| 1 | % Yaros PFS
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| 2 | % =========
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| 3 | %
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| 4 | % Appendix: MPHR
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| 5 |
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| 6 | \chapter{WMO BUFR}\label{app:bufr}
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| 7 |
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| 8 | \ifbool{eps}{
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| 9 |
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| 10 | This Appendix describes the mapping between variables in the EPS RO Level 1 data
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| 11 | format and WMO's \acrfull{bufr} format for RO measurements. The full description
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| 12 | of the RO BUFR format is outside the scope of this document; it is assumed that
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| 13 | the reader is familiar with the details of the RO BUFR format as defined in
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| 14 | \ref{ad:wmo_bufr}. The recommendations of IROWG (see \ref{rd:irowg_bufr}) were
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| 15 | taken into account, assuming they will be implemented in the foreseeable future.
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| 16 | }{% \ifbool{epssg} This Appendix describes the mapping between variables in the
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| 17 | EPS RO Level 1 data format and WMO's \acrfull{bufr} format for RO measurements.
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| 18 | The full description of the RO BUFR format is outside the scope of this
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| 19 | document; it is assumed that the reader is familiar with the details of the RO
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| 20 | BUFR format as defined in [RO-BUFR]. The recommendations of IROWG (see
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| 21 | [IROWG-BUFR]) were taken into account, assuming they will be implemented in the
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| 22 | foreseeable future. }
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| 23 |
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| 24 | \section{BUFR Sections 1 (Identification) and 3 (Data Description)}
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| 25 |
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| 26 | BUFR sections 1 is filled with meta data as described in the BUFR specification
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| 27 | \ifbool{eps}{(\ref{ad:wmo_bufr})}{[RO-BUFR]} using Edition 4 messages. The time
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| 28 | information ``most typical for [the] BUFR message content'' contained in octet
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| 29 | numbers 16-17 (year) and 18--22 (month, day, hour, minute and second) are
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| 30 | derived from the georeferencing time, i.e. from the variables
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| 31 | \texttt{utc_georef_absdate} and \texttt{utc_georef_abstime} in the
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| 32 | \texttt{/data/occultation} group.
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| 33 |
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| 34 | Section 3 is to be set dynamically from the number of profiles (usually 1 in a
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| 35 | single BUFR message) and the message size. Note that there is no Section 2
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| 36 | (Optional Data) in RO BUFR products.
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| 37 |
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| 38 |
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| 39 | \section{BUFR Section 4 (Data Template)}
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| 40 |
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| 41 | Quality information is stored in a single 16-bit data field (octet number 13),
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| 42 | where the detailed meaning of each flag is defined in Table 8 of
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| 43 | \ifbool{eps}{\ref{ad:wmo_bufr}}{[RO-BUFR]}. The mapping between BUFR and RO
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| 44 | Level 1 product quality flags is described in Tab.~\ref{tab:bufr_quality_flags}
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| 45 | below.
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| 46 | %
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| 47 | \begin{table}[b]
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| 48 | \centering
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| 49 | \footnotesize
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| 50 | \begin{tabularx}{0.95\textwidth}{cX>{\texttt\bgroup}l<{\egroup}}
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| 51 | \toprule
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| 52 | \multicolumn{1}{c}{\textbf{Bit}} &
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| 53 | \multicolumn{1}{c}{\textbf{Description}} &
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| 54 | \multicolumn{1}{c}{\textbf{Variable}} \\
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| 55 | \midrule
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| 56 | 1 & Nominal / non-nominal quality & /quality/overall\_quality \\
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| 57 | 2 & NRT / Offline product & /environment \\
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| 58 | 3 & Descending / ascending occultation & /data/occultation/occultation\_type \\
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| 59 | 4 & Excess phase processing (non-) nominal & /quality/cl\_snr\_[ca|p1|p2]\_ok \\
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| 60 | 5 & Bending angle processing (non-) nominal & /quality/thinned\_ok \\
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| 61 | 6 & Refractivity processing (non-) nominal & \textrm{\emph{Unused}} \\
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| 62 | 7 & Meteorological processing (non-) nominal & \textrm{\emph{Unused}} \\
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| 63 | 8 & Closed / open loop data only / included & /quality/ol\_data\_used \\
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| 64 | 9 & (No) Surface reflections detected & \textrm{\emph{Unused}} \\
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| 65 | 10 & L2P / L2C GPS signals used & \textrm{\emph{Unused}} \\
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| 66 | 11-13 & Reserved & \textrm{\emph{Unused}} \\
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| 67 | 14 & Background profile (non-) nominal & \textrm{\emph{Unused}} \\
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| 68 | 15 & Retrieved / background profile & \textrm{\emph{Unused}} \\
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| 69 | \bottomrule
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| 70 | \end{tabularx}
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| 71 | \caption{Mapping between BUFR Section 4 quality flags for RO and \ifbool{epssg}{EPS-SG RO L1}{RO level 1} data format quality flags.\label{tab:bufr_quality_flags}}
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| 72 | \end{table}
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| 73 |
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| 74 | \begin{table}[p]
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| 75 | \centering
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| 76 | \footnotesize
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| 77 | \begin{tabularx}{0.95\textwidth}{cX>{\texttt\bgroup}l<{\egroup}}
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| 78 | \toprule
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| 79 | \multicolumn{1}{c}{\textbf{Octet}} &
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| 80 | \multicolumn{1}{c}{\textbf{Variable(s)}} &
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| 81 | \multicolumn{1}{c}{\textbf{Remarks}} \\
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| 82 | \midrule
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| 83 | \\ \addlinespace[-0.5em]
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| 84 | \multicolumn{3}{l}{\textbf{Nominal Reporting Time}}\\
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| 85 | \midrule
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| 86 | 7-12 & \texttt{/data/occultation/utc\_georef\_absdate} \newline
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| 87 | \texttt{/data/occultation/utc\_georef\_abstime}
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| 88 | & Assumes \ifbool{eps}{\ref{rd:irowg_bufr}}{[IROWG-BUFR]} is implemented \\
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| 89 |
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| 90 | \\ \addlinespace[-0.5em]
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| 91 | \multicolumn{3}{l}{\textbf{RO Summary Quality Information}}\\
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| 92 | \midrule
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| 93 | 13 & \textrm{\emph{various}}
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| 94 | & see Tab.~\ref{tab:bufr_quality_flags} \\
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| 95 | 14 & \texttt{/quality/overall\_quality\_ok}
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| 96 | & 100\% if True, 0\% otherwise \\
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| 97 |
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| 98 | \\ \addlinespace[-0.5em]
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| 99 | \multicolumn{3}{l}{\textbf{LEO \& GNSS POD -- Location of Platform}}\\
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| 100 | \midrule
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| 101 | 15-17 & \texttt{/data/occultation/position\_rec\_fixed} & Antenna phase centre positions\ldots \\
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| 102 | 18-20 & \texttt{/data/occultation/velocity\_rec} & \ldots{}and velocities at georeferencing time \\
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| 103 | 21 & \texttt{/data/transmitter/satellite\_prn} & First letter, e.g. \texttt{Gxx} $\rightarrow$ 401 (for GPS)\\
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| 104 | 22 & \texttt{/data/transmitter/satellite\_prn} & Integer part, e.g. \texttt{1} $\rightarrow$ 1 (for PRN G01) \\
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| 105 | 23-25 & \texttt{/data/occultation/position\_gns\_fixed} & Positions\ldots \\
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| 106 | 26-28 & \texttt{/data/occultation/velocity\_gns} & \ldots{}and velocities at georeferencing time \\
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| 107 |
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| 108 | \\ \addlinespace[-0.5em]
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| 109 | \multicolumn{3}{l}{\textbf{Local Earth Parameters}}\\
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| 110 | \midrule
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| 111 | 29 & \textrm{\emph{always zero}} & Assumes \ifbool{eps}{\ref{rd:irowg_bufr}}{[IROWG-BUFR]} is implemented \\
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| 112 | 30 & \texttt{/data/occultation/latitude} & Valid at georeferencing time \\
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| 113 | 31 & \texttt{/data/occultation/longitude} & \hspace{1em} \emph{ditto} \\
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| 114 | 32-34 & \texttt{/data/occultation/r\_curve\_centre\_fixed} & \hspace{1em} \emph{ditto}\\
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| 115 | 35 & \texttt{/data/occultation/r\_curve} & \hspace{1em} \emph{ditto}\\
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| 116 | 36 & \texttt{/data/occultation/azimuth\_north} & \hspace{1em} \emph{ditto}\\
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| 117 | 37 & \texttt{/data/occultation/undulation} & \hspace{1em} \emph{ditto} \\
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| 118 |
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| 119 | \\ \addlinespace[-0.5em]
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| 120 | \multicolumn{3}{l}{\textbf{RO Step 1b Data}}\\
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| 121 | \midrule
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| 122 | 38 & \texttt{len(/data/level\_1b/thinned/impact)} & Fixed number of levels; same for all products\\
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| 123 | 39 & \texttt{/data/level\_1b/thinned/lat\_tp} & \\
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| 124 | 40 & \texttt{/data/level\_1b/thinned/lon\_tp} & \\
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| 125 | 41 & \texttt{/data/level\_1b/thinned/azimuth\_tp} & \\
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| 126 | 42 & \texttt{3} & for ionospheric corrected, L1, and L2 data \\
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| 127 | 43 & \texttt{0} or nominal carrier frequencies & 0 for ionospheric corrected bending angles \\
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| 128 | 44 & \texttt{/data/level\_1b/thinned/impact} & \\
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| 129 | 45 & \texttt{/data/level\_1b/thinned/bangle} \newline
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| 130 | \texttt{/data/level\_1b/thinned/bangle\_ca} \newline
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| 131 | \texttt{/data/level\_1b/thinned/bangle\_p2} \newline & \\
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| 132 | 46-48 & \textrm{\emph{Currently unused}} & \\
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| 133 | \bottomrule
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| 134 | \end{tabularx}
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| 135 | \caption{Mapping between BUFR Section 4 data fields and \ifbool{epssg}{EPS-SG RO L1}{RO level 1} data format variables.\label{tab:bufr_variable_mapping}}
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| 136 | \end{table}
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| 137 |
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| 138 | Note that values stored in BUFR products will be matching BUFR conventions, in
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| 139 | some cases requiring a translation from the logical values used in the netCDF
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| 140 | granules as described in section~\ref{sec:conventions}. For example, in case on
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| 141 | Bit 1, the global attribute \texttt{environment} may exhibit values of
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| 142 | ``Operational'', ``Validation'', ``Development'', ``Offline'',``Integration \&
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| 143 | Verification'', and ``Support'' (see section~\ref{sec:l1b_root}). Values of
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| 144 | ``Operational'' and ``Validation'' will be mapped to ``NRT product'', while the
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| 145 | remaining ones will be mapped to ``Offline product''. On the other hand, the
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| 146 | excess phase processing flag is calculated as the logical \texttt{and} of the
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| 147 | \verb|quality_snr_ca_ok|, \verb|quality_snr_p1_ok|, and \verb|quality_snr_p2_ok|
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| 148 | flags in the netCDF granule.
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| 149 |
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| 150 | Tab.~\ref{tab:bufr_variable_mapping} links data fields as used in BUFR Section 4
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| 151 | entries (see Table 5 of \ifbool{eps}{\ref{ad:wmo_bufr})}{[RO-BUFR]} to the
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| 152 | corresponding variables in the netCDF granule data format. We finally note that
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| 153 | BUFR products generated by EUMETSAT do not contain any ``Step 2a'', ``Level2a''
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| 154 | or ``Level2b'' data.
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| 155 |
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