For FAQ's about annual cdroms, see cdrom FAQ's.
>From ftp://ftp.cpc.ncep.noaa.gov/wd51we/reanal/random_notes/pre1957.tim
Analysis Times ----
Currently the traditional times for launching sondes are
00Z, 06Z, 12Z and 18Z with the 00Z and 12Z having the most
launches. However, prior to June 1957, the launches occured
at 03Z, 09Z, 15Z, 21Z which most being at the 03Z and 15Z
hours. These "off-time" launches had the potential of reducing
the accuracy of the reanalyses. So to avoid this situation,
the analysis times were changed from 00/06/12/18Z to 03/09/15/21Z
for the period before June 1957. In order to make life easy
for all the users of the reanalysis, 00/06/12/18Z analyses were
made from the 3 hours forecasts. The 0-6 hour forecast averages
(fluxes) were calculated from the 3-6 hour and the following 0-3
hour forecasts to produce averages from the traditional 6 hour
periods.
BTW the program that converted the flux data from 03/09/15/21Z to 00/06/12/18Z treated the runoff as a rate rater than an accumulation and incorrectly divided the results by two. SKY noticed some jumps in the radiative quantities and I have to find time to investigate. (Ebisuzaki, NCEP)
CDAS/Reanalysis did not use all the Indian station data (i.e., stations were "blacklisted") which was NCEP practice when Reanalysis was developed. Since then, operational practice has changed so that Indian stations are not blacklisted and PAOBS are not used. In March 1997, CDAS's GTS decoder had to be changed to the new operational decoder because NCEP's mainframes were removed from service. Through an oversight, the Indian data were not blacklisted for processing by CDAS. This oversight will be corrected. At present, there are no plans to add PAOBS decoding to the new decoder.
The effect of using the "blacklisted" Indian stations was to
drastically increase the Indian monsoon precipitation. According to
Dr. Kumar, the assimilation's too low precipitation became too large.
Removing the "blacklisted" stations is necessary for the sake of
temporal continuity over the Indian subcontinent. On the bright side,
Dr. Kumar found the interannual variability was "reasonably well captured"
(about 0.8 correlation between the total Indian JJAS precipitation
anomalies and Reanalysis for the years 1974-1996.)
The same info is also at NCEP.
PS: 1979 Reanalysis did not use the blacklisted stations
| Layer | Depth | GRIB Description | Abbreviation | Comment |
| Top | 0 - 10 cm | 0-10cm | 10.dlr | |
| Middle | 10 - 200 cm | 10-200cm | 200.dlr | |
| Bottom | 200 - 400 cm | 300cm | 300.dpl | Defined as a level in GRIB, it actually represents a layer |
The operational grib table can be found at opn_nceptab
The Reanalysis grib table can be found at reanal_nceptab