Implications of Cris Full Spectral Resolution Operations on Suomi Npp High Rate Data Direct Broadcast

The suite of instruments on board the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, launched October 28, 2011, retrieve global measurements of the Earth's atmosphere, oceans, land surfaces, and near-space environment with precision and detail never before achieved by operational weather satellites. On February 28, 2012, Suomi NPP began to broadcast these instrument data real-time via the satellite's High Rate Data (HRD) antenna. The HRD broadcast provides users around the world with access to free, high quality sensor data that they can use for a wide range of applications from weather forecasting to disaster response. Suomi NPP transmits HRD at a fixed rate of 15.0 Megabits per second (Mbps), appending fill data to variable-sized sensor data as necessary to maintain this rate.

In 2012, members of the Suomi NPP science community successfully advocated for a program directive to change the permanent operational configuration of the Cross-track Infrared Sounder (CrIS) instrument, to acquire full-length interferograms in the Short Wave Infrared (SWIR) and Mid Wave Infrared (MWIR) bands. When operating in this “full spectrum” mode, the CrIS instrument generates data at a higher rate than the baseline, adding approximately 0.94 Mbps of CrIS data to the total mission data stream.

In 2013, we completed an assessment of expected and observed peak instrument data rates to ensure the total data rate with CrIS in full spectrum mode remains within the 15.0 Mbps specification for HRD. We presented the results from our assessment during the 2014 AMS Meeting, concluding that expected peak data rates exceeded the 15.0 Mbps specification for HRD, and offering methods to optimize the composition and configuration of HRD for safe full spectrum operations. Since then, the program has used our assessment to successfully optimize an approach and select a final configuration for the HRD direct broadcast to accommodate CrIS full spectrum. The program is on-track to re-configure the HRD content and permanently transition the CrIS instrument to full spectrum mode by the end of calendar year 2014.

This paper will summarize the chosen HRD configuration for CrIS full spectrum, its impacts, and the motivation behind the selection. We will provide our technical HRD analysis that has allowed NASA and NOAA to satisfy the program directive for CrIS full spectrum while preserving the fidelity of direct broadcast data products for the Suomi NPP user community. As the operational transition is expected to be complete in 2014, we will provide status and early results of the HRD reconfiguration and on-orbit CrIS full spectral data collection in this paper at the 2015 AMS Meeting.