Changeset 11544 for NEMO/trunk/doc/latex/NEMO/subfiles/chap_DIU.tex
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- 2019-09-13T16:37:38+02:00 (5 years ago)
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NEMO/trunk/doc/latex/NEMO/subfiles/chap_DIU.tex
r11435 r11544 57 57 %=============================================================== 58 58 \section{Warm layer model} 59 \label{sec: warm_layer_sec}59 \label{sec:DIU_warm_layer_sec} 60 60 %=============================================================== 61 61 … … 65 65 \frac{\partial{\Delta T_{\mathrm{wl}}}}{\partial{t}}&=&\frac{Q(\nu+1)}{D_T\rho_w c_p 66 66 \nu}-\frac{(\nu+1)ku^*_{w}f(L_a)\Delta T}{D_T\Phi\!\left(\frac{D_T}{L}\right)} \mbox{,} 67 \label{eq: ecmwf1} \\68 L&=&\frac{\rho_w c_p u^{*^3}_{w}}{\kappa g \alpha_w Q }\mbox{,}\label{eq: ecmwf2}67 \label{eq:DIU_ecmwf1} \\ 68 L&=&\frac{\rho_w c_p u^{*^3}_{w}}{\kappa g \alpha_w Q }\mbox{,}\label{eq:DIU_ecmwf2} 69 69 \end{align} 70 70 where $\Delta T_{\mathrm{wl}}$ is the temperature difference between the top of the warm layer and the depth $D_T=3$\,m at which there is assumed to be no diurnal signal. 71 In equation (\autoref{eq: ecmwf1}) $\alpha_w=2\times10^{-4}$ is the thermal expansion coefficient of water,71 In equation (\autoref{eq:DIU_ecmwf1}) $\alpha_w=2\times10^{-4}$ is the thermal expansion coefficient of water, 72 72 $\kappa=0.4$ is von K\'{a}rm\'{a}n's constant, $c_p$ is the heat capacity at constant pressure of sea water, 73 73 $\rho_w$ is the water density, and $L$ is the Monin-Obukhov length. … … 79 79 the relationship $u^*_{w} = u_{10}\sqrt{\frac{C_d\rho_a}{\rho_w}}$, where $C_d$ is the drag coefficient, 80 80 and $\rho_a$ is the density of air. 81 The symbol $Q$ in equation (\autoref{eq: ecmwf1}) is the instantaneous total thermal energy flux into81 The symbol $Q$ in equation (\autoref{eq:DIU_ecmwf1}) is the instantaneous total thermal energy flux into 82 82 the diurnal layer, \ie 83 83 \[ 84 84 Q = Q_{\mathrm{sol}} + Q_{\mathrm{lw}} + Q_{\mathrm{h}}\mbox{,} 85 % \label{eq: e_flux_eqn}85 % \label{eq:DIU_e_flux_eqn} 86 86 \] 87 87 where $Q_{\mathrm{h}}$ is the sensible and latent heat flux, $Q_{\mathrm{lw}}$ is the long wave flux, 88 88 and $Q_{\mathrm{sol}}$ is the solar flux absorbed within the diurnal warm layer. 89 89 For $Q_{\mathrm{sol}}$ the 9 term representation of \citet{gentemann.minnett.ea_JGR09} is used. 90 In equation \autoref{eq: ecmwf1} the function $f(L_a)=\max(1,L_a^{\frac{2}{3}})$,90 In equation \autoref{eq:DIU_ecmwf1} the function $f(L_a)=\max(1,L_a^{\frac{2}{3}})$, 91 91 where $L_a=0.3$\footnote{ 92 92 This is a global average value, more accurately $L_a$ could be computed as $L_a=(u^*_{w}/u_s)^{\frac{1}{2}}$, … … 99 99 4\zeta^2}{1+3\zeta+0.25\zeta^2} &(\zeta \ge 0) \\ 100 100 (1 - 16\zeta)^{-\frac{1}{2}} & (\zeta < 0) \mbox{,} 101 \end{array} \right. \label{eq: stab_func_eqn}101 \end{array} \right. \label{eq:DIU_stab_func_eqn} 102 102 \end{equation} 103 where $\zeta=\frac{D_T}{L}$. It is clear that the first derivative of (\autoref{eq: stab_func_eqn}),104 and thus of (\autoref{eq: ecmwf1}), is discontinuous at $\zeta=0$ (\ie\ $Q\rightarrow0$ in105 equation (\autoref{eq: ecmwf2})).103 where $\zeta=\frac{D_T}{L}$. It is clear that the first derivative of (\autoref{eq:DIU_stab_func_eqn}), 104 and thus of (\autoref{eq:DIU_ecmwf1}), is discontinuous at $\zeta=0$ (\ie\ $Q\rightarrow0$ in 105 equation (\autoref{eq:DIU_ecmwf2})). 106 106 107 The two terms on the right hand side of (\autoref{eq: ecmwf1}) represent different processes.107 The two terms on the right hand side of (\autoref{eq:DIU_ecmwf1}) represent different processes. 108 108 The first term is simply the diabatic heating or cooling of the diurnal warm layer due to 109 109 thermal energy fluxes into and out of the layer. … … 114 114 115 115 \section{Cool skin model} 116 \label{sec: cool_skin_sec}116 \label{sec:DIU_cool_skin_sec} 117 117 118 118 %=============================================================== … … 121 121 As the cool skin is so thin (~1\,mm) we ignore the solar flux component to the heat flux and the Saunders equation for the cool skin temperature difference $\Delta T_{\mathrm{cs}}$ becomes 122 122 \[ 123 % \label{eq: sunders_eqn}123 % \label{eq:DIU_sunders_eqn} 124 124 \Delta T_{\mathrm{cs}}=\frac{Q_{\mathrm{ns}}\delta}{k_t} \mbox{,} 125 125 \] … … 128 128 $\delta$ is the thickness of the skin layer and is given by 129 129 \begin{equation} 130 \label{eq: sunders_thick_eqn}130 \label{eq:DIU_sunders_thick_eqn} 131 131 \delta=\frac{\lambda \mu}{u^*_{w}} \mbox{,} 132 132 \end{equation} … … 134 134 \citet{saunders_JAS67} suggested varied between 5 and 10. 135 135 136 The value of $\lambda$ used in equation (\autoref{eq: sunders_thick_eqn}) is that of \citet{artale.iudicone.ea_JGR02},136 The value of $\lambda$ used in equation (\autoref{eq:DIU_sunders_thick_eqn}) is that of \citet{artale.iudicone.ea_JGR02}, 137 137 which is shown in \citet{tu.tsuang_GRL05} to outperform a number of other parametrisations at 138 138 both low and high wind speeds. 139 139 Specifically, 140 140 \[ 141 % \label{eq: artale_lambda_eqn}141 % \label{eq:DIU_artale_lambda_eqn} 142 142 \lambda = \frac{ 8.64\times10^4 u^*_{w} k_t }{ \rho c_p h \mu \gamma }\mbox{,} 143 143 \] … … 145 145 $\gamma$ is a dimensionless function of wind speed $u$: 146 146 \[ 147 % \label{eq: artale_gamma_eqn}147 % \label{eq:DIU_artale_gamma_eqn} 148 148 \gamma = 149 149 \begin{cases}
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