[ncl-talk] Problems on Reading Satellite Date
Dennis Shea
shea at ucar.edu
Tue Jun 13 09:09:19 MDT 2017
Please do not send offline emails to me. Reply only to ncl-talk.
" Sorry to bother you again. Your reply help me a lot. But my problem have
not solved completely. The problem is that: There is a station(such as lat
:116.1123E, lon: 36.2323N), and I want to extract the wind_speed on this
station, how can I do it ? "
=============================
Well, I am not going to do any interpolation. The following gives you the
value of the closest grid point to the station.
[SNIP]
; read & unpack desired variables
; https://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml
spd = short2flt( fi->wind_speed ) ; short
wind_speed(NUMROWS, NUMCELLS)
printVarSummary(spd)
printMinMax(spd,0) ; min=0.2 max=19.7
nspd_msg = num(ismissing(spd))
print("nspd_msg="+nspd_msg) ; nspd_msg=119050
print("---------")
; 116.1123E, 36.2323N <==================
LON = 116.1123
LAT = 36.2323
spd1d = ndtooned(spd)
lat1d = ndtooned(lat2d)
lon1d = ndtooned(lon2d)
igood = ind(.not.ismissing(spd1d))
gcdist = gc_latlon(LAT,LON,lat1d(igood),lon1d(igood), 2,2)
printVarSummary(gcdist)
imin = minind(gcdist)
spd_loc = spd1d(imin)
print(spd_loc)
======================
Variable: spd_loc
Type: float
Total Size: 4 bytes
1 values
Number of Dimensions: 1
Dimensions and sizes: [1]
Coordinates:
Number Of Attributes: 1
_FillValue : -32767
(0) 3.24
On Mon, Jun 12, 2017 at 9:22 PM, 宫明晓 <gongmingxiao1988 at 163.com> wrote:
> Dear Shea，
> Sorry to bother you again. Your reply help me a lot. But my problem
> have not solved completely. The problem is that: There is a station(such as
> lat :116.1123E, lon: 36.2323N), and I want to extract the wind_speed on
> this station, how can I do it ?
>
>
>
>
>
> At 2017-06-12 11:43:44, "Dennis Shea" <shea at ucar.edu> wrote:
>
> Please *look* at your file dump. In particular, look at the variable types
> (integer, short) and the scale_factor and add_offset attributes.
>
> See attached.
> ===========
> There are numerous satellite swath examples:
>
> https://www.ncl.ucar.edu/Applications/HDF.shtml
>
> Good luck
>
>
> On Sun, Jun 11, 2017 at 1:30 AM, 宫明晓 <gongmingxiao1988 at 163.com> wrote:
>
>> Dear NCL team,
>>
>> I have read a satellite grid data, but I want to read the data on the
>> fixed longitude and latitude, so I need to change the data from data(
>> NUMROWS, NUMCELLS) to data(lat,lon), how can I do it?
>> Sorry my English is very poor.
>> Thank you very much!
>>
>>
>> ;;-------------------------------------------------------------
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>> ;;----------------------------------------------------------
>> --------------
>>
>> f=addfile("ascat_20130416_134200_metopa_33683_eps_o_coa_2101_ovw.l2.nc
>> ","r")
>> u_speed=f->wind_speed
>> vs = new(dimsizes(f->wind_speed),float,-99999)
>> vs =(f->wind_speed)*0.01
>>
>> lat2d = f->lat
>> lon2d = f->lon
>> lat2d at units = "degrees_north"
>> lon2d at units = "degrees_east"
>>
>> vs at lat2d = lat2d
>> vs at lon2d = lon2d
>> vs at units = "ms-1"
>> vs at coordinmates = "lat2d lon2d"
>>
>> print(vs({11},{11})) ;;;*how can I print the data like this type??????*
>>
>>
>>
>>
>> *;;PrintVarSummary(f)*
>>
>> Variable: f
>> Type: file
>> filename: ascat_20130416_134200_metopa_33683_eps_o_coa_2101_ovw.l2
>> path: ascat_20130416_134200_metopa_33683_eps_o_coa_2101_ovw.l2.nc
>> file global attributes:
>> title : MetOp-A ASCAT Level 2 Coastal Ocean Surface Wind Vector
>> Product
>> title_short_name : ASCAT-L2-Coastal
>> Conventions : CF-1.4
>> institution : EUMETSAT/OSI SAF/KNMI
>> source : MetOp-A ASCAT
>> software_identification_level_1 : 801
>> instrument_calibration_version : 0
>> software_identification_wind : 2101
>> pixel_size_on_horizontal : 12.5 km
>> service_type : eps
>> processing_type : O
>> contents : ovw
>> granule_name : ascat_20130416_134200_metopa_3
>> 3683_eps_o_coa_2101_ovw.l2.nc
>> processing_level : L2
>> orbit_number : 33683
>> start_date : 2013-04-16
>> start_time : 13:42:00
>> stop_date : 2013-04-16
>> stop_time : 15:23:58
>> equator_crossing_longitude : 116.924
>> equator_crossing_date : 2013-04-16
>> equator_crossing_time : 13:41:03
>> rev_orbit_period : 6081.7
>> orbit_inclination : 98.7
>> history : N/A
>> references : ASCAT Wind Product User Manual, http://www.osi-saf.org/,
>> http://www.knmi.nl/scatterometer/
>> comment : Orbit period and inclination are constant values. All wind
>> directions in oceanographic convention (0 deg. flowing North)
>> creation_date : 2013-04-16
>> creation_time : 16:27:43
>> dimensions:
>> NUMROWS = 3259
>> NUMCELLS = 82
>> variables:
>> integer time ( NUMROWS, NUMCELLS )
>> _FillValue : -2147483647 <(214)%20748-3647>
>> missing_value : -2147483647 <(214)%20748-3647>
>> valid_min : 0
>> valid_max : 2147483647 <(214)%20748-3647>
>> long_name : time
>> units : seconds since 1990-01-01 00:00:00
>> coordinates : lat lon
>>
>> integer lat ( NUMROWS, NUMCELLS )
>> _FillValue : -2147483647 <(214)%20748-3647>
>> missing_value : -2147483647 <(214)%20748-3647>
>> valid_min : -9000000
>> valid_max : 9000000
>> long_name : latitude
>> units : degrees_north
>> scale_factor : 1e-05
>> add_offset : 0
>>
>> integer lon ( NUMROWS, NUMCELLS )
>> _FillValue : -2147483647 <(214)%20748-3647>
>> missing_value : -2147483647 <(214)%20748-3647>
>> valid_min : 0
>> valid_max : 36000000
>> long_name : longitude
>> units : degrees_east
>> scale_factor : 1e-05
>> add_offset : 0
>>
>> short wvc_index ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : 0
>> valid_max : 999
>> long_name : cross track wind vector cell number
>> units : 1
>> coordinates : lat lon
>>
>> short model_speed ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : 0
>> valid_max : 5000
>> long_name : model wind speed at 10 m
>> units : m s-1
>> scale_factor : 0.01
>> add_offset : 0
>> coordinates : lat lon
>>
>> short model_dir ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : 0
>> valid_max : 3600
>> long_name : model wind direction at 10 m
>> units : degree
>> scale_factor : 0.1
>> add_offset : 0
>> coordinates : lat lon
>>
>> short ice_prob ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : 0
>> valid_max : 1000
>> long_name : ice probability
>> units : 1
>> scale_factor : 0.001
>> add_offset : 0
>> coordinates : lat lon
>>
>> short ice_age ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : -5000
>> valid_max : 5000
>> long_name : ice age (a-parameter)
>> units : dB
>> scale_factor : 0.01
>> add_offset : 0
>> coordinates : lat lon
>>
>> integer wvc_quality_flag ( NUMROWS, NUMCELLS )
>> _FillValue : -2147483647 <(214)%20748-3647>
>> missing_value : -2147483647 <(214)%20748-3647>
>> valid_min : 0
>> valid_max : 8388607
>> long_name : wind vector cell quality
>> coordinates : lat lon
>> flag_masks : <ARRAY of 17 elements>
>> flag_meanings : distance_to_gmf_too_large data_are_redundant
>> no_meteorological_background_used rain_detected rain_flag_not_usable
>> small_wind_less_than_or_equal_to_3_m_s large_wind_greater_than_30_m_s
>> wind_inversion_not_successful some_portion_of_wvc_is_over_ice
>> some_portion_of_wvc_is_over_land variational_quality_control_fails
>> knmi_quality_control_fails product_monitoring_event_flag
>> product_monitoring_not_used any_beam_noise_content_above_threshold
>> poor_azimuth_diversity not_enough_good_sigma0_for_wind_retrieval
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> * short wind_speed ( NUMROWS, NUMCELLS ) _FillValue : -32767
>> missing_value : -32767 valid_min : 0 valid_max :
>> 5000 long_name : wind speed at 10 m units : m s-1
>> scale_factor : 0.01 add_offset : 0 coordinates :
>> lat lon*
>>
>> short wind_dir ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : 0
>> valid_max : 3600
>> long_name : wind direction at 10 m
>> units : degree
>> scale_factor : 0.1
>> add_offset : 0
>> coordinates : lat lon
>>
>> short bs_distance ( NUMROWS, NUMCELLS )
>> _FillValue : -32767
>> missing_value : -32767
>> valid_min : -500
>> valid_max : 500
>> long_name : backscatter distance
>> units : 1
>> scale_factor : 0.1
>> add_offset : 0
>> coordinates : lat lon
>>
>>
>>
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>
>
>
>
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