evaluating tidal constituents, amplitude and phases from water level data

[sonaljit.m]

Hi all,
This is not a ROMS related problem, but I am looking for some help. I need to find out the tidal components (M2, S2 etc) and their corresponding amplitudes and phase from an hourly water-level data. The data contains date/time, and the corresponding water levels for 1 year duration. Is there a python module that can do this (I don't have Matlab)?

Thanks.

[ymamoutos]

Greetings

check this link https://github.com/wesleybowman/UTide
is the implementation of Matlab's UTIDE package.
According to author is still under development so
use it with some caution. Another option is TAPPY
(https://sourceforge.net/projects/tappy/)

Giannis

[johnluick]

sonaljit.m, first, I have to say you should change your name to sonaljit.py. Second, if your data is in a ROMS hisfile format, if you like, you can put your data on onedrive or somewhere I can access it, I'll analyse it for you and send you the harmonics. Won't take me more than a few minutes. Then, you can take your time getting UTIDE going or whatever, and you can have something to compare results to. How's that? Merry Christmas.

[c.drinkorn]

Hi everyone,

yes I think sonaljit.py would be a more suitable Username.

I think, if you chose the Option AVERAGES_DETIDED and set some of the detided variables True for output, ROMS will make a harmonics file ocean_har.nc which contains the constituents, am I right?

Merry Christmas!

[sonaljit.m]

Hi,
Thanks for the help. I am attaching a csv file, containing AMSEAS 2019 water level outputs from 3 different buoy locations: San Juan, St Thomas and St Croix. The data is 3-hourly, and the starting time is 01/01/2019 00:00:00. There are some nan values near the end of the arrays. I need to find out what are the amplitude and phase of the different tidal constituents at these 3 locations. You can download the csv file from this link https://www.dropbox.com/s/vazlu1er3mhkw ... 9.csv?dl=0

Also, thanks very much for the suggestion to add .py to my username. I will definitely consider it
Thanks.

[johnluick]

Hi Sonaljit,

I have downloaded the file. Looks like tide gauge data. Before I can analyze it, I need to know the time zone the data is in. Also, particularly if it is in the local time zone, let me know whether you want the phases of the harmonics referenced to that time zone, or UT. I would assume UT if you are comparing to ROMS or something.

Please reply to john.luick@austides.com so we don't annoy everyone with these details.

Cheers

John