1 ====================================================================== |
|
2 R E A D M E . P O S T E D I T |
|
3 doc: Wed Jun 13 20:30:10 2012 |
|
4 dlm: Thu Jun 14 18:22:13 2012 |
|
5 (c) 2012 A.M. Thurnherr |
|
6 uE-Info: 95 50 NIL 0 0 72 3 2 8 NIL ofnI |
|
7 ====================================================================== |
|
8 |
|
9 =Summary= |
|
10 |
|
11 This README explains how to post-edit the shear output from b[LADCPproc] |
|
12 before feeding it to [LADCPintsh], e.g. for removing data collected when |
|
13 the ADCP was very shallow and possibly affected by the ship's magnetic |
|
14 field. |
|
15 |
|
16 |
|
17 =Nitty-Gritty= |
|
18 |
|
19 The default output from [LADCPproc] is a so-called time-depth-series |
|
20 (.tds) file with one record per valid shear sample. Each record |
|
21 contains the following fields: |
|
22 |
|
23 ens ensemble number the shear sample is from |
|
24 elapsed elapsed time in seconds of the present ensemble |
|
25 CTD_depth depth of CTD at the time the ensemble was recorded |
|
26 downcast a boolean flag set to 1 (nan) for down(up)cast records |
|
27 depth "nominal" depth of shear sample (center depth in gridded profile) |
|
28 u_z vertical shear of zonal velocity |
|
29 v_z vertical shear of meridional velocity |
|
30 w_z vertical shear of vertical velocity |
|
31 |
|
32 This is the "general" output of [LADCPproc]. For standard processing, |
|
33 the shear is bin-averaged in depth space. While this can easily be |
|
34 accomplished, e.g. with a Matlab script, for convenience the binned |
|
35 output can be requested with the -p option of [LADCPproc]. The binned |
|
36 output cannot be post-edited! |
|
37 |
|
38 The .tds data can be post-edited. Matlab users can import these files |
|
39 with [loadANTS.m] (see [README.Output]), edit the structures, bin the |
|
40 shear in depth space, and export the new structures as ANTS files with |
|
41 [struct2ANTS.m]. For example, to remove all data collected with the |
|
42 ADCP shallower than 5m, simply delete the records for which CTD_depth |
|
43 <= 5. Or, you can bin your shear data with different statistics (e.g. |
|
44 median), instead of the arithmetic mean used by [LADCPproc] -p. |
|
45 |
|
46 Inconveniently, [LADCPintsh] at present requires its shear input to be |
|
47 in the format generated by the -p option of [LADCPproc], with the |
|
48 following fields (Matlab version): |
|
49 |
|
50 depth center depth of bin |
|
51 dc_elapsed mean elapsed time of downcast shear samples in present bin |
|
52 dc_nsamp number of downcast shear samples in bin |
|
53 dc_u_z bin-averaged downcast vertical shear of zonal velocity |
|
54 dc_u_z_sig corresponding standard deviation |
|
55 dc_v_z same for meridional velocity |
|
56 dc_v_z_sig |
|
57 dc_w_z same for vertical velocity |
|
58 dc_w_z_sig |
|
59 uc_elapsed mean elapsed time of upcast shear samples in present bin |
|
60 uc_nsamp number of upcast shear samples in bin |
|
61 uc_u_z bin-averaged upcast vertical shear of zonal velocity |
|
62 uc_u_z_sig corresponding standard deviation |
|
63 uc_v_z same for meridional velocity |
|
64 uc_v_z_sig |
|
65 uc_w_z same for vertical velocity |
|
66 uc_w_z_sig |
|
67 elapsed mean elapsed time of mean dn/upcast shear samples in present bin |
|
68 nsamp number of mean dn/upcast shear samples in bin |
|
69 u_z bin-averaged mean dn/upcast vertical shear of zonal velocity |
|
70 u_z_sig corresponding standard deviation |
|
71 v_z same for meridional velocity |
|
72 v_z_sig |
|
73 w_z same for vertical velocity |
|
74 w_z_sig |
|
75 Sv bin-averaged acoustic volume scattering coefficient |
|
76 Sv.nsamp number of samples in bin |
|
77 |
|
78 Note that the .tds file does not contain acoustic backscatter |
|
79 information, i.e. the Sv field should be set to nan and the Sv.nsamp to |
|
80 zero. |
|
81 |
|
82 After binning the shear data, Matlab users can create a structure with |
|
83 the fields listed above. Metadata (scalars in the .tds import |
|
84 structure) should be copied verbatim from the .tds import structure. |
|
85 Each of the listed fields is a vector and they must all have the same |
|
86 length. (Since the down- and upcasts do not usually cover exactly the |
|
87 same depth range, padding is almost always required.) The resulting |
|
88 structure can then be exported with [struct2ANTS.m]; the 'dependencies' |
|
89 argument should be set to the filename(s) of the .tds file(s) from |
|
90 which the binned shear profile was constructed. |
|
91 |
|
92 The only option for non-Matlab users is to create an ASCII file with |
|
93 the required columns (nan values are permitted) in the order listed |
|
94 above and prepend this with the header from the corresponding |
|
95 [LADCPproc] output file produced by the -p option. |
|