Tool for prediction based on Reference Station

[abfleishman]

It would be cool to access the type of data that is available through this site: https://tidesandcurrents.noaa.gov/noaatidepredictions/NOAATidesFacade.jsp?Stationid=TPT2739)

It has a time and amplitude offset from a reference station

[joethorley]

This is a great idea - is all the information for these sites (name, coordinates, parent station, time offset and amplitude offset) in one place is a machine readable form?

[abfleishman]

I guess I am not sure. This site give a month of data: https://tidesandcurrents.noaa.gov/noaatidepredictions/viewMonthlyPredictions.jsp?bmon=12&bday=20&byear=2016&timelength=monthly&timeZone=1&dataUnits=1&datum=MLLW&timeUnits=2&interval=highlow&format=Submit&Stationid=TPT2739
and seems to be a .jsp form. I am not sure how to access it without downloading the txt or xml with the link on the side. I need to pull down 5 years of tide data ideally so it would be really nice to have a tool to access the data directly from R.

[joethorley]

If you only want for one site why not generate 5 years of data for the parent site from rtide and then manually adjust for the time and amplitude offsets in R?

[abfleishman]

I guess I am not fully understanding those offsets and how to implement them with the rtide output because they are different for high and low tides, and ultimately I want to get tidal heights for individual times (not just the high and low times). Does this make sense?

[joethorley]

Yes it makes sense.
I am willing to work out how to implement (it will be relatively straightforward) for all times if someone was to provide the offsets for all US stations of this type together with their name, latitude, longitude and name of their parent station. However, I'm not willing to figure out how to do it for a single station and I'm not willing to figure how to get all the information together for all the US stations of this type.

[abfleishman]

I will look into putting together that info for all stations... Thanks for your cool package by the way!

[joethorley]

That would be great then we'll have a general solution that will be helpful to a lot of people - thanks -appreciation is always appreciated :)

[abfleishman]

I asked the tidesandcurrents.nooa.gov people and they said that they didn't have a table with all the info we needed so I used rvest to scrape the info from the website. I think I put together all the info about the subordinate tide stations. I have attached a compressed rda file with the resulting table and the script I used to scrape the info. All the info has been pulled from the websites in script. Let me know it all the information that you need is here, if not I can try and grab it.

tide.station.zip

[joethorley]

Good work!!!

I'll add you as a contributor.

Do you want to add your tide.station.r script to data-raw as a pull request so it is tracked for all the world to see (I can do if you don't want to spend the time)?

When do you want the functionality implemented by?

[abfleishman]

In my ideal world I guess I might have a tool to use in the next week or two, however, by no means should you drop what you are doing to work on this. Since I have no idea how much work it will be to implement, I am not sure what a reasonable time frame would be?

[joethorley]

I'll see what I can do.

[joethorley]

I'm making progress -

critical questions

1. do you know what the * in some of the height offsets refers to (+ or -)?
2. I'm still trying to figure out how to get the reference number for the stations in rtide::harmonics$Station - do you have any thoughts?

less critically

1. I'm assuming the time off sets are in minutes
2. the time zones simply state LST/LDT for Local time... do you know a way to query the actual timezone for each station?

[joethorley]

I mean seconds for the time zone off sets

[joethorley]

I've been thinking and I can use the time zone for the reference station for the substation.

[abfleishman]

1. The * in the height offset is multiplying the height of the ref station values
2. I will work on getting the ref number for the rtide::harmonics$Station my first attempt didn't work but I can spend some time today and write something to scrape them from the website.
3. time offsets are in minutes
4. I have code some where to look up time zone based on lat/long so I can add the correct timezone in the OlsonNames() format.

.