# [ncl-talk] Question about the built-in function trop_wmo

Dennis Shea shea at ucar.edu
Wed Sep 20 18:25:07 MDT 2017

```Source variable:  air(time, level, lat, lon)

Then you do

tf   = addfile(dir + "air.mon.mean.nc", "r")
temp = tf->air
temp = temp + 273.15                               ; units conversion (from
degC to K)
ta   = dim_avg_n_Wrap(temp, 0)               ; compute climatology

===
Thie climatology is calculated over all months and year yielding

ta(level,lat,lon)

===

I have *not* run the script or looked at the source  fortran code for the
'trop_wmo' function.

The temporal averaging over all years and months has smeared out the
vertical profiles at each grid point.

I *speculate* that the 'vertical change criterion' used by the function to
detect the tropopause has been 'smoothed away'.

You might try a single year month for testing. Keep in mind that the
monthly averages are also averages.

Good luck

On Wed, Sep 20, 2017 at 8:15 AM, 王娜 <wangna at mail.iap.ac.cn> wrote:

> Hi all,
>
>
> I am trying to calculate the tropopause pressure with the built-in
> function trop_wmo, but got some abnormal values (equal to 85 hPa or -999
> hPa) when using the monthly temperature from NCEP/NCAR reanalysis 1 (17
> levels between 1000 hPa and 10 hPa).  It seems like that this problem is
> related to the vertical resolution of the input temperature. If I use the
> ERA-interim reanalysis data (32 levels between 1000 hPa and 10 hPa), the
> abnormal values are non-existent.  Does the function trop_wmo not apply to
> the renanlysis data with coarse resolution? Any help on how to fix this
> problem?
>
> Attached are my ncl script and input data.
>
>
> Thanks
>
> Wang Na
>
>
> ------------------------------
> *从mail.iap.ac.cn <http://mail.iap.ac.cn>发来的超大附件*
> air.mon.mean.nc
> 2017年10月05日 22:15 到期)
> 查看下载信息
>
>
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