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I am trying to download data from NOAA and I can't figure out how to construct a query to do it.

This URL points to a page that contains data for tides at six minute intervals between Jan 01 2021 and Feb 28 2021:

tidesandcurrents.noaa.gov/waterlevels.html?id=8443970&units=standard&bdate=20210101&edate=20210228&timezone=GMT&datum=MLLW&interval=6&action=data (link to the url)

If I ask for a wider range of data on that web page, the site refuses do serve the data.

I'd like to generate a sequence of queries to download the data in smaller chunks, but I can't figure out how to construct a query.

I've tried:

URLRead[URL["https://tidesandcurrents.noaa.gov/waterlevels.html"], 
 <|"Query" -> {"id" -> 8443970, "units" -> "standard", 
    "bdate" -> 20210101, "edate" -> 20210131, "timeszone" -> "GMT", 
    "datum" -> "MLLW", "interval" -> 6, "action" -> "data"}|>
 ]

and

URLDownload[
 URL["https://tidesandcurrents.noaa.gov/waterlevels.html"], 
 <|"Query" -> {"id" -> 8443970, "units" -> "standard", 
    "bdate" -> 20210101, "edate" -> 20210131, "timeszone" -> "GMT", 
    "datum" -> "MLLW", "interval" -> 6, "action" -> "data"}|>]

which both fail. Does anyone know how to do this?

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1 Answer 1

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Did you try the API at https://api.tidesandcurrents.noaa.gov/api/prod/ ?

Following request seems to work fine:

data = URLExecute[
   "https://api.tidesandcurrents.noaa.gov/api/prod/datagetter" 
   , { "product" -> "predictions"
     , "application" -> "NOS.COOPS.TAC.WL"
     , "begin_date" -> "20250101"
     , "end_date" -> "20250131" 
     , "datum" -> "MLLW"
     , "station" -> "8443970"
     , "time_zone" -> "GMT"
     , "units" -> "english"
     , "interval" -> 6
     , "format" -> "json"}
   , "RAWJson"] 

data["predictions"][[;; 5]]
(*
 {<|"t" -> "2025-01-01 00:00", "v" -> "0.857"|>
, <|"t" -> "2025-01-01 00:06", "v" -> "1.017"|>
, <|"t" -> "2025-01-01 00:12", "v" -> "1.183"|>
, <|"t" -> "2025-01-01 00:18", "v" -> "1.355"|>
, <|"t" -> "2025-01-01 00:24", "v" -> "1.532"|>}
*)
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  • $\begingroup$ Thank you @vindobono $\endgroup$ Commented 4 hours ago

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