I’m using the InVEST Coastal Vulnerability Model to run two different scenarios: the present and the future (SSP 370 for the year 2070). I would like to use future-projected Wind and Wave data instead of the default WaveWatch III (WW3) data .After thoroughly reading the InVEST Guide I still have some doubts about how to build my own Wind and Wave data.
The REI_VX columns represent the mean wind speeds of the highest 10% in each of the 16 sectors, correct?
The REI_PCTX columns indicate the percentage of the highest 10% wind speeds coming from each direction? For example, if the value of REI_PCT22 is 0.0307, does that mean 3% of the highest 10% wind speeds come from the 22° direction?
Regarding WavP_X and WavPPCTX, I understand they follow the same logic as the wind data. Am I correct?
I think you are exactly right, but I’ll try to describe it in a slightly different way to confirm. The tricky part might be the fact that the “10%” is with respect to two different populations for REI_VX vs. REI_PCTX.
For REI_VX, find the top 10% of the wind speed observations in sector X, then average them.
For REI_PCTX, find the top 10% of all wind speed observations across all sectors, then calculate the percentage of those observations that occur in sector X.
So REI_VX answers the question, “what are the top wind speeds observed in sector X”?
And REI_PCTX answers the question, “which sector experiences the most extreme wind speeds most of the time”
After some discussion, it seems like there may actually be a difference in the logic between REI & WavP. I think my previous comment is incorrect for REI, but maybe correct for WavP.
I think this passage from the User’s Guide explains it:
for computation of the REI, sort wind speed time series in descending order, and take the highest 10% values, and associated direction. Sort this sub-series by direction: all wind speeds that have a direction centered around each of the 16 equiangular sectors are assigned to that sector. Then take the average of the wind speeds in each sector. If there is no record of time series in a particular sector because only weak winds blow from that direction, then average wind speed in that sector is assigned a value of zero (0).
First take the top 10% of all wind speed observations. From these, calculate the average for each sector. This is REI_VX. Some sectors may not have any observations in the top 10%. And for each sector, calculate the percentage of these observations occurring in that sector. That is REI_PCTX.
For REI_VX, if a given sector X does not have any observations within the top 10%, is the average wind speed in that sector assigned a value of zero (0)?
Why do REI_VX and WavP_X use different calculation methods?
Now that I understand there’s a difference between REI_VX and WavP_X, does V10PCT_X follow the same logic as one of them? From reading the guide, I understand it’s more similar to WavP_X. Is that correct?
Also, regarding units, wind speeds are in m/s, and wave power is in W/m², right?
Correct, that is how the User’s Guide describes it.
I wish I knew.
Yes, that’s how I read it also. The Coastal Vulnerability model uses WavP as a direct measure of the wave power of “open ocean” waves. And it uses V10P, along with bathymetry depth data, to estimate wave power for local, “wind-driven” waves.