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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). 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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Committee on Atmospheric Sciences
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Philip A. Feiner, William H. Brune, David O. Miller, Li Zhang, Ronald C. Cohen, Paul S. Romer, Allen H. Goldstein, Frank N. Keutsch, Kate M. Skog, Paul O. Wennberg, Tran B. Nguyen, Alex P. Teng, Joost DeGouw, Abigail Koss, Robert J. Wild, Steven S. Brown, Alex Guenther, Eric Edgerton, Karsten Baumann, and Juliane L. Fry

1. Introduction Copious emissions of biogenic volatile organic compounds (BVOCs) dictate the atmospheric chemical composition and chemistry in forests. During the day, these BVOCs are oxidized primarily through reactions with the hydroxyl radical (OH) and ozone (O 3 ), which leads to the production of many oxygen-containing volatile, semivolatile, and low-volatility compounds and secondary organic aerosol. Because forests blanket almost a third of the global land, understanding forest oxidation

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Adam R. Edson and Peter R. Bannon

]. Atmospheric applications include the momentum forcing due to gravity waves that is an important component of the general circulation of the middle atmosphere (e.g., Fritts 1993 ). The sources of the gravity waves include excitation by airflow over orography, tropospheric convective activity, and jet stream adjustment. Various mechanisms (e.g., critical layer absorption and wave breaking) lead to the deposition of the gravity wave momentum. Zhu and Holton (1987) describe the atmospheric response to such

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Bingyi Wu

are generally used to characterize Arctic warming and AA. However, SATs are strongly influenced by the external forcing, such as sea ice concentrations (SICs) and surface sea temperatures (SSTs). Thus differences in SATs between the Arctic and the midlatitudes may exaggerate the thermal contrast of atmospheric circulation in the middle and lower troposphere. The updated study also indicated that warming in the lower troposphere associated with AA is not a direct driver of anomalous midlatitude

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Claude Frankignoul, Nathalie Sennéchael, Young-Oh Kwon, and Michael A. Alexander

1. Introduction Observational evidence that extratropical sea surface temperature (SST) anomalies have an influence on the large-scale atmospheric circulation during certain seasons has been found in the North Atlantic ( Czaja and Frankignoul 1999 , 2002 ; Rodwell and Folland 2002 ) and the North Pacific ( Liu et al. 2006 ; Frankignoul and Sennéchael 2007 , hereafter FS07 ). These air–sea interactions are highly relevant to the short-term climate predictability, as the SST anomalies tend to

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Hua Wang, Shipeng Su, Haichuan Tang, Lin Jiao, and Yunbo Li

1. Introduction Atmospheric radio wave ducting, which has a significant influence on electromagnetic wave propagation ( Dockery 1988 ), is a common phenomenon in some areas ( Abdul-Jauwad et al. 1991 ; Babin 1996 ); the probability of its occurrence is mainly related to the geographical position, season, and weather systems of the area. An atmospheric duct has significant influence on electronic equipment such as radars and communication equipment. It causes surveillance radar, navigation

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Bo Christiansen

1. Introduction The structure of the low-frequency atmospheric circulation in the extratropics is a subject of continuous interest. A far-reaching hypothesis suggests the existence of multiple circulation regimes. If this hypothesis is proven right it may have important consequences for both long-range weather forecasting and the understanding of climate variability and climate change ( Palmer 1999 ). However, the existence of atmospheric circulation regimes is still controversial. Some data

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Hai Lin, Gilbert Brunet, and Jacques Derome

1. Introduction The Madden–Julian oscillation (MJO) is the dominant mode of intraseasonal variability in the Tropics. It organizes convection and precipitation, thus has a great impact on the weather in the Tropics. It has a significant influence on the extratropical atmospheric variability, possibly through Rossby wave propagation (e.g., Ferranti et al. 1990 ; Hsu 1996 ), and thus could provide an important signal source for the extratropical weather forecasts on intraseasonal time scales

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Dale A. Lawrence and Ben B. Balsley

1. Introduction There is a growing need to understand the continuity of atmospheric processes on scales ranging from many kilometers down to scales as small as meters. The underlying impetus driving this need is the importance of understanding the far-reaching effects of multiscale turbulent energy cascading, wherein the energy in large-scale atmospheric processes (e.g., Kelvin–Helmholtz instabilities, convection) is transferred down to submeter scales via turbulent cascading. The consequences

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