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Lessons Learned for Science Processing. Phil Callahan March 13, 2006. Overview. Background Measurement System Engineer Role Science Team Participation Processing Testbed Consistency: Terms, Units, Corrections, Data Flagging Figure out what the data mean
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Lessons Learned for Science Processing Phil Callahan March 13, 2006
Overview • Background • Measurement System Engineer Role • Science Team Participation • Processing Testbed • Consistency: Terms, Units, Corrections, Data Flagging • Figure out what the data mean • Have more than adequate computing power • Deliver documents early, data soon after sensor turn on
Altimeter Measurement System Measurement Sys Eng Role • Maintain Error Budget • Liaison w/ Science Team • Product Definition • Algorithm Development • Calibration / Validation • Focal point for questions, complaints from data users Photo courtesy of JPL/NASA
Science Team Participation • Engaged with Project management, engineering aspects, science team members • Participate in • Data product definition • Algorithm definition / development • Calibration / Validation • Continuing interaction with Project throughout the mission • Publish • Public Outreach
Processing Testbed • Build early during algorithm development to define, test algorithms • Add software backbone as available • Use real products • Process test or simulated data • Process instrument test data as far forward as possible • Push simulated data backwards as far as possible • Use outputs to test final processing system • Will find bugs in both, but overall beneficial • Update and use throughout mission • Especially valuable during Cal/Val to try fixes, new constants • Data quality monitoring, quick-look processing
Consistency • Terms • Common, logical meanings, but make distinctions where useful • Example: Height Vs Range Vs Altitude • Units – in Products, among Algorithms • Correction and Sign Convention • Corrections ADD to value to bring closer to truth • Flag Convention and Design through entire processing chain • Design early, Use in Testbed • Document clearly for users – flags at later stages of processing depend on those earlier and may not be meaningful • Separate data and flags (avoid “flag values”); output calculated value if possible • Example: Bad(1) until test Good(0), clear spares at end
El Nino – Painting the Pacific Photo courtesy of JPL/NASA
Figure out what the data mean / If you don’t understand an answer – Ask • Waveform features • TOPEX Oscillator drift error • SWH drift as PTR changed • Tide Gauge Calibration • Trust, but Verify
Computing Power • Computer hardware is cheap compared to people’s time • Being able to process, reprocess, and reprocess again is extremely important during Cal/Val • Having a substantial amount of data, at least all of the Cal/Val period, on line is crucial • Separate Development, Integration & Test, Operational Systems • Aim for ~10X throughput • After ~ 2 yrs, reprocess all data in <~3 months
TOPEX – Jason-1 – Jason-2: 15+ yr Record Photo courtesy of JPL/NASA