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one-layer atmosphere. They showed the existence of a transient growth of spatial variance in the transport 40 yr after the perturbation sets in. This growth appears through an increase of both the temperature and salinity perturbations due to the circulation anomalies. On the other hand, sensitivity studies of the ocean circulation have been made using the adjoint of ocean general circulation models. Sirkes and Tziperman (2001) have found an oscillatory mode with a centennial time scale, by
one-layer atmosphere. They showed the existence of a transient growth of spatial variance in the transport 40 yr after the perturbation sets in. This growth appears through an increase of both the temperature and salinity perturbations due to the circulation anomalies. On the other hand, sensitivity studies of the ocean circulation have been made using the adjoint of ocean general circulation models. Sirkes and Tziperman (2001) have found an oscillatory mode with a centennial time scale, by
1. Introduction Much of our knowledge about future changes in extreme weather events and the mechanisms causing these changes is based on global climate model simulations that employ general circulation models (GCMs). There is confidence that climate models provide credible quantitative estimates of future climate change, particularly at larger scales, because of their physical basis and the ability of models to reproduce observed climate and past climate changes ( Flato et al. 2013 ). The
1. Introduction Much of our knowledge about future changes in extreme weather events and the mechanisms causing these changes is based on global climate model simulations that employ general circulation models (GCMs). There is confidence that climate models provide credible quantitative estimates of future climate change, particularly at larger scales, because of their physical basis and the ability of models to reproduce observed climate and past climate changes ( Flato et al. 2013 ). The
contain vacillations of the zonal jet like those seen in the atmosphere. Annular modes have also been demonstrated in barotropic models (e.g., Vallis et al. 2004 ), dynamical cores of general circulation models (e.g., Yu and Hartmann 1993 ; Polvani and Kushner 2002 ; Kushner and Polvani 2004 ), aquaplanet GCMs (e.g., Cash et al. 2002 ), and full GCMs with more realistic oceans, topography, or chemistry schemes (e.g., Shindell et al. 1999 ; Kidson and Watterson 1999 ; Fyfe et al. 1999 ). As
contain vacillations of the zonal jet like those seen in the atmosphere. Annular modes have also been demonstrated in barotropic models (e.g., Vallis et al. 2004 ), dynamical cores of general circulation models (e.g., Yu and Hartmann 1993 ; Polvani and Kushner 2002 ; Kushner and Polvani 2004 ), aquaplanet GCMs (e.g., Cash et al. 2002 ), and full GCMs with more realistic oceans, topography, or chemistry schemes (e.g., Shindell et al. 1999 ; Kidson and Watterson 1999 ; Fyfe et al. 1999 ). As
controlled by tight coupling and subtle balance between radiative cooling/heating, turbulence mixing, entrainment drying, microphysics, surface fluxes, and other processes ( Wood 2012 ) and thus exert complex feedbacks on the climate system ( Stephens 2005 ). The lack of coastal stratocumulus is a well-known and robust problem in a number of general circulation models (GCMs) (e.g., Schmidt et al. 2006 ; Donner et al. 2011 ; Voldoire et al. 2012 ) participating in phase 5 of the Coupled Model
controlled by tight coupling and subtle balance between radiative cooling/heating, turbulence mixing, entrainment drying, microphysics, surface fluxes, and other processes ( Wood 2012 ) and thus exert complex feedbacks on the climate system ( Stephens 2005 ). The lack of coastal stratocumulus is a well-known and robust problem in a number of general circulation models (GCMs) (e.g., Schmidt et al. 2006 ; Donner et al. 2011 ; Voldoire et al. 2012 ) participating in phase 5 of the Coupled Model
(2014) ]. There is an increasing body of observational and modeling evidence that AA might strongly impact both the weather and climate, not only in the Arctic region but also remotely in the Northern Hemisphere (NH) midlatitudes [see review articles by Cohen et al. (2014) and Barnes and Screen (2015) and references therein]. In general, most of these studies have detected an atmospheric circulation response resembling a negative North Atlantic Oscillation (NAO) or northern annular mode (NAM
(2014) ]. There is an increasing body of observational and modeling evidence that AA might strongly impact both the weather and climate, not only in the Arctic region but also remotely in the Northern Hemisphere (NH) midlatitudes [see review articles by Cohen et al. (2014) and Barnes and Screen (2015) and references therein]. In general, most of these studies have detected an atmospheric circulation response resembling a negative North Atlantic Oscillation (NAO) or northern annular mode (NAM
. , 107 . 4646, doi:10.1029/2001JD000975 . Chase , T. N. , R. A. Pielke , T. G. F. Kittel , R. Nemai , and S. W. Running , 1996 : Sensitivity of a general circulation model to global changes in leaf area index. J. Geophys. Res. , 101 , 7393 – 7408 . Clark , D. B. , Y. Xue , R. J. Harding , and P. J. Valdes , 2001 : Modeling the impact of land surface degradation on the climate of tropical North Africa. J. Climate , 14 , 1809 – 1822 . Dickinson , R. E. , and A
. , 107 . 4646, doi:10.1029/2001JD000975 . Chase , T. N. , R. A. Pielke , T. G. F. Kittel , R. Nemai , and S. W. Running , 1996 : Sensitivity of a general circulation model to global changes in leaf area index. J. Geophys. Res. , 101 , 7393 – 7408 . Clark , D. B. , Y. Xue , R. J. Harding , and P. J. Valdes , 2001 : Modeling the impact of land surface degradation on the climate of tropical North Africa. J. Climate , 14 , 1809 – 1822 . Dickinson , R. E. , and A
in a scattering and absorbing medium is difficult to obtain in a computationally efficient manner even under a plane-parallel assumption, approximate methods are necessary ( Li and Ramaswamy 1996 ). In radiative transfer approximations, the higher the order of stream expansions, the more accurate the approximation becomes. However, such a gain in accuracy comes at the expense of a more computationally intensive scheme. In general circulation models (GCMs), where radiative transfer calculations
in a scattering and absorbing medium is difficult to obtain in a computationally efficient manner even under a plane-parallel assumption, approximate methods are necessary ( Li and Ramaswamy 1996 ). In radiative transfer approximations, the higher the order of stream expansions, the more accurate the approximation becomes. However, such a gain in accuracy comes at the expense of a more computationally intensive scheme. In general circulation models (GCMs), where radiative transfer calculations
1. Introduction The Met Office’s Unified Model (MetUM; Martin et al. 2006 ), used for climate and weather prediction, is one of the few general circulation models (GCMs) based on the general, nonhydrostatic primitive equations. Another is the nonhydrostatic icosahedral atmospheric model (NICAM) described by Tomita and Satoh (2004) . Before suitable semi-implicit numerical methods were developed, use of the general equations in GCMs was not practicable and the hydrostatic primitive equations
1. Introduction The Met Office’s Unified Model (MetUM; Martin et al. 2006 ), used for climate and weather prediction, is one of the few general circulation models (GCMs) based on the general, nonhydrostatic primitive equations. Another is the nonhydrostatic icosahedral atmospheric model (NICAM) described by Tomita and Satoh (2004) . Before suitable semi-implicit numerical methods were developed, use of the general equations in GCMs was not practicable and the hydrostatic primitive equations
the ECMWF model: From synoptic to decadal time-scales . Quart. J. Roy. Meteor. Soc. , 134 , 1337 – 1351 . Bengtsson , L. , H. Böttger , and M. Kanamitsu , 1982 : Simulation of hurricane-type vortices in a general circulation model . Tellus , 34 , 440 – 457 . Bengtsson , L. , M. Botzet , and M. Esch , 1995 : Hurricane-type vortices in a general circulation model . Tellus , 47A , 175 – 196 . Bengtsson , L. , M. Botzet , and M. Esch , 1996 : Will greenhouse gas
the ECMWF model: From synoptic to decadal time-scales . Quart. J. Roy. Meteor. Soc. , 134 , 1337 – 1351 . Bengtsson , L. , H. Böttger , and M. Kanamitsu , 1982 : Simulation of hurricane-type vortices in a general circulation model . Tellus , 34 , 440 – 457 . Bengtsson , L. , M. Botzet , and M. Esch , 1995 : Hurricane-type vortices in a general circulation model . Tellus , 47A , 175 – 196 . Bengtsson , L. , M. Botzet , and M. Esch , 1996 : Will greenhouse gas
general circulation models (GCMs) in simulating the diurnal variability of the PBL parameters had received little attention until several years ago, while a number of GCM studies had been concerned with the variations at monthly, seasonal, and annual time scales, or the diurnal cycles of cloud cover and precipitation (cf. Lin et al. 2000 ). This was attributed at least in part to the lack of a database for the observed climatological diurnal cycles in different surface conditions across the globe. In
general circulation models (GCMs) in simulating the diurnal variability of the PBL parameters had received little attention until several years ago, while a number of GCM studies had been concerned with the variations at monthly, seasonal, and annual time scales, or the diurnal cycles of cloud cover and precipitation (cf. Lin et al. 2000 ). This was attributed at least in part to the lack of a database for the observed climatological diurnal cycles in different surface conditions across the globe. In
