## How is height converted to pressure when using hybrid sigma-pressure levels?

### How is height converted to pressure when using hybrid sigma-pressure levels?

My input data is on hybrid sigma-pressure levels, similar to ECMWF (vertical coordinate system flag 4). How is the final column of the trajectory endpoints file, 'PRESSURE', calculated? I would like to be able to plot my source data in either height or pressure coordinates, but I want to make sure the conversion I'm using on my data matches that used in the trajectories so that they line up correctly.

### Re: How is height converted to pressure when using hybrid sigma-pressure levels?

You may use the hypsometric equation to compute the pressure from temperature and geopotential height.

https://en.wikipedia.org/wiki/Hypsometric_equation or you can find it in any meteorological textbook.

https://en.wikipedia.org/wiki/Hypsometric_equation or you can find it in any meteorological textbook.