2.7.3.4. Adding watertrack calibration points if the ship was slow

Question:

I have a UHDAS+CODAS Python processing directory with lots of short, straight segments, surveying a small feature at slow speeds. How can I increase the number of watertrack points?

Answer:

Watertracking calibration consists of 3 steps: In nav” directory:

  1. adcpsect as_nav.tmp # by default: whole cruise, run once

In cal/watertrk

  1. timslip timslip.tmp # by default: whole cruise, run once

  2. python3 Wtplot_script.py # by default: whole cruise, run once

Step 1 is not changed.

Step 2 controls what points are extracted for watertrack.

Here’s the ‘diff’ of the change timslip.tmp to make it get more points:

  • first, copy to another name, eg timeslip_morepts.tmp

  • second, make these changes:

    1. change output file name

    2. change filtering

    3. change thresholds

To read the difference below,

  • “<” refers to the first file, timeslip.tmp

  • “>” refers to the second file, timeslip_morepts.tmp

Here’s the difference between the two:

ulili:(watertrk)$ diff timslip.tmp  timslip_morepts.tmp
6c6
<         output_file:        aship_7.cal
---
>         output_file:        aship_5.cal   /* new name!! */
9,20c9,20
<         min_n_fixes=        7 /* 5 7 9 */
<
<         n_refs=             7 /* 5 7 9 */
<
<         i_ref_l0=           1
<         i_ref_l1=           2 /* 1 2 3 */
<         i_ref_r0=           5 /* 4 5 6 */
<         i_ref_r1=           6 /* 4 6 8 */
<
<         up_thresh=          3.0        /* m/s */
<         down_thresh=        3.0        /* m/s */
<         turn_speed=         2.0        /* m/s */
---
>         min_n_fixes=       5   /* 5 7 9 */
>
>         n_refs=            5   /* 5 7 9 */
>
>         i_ref_l0=              1
>         i_ref_l1=          1   /* 1 2 3 */
>         i_ref_r0=          4   /* 4 5 6 */
>         i_ref_r1=          4   /* 4 6 8 */
>
>         up_thresh=          1.5        /* m/s */
>         down_thresh=        1.5        /* m/s */
>         turn_speed=         1.0        /* m/s */

Step 2, last part: run

timslip timslip_morepts.tmp

In this example, the output is a file called aship_5.cal

Step 3: Alter Wtplot_script.py as one can for Bottom Track.

  • copy to Wtplot_script_morepts.py

  • edit so the diff is

::

< 40c37 < WT(cal_filename = ‘aship_7.cal’, — > WT(cal_filename = ‘aship_5.cal’, ## read new file 42a40,42 > statsfile = ‘adcpcal_morepts.out’, # different output > ## add these here if you need to edit out some of the points you added: > ## clip_ph, clip_amp, clip_var, clip_dt, clip_u, clip_v

Then run

python3 Wtplot_script_morepts.py

and look at the output, both in the ascii file and the figures (sorry, at the moment the png files will overwrite – save copies if you want to keep them):

##------------- begin "timslip_morepts.tmp" ----------------------

        fix_file_type:      simple
        fix_file:           ../../nav/aship.gps

        reference_file:     ../../nav/aship.nav
        output_file:        aship_5.cal   /* new name!! */

        year_base=          2013
        min_n_fixes=       5   /* 5 7 9 */

        n_refs=            5   /* 5 7 9 */

        i_ref_l0=              1
        i_ref_l1=          1   /* 1 2 3 */
        i_ref_r0=          4   /* 4 5 6 */
        i_ref_r1=          4   /* 4 6 8 */

        up_thresh=          1.5        /* m/s */
        down_thresh=        1.5        /* m/s */
        turn_speed=         1.0        /* m/s */
        turn_thresh=        60         /* degrees */

        dtmax=              360        /* seconds, for 300-second ensembles */
        tolerance=          5.e-5      /* days, about 5 seconds */
        grid:               ensemble

        use_shifted_times?  no

#----------------- end -------------------------------------

and:

# --------------- begin Wtplot_script_morepts.py ----------------
#!/usr/bin/env python

## written by quick_mplplots.py -- edit as needed:

## cruiseid      is 'ADCP'
## dbname        is 'aship'
## proc_yearbase is 2013
## printformats   is 'png'

import matplotlib.pyplot as plt


from pycurrents.adcp.quick_mplplots import Wtplot

## other options that can be chosen
##
##       name                    value
##      -------------          -----------
##        cruiseid             'ADCP
##        printformats         'pdf'
##        dpi                   100
##        outfilebase          'wtcal'
##        statsfile            'adcpcal.out'
##        comment              '#'
##        ddrange              'all'
##        clip_ph               3,
##        clip_amp              0.04
##        clip_var              0.05
##        clip_dt               60
##        clip_u                [-100,100]
##        clip_v                [-100,100]



WT = Wtplot()
WT(cal_filename = 'aship_5.cal',     ## read new file
  printformats = 'png',
  cruiseid = 'ADCP',
  statsfile =  'adcpcal_morepts.out',   # different output
  ## add these here if you need to edit out some of the points you added:
  ##    clip_ph, clip_amp, clip_var, clip_dt, clip_u, clip_v
  proc_yearbase = '2013')

plt.show()
#------------------------------ end-------------------------------