SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys)  was a large field campaign with multiple objectives that was conducted in August and September of 2013. It was based in at NASA AFRC in Palmdale, California at the start of the campaign and later in Houston, Texas. The AirMSPI and RSP instruments were on the ER-2, but the PACS instrument was not involved - so intercomparisons can be performed between only between RSP and AirMSPI for these data. An instrument similar to the PACS (called RPI) was deployed on the DC-8 aircraft). The SEAC4RS field campaign was also coordinated with the Houston deployment of DISCOVER-AQ in 2013.