[ncl-talk] masking the contiguous United States
Ming Chen
chen1718 at umn.edu
Wed Jul 8 12:00:45 MDT 2015
Mary,
Thank you for the information. I tried -127, the result is the same. I
guess this is a bug in the shapefile_mask_data.ncl script.
Anyway, I used ArcGIS to subset the shapefile to conterminous US and it
worked.
Thanks!
Ming
On Wed, Jul 8, 2015 at 12:21 PM, Mary Haley <haley at ucar.edu> wrote:
> Hi Ming,
>
> Sorry for the delay in response. I think you might need to use something
> larger than -130, like -127.
>
> I'm in a conference this week. If you continue to have problems, you might
> try the masking using shapefile names, rather than lat/lon boundaries.
>
> --Mary
>
>
> On Sun, Jul 5, 2015 at 12:34 PM, Ming Chen <chen1718 at umn.edu> wrote:
>
>> Thanks a lot Mary!
>>
>> The lonFlip function worked and I was able to mask the data.
>> However, I found that Alaska is also masked in, while I just need the
>> contiguous US.
>> I have specified the max/min of longitude and latitude, is it not working?
>>
>> Here is the debug message:
>> (0) ==================================================
>> (0) Shapefile: cb_2014_us_nation_20m.shp *###NOTE that I
>> changed a shape file because the previous one did not work well and only
>> masked in the Alaska area. ###* This one could be download at
>> https://www.census.gov/geo/maps-data/data/cbf/cbf_nation.html
>> (0) Areas of interest: the whole shapefile
>> (0) min_lat_chk: 20
>> (0) max_lat_chk: 50
>> (0) min_lon_chk: -130
>> (0) max_lon_chk: -65
>> (0) min_lat_data: -90
>> (0) max_lat_data: 90
>> (0) min_lon_data: -180
>> (0) max_lon_data: 177.5
>> (0) 13824 data values originally
>> (0) Will keep data values inside given shapefile areas
>> (0) ==================================================
>> (0) 229 data values kept
>> (0) shapefile_mask_data: elapsed time: 0.377945 CPU seconds.
>> (0) ==================================================
>>
>> Thanks,
>> Ming
>>
>> On Sat, Jul 4, 2015 at 11:45 PM, Mary Haley <haley at ucar.edu> wrote:
>>
>>> If you have lat/lon coordinate arrays attached to your data, then can
>>> try the "lonFlip" function to convert your data to be -180 to 180 longitude:
>>>
>>> http://www.ncl.ucar.edu/Document/Functions/Contributed/lonFlip.shtml
>>>
>>> If you don't have coordinate arrays, but instead are using the special
>>> lat2d/lon2d or lat1d/lon1d attributes, then you can try the "where"
>>> function:
>>>
>>> NEE_AVG at lon2d = where(lon2d.gt.180, lon2d - 360, lon2d)
>>>
>>> Note: I don't know what your longitude array is called. I'm just using
>>> "lon2d" as an example here. You can operate on the attribute directly:
>>>
>>> NEE_AVG at lon2d = where(NEE_AVG @lon2d.gt.180, NEE_AVG @lon2d - 360,
>>> NEE_AVG at lon2d)
>>>
>>> You will also need to update your minlon/maxlon attributes to be in -180
>>> to 180
>>>
>>> opt at minlon = -130 ; 230 - 360
>>> opt at maxlon = -65 ; 295 - 360
>>>
>>>
>>> --Mary
>>>
>>>
>>>
>>> On Sat, Jul 4, 2015 at 9:34 PM, Ming Chen <chen1718 at umn.edu> wrote:
>>>
>>>> I think I know why it is happening... The data I'm trying to mask has
>>>> the longitude from 0 to 357.5, while the shapefile has the longitude from
>>>> -179.1 to 179.8...
>>>>
>>>> Does anyone has suggestion how I can fix that? Thanks!
>>>>
>>>> Ming
>>>>
>>>>
>>>>
>>>> On Sat, Jul 4, 2015 at 10:19 PM, Ming Chen <chen1718 at umn.edu> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I was trying to mask the contiguous United States using a shape file
>>>>> and the script "shapefile_mask_data.ncl", but got all missing values.
>>>>>
>>>>> I used ncl 6.2.1. The script I used is here:
>>>>>
>>>>> ;Begins to calculate US averaged NEE
>>>>> shp_filename = "coastl_usa.shp"
>>>>> opt = True
>>>>> opt at minlat = 20
>>>>> opt at maxlat = 50
>>>>> opt at minlon = 230
>>>>> opt at maxlon = 295
>>>>> opt at debug = True
>>>>> opt at keep = True
>>>>> opt at loop_check = True
>>>>> data_mask = shapefile_mask_data(NEE_AVG,shp_filename,opt)
>>>>> NEE_scalar = wgt_areaave(data_mask,1.,1.,0) ;averaged NEE over the
>>>>> United States
>>>>>
>>>>>
>>>>> And here is the message I got:
>>>>> (0) ==================================================
>>>>> (0) Shapefile: coastl_usa.shp
>>>>> (0) Areas of interest: the whole shapefile
>>>>> (0) min_lat_chk: 20
>>>>> (0) max_lat_chk: 50
>>>>> (0) min_lon_chk: 230
>>>>> (0) max_lon_chk: 295
>>>>> (0) min_lat_data: -90
>>>>> (0) max_lat_data: 90
>>>>> (0) min_lon_data: 0
>>>>> (0) max_lon_data: 357.5
>>>>> (0) 13824 data values originally
>>>>> (0) Will keep data values inside given shapefile areas
>>>>> (0) ==================================================
>>>>> (0) 0 data values kept
>>>>> (0) shapefile_mask_data: elapsed time: 0.930859 CPU seconds.
>>>>> (0) ==================================================
>>>>>
>>>>> I can see there are 13824 data points in my NEE_AVG data. And I have
>>>>> plot that without problem. Why there was no data masked?
>>>>>
>>>>> Thanks,
>>>>> Ming
>>>>>
>>>>>
>>>>> --
>>>>> Department of Soil, Water and Climate
>>>>> 439 Borlaug Hall 1991 Upper Buford Cir.
>>>>> St. Paul 55108
>>>>> MN USA
>>>>> Office: 612-624-1645
>>>>> http://www.biometeorology.umn.edu/people_ming.php
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Department of Soil, Water and Climate
>>>> 439 Borlaug Hall 1991 Upper Buford Cir.
>>>> St. Paul 55108
>>>> MN USA
>>>> Office: 612-624-1645
>>>> http://www.biometeorology.umn.edu/people_ming.php
>>>>
>>>> _______________________________________________
>>>> ncl-talk mailing list
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>>>>
>>>>
>>>
>>
>>
>> --
>> Department of Soil, Water and Climate
>> 439 Borlaug Hall 1991 Upper Buford Cir.
>> St. Paul 55108
>> MN USA
>> Office: 612-624-1645
>> http://www.biometeorology.umn.edu/people_ming.php
>>
>
>
--
Department of Soil, Water and Climate
439 Borlaug Hall 1991 Upper Buford Cir.
St. Paul 55108
MN USA
Office: 612-624-1645
http://www.biometeorology.umn.edu/people_ming.php
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