NGIMS Data Processing Level 2 abundances - PowerPoint Presentation

1. NGIMS Data ProcessingLevel 2 abundancesMeredith ElrodNGIMS LEVEL 2 Data: AbundancesA Brief overview pt1By Meredith K Elrod

2. MAVEN Orbit SegmentsCurrent Science – Orbit Period 4.5hrsNGIMS runs starting on Inbound for warmup (67.6 min) and conducts default science during periapsis. NGIMS standard operations include alternating neutral orbits with ion orbits. Twice a week on outbound and apoapse background is run and a functional CPT to monitor the health of the instrument.NGIMS begins science operation during inbound segment in order to warm up filaments for an hour to enable the filaments to be closer to thermal stability before the beginning of science during the periapsis segment.Beginning during walkout of deep dip 5 and 6 NGIMS running wind scan experiments. At the end of 2016 these wind scans were run monthly (10 orbits 5 neutral 5 ion when possible) Wind data to be released.NGIMS has also participated in PF cold ion outflow experiments on the side segments running ion only.

3. Odd orbitFast switching between closed source neutral (CSN) and open source ion (osion) mode. Allows for quick comparison between neutral and ion species within one orbitMaintains same conditions for ion and neutral examinationsLimited neutral species can be computed in closed source mode: Ar, CO2, He, N2Ion mode can compute densities for ion masses 2-90.Standard Operations and products developedEven OrbitFast switching between closed source neutral (CSN) and open source neutral beaming (OSNB)Allows for a complete computation of the neutral compositionCan compute the reactive chemicals, requires comparison with closed sourceAr, CO2, He, N2, O, CO, NO**NOTE: O2 (from older versions) is no longer considered to be reliably measured as O2 thought to be mostly recombined atomic O from atmosphere. NO is produced, but is unreliable also due to recombination in instrument

4. Identification number for each experimentGenerally even # corresponds to periapsis passEarly in the mission did not correlateSiding Spring Range 14015-14021 (all) 14025-14049 (odds)Occasionally run an experiment on outboundFunctional (no L1b produced)Run csn/osnb science on oubound/apoasis to obtain a better picture of open source and closed source data (L1b generated)Run this Background OSNB scan (OB to APO) every other week and daily during deep dips.Why relevant?Number is in EVERY filename:mvn_ngi_l2_cso-abund-21496_20161018T202517_v07_r02.csvngims_tid_caveats.pdf (ngims_tid_caveats.xls also available on request) List of bad TIDs or orbits. This is most often a comm pass when NGIMS is off pointing, will also include safe periods, mag rolls, engineering tids, wind campaigns etc. Does not yet include RELAY passes, but will be updated to include in next update.TID

5. Headerst_unix, t_sclk, t_tid, tid, umkid, orbit, focus_mode, multiplier, filament, temperature_s, mass, counts, cps_raw, cps_raw_bkd, cps_dt, cps_dt_bkd, bkgd, alt_iau, vsc_iau, ram1, ram2_rot_angle, sol_lon, sol_lat, lst, x_iau, y_iau, z_iau, vx_iau, vy_iau, vz_iautid, umkid, mulitplier, filament, ram2_rot_angle-generally used internally by ngims teamOnly contains data from after slew beginning of periapsis from ~500km to periapsis back to ~500km Warmup data has been removedBackground determined by polynomial fit to inbound and outbound upper 100km by mass (those with counts > instrument noise) and first 5s inbound and last 5 second outbound. (possible next revision will exclude outbound background may be too high right now)All ephemeris IAU: WRT to geodetic L1b is produced for every scientific orbit with good pointing. Current exception is the winds campaign. L1b files are pending. All wind data in currently embargoed to the MAVEN team for review.Currently 4 types of L1b: osion—default science CS/ION; osnb--default science CS/OSNB; obion-–ion only data from cold ion outflow OB side. (Pending) ibion—ion only data from cold ion outflow IB side.L1b Files

6. L2 files labeled L2_ion-abundt_unix, t_sclk, t_tid, tid, orbit, focusmode, alt, vsc, ram, ionmass, cps_dt, abundance, sensitivity, potential, precision, qualityIon Sensitivity is computed using STATIC ion computation and LPW electron densities.Abundance is computed by mass per charge, we do not release a species for masses. It is fair to assume O+ is mass 16, however, m28 is likely to be CO+ or N2+ and there is no way for our instrument to distinguish these ions. Compare Density with LPW and STATIC for calibrationUses STATIC computation for SC_potentialNOTE--when SC_potential is <-5 V the SC is too strongly charged for STATIC to accurately measure ion density. This also affects LPW measurement of electrons. Therefore NGIMS sensitivity cannot be commuted. THESE ION ABUNDANCES ARE ONLY RELATIVE NOT ABSOLUTE. Ion Abundancesmvn_ngi_l2_ion-abund-21498_20161019T010257_v07_r01.csv

7. Neutrals—v07L2_csn-abund, L2_cso-abundt_unix, t_sclk, t_tid, tid, orbit, focusmode, alt, mass, species, cps_dt_bkgd, abundance, precision, qualityIn closed source only produce Ar, CO2, He, N2, O and CO.In computing Ar primary mass channel is 40, we use m20 and m190 to correct for saturationIn computing CO2 primary channel 44, use 22, 45, 46, and 13 to correct for saturationHe uses m4 no correction neededN2 primary channel 14 and is corrected with CO2 and CO factors.O primary channel 32 computed assuming total recombination in CS. Corrections with CO2, CO, and N2CO primary channel 28, use 29 179, 178 to correct for saturation. Densities are computed with correction from N2, CO2NO only appears in cso files, primary channel 30 corrected with CO2, CO, O2.Neutral Abundances: what to look for

8. Closed SourceFirst determine attenuation factors between 40/190 and 44/194/344 determine total 40cps and 44 cps accounting for rollover. (4 and 14 don’t rollover) with higher background m16 and m28 also rollover.Compute Scale Height and Temperatures (use Ar temperature as atmosphere for computing all other species) Open sourceRollover hasn’t been an issue in open source, continue to watch m16 with increasing background in case it does.Needs closed source to calibrate (Ar closed to Ar open) to determine open source sensitivity Neutral Abundances: Quick Method Summary

9. Example plot-Neutrals

10. Example plot Ions