# [ncl-talk] Ice/liquid water path

Dennis Shea shea at ucar.edu
Sun Jul 10 20:12:07 MDT 2016

```Well, NCL has several standard integration functions:

http://www.ncl.ucar.edu/Document/Functions/Built-in/simpne.shtml
http://www.ncl.ucar.edu/Document/Functions/Built-in/simpeq.shtml
http://www.ncl.ucar.edu/Document/Functions/Built-in/ftcurvi.shtml

===
However, I suggest weighting the values by the appropriate layer
thicknesses.

vertical_average  = SUM[q*dp]/SUM[dp]
vertical_integral   = SUM[q*dp]

LWP = SUM[q*dp]/gravity    ; g/m^2

===

'dp' can be calculated via:

http://www.ncl.ucar.edu/Document/Functions/Built-in/dpres_hybrid_ccm.shtml

http://www.ncl.ucar.edu/Document/Functions/Built-in/dpres_plevel.shtml

===

The 6.4.0 NCL has

http://www.ncl.ucar.edu/Document/Functions/Contributed/wgt_vertical_n.shtml

http://www.cgd.ucar.edu/~shea/contributed.ncl_beta_640

To use it:

or

===
Another, definition of LWP is here
https://climatedataguide.ucar.edu/climate-data/liquid-water-path-overview

Good Luck

On Sat, Jul 9, 2016 at 4:50 PM, Marston Johnston <shejo284 at gmail.com> wrote:

> Hi,
>
> I'm wondering if NCL has a function for calculating the vertically
> integrated ice/liquid water path? I did this a long time ago in python
> using a trapezoid rule but I can't seem to find something similar in NCL.
> If anyone has a code to do this, I would appreciate some tips in how to do
> it in NCL.
>
> /M
>
>
>
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