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THEMIS SCIENCE WORKING TEAM MEETING Level 0 (raw) and Level 1 (processed) Products Jim Lewis

THEMIS SCIENCE WORKING TEAM MEETING Level 0 (raw) and Level 1 (processed) Products Jim Lewis University of California - Berkeley. Overview. Overview Level 0 Packet Processing Receive ITOS TM archives from ground stations Extract transfer frames, split packets by VC and APID

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THEMIS SCIENCE WORKING TEAM MEETING Level 0 (raw) and Level 1 (processed) Products Jim Lewis

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  1. THEMIS SCIENCE • WORKING TEAM MEETING • Level 0 (raw) and Level 1 (processed) Products • Jim Lewis • University of California - Berkeley

  2. Overview • Overview • Level 0 Packet Processing • Receive ITOS TM archives from ground stations • Extract transfer frames, split packets by VC and APID • Packet-level decompression • Merge VCs to obtain 24-hour single-apid Level 0 PKT files • Time Tagging and Preliminary CDF Generation • Extract ONESECMARK and sun pulse timing information from housekeeping apids • (DFB apids) Rearrange samples in time order • Generate time-tagged preliminary CDFs • Level 1 CDF processing • Prelim CDFs + Master CDFs = Level 1 CDFs • “Generic” variable names in prelim CDFs renamed to follow established naming convention in L1 CDFs • Master (and L1) CDFs contain useful metadata

  3. Level 0 PKT processing ITOS archive file JPLPCA.THEMIS_B.TLM_VC0_2006_310_211730.0 …VC1_2006_310… splitvc0_300.pkt, splitvc0_404.pkt, etc splitvc1_300.pkt, splitvc1_404.pkt, etc VC0 + VC1: housekeeping VC2 + VC3: science data merged_300.pkt, merged_404.pkt, etc Huffman decompress, Deltamod decompress Sort by UTC YYYY_MM_DD VC merged, single apid pkt files 24-hour Level 0 Packets: thb_l0_20061106_404.pkt

  4. Lvl 0 PKT -> preliminary CDF • Time Tagging and Preliminary CDF Generation • Field data time tags depend on packet header times, ONESECMARK values in apid 0x404, and apid-dependent timing offsets • Particle data time tags depend on packet header times, sun pulse times from BAU housekeeping apids 0x305 (sun pulse MET) and 0x30c (UTC offset of MET) • Raw sun pulse data is smoothed to obtain a “spin model” suitable for time tagging moments and distributions • DFB apids (EFI and SCM) with sample frequency >= 32 Hz need to be “unscrambled” to put samples in time order • Some apids (EFI FFTs, particle distributions) may contain several modes, and result in multiple CDFs for one PKT file. • Preliminary CDFs contain time-ordered packet data, time tags for each sample, no metadata, and “generic” variable names.

  5. Level 1 CDF processing • Level 1 CDF processing • Master CDF for each type of data contains metadata to support automatic plot generation (e.g. CDAWeb) • CDF attributes tie a CDF variable name to a plot type, time variable, axis labels, etc. • Master CDF copied to processing directory and renamed appropriately • Contents of preliminary (data-only) CDF is copied into new soon-to-be L1 CDF • Generic variable names in the preliminary CDF renamed to follow THEMIS conventions and match Master CDF metadata. A distribution variable “counts” in the preliminary CDF might be renamed to “tha_sib_064” (Probe A, SST ion burst distribution with 64 angle bins). • Variable names in L1 CDFs are guaranteed distinct, so many L1 CDFs can be merged into a single product for end users to download.

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