remote sensing - What are the necessary correction/calibration on Landsat 8 imagery for land cover classification?

I downloaded calibrated/corrected Landsat 8 data (Level 2) from ESPA (https://espa.cr.usgs.gov/) to do land cover classification. But there are many corrections and calibrations can be done as listed below and maybe more, such as:

 - Surface Reflectance
 - Top of Atmospheric 
 - sensor zenith and azimuth 
 - solar zenith and azimuth  

 - geometric 
 - radiometric

I am not sure all of them were processed on the scene. What are the must do corrections/calibrations for Land cover classification analysis?

Answer

You can perform a land cover classification on a single Landsat scene without performing spectral and radiometric corrections. You will only need to do those corrections if you're trying to apply reference spectra to your classification, performing a classification that covers multiple scenes or performing a classification over a time series of the same scene.

You may need to apply a geometric correction if you find that the image has significant differences when compared to your reference data.

If you do want to apply a correction you will need to reference the image metadata and associated Landsat User Guide. In ArcGIS, the Spatial Analyst - Raster Calculator tool can be used to apply the appropriate correction formula to each band in the image.