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. Miller , 2009 : Seasonal effects of Indian Ocean freshwater forcing in a regional coupled model . J. Climate , 22 , 6577 – 6596 , doi: 10.1175/2009JCLI2990.1 . Seo , K.-H. , and W. Wang , 2010 : The Madden–Julian oscillation simulated in the NCEP Climate Forecast System Model: The importance of stratiform heating . J. Climate , 23 , 4770 – 4793 , doi: 10.1175/2010JCLI2983.1 . Seo , K.-H. , W. Wang , J. Gottschalck , Q. Zhang , J.-K. E. Schemm , W. R. Higgins , and A
. Miller , 2009 : Seasonal effects of Indian Ocean freshwater forcing in a regional coupled model . J. Climate , 22 , 6577 – 6596 , doi: 10.1175/2009JCLI2990.1 . Seo , K.-H. , and W. Wang , 2010 : The Madden–Julian oscillation simulated in the NCEP Climate Forecast System Model: The importance of stratiform heating . J. Climate , 23 , 4770 – 4793 , doi: 10.1175/2010JCLI2983.1 . Seo , K.-H. , W. Wang , J. Gottschalck , Q. Zhang , J.-K. E. Schemm , W. R. Higgins , and A
. Sensitivity experiments with the same regional WRF configuration in Zhang et al. (2017) subsequently demonstrated the crucial importance of the global circumnavigating mode in the MJO initiation and propagation. These results motivate the use of such a model as a proxy of the tropical atmosphere for studying its predictability. To the best of our knowledge, the current study represents the first systematic investigation of both the practical and intrinsic limits of multiscale predictability of tropical
. Sensitivity experiments with the same regional WRF configuration in Zhang et al. (2017) subsequently demonstrated the crucial importance of the global circumnavigating mode in the MJO initiation and propagation. These results motivate the use of such a model as a proxy of the tropical atmosphere for studying its predictability. To the best of our knowledge, the current study represents the first systematic investigation of both the practical and intrinsic limits of multiscale predictability of tropical
enhanced subsidence is evident on either side of the ITCZ, with it being somewhat diminished over the NSA in comparison to that observed south of the ITCZ. To emphasize the regional impacts of Q r on the circulation, Fig. 13b shows ω r as a deviation from its north–south (i.e., 15°N–15°S) mean at each local time. This analysis demonstrates that at all times of day the differential radiative warming resulting from the effects of clouds and enhanced moisture in the ITCZ supports the local Hadley
enhanced subsidence is evident on either side of the ITCZ, with it being somewhat diminished over the NSA in comparison to that observed south of the ITCZ. To emphasize the regional impacts of Q r on the circulation, Fig. 13b shows ω r as a deviation from its north–south (i.e., 15°N–15°S) mean at each local time. This analysis demonstrates that at all times of day the differential radiative warming resulting from the effects of clouds and enhanced moisture in the ITCZ supports the local Hadley
anomalies in the large-scale circulation associated with the MJO have been shown to circumnavigate the global tropics ( Madden and Julian 1994 ; Zhang 2005 ). Furthermore, the MJO has been implicated as a modulator of regional monsoon patterns, tropical cyclones, tornadoes, lightning, and extratropical weather/climate ( Zhang 2013 ). The Dynamics of the Madden–Julian Oscillation (DYNAMO) field campaign ( Yoneyama et al. 2013 ) took place during boreal fall and winter of 2011/12 in the central
anomalies in the large-scale circulation associated with the MJO have been shown to circumnavigate the global tropics ( Madden and Julian 1994 ; Zhang 2005 ). Furthermore, the MJO has been implicated as a modulator of regional monsoon patterns, tropical cyclones, tornadoes, lightning, and extratropical weather/climate ( Zhang 2013 ). The Dynamics of the Madden–Julian Oscillation (DYNAMO) field campaign ( Yoneyama et al. 2013 ) took place during boreal fall and winter of 2011/12 in the central
). Moisture, on the other hand, varies significantly in the tropics ( Fig. 1b ) depending on the local conditions. Sources of tropical moisture can be divided into large-scale convergence and surface latent heat flux. We further divide surface latent heat flux into regional average values and anomalies generated by locally enhanced evaporation from surface wind variations in cold pools produced during convective events. We address the relative role of these different water sources on convection as the
). Moisture, on the other hand, varies significantly in the tropics ( Fig. 1b ) depending on the local conditions. Sources of tropical moisture can be divided into large-scale convergence and surface latent heat flux. We further divide surface latent heat flux into regional average values and anomalies generated by locally enhanced evaporation from surface wind variations in cold pools produced during convective events. We address the relative role of these different water sources on convection as the
, https://doi.org/10.1175/MWR-D-13-00022.1 . 10.1175/MWR-D-13-00022.1 Hagos , S. , Z. Feng , S. McFarlane , and L. R. Leung , 2013 : Environment and the lifetime of tropical deep convection in a cloud-permitting regional model simulation . J. Atmos. Sci. , 70 , 2409 – 2425 , https://doi.org/10.1175/JAS-D-12-0260.1 . 10.1175/JAS-D-12-0260.1 Harrington , J. Y. , 1997 : The effects of radiative and microphysical processes on simulated warm and transition season Arctic stratus. Ph
, https://doi.org/10.1175/MWR-D-13-00022.1 . 10.1175/MWR-D-13-00022.1 Hagos , S. , Z. Feng , S. McFarlane , and L. R. Leung , 2013 : Environment and the lifetime of tropical deep convection in a cloud-permitting regional model simulation . J. Atmos. Sci. , 70 , 2409 – 2425 , https://doi.org/10.1175/JAS-D-12-0260.1 . 10.1175/JAS-D-12-0260.1 Harrington , J. Y. , 1997 : The effects of radiative and microphysical processes on simulated warm and transition season Arctic stratus. Ph
; Wang et al. 2015 ; Janiga and Zhang 2016 ; Wang et al. 2016 ). It was found that low-level moistening preceding the passage of the MJO is dominated by the effects of shallow precipitating clouds. Eddy transport by congestus and deep convective clouds contribute to subsequent mid- and upper-level moistening, respectively, as well as low-level drying. Nonprecipitating clouds mainly modulate the column-confined moisture tendency through their effects on radiation. Local surface evaporation
; Wang et al. 2015 ; Janiga and Zhang 2016 ; Wang et al. 2016 ). It was found that low-level moistening preceding the passage of the MJO is dominated by the effects of shallow precipitating clouds. Eddy transport by congestus and deep convective clouds contribute to subsequent mid- and upper-level moistening, respectively, as well as low-level drying. Nonprecipitating clouds mainly modulate the column-confined moisture tendency through their effects on radiation. Local surface evaporation
-resolving simulation . J. Climate , 24 , 5571 – 5583 , doi: 10.1175/2011JCLI4212.1 . Hagos , S. , L. R. Leung , and J. Duddhia , 2011 : Thermodynamics of the Madden–Julian oscillation in a regional model with constrained moisture . J. Atmos. Sci. , 68 , 1974 – 1989 , doi: 10.1175/2011JAS3592.1 . Holloway , C. E. , S. J. Woolnough , and G. M. S. Lister , 2013 : The effects of explicit versus parameterized convection on the MJO in a Large-domain high-resolution tropical case study. Part I
-resolving simulation . J. Climate , 24 , 5571 – 5583 , doi: 10.1175/2011JCLI4212.1 . Hagos , S. , L. R. Leung , and J. Duddhia , 2011 : Thermodynamics of the Madden–Julian oscillation in a regional model with constrained moisture . J. Atmos. Sci. , 68 , 1974 – 1989 , doi: 10.1175/2011JAS3592.1 . Holloway , C. E. , S. J. Woolnough , and G. M. S. Lister , 2013 : The effects of explicit versus parameterized convection on the MJO in a Large-domain high-resolution tropical case study. Part I
simulation and linearly interpolated to the model's internal calendar day. To limit effects of α to the equatorial zone, after synthesis of the full velocities U and from their spherical harmonic subcomponents on the global Gaussian grid, the hybrid auxiliary velocity is calculated as That is, transitions smoothly via a smooth Heaviside approximation in latitude ϕ from the vortically perturbed velocity field (equatorward of a critical latitude ϕ 0 ) to the actual velocity field (poleward of
simulation and linearly interpolated to the model's internal calendar day. To limit effects of α to the equatorial zone, after synthesis of the full velocities U and from their spherical harmonic subcomponents on the global Gaussian grid, the hybrid auxiliary velocity is calculated as That is, transitions smoothly via a smooth Heaviside approximation in latitude ϕ from the vortically perturbed velocity field (equatorward of a critical latitude ϕ 0 ) to the actual velocity field (poleward of
regional model simulations (e.g., Sun et al. 2006 ; Stephens et al. 2010 ; Hagos et al. 2014 ). Fig . 4. The mean relationship between saturation fraction and precipitation (rain rate) at Addu Atoll from observations and the model simulations. The error bars represent the standard deviations of the precipitation in each of the 15 bins of saturation fraction. Even though this bias in the relationship between saturation fraction and precipitation is common, its overall contribution to the biases in
regional model simulations (e.g., Sun et al. 2006 ; Stephens et al. 2010 ; Hagos et al. 2014 ). Fig . 4. The mean relationship between saturation fraction and precipitation (rain rate) at Addu Atoll from observations and the model simulations. The error bars represent the standard deviations of the precipitation in each of the 15 bins of saturation fraction. Even though this bias in the relationship between saturation fraction and precipitation is common, its overall contribution to the biases in
