how to select data from a specific lat-long grid

[Costa, Ozeas]

Hello,

I would like to download GRACE LWE tickness for a specific lat-long grid (lat: -2 to -4; long: -43 to -47) but am struggling to understand how to select the lat-long variables in OPeNDAP. For example, the latitude range listed goes from 0 to 359 (shouldn’t it be from 0-180?) and the longitude range goes from 0-719 (shouldn’t it be from 0-360?). See image below:

 

 

I appreciate any help you can provide.

Best,

Ozeas

 

Ozeas S. Costa, Jr., PhD
Associate Professor, School of Earth Sciences

Affiliated Faculty, Ohio State Sustainability Institute

The Ohio State University at Mansfield
395 Ovalwood Hall, 1760 University Drive, Mansfield, OH 44906
419-755-4128 Office / 419-755-4367 Fax
cost...@osu.edu  

http://u.osu.edu/costa.47/

Pronouns: he/him/his

 

[James Gallagher]

On May 31, 2021, at 13:53, Costa, Ozeas <cost...@osu.edu> wrote:

Hello,

I would like to download GRACE LWE tickness for a specific lat-long grid (lat: -2 to -4; long: -43 to -47) but am struggling to understand how to select the lat-long variables in OPeNDAP. For example, the latitude range listed goes from 0 to 359 (shouldn’t it be from 0-180?) and the longitude range goes from 0-719 (shouldn’t it be from 0-360?). See image below:

 

<image003.png>

 

I appreciate any help you can provide.

OPeNDAP servers do not typically provide subsetting in lat/lon but instead use the array index values of the data as they are stored in databases, files, etc. In this case, there are two ways to access specific lat/lob regions.

1. The 360 index values for ‘lat’ probably map to half degree increments so lat -2 is likely 179 + 4. You can check this by clicking on the 'lat’ variable and looking at it’s values and then mapping those to the indices. Using ‘Get as CSV’ is really useful for this. Similarly, look at the values for ‘lon’ to determine the correct indices for your range. Sometimes datasets store data reversed or with odd offsets, so while the obvious mapping is usually correct, it’s best to check.

2. You can use the grid or geogrid server functions. Since this is the Hyrax server, you can use server functions for this operation: https://docs.opendap.org/index.php/Server_Side_Processing_Functions

Let me know if you need more information.

James

Best,

Ozeas

 

<image001.png>

Ozeas S. Costa, Jr., PhD
Associate Professor, School of Earth Sciences

Affiliated Faculty, Ohio State Sustainability Institute

The Ohio State University at Mansfield 
395 Ovalwood Hall, 1760 University Drive, Mansfield, OH 44906
419-755-4128 Office / 419-755-4367 Fax
cost...@osu.edu  

http://u.osu.edu/costa.47/

Pronouns: he/him/his

<image002.png>

—

James Gallagher

jgall...@opendap.org