GriddingMachine Tutorial 4

The Requestor module of the GriddingMachine.jl is designed to request data directly from the server so that users do not need to download the data, which could be time consuming.

Currently, the Requestor module has two key functions that are meant to query data for different purposes:

request_LUT to request data from a particular artifact
request_GMDICT to request a dictionary of data that is used for site level simulations

For example, one can use request_LUT to query the leaf area index data; or he/she can use request_GMDICT to get all the associated model input parameters including leaf area index and chlorophyll content etc. Note that these two functions are meant to use directly with Julia code. One can also add support to other languages, such as Python and Matlab/Octave, as did in (Wang et al., 2022).

request_LUT

The request_LUT function takes the following parameters (may up to changes in future versions):

artname Artifact full name such as LAI_MODIS_2X_8D_2017_V1
lat Latitude
lon Longitude
cyc Cycle index, default is 0 (read entire time series)
include_std Optional. If true, include the standard deviation
interpolation Optional. If true, interpolate the data linearly
port Optional. Port number for the GriddingMachine server
server Optional. Server address such as http://tropo.gps.caltech.edu
user Optional. User name (non-registered users need to wait for 2 seconds before the server processes the request)

Some examples are

request_LUT("LAI_MODIS_2X_8D_2017_V1", 30.5, 115.5);
request_LUT("LAI_MODIS_2X_8D_2017_V1", 30.5, 115.5; interpolation=true);
request_LUT("LAI_MODIS_2X_8D_2017_V1", 30.5, 115.5, 8);
request_LUT("LAI_MODIS_2X_8D_2017_V1", 30.5, 115.5, 8; interpolation=true);

request_GMDICT

The request_GMDICT function can be imagined as a series of request_LUT functions, taking the following parameters (may subject to changes in future versions):

gmversion Emerald version such as gm2. See Emerald Documentation for more details
year Year
lat Latitude
lon Longitude
port Optional. Port number for the GriddingMachine server
server Optional. Server address such as https://tropo.gps.caltech.edu
user Optional. User name (non-registered users need to wait for 5 seconds before the server processes the request)

An example is

gmdict = request_GMDICT("gm2", 2019, 30.5, 115.5);

Web Interfaces

Given that there are many artifacts for users to choose from, we also provide two web interface for users to request the data mannually (not fancy though):