NASAaccess
=====================
Ibrahim N. Mohammed (Ibrahim.mohammed@nasa.gov)

What is NASAaccess?
NASAaccess is a software application in the form of a R package (https://www.r-project.org/about.html) and a web application.  NASAaccess software can generate gridded ascii tables of climate (CIMP5) and weather data (GPM, TRMM, GLDAS) needed to drive various hydrological models (e.g., SWAT, VIC, RHESSys, ...etc.).

How to cite the NASAaccess software?
Mohammed, I. N., 2019, NASAaccess: Downloading and reformatting tool for NASA earth observation data products [software]. National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, Maryland. https://github.com/nasa/NASAaccess

Where to find the NASAaccess software?
The NASAaccess R package is an open source software package under NASA Open Source Agreement v1.3 (https://opensource.org/licenses/NASA-1.3) and can be downloaded from Github at https://github.com/nasa/NASAaccess.

NASAaccess is also available as a web-based application that can be installed on servers for multiple usage suited for agencies and centers.  Full details on installing the web-based version of NASAaccess at local servers can be found at https://github.com/BYU-Hydroinformatics/SWATOnline/blob/master/Documentation/nasaaccess%20-%20Installation%20Guide.pdf

What is needed to run the NASAaccess software on my local machine?
On a local machine the user should have installed the following programs as well as setting up a user account.  The list below gives a summary of what is needed to be done prior to work with NASAaccess software on any local machine:
	•	Installing R software — https://cloud.r-project.org/
	•	Installing Rstudio software — https://rstudio.com/ (OPTIONAL)
	•	NASAaccess R package needs a user registration access with Earthdata (https://earthdata.nasa.gov/).  Users should set up a registration account(s) with Earthdata login as well as well as authorizing NASA GESDISC data access.  Please refer to https://disc.gsfc.nasa.gov/data-access for further details.
	•	After registration with Earthdata the NASAaccess software package users should create a reference file (‘netrc’) with Earthdata credentials stored in it to streamline the retrieval access to NASA servers.
			o	Creating the ‘.netrc’ file at the user machine 'Home' directory and storing the user NASA GESDISC logging information in it is needed to execute the package commands is explained at https://wiki.earthdata.nasa.gov/display/EL/How+To+Access+Data+With+cURL+And+Wget
			o	For Windows users the NASA GESDISC logging information should be saved in a file ‘_netrc’ beside the ‘.netrc’ file explained above.
	•	Installing ‘curl’ software (https://curl.haxx.se/).  Since Mac users have ‘curl’ as part of macOS build, Windows users should make sure that their local machines build have 'curl' installed properly.
	•	Checking if you can run curl from your command prompt.  Type curl --help and you should see the help pages for the curl program once everything is defined correctly.
	•	Within Rstudio or R terminal run the following commands to install NASAaccess:
			o	library(devtools)
			o	install_github("nasa/NASAaccess")
			o	library(NASAaccess)

Within the Rstudio help tab the user can verify that the package has been installed and browse the help pages of the various functions of NASAaccess.