Scheduled to be launched this month, the first NASA Earth-observing instrument called ISS-RapidScat will monitor ocean winds for climate research as well as weather predictions and hurricane monitoring.
The second instrument scheduled for a December launch is the Cloud Aerosol Transport System (CATS), a laser instrument that will measure clouds and the location and distribution of airborne particles such as mineral dust and smoke in the atmosphere, the US space agency said in a statement.
Before the end of the decade, six NASA Earth science instruments will be mounted atop the ISS to help scientists study our changing planet.
"We are seeing the space station come into its own as an Earth-observing platform," said Julie Robinson, a chief scientist for the ISS Programme at NASA's Johnson Space Center in Houston.
"It has a different orbit than other Earth remote sensing platforms. It is closer to Earth and it sees Earth at different times of day with a different schedule. That offers opportunities that complement other Earth-sensing instruments in orbit today," Robinson added.
The space station-based instruments join a fleet of 17 NASA Earth observing missions currently providing data on the dynamic and complex Earth system.
ISS-RapidScat and CATS follow the February launch of the Global Precipitation Measurement Core Observatory, a joint mission with the Japan Aerospace Exploration Agency, and the July launch of the Orbiting Carbon Observatory-2.
Most of the agency's free flying, Earth observing satellites orbit the planet over the poles at altitudes higher than 400 miles in order to gather data from all parts of the planet.
Although the space station does not pass over Earth's polar regions, its 240-mile-high orbit does offer logistical and scientific advantages.
"With the space station, we do not have to build a spacecraft to gather new data - it is already there," said Stephen Volz, associate director of flight programmes in the Earth Science Division at the NASA Headquarters in Washington, DC.
Two additional NASA Earth science instruments are scheduled to launched in 2016.