Max J. Suarez, Editor The GEOS-5 Data Assimilation System— Documentation of Versions 5.0.1, 5.1.0, and 5.2.0

Since its founding, NASA has been ded i cat ed to the ad vance ment of aeronautics and space science. The NASA Sci en tifi c and Technical Information (STI) Pro gram Offi ce plays a key part in helping NASA maintain this im por tant role. The NASA STI Program Offi ce is operated by Langley Re search Center, the lead center for NASA ̓ s scientifi c and technical in for ma tion. The NASA STI Program Offi ce pro vides ac cess to the NASA STI Database, the largest col lec tion of aero nau ti cal and space science STI in the world. The Pro gram Offi ce is also NASA ̓ s in sti tu tion al mech a nism for dis sem i nat ing the results of its research and de vel op ment ac tiv i ties. These results are published by NASA in the NASA STI Repor