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By API Hood | Updated 3 months ago | Weather
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Caribbean Sea predictions time range

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aandrey2ag
6 months ago

Hi good night. I want to clarify some “issues” or inconsistencies we might be experiencing on Caribbean Sea.

  1. Comparing results with other 9 sites I saw inconsistencies in all of them. Predictions vary up to 2 hours in some cases. So is it possible to have a validation of the predictions on this zone? And how accurate are the predictions of this sea?

  2. I’m expecting a 54m-1h:12m between each extreme tide or around 12h:25m between high tides. But I’m able to see up to 7h:41m between high and low tides. Also in other cases, duration between extreme tides took around 4h:10m.

I know Caribbean Sea is a microtidal zone, but I’m not sure how much that affects and I don’t have a way to validate our data is accurate.

I feel really confident about our predictions, I really love this service, but I want to understand better what’s going on here in order to provide better support to my users.

Thanks in advance for the help and I appreaciate all the feedback you can provide.

PS: I compared my app results against marea.ooo https://marea.ooo/en/9.7384806/-82.8407626

Test Location
Cahuita, Limón, Costa Rica.
9.7384806/-82.8407626
Validated Dates between May 17 and May 18.

Saludos,
Andrey AG

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apihood commented 6 months ago

Good morning Andrey,

thank you for the message. I’m not 100% sure I understand you right so before I do the investigation I’d like to ask few question to avoid some confusion.

Your app comparison is made against marea.ooo website? Are the results of your app the same as they are at marea.ooo? (it should be same as marea.ooo is using the Global Tides API).

Could you post some of the websites you were comparing results with?

We are preparing the code update as there is some minor change in tide prediction calculation. I took a quick look at the results for the 9.7384806/-82.8407626 location, but it seems it doesn’t have any significant effect in this particular location (as far as I can see there are small changes in the water heights and extremes timestamp difference is in the order of minutes)

Just for clarification, the predictions are made by the mathematical model which uses historical water level measurements and satellite altimetry. The model is global (meaning for all world oceans), but the quality may vary. We are considering to add another data sources or to use actual measurements from nearby buoys, ports etc to validate the data. But unfortunately we do not have any ETA for now…

Have a nice day
Vojta

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aandrey2ag commented 6 months ago

Thank you so much for reviewing this.

My appologies, I can see what I wrote is not clear.

  1. To clarify, I used marea.ooo in order to validate my app results are ok, which is true. The logic I have is working good, same as marea.ooo. nothing else.

  2. Here are some of the sites I used to compare:

  3. Pacific coast looks as I expect, there is a common patern between high and low tide of around 6 hours which is fine. But when I change to Caribbean coast, time between high and low can vary from 4h10m to 8h.

    • For example I can see Hight tide at 7:21am and next low tide at 11:25am. Only 4 hours when I expect around 6 as global pattern?
    • In other example I can see Hight tide at 5:29am and next low tide at 12:54pm. Almost 8 hours when I expect around 6 as global pattern?
    • This behavior can be also o

So, is there a reason for caribbean predictions to vary 4h10m to 8h between?

Thank you so much, please let me know if you require more information.

Saludos,
Andrey
http://uvitatides.com/

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apihood commented 6 months ago

Hi Andrey,

thank you for the clarification.

I took a quick look at the sites you posted and it seems you are right that there are differences.

I just wanted to point out that for example for https://magicseaweed.com/Playa-Negra-Limon-Surf-Report/2497/ tide forecast is from Limon (“Tide Location Limon - 21.87 miles away”) which is quite far, so I was comparing following for 20th May 2021

https://marea.ooo/en/9.974054/-83.01094
https://magicseaweed.com/Playa-Negra-Limon-Surf-Report/2497/
https://tablademareas.com/cr/costa-mar-caribe/limon#_oleaje
https://www.tideschart.com/Costa-Rica/Limon/Limon/Limon/

Provider High Tide Low Tide High Tide Low Tide
Tideschart 5:30 12:54 19:42 0:49
MSW 4:30 11:54 18:42 23:49
Tabla de Mareas 6:00 12:34 20:12 0:29
Marea.ooo 4:57 12:38 19:08 0:52

So it seems to me that MSW has the same results, but moved by 1 hour as Tideschart. Marea.ooo for location near Limon is somewhat between the sources you posted. The important thing is to compare locations which are close to each other as bathymetry and other factors influence the prediction.

The good news is that you are using the API correctly (sometimes people have problems with timezones and tidal datums) but bad news is that I can’t help you more as the prediction is what it is. As I mentioned before, the quality of global model can vary by location.

As I mentioned we are looking for a way how to validate the data in places with available (near)real time measurements. So when we have something new in this particular location I’ll let you know.

Please let me know if you have other questions.

Have a nice day
Vojta

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aandrey2ag commented 6 months ago

Hi, thank you so much for the information. Thanks to this I have a better understading of how tides works.
I have applied a fix for microtidal predictions.

No more questions for now.

Have a really nice day.

Andrey

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