Creating new Wind and Wave data for Coastal Vulnerability Model

Science, Research & Data
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I’m trying to create my own wind and wave data for a Coastal Vulnerability model, starting by using ERA5 time series data for the daily maximum of wind from 2019-2024.

I’ve read through the previous forum posts about the required columns for the shapefile and how these are used in the model. I feel I understand how to create a new file, although I am still unclear as to how to original WWIII dataset, provided with the software, was created. Seeing as the new data is meant to be in the same format as this dataset, I want to be sure I’m doing it correctly.

Firstly, the description in the User Manual for how to create your own Wind and Wave data explains the 5 variables needed (each with 16 equiangular segments), with REI_VX and V10PCT_X appearing to be the same calculation - the highest 10% of wind speeds per segment. However checking this against the WWIII data provided shows these values are different. For example, point at LONG -5 LAT 53.5 has a REI_V180 of 15.78m/s and a V10PCT_180 of 18.42m/s.
There are also columns for V20PCT_X and V_MAX_X, I assume these are the top 20% of wind speeds and the max wind speed for each sector but it’s unclear what these are for or if they are needed in a new dataset.

Any help would be greatly appreciated!

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Hi @kevin.walsh , welcome to the forum. This is not an easy task. Hopefully I can help to explain it.

There is a subtle difference between REI_V* and V10PCT_*.

For REI, start with your entire timeseries of wind speeds across all sectors and select the top 10% of these observations. Then assign each observation in this subset to one of 16 sectors based on direction. From these, calculate the average speed in each sector. Some sectors may have 0 observations and that is okay.

For V10PCT, start with your entire timeseries of wind speeds. Assign each observation to one of 16 sectors. Take the top 10% of the observations in each sector and calculate their average.

If they are not described in the User’s Guide, then they are not used by the model and can be omitted.

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Thanks so much Dave, that really clears it up!
I did had that impression originally after reading the User manual but I wasn’t sure after checking the forum and the examining WaveWatchIII data that is supplied with the software.

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For REI, start with your entire timeseries of wind speeds across all sectors and select the top 10% of these observations. Then assign each observation in this subset to one of 16 sectors based on direction. From these, calculate the average speed in each sector. Some sectors may have 0 observations and that is okay.

For V10PCT, start with your entire timeseries of wind speeds. Assign each observation to one of 16 sectors. Take the top 10% of the observations in each sector and calculate their average.

This description was indeed very clear and helpful. The calculation of WAVP_X values is also done as for the V10PCT and not the REI ones, is this correct? Thank you

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Yes, that is true for WavP_X. But for WavPPCT_X, it follows the same logic as for REI_PCTX. I have updated the User’s Guide to hopefully make these variables more clear:

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