Search Results

You are looking at 121 - 130 of 46,301 items for :

  • All content x
Clear All
F. Hugo Lambert, Mark J. Webb, and Manoj M. Joshi

consider that, in a given GCM, perturbed climates relax strongly toward a similar value of ϕ under a variety of very different scenarios. For example, if a coupled atmosphere–ocean GCM is perturbed by applying a radiative forcing, then we can calculate a value of ϕ based on the land and ocean surface temperature anomalies at the new equilibrium. If the same GCM is perturbed by imposing an ocean surface temperature anomaly, we find that land temperatures rapidly adjust to produce a similar value of

Full access
Byung-Ju Sohn, Johannes Schmetz, Rolf Stuhlmann, and Joo-Young Lee

, the term A c ( L * f − L * c ) in Eq. (1) can be referred to as the cloud radiative forcing (CRF). In a satellite approach, CRF is generally determined by differencing the observed total flux from the clear-sky flux (e.g., Ramanathan et al. 1989 ). Thus, LW cloud radiative forcing [CRF( L )] is where L * is a direct measurement by the radiometer at the TOA while L * f is estimated from the composite of clear-sky pixels, which for longwave infrared measurements must be away from the cloudy

Full access
Timothy Andrews and Mark A. Ringer

1. Introduction a. Conceptual framework The earth’s energy balance provides a convenient framework for understanding the global response of the climate system to natural and anthropogenic forcings. During transient climate change, the global surface air temperature change Δ T (K) is determined by forcing, feedback, and heat uptake processes. These quantities can be related through a simple linear relationship whereby the net heat flux into the climate system N (W m −2 )—which is

Full access
David K. Hutchinson, Andrew Mc C. Hogg, and Jeffrey R. Blundell

Blundell 2006 ). Present day coarse-resolution models use vastly improved eddy parameterization schemes, which allow for an effective vertical momentum flux (see Gent et al. 1995 ). Thus, realistic values of circumpolar transport in the ACC are now achieved by coarse-resolution models ( Gent et al. 2001 ; Fyfe and Saenko 2005 ). However, the response of the ACC models to changes in wind forcing depends greatly on the resolution of the model. In coarse-resolution models, circumpolar transport strongly

Full access
Bruce T. Anderson, Jeff R. Knight, Mark A. Ringer, Jin-Ho Yoon, and Annalisa Cherchi

extreme precipitation ( Zhang et al. 2007 ; Min et al. 2009 ); atmospheric humidity ( Santer et al. 2007 ; Willett et al. 2010 ); and streamflow ( Hidalgo et al. 2009 )—are consistent with increased anthropogenic emissions of greenhouse gases and aerosols and inconsistent with other known forcing agents, including solar and volcanic activity ( Barnett et al. 2005 ; Solomon et al. 2007 ). However, such consistency does not preclude the possible influence of other unknown forcing agents ( Stone et al

Full access
Linda Schlemmer, Olivia Martius, Michael Sprenger, Cornelia Schwierz, and Arwen Twitchett

; Fuhrer and Schär 2005 ). On the synoptic-scale, high potential vorticity (PV) intrusions over western Europe play an important role in forcing HP along the Alpine south side ( Massacand et al. 1998 , 2001 ; Martius et al. 2006 ; Hoinka and Davies 2007 ). Generally, these intrusions adopt the form of narrow (∼500 km), deep (∼4 km), and meridionally elongated (∼2000 km) filaments of stratospheric air, termed PV streamers ( Appenzeller and Davies 1992 ), and reach from the British Isles southward to

Full access
Hyun-Ju Ahn, Soon-Ung Park, and Lim-Seok Chang

aerosols ( Miller and Tegen 1998 ; Tegen and Fung 1994 , 1995 ; Tegen et al. 1996 ; Li et al. 1996 ; Andreas 1996 ) on the climate. On a global scale, the radiative forcing by dust generally causes a reduction in the atmospheric dust load ( Perlwitz et al. 2001 ). Their experiments also showed that dust radiative forcing can lead to significant changes both in the soil dust cycle and the climate state. Miller et al. (2004) interpreted this reduction as an interaction between dust radiative

Full access
Reinout Boers, Fred Bosveld, Henk Klein Baltink, Wouter Knap, Erik van Meijgaard, and Wiel Wauben

Experiment (ERBE) and the Clouds and the Earth’s Radiant Energy System (CERES). Both datasets provide top-of-atmosphere (TOA) radiative fluxes that can be used to evaluate the model cloud representation or to determine the impact of clouds on the radiation balance of Earth. An often used method to determine cloud impact is to measure cloud forcing, which is defined as the difference between the net all-sky and the net clear-sky radiant fluxes ( Charlock and Ramanathan 1985 ). However, TOA fluxes only

Full access
E. J. Rohling, M. Medina-Elizalde, J. G. Shepherd, M. Siddall, and J. D. Stanford

1. Introduction Records of palaeoclimate change through glacial cycles in the recent geological past provide important observational evidence concerning the climate response to changes in radiative forcing (e.g., Hansen et al. 2007 , 2008 ; Köhler et al. 2010 ; Masson-Delmotte et al. 2010a ). However, uncertainties remain regarding important variables, such as temperature responses, the amplitude and causes of polar amplification, and about the magnitude of radiative forcing changes on

Full access
Yoshio Kawatani, Shingo Watanabe, Kaoru Sato, Timothy J. Dunkerton, Saburo Miyahara, and Masaaki Takahashi

the mean upward motion existing in the equatorial lower stratosphere, which has an estimated magnitude of approximately 0.3 mm s −1 (e.g., Mote et al. 1996 , 1998 ; Schoeberl et al. 2008 ). On the other hand, the downward-propagating speed of the QBO is approximately 0.5 mm s −1 . The equatorial mean upward motion makes the QBO phase move upward, whereas the wave forcing makes the QBO phase move downward. Therefore, the wave forcing should have a stronger effect than the equatorial upward flow

Full access