[ncl-talk] Azimuthal average of vertical velocity
David Warner
davidwarnerdavid1992 at gmail.com
Thu May 16 02:52:59 MDT 2019
Thank you very much for your response.
I am trying to implement the same method for a variable chosen from the
model output which is in GRIB2 format.
I have many forecast files(126hr forecast) initialized at 1-Dec-2017 00:00
during the cyclone time. For time being I am attaching 5 forecast files
(f000, f006, f012, f018, f024) and I used "join" to concatenate all the
five files. (uploaded data files using ftp)
Each grib2 file has got the following variables. And my task is to compute
the radius-height cross-section of the variable "TMP_P0_L100_GLL0" for the
desired forecast hour and lat/lon location.
*Variable: vNamesType: stringTotal Size: 568 bytes 71
valuesNumber of Dimensions: 1Dimensions and sizes: [71]Coordinates:
(0) TMP_P0_L1_GLL0(1) TMP_P0_L7_GLL0(2) TMP_P0_L100_GLL0(3)
TMP_P0_L103_GLL0(4) POT_P0_L7_GLL0(5) DPT_P0_L100_GLL0(6)
DPT_P0_L103_GLL0(7) LHTFL_P0_L1_GLL0(8) SHTFL_P0_L1_GLL0(9)
SPFH_P0_L100_GLL0(10) SPFH_P0_L103_GLL0(11) RH_P0_L100_GLL0(12)
RH_P0_L103_GLL0(13) PWAT_P0_L200_GLL0(14) CLWMR_P0_L100_GLL0(15)
RWMR_P0_L100_GLL0(16) SNMR_P0_L100_GLL0(17) RIME_P0_L100_GLL0(18)
TCOLR_P0_L200_GLL0(19) TCOLS_P0_L200_GLL0(20) UGRD_P0_L7_GLL0(21)
UGRD_P0_L100_GLL0(22) UGRD_P0_L103_GLL0(23) VGRD_P0_L7_GLL0(24)
VGRD_P0_L100_GLL0(25) VGRD_P0_L103_GLL0(26) VVEL_P0_L100_GLL0(27)
ABSV_P0_L100_GLL0(28) UFLX_P0_L1_GLL0(29) VFLX_P0_L1_GLL0(30)
VWSH_P0_L7_GLL0(31) CD_P0_L103_GLL0(32) PRES_P0_L1_GLL0(33)
PRES_P0_L7_GLL0(34) PRMSL_P0_L101_GLL0(35) HGT_P0_L1_GLL0(36)
HGT_P0_L7_GLL0(37) HGT_P0_L100_GLL0(38) HPBL_P0_L1_GLL0(39)
DSWRF_P0_L1_GLL0(40) USWRF_P0_L1_GLL0(41) DLWRF_P0_L1_GLL0(42)
ULWRF_P0_L1_GLL0(43) CICE_P0_L100_GLL0(44) TCOND_P0_L100_GLL0(45)
TCOLW_P0_L200_GLL0(46) TCOLI_P0_L200_GLL0(47)
TCOLC_P0_L200_GLL0(48) CAPE_P0_L1_GLL0(49) CIN_P0_L1_GLL0(50)
HLCY_P0_2L103_GLL0(51) REFD_P0_L100_GLL0(52) REFC_P0_L200_GLL0(53)
NLAT_P0_L1_GLL0(54) ELON_P0_L1_GLL0(55) LAND_P0_L1_GLL0(56)
SFCR_P0_L1_GLL0(57) WTMP_P0_L1_GLL0(58) LCH_P0_L103_GLL0(59)
APCP_P8_L1_GLL0_acc(60) NCPCP_P8_L1_GLL0_acc(61)
ACPCP_P8_L1_GLL0_acc(62) DSWRF_P8_L1_GLL0_avg(63)
USWRF_P8_L1_GLL0_avg(64) DLWRF_P8_L1_GLL0_avg(65)
ULWRF_P8_L1_GLL0_avg(66) lv_HTGL2(67) lv_ISBL1(68) lv_ISBL0(69)
lat_0(70) lon_0*
But before proceeding to the averaging stuff, first I tried to understand
the input variable. I picked up "TMP_P0_L100_GLL0" (temperature) and this
is how it looks like after joining.
*Variable: tempType: floatTotal Size: 584384920 bytes 146096230
valuesNumber of Dimensions: 4Dimensions and sizes: [ncl_join | 5] x
[lv_ISBL0 | 46] x [lat_0 | 721] x [lon_0 | 881]Coordinates:
lv_ISBL0: [200..100000] lat_0: [57..-33] lon_0:
[14.2..124.2]Number Of Attributes: 12 center : US National Weather
Service - NCEP (WMC) production_status : Operational products
long_name : Temperature units : K _FillValue : 1e+20 grid_type
: Latitude/longitude parameter_discipline_and_category :
Meteorological products, Temperature
parameter_template_discipline_category_number : ( 0, 0, 0, 0 )
level_type : Isobaric surface (Pa) forecast_time : 0
forecast_time_units : hours initial_time : 12/01/2017 (00:00)*
Since this is forecast, there is only* forecast_time : 0* information
available from individual grib files. Now, how must I proceed to assign the
time information for the temp variable when I use "join"? Which option
would fit better to concatenate the forecast grib files ("join" or "cat")?
ncl 0>dnam = getvardimnames(temp)
ncl 1>print(dnam(0))
*Variable: temp (subsection)Type: floatTotal Size: 20 bytes 5
valuesNumber of Dimensions: 1Dimensions and sizes: [ncl_join |
5]Coordinates: Number Of Attributes: 15 lon_0 : 14.2 lat_0 : 57
lv_ISBL0 : 200 initial_time : 12/01/2017 (00:00)
forecast_time_units : hours forecast_time : 0 level_type :
Isobaric surface (Pa) parameter_template_discipline_category_number : (
0, 0, 0, 0 ) parameter_discipline_and_category : Meteorological
products, Temperature grid_type : Latitude/longitude _FillValue :
1e+20 units : K long_name : Temperature production_status :
Operational products center : US National Weather Service - NCEP
(WMC)(0) 1e+20(1) 1e+20(2) 1e+20(3) 1e+20(4) 1e+20*
Shouldn't the output of the above command be 0,1,2,3,4 instead of 1e+20? I
am new to NCL and trying my best to figure out the things. Kindly help me.
Thanks in advance for your time and support.
On Sat, May 11, 2019 at 4:11 AM Dennis Shea <shea at ucar.edu> wrote:
> For sure, the [nice] plot was generated by NCL [panel plot with common
> labelbar].
> ---
> There was a 2017 thread on this topic. A rough approach [tst_polar.ncl]
> was attached to that thread.
> I cleaned it up and made it a function. A pic of the methodology used by
> the function (or tries to do) is here:
>
> ; A conceptual sketch: A pic:
> ;
> *https://cs.stackexchange.com/questions/43744/fast-algorithm-for-interpolating-data-from-polar-coordinates-to-cartesian-coordi*
> <https://cs.stackexchange.com/questions/43744/fast-algorithm-for-interpolating-data-from-polar-coordinates-to-cartesian-coordi>
>
> This works in degrees not km.
>
> However, if your convert the 'radius' [degrees] to those that coincide
> with km distance, this should work! I hope!!!
>
> The attached uses *random data *so the plot [azimuthal_avg.png] does not
> look too good.
> =====
>
> A better function would use "*geolocation_circle*
> <https://www.ncl.ucar.edu/Document/Functions/Contributed/geolocation_circle.shtml>
> "
> This optionally allows 'degrees' or 'km' as input and would allow for
> *much* higher spatial sample at each radii.
> Some example of its use are at:
>
> *https://www.ncl.ucar.edu/Applications/polyg.shtml*
> <https://www.ncl.ucar.edu/Applications/polyg.shtml>
> Examples*:*
>
> *polyg_24, polyg_25*
> *polyg_29, polyg_30 and polyg_31*
>
> Good luck
>
> On Fri, May 10, 2019 at 7:19 AM David Warner <
> davidwarnerdavid1992 at gmail.com> wrote:
>
>> [image: image.png]
>>
>> On Fri, May 10, 2019 at 6:46 PM David Warner <
>> davidwarnerdavid1992 at gmail.com> wrote:
>>
>>> Dear NCL community,
>>>
>>> Is there any function available in NCL to compute the azimuthal average of a 3D variable.
>>>
>>> For example, I need to plot something similar to the image displayed which is the height-radius crosssection of azimuthal average of vertical velocity.
>>>
>>> Given the lat and lon locations by the user, the function must compute the azimuthal mean of the variable.
>>>
>>> Any suggestions would be highly appreciated. Kindly reply at your earliest convenience.
>>>
>>>
>>> [image: image.png]
>>> (Image courtesy: Hui Wang et al., 2014)
>>>
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