| 1 | heimbach | 1.1 | \section{The ECCO state estimation cost function DRAFT!!! | 
| 2 |  |  | \label{sectioneccocost}} | 
| 3 | edhill | 1.4 | \begin{rawhtml} | 
| 4 |  |  | <!-- CMIREDIR:ecco_cost: --> | 
| 5 |  |  | \end{rawhtml} | 
| 6 | heimbach | 1.1 |  | 
| 7 | heimbach | 1.6 | Author: Patrick Heimbach | 
| 8 |  |  |  | 
| 9 | heimbach | 1.1 | The current ECCO state estimation covers an $nYears = 11$ year | 
| 10 |  |  | model trajectory. | 
| 11 |  |  | A variety of data sets enter a least squares cost function, | 
| 12 |  |  | in addition to penalty terms which constrain deviations | 
| 13 |  |  | of control variables beyound their a priori errors. | 
| 14 |  |  |  | 
| 15 |  |  | \subsection{Sea surface height from TOPEX/Poseidon and ERS-1/2 altimetry} | 
| 16 |  |  |  | 
| 17 |  |  | Altimetric SSH contributions from T/P and ERS-1/2 are four-fold: | 
| 18 |  |  | % | 
| 19 |  |  | \begin{enumerate} | 
| 20 |  |  | % | 
| 21 |  |  | \item | 
| 22 |  |  | an $nYears$ time mean SSH misfit between | 
| 23 |  |  | model and T/P | 
| 24 |  |  | % | 
| 25 |  |  | \item | 
| 26 |  |  | daily SSH anomaly misfits between T/P and model | 
| 27 |  |  | % | 
| 28 |  |  | \item | 
| 29 |  |  | daily SSH anomaly misfits between ERS-1/2 and model | 
| 30 |  |  | % | 
| 31 |  |  | \item | 
| 32 |  |  | daily absolute SSH misfit between T/P and model, | 
| 33 |  |  | weighted by the full geoid error covariance. | 
| 34 |  |  | % | 
| 35 |  |  | \end{enumerate} | 
| 36 |  |  |  | 
| 37 |  |  | \subsubsection{Input fields} | 
| 38 |  |  | ~ | 
| 39 |  |  |  | 
| 40 |  |  | \begin{table}[h!] | 
| 41 |  |  | \begin{center} | 
| 42 |  |  | \begin{tabular}{lllc} | 
| 43 |  |  | \hline \hline | 
| 44 |  |  | ~&~&~&~\\ | 
| 45 |  |  | field & file name & deccription & unit \\ | 
| 46 |  |  | ~&~&~&~\\ | 
| 47 |  |  | \hline | 
| 48 |  |  | ~&~&~&~\\ | 
| 49 |  |  | {\it psbar} & {\tt psbarfile} & daily model mean SSH fields & [m] \\ | 
| 50 |  |  | {\it tpmean} & {\tt topexmeanfile} & $nYears$ T/P mean & [cm] \\ | 
| 51 |  |  | {\it tpobs}  & {\tt topexfile} & daily T/P SSH anomalies & [cm] \\ | 
| 52 |  |  | {\it erspobs}  & {\tt ersfile} & daily ERS-1/2 SSH anomalies & [cm] \\ | 
| 53 |  |  | {\it wp} & {\tt geoid\_errfile} & diagonal of geoid error covariance & [m] \\ | 
| 54 |  |  | {\it wtp, wers} & {\tt ssh\_errfile} & rms of SSH anomalies & [cm] \\ | 
| 55 |  |  | ~&~&~&~\\ | 
| 56 |  |  | \hline \hline | 
| 57 |  |  | \end{tabular} | 
| 58 |  |  | \end{center} | 
| 59 |  |  | \end{table} | 
| 60 |  |  |  | 
| 61 |  |  |  | 
| 62 | heimbach | 1.2 | \subsubsection{\textit{\textbf{nYears}} time mean SSH misfit} | 
| 63 | heimbach | 1.1 |  | 
| 64 |  |  | \begin{enumerate} | 
| 65 |  |  | % | 
| 66 |  |  | \item | 
| 67 | heimbach | 1.3 | Compute $nYears$ model mean spatial distribution | 
| 68 | heimbach | 1.1 | % | 
| 69 |  |  | \begin{equation} | 
| 70 |  |  | psmean(i,j)\, =\, | 
| 71 |  |  | \frac{1}{nDaysRec} \sum_{i=1}^{nDaysRec} | 
| 72 |  |  | psbar(i,j) | 
| 73 |  |  | \end{equation} | 
| 74 |  |  | % | 
| 75 |  |  | \item | 
| 76 | heimbach | 1.3 | Compute global offset between $nYears$ model and T/P mean: | 
| 77 | heimbach | 1.1 | % | 
| 78 |  |  | \begin{equation} | 
| 79 |  |  | \begin{split} | 
| 80 |  |  | offset & = \, \overline{tpmean} \, - \, \overline{psmean} \\ | 
| 81 |  |  | ~ & = \, \frac{1}{normaliz.} \sum_{i,j} | 
| 82 |  |  | \left\{ tpmean(i,j) \, - \, psmean(i,j) \right\} | 
| 83 |  |  | \cdot cosphi(i,j) \cdot tpmeanmask(i,j) | 
| 84 |  |  | \end{split} | 
| 85 |  |  | \end{equation} | 
| 86 |  |  | % | 
| 87 |  |  | \item | 
| 88 |  |  | Misfits are computed w.r.t. global $offset$. | 
| 89 |  |  | \\ | 
| 90 |  |  | First spatial distribution: | 
| 91 |  |  | % | 
| 92 |  |  | \begin{equation} | 
| 93 |  |  | \begin{split} | 
| 94 |  |  | cost\_ssh\_mean(i,j) & = \, | 
| 95 |  |  | \frac{1}{wp^2} \left\{ \, | 
| 96 |  |  | \left[ \, psmean(i,j) - \overline{psmean} \, \right] \, - \, | 
| 97 |  |  | \left[ \, tpmean(i,j) - \overline{tpmean} \, \right] \, \right\}^2 \\ | 
| 98 |  |  | ~ & = \, \frac{1}{wp^2} \left\{ \, | 
| 99 |  |  | psmean(i,j) \, - \, tpmean(i,j) \, + \, offset \, \right\}^2 | 
| 100 |  |  | \end{split} | 
| 101 |  |  | \end{equation} | 
| 102 |  |  |  | 
| 103 |  |  | % | 
| 104 |  |  | Finally, sum over all spatial entries: | 
| 105 |  |  | \begin{equation} | 
| 106 |  |  | \overline{cost\_ssh\_mean} \, = \, | 
| 107 |  |  | \sum_{i,j} cost\_ssh\_mean(i,j) | 
| 108 |  |  | \end{equation} | 
| 109 |  |  |  | 
| 110 |  |  |  | 
| 111 |  |  |  | 
| 112 |  |  | \end{enumerate} | 
| 113 |  |  |  | 
| 114 |  |  | \subsubsection{Misfit of daily SSH anomalies} | 
| 115 |  |  |  | 
| 116 |  |  | Computation is same for T/P and ERS-1/2. | 
| 117 |  |  | Here we write out computation for T/P. | 
| 118 |  |  |  | 
| 119 |  |  | \begin{enumerate} | 
| 120 |  |  | % | 
| 121 |  |  | \item | 
| 122 |  |  | Compute difference in anomalies: | 
| 123 |  |  |  | 
| 124 |  |  | \begin{equation} | 
| 125 |  |  | \begin{split} | 
| 126 |  |  | cost\_ssh\_anom(i,j,t) & = \, \frac{1}{wtp^2} \left\{ \, | 
| 127 |  |  | \left[ \, psbar(i,j,t) - psmean(i,j) \, \right] \, - \, | 
| 128 |  |  | \left[ \, tpobs(i,j,t) \, \right] \, | 
| 129 |  |  | \right\}^2 | 
| 130 |  |  | \end{split} | 
| 131 |  |  | \end{equation} | 
| 132 |  |  | % | 
| 133 |  |  | where $t$ denotes time (day) index, and | 
| 134 |  |  | where it is assumed that $ nYears$ mean T/P spatial distribution | 
| 135 |  |  | $tpmean(i,j)$ has already been removed from data $tpobs(i,j)$! | 
| 136 |  |  |  | 
| 137 |  |  | \item | 
| 138 |  |  | Sum over all spatial points and all times | 
| 139 |  |  |  | 
| 140 |  |  | \begin{equation} | 
| 141 |  |  | \begin{split} | 
| 142 |  |  | \overline{cost\_ssh\_anom} & = \, \sum_{t} \sum_{i,j} | 
| 143 |  |  | cost\_ssh\_anom(i,j,t) | 
| 144 |  |  | \end{split} | 
| 145 |  |  | \end{equation} | 
| 146 |  |  |  | 
| 147 |  |  | \end{enumerate} | 
| 148 |  |  |  | 
| 149 |  |  | \subsubsection{Flow chart} | 
| 150 |  |  |  | 
| 151 |  |  | \begin{verbatim} | 
| 152 |  |  |  | 
| 153 |  |  | cost_ssh | 
| 154 |  |  | | | 
| 155 |  |  | |- < compute nYears model mean > | 
| 156 |  |  | | | 
| 157 |  |  | |- < read nYears T/P mean > | 
| 158 |  |  | |  CALL COST_READTOPEXMEAN | 
| 159 |  |  | | | 
| 160 |  |  | |- < compute global T/P vs. model offset > | 
| 161 |  |  | | | 
| 162 |  |  | |- < compute cost_hmean > | 
| 163 |  |  | |  CALL COST_SSH_MEAN | 
| 164 |  |  | | | 
| 165 |  |  | |- < ... > | 
| 166 |  |  |  | 
| 167 |  |  | \end{verbatim} | 
| 168 |  |  |  | 
| 169 | heimbach | 1.2 | \subsubsection{Weights and notes} | 
| 170 | heimbach | 1.1 |  | 
| 171 |  |  | \begin{itemize} | 
| 172 |  |  | % | 
| 173 |  |  | \item | 
| 174 |  |  | All data are currently masked to zero where less than 13 depth levels, | 
| 175 |  |  | mimicing no contribution for depth less than 1000m. | 
| 176 |  |  | % | 
| 177 |  |  | \item | 
| 178 |  |  | $cosphi$ term in weights is set to 1. | 
| 179 |  |  | % | 
| 180 |  |  | \item | 
| 181 |  |  | bad T/P and ERS-1/2 values are flagged $ \le \, -9990. $ | 
| 182 |  |  | % | 
| 183 |  |  | \item | 
| 184 |  |  | T/P and ERS-1/2 data $ \le \, 1.\exp^{-8}$ cm are flagged as bad values | 
| 185 |  |  | % | 
| 186 |  |  | \item | 
| 187 |  |  | $wp$ is read from {\tt geoid\_errfile} | 
| 188 |  |  | and $1/wp^2$ is pre-computed in {\tt ecco\_cost\_weights} | 
| 189 |  |  | % | 
| 190 |  |  | \end{itemize} | 
| 191 |  |  |  | 
| 192 |  |  | \paragraph{$wp$ for SSH mean misfit} ~ | 
| 193 |  |  |  | 
| 194 |  |  | $1/wp^2$ is pre-computed in {\tt ecco\_cost\_weights}; \\ | 
| 195 |  |  | $wp$ is read from {\tt geoid\_errfile}; | 
| 196 |  |  |  | 
| 197 |  |  | \paragraph{$wtp$ and $wers$ for SSH anomaly misfit} ~ | 
| 198 |  |  |  | 
| 199 |  |  | $1/wtp^2$, $1/wers^2$ are pre-computed in {\tt ecco\_cost\_weights}; \\ | 
| 200 |  |  | % | 
| 201 |  |  | \begin{itemize} | 
| 202 |  |  | % | 
| 203 |  |  | \item | 
| 204 |  |  | $wtp$, $wers$ are read from single {\tt ssh\_errfile} | 
| 205 |  |  | % | 
| 206 |  |  | \item | 
| 207 |  |  | both are converted to meters and halved \\ | 
| 208 |  |  | $ wtp \, \longrightarrow \, wtp \cdot 0.01 \cdot 0.5 $ | 
| 209 |  |  | % | 
| 210 |  |  | \item | 
| 211 |  |  | ERS error is set to T/P error + 5cm \\ | 
| 212 |  |  | $ wers \, = \, wtp \, + 0.5cm $ | 
| 213 |  |  | % | 
| 214 |  |  | \end{itemize} | 
| 215 |  |  |  | 
| 216 |  |  | \subsubsection{Cost diagnostics} | 
| 217 |  |  |  | 
| 218 |  |  | \begin{itemize} | 
| 219 |  |  | % | 
| 220 |  |  | \item | 
| 221 |  |  | Map out $ cost\_ssh\_mean(i,j) $ | 
| 222 |  |  | % | 
| 223 |  |  | \item | 
| 224 |  |  | Map out $ cost\_ssh\_anom(i,j,t) $ averaged over 1 month, i.e. | 
| 225 |  |  | \[ | 
| 226 |  |  | \frac{1}{\text{monthly entries}} \sum_{t}^{monthly} cost\_ssh\_anom(i,j,t) | 
| 227 |  |  | \] | 
| 228 |  |  | % | 
| 229 |  |  | \item | 
| 230 |  |  | sum over daily entries and plot daily average as function of time. i.e. | 
| 231 |  |  | \[ | 
| 232 |  |  | \frac{1}{\text{daily entries}} \sum_{i,j} cost\_ssh\_anom(i,j,t) | 
| 233 |  |  | \] | 
| 234 |  |  | \end{itemize} | 
| 235 | heimbach | 1.2 |  | 
| 236 |  |  | \subsection{Hydrographic constraints} | 
| 237 |  |  |  | 
| 238 |  |  | Observation of temperature and salinity from various sources are | 
| 239 |  |  | used to constrain the model. These are: | 
| 240 |  |  | % | 
| 241 |  |  | \begin{enumerate} | 
| 242 |  |  | % | 
| 243 |  |  | \item | 
| 244 |  |  | CTD obs. for $T$, $S$ from various WOCE sections | 
| 245 |  |  | % | 
| 246 |  |  | \item | 
| 247 |  |  | XBT obs. for $T$ | 
| 248 |  |  | % | 
| 249 |  |  | \item | 
| 250 |  |  | Sea surface temperature (SST) and salinity (SSS) from | 
| 251 |  |  | Reynolds et al. (???) | 
| 252 |  |  | % | 
| 253 |  |  | \item | 
| 254 |  |  | $T$, $S$ from ARGO floats | 
| 255 |  |  | % | 
| 256 |  |  | \item | 
| 257 |  |  | $T$, $S$ from fields from Levitus (???) | 
| 258 |  |  | % | 
| 259 |  |  | \end{enumerate} | 
| 260 |  |  |  | 
| 261 |  |  | \subsubsection{Input fields} | 
| 262 |  |  | ~ | 
| 263 |  |  |  | 
| 264 |  |  | \begin{table}[h!] | 
| 265 |  |  | \begin{center} | 
| 266 |  |  | \begin{tabular}{lllc} | 
| 267 |  |  | \hline \hline | 
| 268 |  |  | ~&~&~&~\\ | 
| 269 |  |  | field & file name & deccription & unit \\ | 
| 270 |  |  | ~&~&~&~\\ | 
| 271 |  |  | \hline | 
| 272 |  |  | ~&~&~&~\\ | 
| 273 |  |  | {\it tbar} & {\tt tbarfile} & monthly model mean pot. temperature & | 
| 274 |  |  | [$^{\circ}$C] \\ | 
| 275 |  |  | {\it sbar} & {\tt sbarfile} & monthly model mean salinity & | 
| 276 |  |  | [ppt] \\ | 
| 277 |  |  | {\it tdat} & {\tt tdatfile} & monthly mean Levitus pot. temperature & | 
| 278 |  |  | [$^{\circ}$C] \\ | 
| 279 |  |  | {\it sdat} & {\tt sdatfile} & monthly mean Levitus salinity & | 
| 280 |  |  | [ppt] \\ | 
| 281 |  |  | {\it ctdtobs}  & {\tt ctdtfile} & monthly WOCE CTD pot. temperature & | 
| 282 |  |  | [$^{\circ}$C] \\ | 
| 283 |  |  | {\it ctdsobs}  & {\tt ctdsfile} & monthly WOCE CTD salinity & | 
| 284 |  |  | [ppt] \\ | 
| 285 |  |  | {\it xbtobs} & {\tt xbtfile} & monthly XBT in-situ(!) temperature & | 
| 286 |  |  | [$^{\circ}$C] \\ | 
| 287 |  |  | {\it sstdat}  & {\tt sstdatfile} & monthly Reynolds pot. SST & | 
| 288 |  |  | [$^{\circ}$C] \\ | 
| 289 |  |  | {\it sssdat}  & {\tt sssdatfile} & monthly Reynolds SSS & | 
| 290 |  |  | [ppt] \\ | 
| 291 |  |  | {\it argotobs}  & {\tt argotfile} & monthly ARGO in-situ(!) temperature & | 
| 292 |  |  | [$^{\circ}$C] \\ | 
| 293 |  |  | {\it argosobs}  & {\tt argosfile} & monthly ARGO salinity & | 
| 294 |  |  | [ppt] \\ | 
| 295 |  |  | {\it wti, wsi} & {\tt data\_errfile} & vert. stdev. profile for $T$, $S$ & | 
| 296 |  |  | ~ \\ | 
| 297 | heimbach | 1.3 | {\it wtvar} & {\tt temperrfile} & spatially varying stdev. & [$^{\circ}$C] \\ | 
| 298 |  |  | {\it wsvar} & {\tt salterrfile} & spatially varying stdev. & [ppt] \\ | 
| 299 | heimbach | 1.2 | ~&~&~&~\\ | 
| 300 |  |  | \hline \hline | 
| 301 |  |  | \end{tabular} | 
| 302 |  |  | \end{center} | 
| 303 |  |  | \end{table} | 
| 304 |  |  |  | 
| 305 |  |  | \subsubsection{XBT data} | 
| 306 |  |  |  | 
| 307 |  |  | \begin{equation} | 
| 308 |  |  | \begin{split} | 
| 309 | heimbach | 1.3 | cost\_xbt\_t(i,j,k) & = \, | 
| 310 |  |  | \left[ \, \frac{fac \cdot ratio}{wti^2 + wtvar^2} \sum_{\tau=1}^{nMonsRec} | 
| 311 |  |  | \left\{ Tbar(\tau) \, - \, T2\theta[xbtobs(\tau)] \right\}^2 \, \right](i,j,k) | 
| 312 | heimbach | 1.2 | \\ | 
| 313 |  |  | \end{split} | 
| 314 |  |  | \end{equation} | 
| 315 |  |  |  | 
| 316 |  |  | \subsubsection{WOCE CTD data} | 
| 317 |  |  |  | 
| 318 |  |  | \begin{equation} | 
| 319 |  |  | \begin{split} | 
| 320 | heimbach | 1.3 | cost\_ctd\_t(i,j,k) & = \, | 
| 321 |  |  | \left[ \, \frac{fac \cdot ratio}{wti^2 + wtvar^2} \sum_{\tau=1}^{nMonsRec} | 
| 322 |  |  | \left\{ Tbar(\tau) \, - \, ctdTobs(\tau) \right\}^2 \, \right](i,j,k) | 
| 323 | heimbach | 1.2 | \\ | 
| 324 | heimbach | 1.3 | cost\_ctd\_s(i,j,k) & = \, | 
| 325 |  |  | \left[ \, \frac{fac \cdot ratio}{wsi^2 + wsvar^2} \sum_{\tau=1}^{nMonsRec} | 
| 326 |  |  | \left\{ Sbar(\tau) \, - \, ctdSobs(\tau) \right\}^2 \, \right](i,j,k) | 
| 327 | heimbach | 1.2 | \\ | 
| 328 |  |  | \end{split} | 
| 329 |  |  | \end{equation} | 
| 330 |  |  |  | 
| 331 |  |  | \subsubsection{ARGO float data} | 
| 332 |  |  |  | 
| 333 |  |  | \begin{equation} | 
| 334 |  |  | \begin{split} | 
| 335 | heimbach | 1.3 | cost\_argo\_t(i,j,k) & = \, | 
| 336 | heimbach | 1.5 | \left[ \, \frac{fac \cdot ratio}{wti^2 + wtvar^2} \sum_{\tau=1}^{nMonsRec} | 
| 337 | heimbach | 1.3 | \left\{ Tbar(\tau) \, - \, T2\theta[argoTobs(\tau)] \right\}^2 \, \right](i,j,k) | 
| 338 | heimbach | 1.2 | \\ | 
| 339 | heimbach | 1.3 | cost\_argo\_s(i,j,k) & = \, | 
| 340 |  |  | \left[ \, \frac{fac \cdot ratio}{wsi^2 + wsvar^2} \sum_{\tau=1}^{nMonsRec} | 
| 341 |  |  | \left\{ Sbar(\tau) \, - \, argoSobs(\tau) \right\}^2 \, \right](i,j,k) | 
| 342 | heimbach | 1.2 | \\ | 
| 343 |  |  | \end{split} | 
| 344 |  |  | \end{equation} | 
| 345 |  |  |  | 
| 346 |  |  | \subsubsection{Reynolds sea surface T, S data} | 
| 347 |  |  |  | 
| 348 |  |  | \begin{equation} | 
| 349 |  |  | \begin{split} | 
| 350 |  |  | cost\_sst(i,j) & = \, | 
| 351 | heimbach | 1.3 | \left[ \, wsst \sum_{\tau=1}^{nMonsRec} | 
| 352 | heimbach | 1.2 | \left\{ Tbar(\tau) \, - \, sstDat(\tau) \right\}^2 \, \right](i,j) | 
| 353 |  |  | \\ | 
| 354 |  |  | cost\_sss(i,j) & = \, | 
| 355 | heimbach | 1.3 | \left[ \, wsss \sum_{\tau=1}^{nMonsRec} | 
| 356 | heimbach | 1.2 | \left\{ Sbar(\tau) \, - \, sssDat(\tau) \right\}^2 \, \right](i,j) | 
| 357 |  |  | \\ | 
| 358 |  |  | \end{split} | 
| 359 |  |  | \end{equation} | 
| 360 |  |  |  | 
| 361 |  |  | \subsubsection{Levitus montly T, S climatological data} | 
| 362 |  |  |  | 
| 363 | heimbach | 1.3 | Model vs. data misfits are taken from $nYears$ monthly model means | 
| 364 |  |  | vs. Levitus monthly data. | 
| 365 |  |  | The description below is for potential temperature. | 
| 366 |  |  | Procedure for salinity is fully analogous. | 
| 367 |  |  | Spatial indices $(i,j,k)$ are omitted throughout. | 
| 368 |  |  | % | 
| 369 |  |  | \begin{enumerate} | 
| 370 |  |  | % | 
| 371 |  |  | \item | 
| 372 |  |  | Compute $nYears$ monthly model means for each month $imon$: | 
| 373 |  |  | \[ | 
| 374 |  |  | \overline{Tbar}(imon) \, = \, \frac{1}{nYears} | 
| 375 |  |  | \sum_{iyear=1}^{nYears} Tbar(iyear,imon) | 
| 376 |  |  | \] | 
| 377 |  |  | % | 
| 378 |  |  | \item | 
| 379 |  |  | Compute misfit: | 
| 380 |  |  | \[ | 
| 381 |  |  | cost\_theta(i,j,k) \, = \, \left[ | 
| 382 |  |  | \frac{fac \cdot ratio}{wti^2} \sum_{imon=1}^{12} | 
| 383 |  |  | \left\{ \overline{Tbar}(imon) \, - \, Tdat(imon) \right\}^2  \right] (i,j,k) | 
| 384 |  |  | \] | 
| 385 |  |  |  | 
| 386 |  |  | \end{enumerate} | 
| 387 |  |  |  | 
| 388 | heimbach | 1.2 |  | 
| 389 |  |  | \subsubsection{Weights and notes} | 
| 390 |  |  |  | 
| 391 |  |  | \begin{itemize} | 
| 392 |  |  | % | 
| 393 |  |  | \item | 
| 394 |  |  | $T2\theta$ is an operator mapping in-situ to potential temperatures | 
| 395 |  |  | % | 
| 396 |  |  | \item | 
| 397 |  |  | Latitudinal weight not used: | 
| 398 |  |  | \[ | 
| 399 |  |  | cosphi(i,j) \, = \, 1 | 
| 400 |  |  | \] | 
| 401 |  |  | % | 
| 402 |  |  | \item | 
| 403 | heimbach | 1.3 | $ fac \, = \, cosphi \cdot mask $ | 
| 404 |  |  | % | 
| 405 |  |  | \item | 
| 406 |  |  | Spatially {\it constant} weights: | 
| 407 | heimbach | 1.2 | % | 
| 408 |  |  | \begin{enumerate} | 
| 409 |  |  | % | 
| 410 |  |  | \item | 
| 411 | heimbach | 1.3 | Read standard deviation vertical profiles for $T$, $S$ \\ | 
| 412 | heimbach | 1.2 | $ {\tt data\_errfile} \, \longrightarrow \, | 
| 413 |  |  | wti(k), \,\, wsi(k) $ \\ | 
| 414 |  |  | $ {\tt data\_errfile} \, \longrightarrow \, | 
| 415 |  |  | ratio = 0.25 = \left( \frac{1}{2} \right)^2 $ | 
| 416 |  |  | % | 
| 417 |  |  | \item | 
| 418 |  |  | Take inverse squares: | 
| 419 |  |  | \[ | 
| 420 |  |  | \begin{split} | 
| 421 | heimbach | 1.3 | wtheta(k) & = \, \frac{ratio}{wti(k)^2} \\ | 
| 422 |  |  | wsalt(k) & = \, \frac{ratio}{wsi(k)^2} \\ | 
| 423 | heimbach | 1.2 | \end{split} | 
| 424 |  |  | \] | 
| 425 |  |  | % | 
| 426 |  |  | \end{enumerate} | 
| 427 |  |  | % | 
| 428 |  |  | \item | 
| 429 | heimbach | 1.3 | Spatially {\it varying} weights: | 
| 430 | heimbach | 1.2 | % | 
| 431 |  |  | \begin{enumerate} | 
| 432 |  |  | % | 
| 433 |  |  | \item | 
| 434 |  |  | Read standard deviation fields \\ | 
| 435 | heimbach | 1.3 | $ {\tt temperrfile} \, \longrightarrow \, wtvar(i,j,k) $ \\ | 
| 436 |  |  | $ {\tt salterrfile} \, \longrightarrow \, wsvar(i,j,k) $ \\ | 
| 437 | heimbach | 1.2 | % | 
| 438 |  |  | \item | 
| 439 |  |  | Weights are combination of spatially constant and varying parts: | 
| 440 |  |  | \[ | 
| 441 |  |  | \begin{split} | 
| 442 |  |  | wtheta2(i,j,k) & = \, \frac{ratio} | 
| 443 | heimbach | 1.3 | {wti(k)^2 \, + \,wtvar(i,j,k)^2 } \\ | 
| 444 | heimbach | 1.2 | wsalt2(i,j,k) & = \, | 
| 445 |  |  | \frac{ratio} | 
| 446 | heimbach | 1.3 | {wsi(k)^2 \, + \,wsvar(i,j,k)^2 } \\ | 
| 447 | heimbach | 1.2 | \end{split} | 
| 448 |  |  | \] | 
| 449 |  |  | % | 
| 450 |  |  | \end{enumerate} | 
| 451 |  |  | % | 
| 452 |  |  | \item | 
| 453 |  |  | Sea surface $T$, $S$ weights: | 
| 454 |  |  | \begin{itemize} | 
| 455 |  |  | \item | 
| 456 | heimbach | 1.3 | SST: $ wsst \, = \, fac \cdot wtheta(1)$: horizontally constant | 
| 457 | heimbach | 1.2 | \item | 
| 458 | heimbach | 1.3 | SSS: $ wsss \, = \, fac \cdot wsalt2(i,j,1)$: horizontally varying | 
| 459 | heimbach | 1.2 | \end{itemize} | 
| 460 |  |  | (Why this difference? I don't know.) | 
| 461 |  |  | % | 
| 462 |  |  | \end{itemize} | 
| 463 |  |  |  | 
| 464 |  |  |  | 
| 465 |  |  | \subsubsection{Diagnostics} | 
| 466 |  |  |  | 
| 467 |  |  | \begin{itemize} | 
| 468 |  |  | % | 
| 469 |  |  | \item | 
| 470 | heimbach | 1.3 | Map out $wtheta2(i,j,k)$, $wsalt2(i,j,k)$. | 
| 471 | heimbach | 1.2 |  | 
| 472 |  |  | % | 
| 473 |  |  | \end{itemize} | 
| 474 |  |  |  |