Some Programmatic Comments Hal Maring A-Train Program Scientist NASA Headquarters

Who is responsible for all this? Symposium Program Committee: Matthew Lebsock Deb Vane Liz Juvera Howard Barker David Crisp Bryan Duncan Hal Maring Lazaros Oreopoulos Jacques Pelon Steven Platnick Jerome Riedi Graeme Stephens Pierre Tabary Didier Tanre Chip Trepte Tobias Wehr

Content of the Symposium Clouds, Radiation and Hydrology (1) Atmospheric Composition and Carbon (1) Clouds, Radiation and Hydrology (posters) Aerosols (1) Clouds, Radiation and Hydrology (2) Aerosols and Atmospheric Chemistry and Carbon (posters) Weather Special Session Special Session, Weather & Applications, Data and Other Topics (posters) Discussion – Future Constellations: Challenges and Opportunities Atmospheric Composition and Carbon (2) Clouds, Radiation and Hydrology (3) Aerosols (2) Two Special Topical Lectures: Graeme Stephens and Bruce Wielicki

Expected Close Approaches Assuming TanSat does not perform a maneuver, it will pass the A-Train on the following dates: 20 Apr 2017 – OCO-2 23 Apr 2017 – CGOM-W 30 Apr 2017 – Aqua 1 May 2017 – CALIPSO 4 May 2017 – CloudSat 11 May 2017 - Aura (Locations based on relative equator crossing times) Response: If the TanSat approach is close, then the A-Train satellites will try to postpone any maneuver until after the approach. If the A-Train satellite has to maneuver, then a communication will be initiated via the State Department.

A-Train Satellite Longevity DRAFT from Sept 2016 MOWG Senior Review CloudSat GCOM-W1 OCO-2 MOWG Meeting Aura CALIPSO Aqua IAM Approved Ops Possible Extended Ops End of Mission Ops Proposed IAMs 2017 2018 2019 2020 2021 ? 1. Not necessarily sensor longevity

Possible Changes in the A-Train Configuration As missions deplete the fuel allocated for orbit maintenance, they may skip some or all of their annual inclination corrections and let their orbits drift CALIPSO and Aqua will be the first two missions in this situation Mission planners can then execute one of two options: Keep the temporal separation with respect to the anchor satellite (Aqua), and let their ground tracks drift eastward (later in the afternoon) or Maintain their ground tracks and decrease their temporal separation (if in front of Aqua) or increase their temporal separation (if behind Aqua) How do these choices affect Science products produced from 2 (or more) A–Train satellites?

Example: CALIPSO/CloudSat/OCO-2 Aqua GCOM W1 OCO-2 CALIPSO CloudSat Aura MLTAN Aqua GCOM W1 OCO-2 CALIPSO CloudSat Aura MLTAN Two Options Change ground track Change temporal separation ? Drift Later Change Temporal Separation

Considering A-Train Orbit Change MOWG Change Request # Submitter Description Status / Comments and Due Date 17 M. Vincent Reduce the size of the Constellation Envelope Submitted – April 29 Revision submitted – May 31 Status – On hold. The topic is to be re-presented at the Fall 2016 MOWG meeting 4, 6 or 8 km? OCO-2 GCOM-W1 CALIPSO Aqua Aura CloudSat 240 sec 86 sec 43 sec 60 sec 30s 195 sec 98.5s Trade: Equator crossing time (orbit inclination) for satellite longevity MOWG or some other appropriate meeting Fair warning for the science leads and an invitation for us all to think about how to go about maximizing the overall science we get out of the A-Train Need to have Science weigh in on possible changes in orbit. Suggest: Science leads meet at the next MOWG, 13-15 Jun 2017 @ GSFC

A-Train Data Analysis Support In the past, the Science of Terra and Aqua, Aura, CALIPSO & CloudSat ROSES solicitations have included/encouraged the utilization data from other satellite sensors in addition to the sensors specifically identified by the solicitation A new Science of Terra and Aqua solicitation is to be release in ROSES-17 immanently, I expect this solicitation will follow the pattern of previous solicitations in this regard