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Carynelisa Erlick, Jonathan P. D. Abbatt, and Yinon Rudich

1. Introduction Ammonium sulfate (AS)–containing aerosols are among the most common aerosols in the troposphere, contributing significantly to direct solar radiative forcing of the climate (e.g., Forster et al. 2007 ). An important consideration in assessing their direct radiative forcing is their change in size and composition due to uptake of water at different relative humidities, which exhibits a well-known hysteresis pattern. As the relative humidity increases from 0%, a crystalline AS

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Jinwon Kim, Yu Gu, and K. N. Liou

1. Introduction The impact of aerosol radiative forcing on the energy and water cycle is an important concern in understanding regional climate, but the details of its spatiotemporal variability remain uncertain. Aerosols influence the energy and water cycle primarily via scattering and absorption of solar radiation (direct effect) and via their impact on the characteristics of clouds and precipitation (indirect effect). In climate modeling and long-range forecasts, uncertainties in aerosol

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Masakazu Yoshimori and Anthony J. Broccoli

1. Introduction The effect of elevated atmospheric carbon dioxide on climate has been a focus of many climate change studies. While CO 2 is the most important radiative forcing agent between the preindustrial period and the present day, contributions of other forcing agents are not negligible (e.g., Charlson et al. 1992 ; Haywood and Boucher 2000 ; Solomon et al. 2007 ; Hansen and Sato 2001 ; NRC 2005 ). In addition, it has been shown that climate sensitivity, defined here as the global

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Pablo F. Dornes, John W. Pomeroy, Alain Pietroniro, and Diana L. Verseghy

environment. The evaluation is conducted by comparing the effects on model performance of aggregated to distributed initial conditions and forcing data. 2. Study basin and observations The selected study area was Granger Basin (60°31′N, 135°07′W) which is part of Wolf Creek Research Basin situated 15 km south of Whitehorse, Yukon Territory, Canada ( Fig. 1 ). Granger Basin, drained by Granger Creek, is located in the mountainous headwaters of the Yukon River basin and compromises a drainage area about 8

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Masakazu Yoshimori, Julia C. Hargreaves, James D. Annan, Tokuta Yokohata, and Ayako Abe-Ouchi

climate sensitivity ( Edwards et al. 2007 ). In particular, the last glacial maximum (LGM) has received much of the attention as the forcing is relatively large and well known, and reasonably accurate quantitative reconstructions of the climate response are available. The past and future temperature changes are linked through the so-called climate sensitivity parameter λ , defined as surface temperature change Δ T s normalized by adjusted radiative forcing F ; Here the overbar denotes global

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Jae N. Lee, Drew T. Shindell, and Sultan Hameed

, 2007 ). Kodera and Shibata (2006) suggest that Indian Ocean monsoon circulation is correlated with 11-yr solar cycle via altered planetary wave fraction and stratospheric meridional circulation changes. Paleoclimate lake and marine records indicate changes on longer time scales in the regional hydrological cycle during the Holocene (to ∼10 kyr BP), even though discrepancies exist between them about the timing and nature of the changes. The dominant forcing for the Holocene is known to be the

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Thomas R. Parish, Matthew D. Burkhart, and Alfred R. Rodi

1. Introduction The most fundamental forcing term in the equation of motion that governs atmospheric dynamics is the pressure gradient force. In particular, it is the horizontal component of the pressure gradient force that is critical to the understanding of atmospheric motion. Typically, the horizontal component of the pressure gradient force (PGF) is four orders of magnitude smaller than the vertical component, yet is responsible for the forcing of nearly all atmospheric motions. Knowledge

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John B. Mickett, Yolande L. Serra, Meghan F. Cronin, and Matthew H. Alford

1. Introduction Weakly damped systems have the potential to become resonant when the forcing is closely tuned to the preferential or natural frequency response of the system. In the case of the ocean mixed layer, which has a dominant response to wind stress in the form of inertial motions with frequencies near the local Coriolis frequency f , resonance is likely to occur when the wind stress vector ( τ ) either rotates in phase with the mixed layer inertial motions or forces the mixed layer in

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Paulo Ceppi, Giuseppe Zappa, Theodore G. Shepherd, and Jonathan M. Gregory

1. Introduction A well-known feature of the atmospheric circulation response to CO 2 forcing is the overall poleward shift of extratropical circulation, including the jet streams ( Kushner et al. 2001 ; Yin 2005 ; Barnes and Polvani 2013 ), the storm tracks ( Chang et al. 2012 ; Harvey et al. 2014 ), and the edge of the tropics ( Lu et al. 2007 ; Kang and Polvani 2011 ; Ceppi et al. 2013 ). This poleward shift is primarily mediated by sea surface temperature (SST) changes, as demonstrated

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Ian M. Ferguson, John A. Dracup, Philip B. Duffy, Philip Pegion, and Siegfried Schubert

conditions in conjunction with warm SST anomalies in the Indian Ocean. Similarly, Schubert et al. (2004b) and Seager et al. (2005) showed that ensembles of AGCM simulations forced with observed twentieth-century SST reproduced much of the observed low-frequency variability in twentieth-century precipitation over the U.S. Great Plains, including the timing and duration of major droughts of the 1930s and 1950s. These studies suggest that ocean–atmosphere forcing by persistent SST anomalies is a primary

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