How do I download VIIRS surface reflectance data?

The surface reflectance data are created by applying corrections for atmospheric gases and aerosols to the top of atmosphere reflectance data.  Surface reflectance data are available from January 19, 2012 to present.  Through LP DAAC, several surface reflectance products are available:

Refectance product temporal frequency spatial resolution
VNP09GA Daily 500 m (I-bands), 1 km (M-bands)
VNP09A1 8-day composite 1 km (M-bands)
VNP09H1 8-day composite 500 m (I-bands)
VNP09CMG Daily 5600 m (0.05 degrees)

In the VIIRS Product Table, you can click on each surface reflectance product to obtain more information and to find links to access the data. 

NASA Earthdata Search  provides access to surface reflectance data as well as the other NASA VIIRS products. 

After creating an account and/or logging in, you may search for the product name (e.g. VNP09A1), as well as define your geographic area of interest and temporal range.  The footprint of the VIIRS tile(s) that covers your area of interest will be shown on the map.  You can then download some or all of the tiles that meet your criteria, or have them emailed to you.

For first-time users, it is recommended to watch Getting Started with VIIRS Surface Reflectance Data Part 1, which provides a step-by-step guide of finding and downloading VIIRS surface reflectance data from NASA Earthdata Search.