MERRA2 Data Lessons for next REANL

This is just a scratch place to put notes on obs as they are found in MERRA2.

• AMSU-A N19. The date of death in active channels database is 20091222 000000 for Channel 8. This isn't proper, however, as the channel is seemingly dead from the get-go of the Jan10 stream. Eventually, a true death date will need to be determined.

• RapidScat will come in at some point. Initial dev was w/ QuikSCAT slot but no code changes. NESDIS (Sid's team) passed developments to use the OSCAT slot. If OSCAT is considered in the future, both instruments will likely share the same slot. From my end (wm), the largest development was the implementation of a thinning mesh similar to ASCAT for RapidScat. This is probably ideal for QuikSCAT in the future no matter. I do not know offhand what thinning, if any, OSCAT used. It may also be worth considering thinning for ERS instruments.

• Aircraft observations. Prior to 20130731/00z our reanalysis data uses a table incompatible with the new NRL aircraft quality control. There was also a problem in the way the height (derived from pressure) was calculated in the earlier MDCRS obs that would be flagged by NRLQC. One more issue is that our MDCRS data is being written with +/-3 hour window and the QC would benefit from having observations beyond these limits (just as Profiler and AMDAR windows are larger). For the next reanalysis the aircraft observations should be replaced, preferably processed with a recent version of PREPDATA so that TAMDAR observations get tail number IDs. (Even if we don't use them we may want to look at them.) Alternatively we could try to rewrite the data we have with corrected ACARS heights, updated BUFR table, and possibly wider time windowing.

• A shift in RAOB T O-F bias @ 700 hPa was seen to occur in Nov 1991 and seemingly recover in later years. The only real signal to correlate was SSMI Wind Speeds over that month, which showed a reduction in O-F bias. Otherwise, no real obvious signal was seen, but further investigation is necessary. It may be worthwhile to consider this transition as a period of testing in the next reanalysis.
  • Media:Large.300_700_raobt_o-f_m2_vs_merra.png
  • Media:Large.300_700_raobt_o-f_m2_vs_merra.1991-1992.png
  • Media:Large.300_700_raobt_o-f_m2_vs_merra.2004-2008.png

• An issue was seen in the OSTIA SST field for Feb-Mar 2016. Refer to Gary's monitoring slides from 15 Apr 2016.
  • Media:gp_15apr2016-slide4.png

• Drifting buoys with WMO IDs 48513 and 48517 have been added to the MERRA2 and FP/FPIT blacklists to stop assimilating temperature since the observations appear to be bad. This blacklist has not been checked in to the repository since the buoy IDs were used in earlier periods and we're not sure we want to blacklist these for all time. We need to work on blacklisting (possibly time dependent) and/or improved quality control of buoy data for the next reanalysis.

• We will need to give some attention to radiosonde radiation correction and the Haimberger homogenization database for the next reanalysis. Our current Haimberger data runs through 2005 (I think) and there have been new radiosonde types introduced e.g. in the US since then.