Hello:
I wish to calculate Vertically Integrated Water Vapor Transport on a daily basis using ERA-Interim dataset and present a composite map for the same for a 10-day time span. Is this IVT values are directly available at ERA-Interim repository, how to present 10-day average for this. Please suggest how to do so.
Go through equation 1a and 1b of https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD031205
You need to download the specific humidity and wind fields at different pressure levels and then integrate them based on these equations. Hope this helps.
In ERA-Interim archive, there are already a few dataset available, for example, Vertical integral of eastward water vapour flux, Vertical integral of northward water vapour flux and Vertical integral of water vapour. I am wondering, can we download these variables from the archive and use them for our purpose?
Okay. Sorry for misunderstanding your question. I am not sure, but from the looks of it, considering the Northward and eastward IVT as two components of the vector, you may try to estimate the resultant and plot them to see if it make sense.
Hi Poulomi
The ivt values are not available directly.
You will need u-wind (u), v-wind(v), and specific humidity(q) at different pressure levels from the surface (~1000hpa) up to somewhere near 300hpa.
For first two levels, you can take the average q, u, v, and compute q*u and q*v for it.
similarly, for the second and third level, and so on to the last level.
All all the qu values over all the levels to get integrated vapor flux in u direction, call it QU. (you'll also multiply the entire terms by 1/g to make is flux in kgm-1-1). Similalrly, you can find the integrated flux in v direction QV.
After this, you can take the square root of the QU and QV vector to give you IVT.
Hope this helps. Let me know if you need have any question.
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