environmental cooling (e.g., Dudhia 1989 ; Tao et al. 1996 ; Melhauser and Zhang 2014 ; Tang and Zhang 2016 ). The absence of shortwave heating makes the troposphere cooler at night, which favors convection by increasing relative humidity and enhancing convective

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