topic Re: Lambert conformal conic p in ArcGIS Mapping and Charting Questions

Lambert conformal conic p

AdamVaughan — Fri, 18 Aug 2017 10:14:18 GMT

Dear Community,

I'm trying to import and make rasters from netcdf data. It is 1 km resolved data and has a Lambert Conformal Conic projection system. I've tried making a custom projection for it but cannot seem to get the parameters right. Any ideas what parameters I would need to use for the following. The domain is centred on 39.31N, 116.65E.

char Lambert;

:grid_mapping_name = "lambert_conformal_conic";

:latitude_of_projection_origin = 39.51774597167969;

:longitude_of_central_meridian = 110.0;

:standard_parallel = 20.0, 50.0;

:earth_radius = 6370000.0;

Cheers,

Re: Lambert conformal conic p

DanPatterson_Retired — Fri, 18 Aug 2017 10:52:12 GMT

longitude is negative in the western hemisphere ie -110, and you are sure yours is 110E?

Are you modifying a lambert from the country where the dataset resides?

Re: Lambert conformal conic p

AdamVaughan — Fri, 18 Aug 2017 11:16:14 GMT

Hi Dan,

Yes 110E is correct as the data is situated over China.

Cheers,

Re: Lambert conformal conic p

DanPatterson_Retired — Fri, 18 Aug 2017 12:04:37 GMT

And you have ruled out it just being a LCC that is routinely used within China?

MKennedy-esristaff‌ would have more insight on whether this may be the case or how to safely modify a LCC

I just wanted to make sure that East was indeed East

Re: Lambert conformal conic p

AdamVaughan — Fri, 18 Aug 2017 12:54:13 GMT

Hi Dan,

I'm pretty sure its a custom LCC. The most similar LCC projection (Asia_North_Lambert_Conformal_Conic) which I was able to find in Arc has standard parallels different by a few degrees.

I've tried viewing the data quickly using NASA's Panoply 4 view and it looks OK when projected.

Cheers,

Re: Lambert conformal conic p

MelitaKennedy — Fri, 18 Aug 2017 16:50:10 GMT

The hard part is probably making the custom GCS. Here's the complete well-known text:

PROJCS["China_NetCDF",GEOGCS["GCS_Sphere_6370000",DATUM["Sphere_6370000",SPHEROID["Sphere_6370000",6370000.0,0.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",110.0],PARAMETER["Standard_Parallel_1",20.0],PARAMETER["Standard_Parallel_2",50.0],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",39.51774597167969],UNIT["Meter",1.0]]

Copy the string to a text file (Notepad, not Wordpad or Word) and give it a .prj extension. Then you should be able to Import it when setting the data frame or defining the coordinate system of a dataset.

Melita