1. Potential Use of Airborne Radio Occultation to Study Atmospheric Rivers Jennifer S. Haase SIO/UCSD jhaase@ucsd.edu

2. GISMOS Airborne Radio Occultation Provides a limb-sounding profile of refractivity using the same technique as COSMIC Haase et al, 2014, GRL

3. Airborne Radio Occultation Advantages: –More control on location of profiles –Occultations will occur within 300 km of the flight path rather than randomly distributed Airborne system for a 6 hour flight path: ~23 occultations COSMIC during the same time period: ~21 occultations Both can be assimilated into the WRF model

4. Example Flight Path Atmospheric river event December 12, 2010 Cosmic sounding Airborne sounding

5. Deployed for Hurricane Karl Data assimilation in WRF is in process Nature Highlights (2014): Aircraft Spy on Tropical Storms http://www.nature.com/nature/journal/v507/n7493/full/507402b.html Collaborative work with Shu-Hua Chen at UCDavis

6. Accuracy compared to dropsondes 26 flights into tropical storms during 2010 PREDICT-IFEX-GRIP campaign Refractivity is within 2% of observations made with dropsondes Airborne specific WRFDA observation operators have been developed (S-H Chen, UC Davis) Haase et al., 2014, GRL

7. GISMOS Ocean surface wind sensing Sharpness of GPS signal reflection provides estimate of sea surface roughness, and wind speed based on Cox and Munk theory. Current experimental limitation of 3 channel recordings => occultation or reflection, but not simultaneously

8. NCAR EOL deployment pool Can be deployed on NSF GV or any aircraft with space for 19” rack Antenna profile is minimal

9. Operational Status Current analysis system –Post-processing of GPS/INS data for increased precision –Raw RF signal recording allows optimization, development, testing of new receiver tracking techniques –Large SCSI disk datasets (400 Gbytes per flight) from continuous recording, no operator intervention required during flights, only startup up and shut down operations required. Modest NSF funding is already available for deployment for a mission before June 2015

10. Deployment Requirements GPS antenna size is not to scale, see data sheet Top navigation antenna, can use feed from existing navigation antennas, anywhere on top of fuselage Port and starboard antennas should be as far forward of the wings as possible to increase azimuthal visibility at the horizon Polarized H-V GPS antenna, could be installed on same window blank as port antenna Optional nadir reflection antenna for surface wind speed, anywhere on underside of fuselage IMU attached to aircraft frame (seat rails) within 15’ cable run of rack, near side antennas (proximity is not limiting error) Standard HIAPER GV 19” rack (provided) 60” tall x 32” deep, attaches to seat rails

11. Deployment Requirements Maximum cable run from rack: IMU = 15’ Maximum with existing RF cables: Top antenna = 40’ H-V antenna = 20’ (H-V antenna could be installed on either port or starboard side) Port and Starboard antenna = 30’ Nadir antenna = 30’