CORe is an atmospheric reanalysis from the Climate Prediction Center NCEP/NWS/NOAA with collaboration with Environmental Modeling Center NCEP/NWS/NOAA and Physical Sciences Laboratory NOAA. CORe is designed to replace CDAS (real-time extension to NCEP/NCAR Reanalysis). CORe covers a similar period of time (1950 to real time vs 1948 to real time), and was designed for climate monitoring, one of the Climate Prediction Center's major tasks. Unlike most modern reanalyses, CORe does not assimilate satellite data except for Atmospheric Motion Vectors (AMV). This was done to eliminate spurious "climate shifts" caused by the ingest of satellite data. This problem affected the earlier NCEP/NCAR and Climate Forecast System Reanalyses. This design emphasizes improving the climate trends and anomalies over getting the best state for a forecast.

This web page provides information on the data that will be available from CORe, and a description of the look alike files which are CORe files that looks like the CDAS (NCEP/NCAR Reanalysis) pgb and flux files.

CORe vs CDAS Output

CORe output is much different from the CDAS output. This is natural because much has changed in the 30 years since CDAS was developed. CORe is a modern reanalysis, so it uses a modern model, modern formats and the needs of the users have changed.

                      CORe                        CDAS
Output
grid format           grib version 2              grib version 1
output frequency      every 3 hours               every 6 hours
pgb grid              512 x 256 Gaussian grid     144 x 73 latitude-longitude grid
flux grid             512 x 256 Gaussian grid     192 x 94 Gaussian grid
post processor        NCEP post, simple post      MRF post, isentropic post, sigma post
high prec output      nemsio                      binary              *grib has reduced prec
restart files         some (6 every 24 hours)     yes (1 every 6 hours)
ensemble members      80                          no
ensemble statistics   yes                         no
extended forecasts    no                          yes
fields on model Z     yes (nemsio)                spectral and grid
isentropic            no                          yes
sigma                 no                          yes

System
model                 FV3GFS (UFS)                MRF
X-Y                   C128 cubed sphere           T62 Gaussian grid
resolution            about 0.7 degree            about 2 degrees
number of Z           64 layers                   28 levels
Z coordinates         pressure-sigma              sigma
pressure              non-hydrostatic             hydrostatic
clouds                prognostic                  diagnostic
sea ice               observed fractional         observed either 0% or 100% ice covered
land surface model    Noah                        OSU
soil layers           4                           2
ensemble              80 members                  1 (not ensemble based)
data assimilation     Ensemble Kalman Filter      3-D Var
original # cpus       720                         1/3 of Cray XP
current # cpus        128 (small) or 256 (fast)   1

The output from CORe has changed reflecting a changing demand. Extended forecasts were expensive to produce and store. They were used to evaluate the (relative) quality of the analyses. Now we evaluate the quality of the analyses by comparing to other reanalyses. Isentropic analyses are not available because the lack of an operational isentropic post processor suggesting that there are fewer users. The sigma analyses were grib files on the MRF model's native vertical coordinates. One can generate grib2 files on the CORe model's native vertical coordinates with the program "gfsnemsio2grb". All the flux and pgb files are on a 512x256 Gaussian grid which is the data assimilation grid. Using modern software (ex. wgrib2), fields can be regridded to the user's grid which could potentially eliminate a double interpolation.

Sample CORe Output

One day's output from CORe can be found at https://ftp.cpc.ncep.noaa.gov/CORe/1_day_sample/. Missing are the diagnostic files which are netcdf files which contain the observations and corresponding analysis and forecast. The diagnostic files are missing because they contain restricted data. Software to remove the restricted observations needs to developed before the diagnostic files can be released to the public.

Missing are the raw observations (bufr format) which are identical to thosed used by CDAS.

The sample does do not include the monthly means. Operations will not be making monthly means which will be will be created and distributed by CPC.

Primary Output, 3 hourly, grib version 2

Directory Structure:   https://ftp.cpc.ncep.noaa.gov/CORe/1_day_sample/.

flx
   YYYYMMDDHH                               analysis cycle (6 hourly)
             flx_yyyymmhh_mem0XX.grb        flux files yyyymmddhh for ensemble member XX
             flx_yyyymmhh_mem0XX.grb.idx    index file
             flx_yyyymmhh_ensmean.grb       flux files yyyymmddhh for ensemble mean
             flx_yyyymmhh_mem0XX.grb.idx    index file
flx_stats
   flx_yyyymmddhh_ensstats.grb              flux ensemble statistics for yyyymmddhh
   flx_yyyymmddhh_ensstats.grb.idx          index file
nceppost
   pgb_yyyymmddhh_ensmean                   pgb for yyyymmddhh (ensemble mean) created by ncep post (UPP)
   pgb_yyyymmddhh_ensmean.idx               index file
spost   simple post
   YYYYMMDDHH                               analysis cycle (6 hourly)
             pgb_yyyymmddhh_mem0XX.grb      spost pgb for yyyymmddhh ensemble member XX 
             pgb_yyyymmddhh_mem0XX.grb.idx  index file
             pgb_yyyymmddhh_ensmean.grb     spost ensemble mean pgb for yyyymmddhh
             pgb_yyyymmddhh_ensmean.grb.idx index file
spost_stats
    pgb_yyyymmddhh_ensstats.grb             spost pgb ensemble statisticss for yyyymmddhh
    pgb_yyyymmddhh_ensstats.grb.idx         index file

The primary CORe output are written in grib version 2. There are many software packages that can read grib version 2. All the grib files have associated *.idx files. These are human-readable index/inventory files which are used by the NCEP nomads site for random-access downloads.

CORe Output: CDAS look alike files (1950-2023+)

The plan to to update the look-alike files monthly in a non-operational process until the CORe 1950-present grib version 2 files are available from an archive site. The CDAS look alike files are for evaluation and for the period time until a public archive site is available. The purpose of the extension is to allow people to start using CORe for climate monitoring before an archive site is available.

The grids were interpolated using a bilinear interpolation using wgrib2's -new_grid option. This bilinear interpolation includes the precipitation fields.

1:4:d=1950010100:CPRAT:sfc:0-6hr ave:NAve=0
2:24912:d=1950010100:CSDLF:sfc:0-6hr ave:NAve=0
3:61100:d=1950010100:CSDSF:sfc:0-6hr ave:NAve=0
4:95032:d=1950010100:CSULF:nom. top:0-6hr ave:NAve=0
5:131220:d=1950010100:CSUSF:nom. top:0-6hr ave:NAve=0
6:167408:d=1950010100:CSUSF:sfc:0-6hr ave:NAve=0
7:203596:d=1950010100:CWORK:atmos col:0-6hr ave:NAve=0
8:239784:d=1950010100:DLWRF:sfc:0-6hr ave:NAve=0
9:275972:d=1950010100:DSWRF:nom. top:0-6hr ave:NAve=0
10:312160:d=1950010100:DSWRF:sfc:0-6hr ave:NAve=0
11:348348:d=1950010100:GFLUX:sfc:0-6hr ave:NAve=0
12:362844:d=1950010100:ICEC:sfc:6hr fcst:NAve=0
13:389152:d=1950010100:LAND:sfc:6hr fcst:NAve=0
14:425340:d=1950010100:LHTFL:sfc:0-6hr ave:NAve=0
15:461528:d=1950010100:NBDSF:sfc:0-6hr ave:NAve=0
16:497716:d=1950010100:NDDSF:sfc:0-6hr ave:NAve=0
17:533904:d=1950010100:PEVPR:sfc:6hr fcst:NAve=0
18:548400:d=1950010100:PRATE:sfc:0-6hr ave:NAve=0
19:575564:d=1950010100:PRES:sfc:6hr fcst:NAve=0
20:611752:d=1950010100:PWAT:atmos col:6hr fcst:NAve=0
21:647940:d=1950010100:RUNOF:sfc:0-6hr acc:NAve=0
22:662436:d=1950010100:SFCR:sfc:6hr fcst:NAve=0
23:676932:d=1950010100:SHTFL:sfc:0-6hr ave:NAve=0
24:713120:d=1950010100:SNOEV:sfc:0-6hr ave:NAve=0
25:749308:d=1950010100:SNOHF:sfc:0-6hr ave:NAve=0
26:783240:d=1950010100:SOILW:0-10 cm down:6hr fcst:NAve=0
27:797736:d=1950010100:SPFH:2 m above gnd:6hr fcst:NAve=0
28:833924:d=1950010100:TCDC:high cld lay:0-6hr ave:NAve=0
29:870112:d=1950010100:TCDC:mid cld lay:0-6hr ave:NAve=0
30:906300:d=1950010100:TCDC:low cld lay:0-6hr ave:NAve=0
31:942488:d=1950010100:TMAX:2 m above gnd:valid 0-6hr:NAve=0
32:978676:d=1950010100:TMIN:2 m above gnd:valid 0-6hr:NAve=0
33:1014864:d=1950010100:TMP:sfc:6hr fcst:NAve=0
34:1051052:d=1950010100:TMP:2 m above gnd:6hr fcst:NAve=0
35:1087240:d=1950010100:UFLX:sfc:0-6hr ave:NAve=0
36:1121172:d=1950010100:UGRD:10 m above gnd:6hr fcst:NAve=0
37:1155104:d=1950010100:U-GWD:sfc:0-6hr ave:NAve=0
38:1189036:d=1950010100:ULWRF:nom. top:0-6hr ave:NAve=0
39:1225224:d=1950010100:ULWRF:sfc:0-6hr ave:NAve=0
40:1261412:d=1950010100:USWRF:nom. top:0-6hr ave:NAve=0
41:1297600:d=1950010100:USWRF:sfc:0-6hr ave:NAve=0
42:1333788:d=1950010100:VBDSF:sfc:0-6hr ave:NAve=0
43:1369976:d=1950010100:VDDSF:sfc:0-6hr ave:NAve=0
44:1406164:d=1950010100:VFLX:sfc:0-6hr ave:NAve=0
45:1440096:d=1950010100:VGRD:10 m above gnd:6hr fcst:NAve=0
46:1474028:d=1950010100:V-GWD:sfc:0-6hr ave:NAve=0
47:1507960:d=1950010100:WEASD:sfc:6hr fcst:NAve=0
48:1541892:d=1950010100:TCDC:atmos col:0-6hr ave:NAve=0
49:1578080:d=1950010100:SOILW:10-200 cm down:6hr fcst:NAve=0
50:1589540:d=1950010100:TMP:0-10 cm down:6hr fcst:NAve=0
51:1604036:d=1950010100:TMP:10-200 cm down:6hr fcst:NAve=0

Note: the "6hr fcst" is really the analysis valid at the verfication time.
Note: the "0-6hr ave" is really the average of two 0-3 hour averages.

Missing from CORe:
  CDCON convective cloud cover
  CFNLF, CFNSF cloud forcing
  CDLYR non-convective cloud cover
  MLYNO model cloud amounts by layer (CORe: CLMR cloud mixing ratio in pgb)
  SRWEQ Snowfall Rate Water Equivalent
   CORe: CPOFP Percent frozen precipitation

The pgb files are on a 144x73 2.5 degree grid and have an inventory

1:4:d=1950010100:HGT:1000 mb:anl:NAve=0
2:21120:d=1950010100:HGT:925 mb:anl:NAve=0
3:42236:d=1950010100:HGT:850 mb:anl:NAve=0
4:63352:d=1950010100:HGT:700 mb:anl:NAve=0
5:83154:d=1950010100:HGT:600 mb:anl:NAve=0
6:104270:d=1950010100:HGT:500 mb:anl:NAve=0
7:125386:d=1950010100:HGT:400 mb:anl:NAve=0
8:146502:d=1950010100:HGT:300 mb:anl:NAve=0
9:167618:d=1950010100:HGT:250 mb:anl:NAve=0
10:188734:d=1950010100:HGT:200 mb:anl:NAve=0
11:209850:d=1950010100:HGT:150 mb:anl:NAve=0
12:230966:d=1950010100:HGT:100 mb:anl:NAve=0
13:252082:d=1950010100:HGT:70 mb:anl:NAve=0
14:273198:d=1950010100:HGT:50 mb:anl:NAve=0
15:294314:d=1950010100:HGT:30 mb:anl:NAve=0
16:315430:d=1950010100:HGT:20 mb:anl:NAve=0
17:336546:d=1950010100:HGT:10 mb:anl:NAve=0
18:357662:d=1950010100:UGRD:1000 mb:anl:NAve=0
19:373522:d=1950010100:UGRD:925 mb:anl:NAve=0
20:390696:d=1950010100:UGRD:850 mb:anl:NAve=0
21:407870:d=1950010100:UGRD:700 mb:anl:NAve=0
22:425044:d=1950010100:UGRD:600 mb:anl:NAve=0
23:442218:d=1950010100:UGRD:500 mb:anl:NAve=0
24:459392:d=1950010100:UGRD:400 mb:anl:NAve=0
25:476566:d=1950010100:UGRD:300 mb:anl:NAve=0
26:495054:d=1950010100:UGRD:250 mb:anl:NAve=0
27:513542:d=1950010100:UGRD:200 mb:anl:NAve=0
28:532030:d=1950010100:UGRD:150 mb:anl:NAve=0
29:550518:d=1950010100:UGRD:100 mb:anl:NAve=0
30:567692:d=1950010100:UGRD:70 mb:anl:NAve=0
31:584866:d=1950010100:UGRD:50 mb:anl:NAve=0
32:602040:d=1950010100:UGRD:30 mb:anl:NAve=0
33:619214:d=1950010100:UGRD:20 mb:anl:NAve=0
34:636388:d=1950010100:UGRD:10 mb:anl:NAve=0
35:654876:d=1950010100:VGRD:1000 mb:anl:NAve=0
36:670736:d=1950010100:VGRD:925 mb:anl:NAve=0
37:687910:d=1950010100:VGRD:850 mb:anl:NAve=0
38:703770:d=1950010100:VGRD:700 mb:anl:NAve=0
39:720944:d=1950010100:VGRD:600 mb:anl:NAve=0
40:738118:d=1950010100:VGRD:500 mb:anl:NAve=0
41:755292:d=1950010100:VGRD:400 mb:anl:NAve=0
42:773780:d=1950010100:VGRD:300 mb:anl:NAve=0
43:792268:d=1950010100:VGRD:250 mb:anl:NAve=0
44:810756:d=1950010100:VGRD:200 mb:anl:NAve=0
45:827930:d=1950010100:VGRD:150 mb:anl:NAve=0
46:845104:d=1950010100:VGRD:100 mb:anl:NAve=0
47:862278:d=1950010100:VGRD:70 mb:anl:NAve=0
48:879452:d=1950010100:VGRD:50 mb:anl:NAve=0
49:896626:d=1950010100:VGRD:30 mb:anl:NAve=0
50:913800:d=1950010100:VGRD:20 mb:anl:NAve=0
51:930974:d=1950010100:VGRD:10 mb:anl:NAve=0
52:948148:d=1950010100:TMP:1000 mb:anl:NAve=0
53:961380:d=1950010100:TMP:925 mb:anl:NAve=0
54:974612:d=1950010100:TMP:850 mb:anl:NAve=0
55:987844:d=1950010100:TMP:700 mb:anl:NAve=0
56:1001076:d=1950010100:TMP:600 mb:anl:NAve=0
57:1012994:d=1950010100:TMP:500 mb:anl:NAve=0
58:1024912:d=1950010100:TMP:400 mb:anl:NAve=0
59:1036830:d=1950010100:TMP:300 mb:anl:NAve=0
60:1048748:d=1950010100:TMP:250 mb:anl:NAve=0
61:1059352:d=1950010100:TMP:200 mb:anl:NAve=0
62:1069956:d=1950010100:TMP:150 mb:anl:NAve=0
63:1081874:d=1950010100:TMP:100 mb:anl:NAve=0
64:1093792:d=1950010100:TMP:70 mb:anl:NAve=0
65:1105710:d=1950010100:TMP:50 mb:anl:NAve=0
66:1117628:d=1950010100:TMP:30 mb:anl:NAve=0
67:1129546:d=1950010100:TMP:20 mb:anl:NAve=0
68:1141464:d=1950010100:TMP:10 mb:anl:NAve=0
69:1154696:d=1950010100:VVEL:1000 mb:anl:NAve=0
70:1174498:d=1950010100:VVEL:925 mb:anl:NAve=0
71:1194300:d=1950010100:VVEL:850 mb:anl:NAve=0
72:1214102:d=1950010100:VVEL:700 mb:anl:NAve=0
73:1233904:d=1950010100:VVEL:600 mb:anl:NAve=0
74:1252392:d=1950010100:VVEL:500 mb:anl:NAve=0
75:1270880:d=1950010100:VVEL:400 mb:anl:NAve=0
76:1289368:d=1950010100:VVEL:300 mb:anl:NAve=0
77:1307856:d=1950010100:VVEL:250 mb:anl:NAve=0
78:1327658:d=1950010100:VVEL:200 mb:anl:NAve=0
79:1348774:d=1950010100:VVEL:150 mb:anl:NAve=0
80:1368576:d=1950010100:VVEL:100 mb:anl:NAve=0
81:1387064:d=1950010100:RH:1000 mb:anl:NAve=0
82:1400296:d=1950010100:RH:925 mb:anl:NAve=0
83:1413528:d=1950010100:RH:850 mb:anl:NAve=0
84:1426760:d=1950010100:RH:700 mb:anl:NAve=0
85:1439992:d=1950010100:RH:600 mb:anl:NAve=0
86:1453224:d=1950010100:RH:500 mb:anl:NAve=0
87:1466456:d=1950010100:RH:400 mb:anl:NAve=0
88:1479688:d=1950010100:RH:300 mb:anl:NAve=0
89:1492920:d=1950010100:ABSV:1000 mb:anl:NAve=0
90:1510094:d=1950010100:ABSV:925 mb:anl:NAve=0
91:1527268:d=1950010100:ABSV:850 mb:anl:NAve=0
92:1544442:d=1950010100:ABSV:700 mb:anl:NAve=0
93:1561616:d=1950010100:ABSV:600 mb:anl:NAve=0
94:1578790:d=1950010100:ABSV:500 mb:anl:NAve=0
95:1595964:d=1950010100:ABSV:400 mb:anl:NAve=0
96:1613138:d=1950010100:ABSV:300 mb:anl:NAve=0
97:1630312:d=1950010100:ABSV:250 mb:anl:NAve=0
98:1646172:d=1950010100:ABSV:200 mb:anl:NAve=0
99:1662032:d=1950010100:ABSV:150 mb:anl:NAve=0
100:1677892:d=1950010100:ABSV:100 mb:anl:NAve=0
101:1693752:d=1950010100:ABSV:70 mb:anl:NAve=0
102:1709612:d=1950010100:ABSV:50 mb:anl:NAve=0
103:1725472:d=1950010100:ABSV:30 mb:anl:NAve=0
104:1741332:d=1950010100:ABSV:20 mb:anl:NAve=0
105:1757192:d=1950010100:ABSV:10 mb:anl:NAve=0
106:1773052:d=1950010100:UGRD:30-0 mb above gnd:anl:NAve=0
107:1788912:d=1950010100:VGRD:30-0 mb above gnd:anl:NAve=0
108:1804772:d=1950010100:TMP:30-0 mb above gnd:anl:NAve=0
109:1818004:d=1950010100:RH:30-0 mb above gnd:anl:NAve=0
110:1827294:d=1950010100:UGRD:1829 m above MSL:anl:NAve=0
111:1843038:d=1950010100:UGRD:2743 m above MSL:anl:NAve=0
112:1860616:d=1950010100:VGRD:1829 m above MSL:anl:NAve=0
113:1876360:d=1950010100:VGRD:2743 m above MSL:anl:NAve=0
114:1893938:d=1950010100:PRES:sfc:anl:NAve=0
115:1913740:d=1950010100:RH:atmos col:anl:NAve=0
116:1923030:d=1950010100:TMP:tropopause:anl:NAve=0
117:1934948:d=1950010100:PRES:tropopause:anl:NAve=0
118:1956064:d=1950010100:UGRD:tropopause:anl:NAve=0
119:1974552:d=1950010100:VGRD:tropopause:anl:NAve=0
120:1993040:d=1950010100:VSSH:tropopause:anl:NAve=0
121:2003644:d=1950010100:LFTX:sfc:anl:NAve=0
122:2016876:d=1950010100:4LFTX:sfc:anl:NAve=0
123:2028794:d=1950010100:TMP:max wind lev:anl:NAve=0
124:2042026:d=1950010100:PRES:max wind lev:anl:NAve=0
125:2063142:d=1950010100:UGRD:max wind lev:anl:NAve=0
126:2077688:d=1950010100:VGRD:max wind lev:anl:NAve=0
127:2090920:d=1950010100:HGT:sfc:anl:NAve=0
128:2112036:d=1950010100:RH:sigma 0.44-1.00:anl:NAve=0
129:2121326:d=1950010100:RH:sigma 0.72-0.94:anl:NAve=0
130:2134558:d=1950010100:RH:sigma 0.44-0.72:anl:NAve=0
131:2143848:d=1950010100:POT:sigma=0.9950:anl:NAve=0
132:2162336:d=1950010100:TMP:sigma=0.9950:anl:NAve=0
133:2179510:d=1950010100:VVEL:sigma=0.9950:anl:NAve=0
134:2199312:d=1950010100:RH:sigma=0.9950:anl:NAve=0
135:2212544:d=1950010100:UGRD:sigma=0.9950:anl:NAve=0
136:2228404:d=1950010100:VGRD:sigma=0.9950:anl:NAve=0
137:2244264:d=1950010100:SPFH:1000 mb:anl:NAve=0
138:2260124:d=1950010100:SPFH:925 mb:anl:NAve=0
139:2274670:d=1950010100:SPFH:850 mb:anl:NAve=0
140:2289216:d=1950010100:SPFH:700 mb:anl:NAve=0
141:2303762:d=1950010100:SPFH:600 mb:anl:NAve=0
142:2320936:d=1950010100:SPFH:500 mb:anl:NAve=0
143:2336796:d=1950010100:SPFH:400 mb:anl:NAve=0
144:2351342:d=1950010100:SPFH:300 mb:anl:NAve=0
145:2368516:d=1950010100:STRM:1000 mb:anl:NAve=0
146:2389632:d=1950010100:VPOT:1000 mb:anl:NAve=0
147:2410748:d=1950010100:STRM:925 mb:anl:NAve=0
148:2431864:d=1950010100:VPOT:925 mb:anl:NAve=0
149:2452980:d=1950010100:STRM:850 mb:anl:NAve=0
150:2474096:d=1950010100:VPOT:850 mb:anl:NAve=0
151:2495212:d=1950010100:STRM:700 mb:anl:NAve=0
152:2516328:d=1950010100:VPOT:700 mb:anl:NAve=0
153:2537444:d=1950010100:STRM:600 mb:anl:NAve=0
154:2558560:d=1950010100:VPOT:600 mb:anl:NAve=0
155:2579676:d=1950010100:STRM:500 mb:anl:NAve=0
156:2600792:d=1950010100:VPOT:500 mb:anl:NAve=0
157:2621908:d=1950010100:STRM:400 mb:anl:NAve=0
158:2643024:d=1950010100:VPOT:400 mb:anl:NAve=0
159:2664140:d=1950010100:STRM:300 mb:anl:NAve=0
160:2685256:d=1950010100:VPOT:300 mb:anl:NAve=0
161:2706372:d=1950010100:STRM:250 mb:anl:NAve=0
162:2727488:d=1950010100:VPOT:250 mb:anl:NAve=0
163:2748604:d=1950010100:STRM:200 mb:anl:NAve=0
164:2769720:d=1950010100:VPOT:200 mb:anl:NAve=0
165:2790836:d=1950010100:STRM:150 mb:anl:NAve=0
166:2811952:d=1950010100:VPOT:150 mb:anl:NAve=0
167:2833068:d=1950010100:STRM:100 mb:anl:NAve=0
168:2854184:d=1950010100:VPOT:100 mb:anl:NAve=0
169:2875300:d=1950010100:STRM:70 mb:anl:NAve=0
170:2896416:d=1950010100:VPOT:70 mb:anl:NAve=0
171:2917532:d=1950010100:STRM:50 mb:anl:NAve=0
172:2938648:d=1950010100:VPOT:50 mb:anl:NAve=0
173:2959764:d=1950010100:STRM:30 mb:anl:NAve=0
174:2980880:d=1950010100:VPOT:30 mb:anl:NAve=0
175:3001996:d=1950010100:STRM:20 mb:anl:NAve=0
176:3023112:d=1950010100:VPOT:20 mb:anl:NAve=0
177:3044228:d=1950010100:STRM:10 mb:anl:NAve=0
178:3065344:d=1950010100:VPOT:10 mb:anl:NAve=0
179:3086460:d=1950010100:PRES:MSL:anl:NAve=0


RELV (relative vorticity), RELD (divergence): need to be computed from U/V by the user
PWAT:  in CORe flux file
PRMSL: CORe, use PRES at mean sea level, uses same method of computation
3658 m above MSL:  not available in CORe

Directory Structure   https://ftp.cpc.ncep.noaa.gov/CORe/CDAS_clone_temporary

6hr
   grb2d
        YYYY
            grb2dYYYYMMDDHH  flux file for YYYYMMDDHH
6hr
   pgb
      YYYY
          pgb.f00YYYYMMDDHH  pgb file for YYYYMMDDHH
month
     grb2d
          grb2dYYYYMMDD  month-average flux file for YYYYMMDD
month
     pgb
        pgb.f00YYYYMMDD  month-average pgb file for YYYYMMDD

All grib files have a corresponding *.idx which serves as a human readable
file inventory.  The *.idx files can be used for downlaoding selected fields
ing 
fast grib downloading.

CORe secondary output: bfg, sfg

The bfg and sfg are FV3GFS model states which can be used as
forecast restart files and as inputs to the post processors.
The bfg_grb2 is conversion of the bfg (flux) nemsio file to
grib using the program "gfsnemsio2grb".

The time stamp convention is confusing.
   YYYYMMDDHH = assimilation cycle, every 6 hours, 00/06/12/18Z
                uses observations YYYYMMDDHH +/- 3 hours

The assimilation cycle runs a forecast that has an incremental update
which is how the observations influence the analysis, then the forecast
is continued without forcing. This unforced extention of the forecast is
used as the analyses, and the first guess for next data assimilation cycle.

   fhr03        03Z, 09Z, 15Z or 21Z analysis
   fhr06        06Z, 12Z, 19Z or 00Z analysis, 3 hour extension of the fhr03 forecast
   fhr09        6 hour extension of the fhr03 forecast

bfg_nemsio                                               bfg nemsio format file
          YYYYMMDDHH                                     analysis cycle
	             bfg_yyyymmddhh_fhrN_mem0ZZ.gz       gzip compressed bfg ensemble member nemsio file
	             bfg_yyyymmddhh_fhrN_ensmean.gz      gzip compressed bfg ensemble meannemsio file
bfg_grb2                                                 bfg nemsio converted to grib2
          YYYYMMDDHH                                     analysis cycle
	             bfg_yyyymmddhh_fhrN_mem0ZZ.grb      bfg ensemble member grib file
		     bfg_yyyymmddhh_fhrN_ensmean.grb     bfg ensemble-mean grib file

ensmean                                                  bfg, sfg ensemble mean nemsio
        TYPE_yyyymmddhh_fhrN_ensmean                     nemsio ensemble mean bfg or sfg
                                                         TYPE=bfg or sfg
ens_nemsio                                               restart files for 6 ensemble members every 24 hours
          YYYYMMDDHH                                     analysis time only on 18Z
	             bfg_yyyymmddhh_fhr06_mem0ZZ.gz      gzip compressed bfg ensemble member nemsio file
	             sfg_yyyymmddhh_fhr06_mem0ZZ.gz      gzip compressed sfg ensemble member nemsio file
		                                         ZZ=12, 24, 36, 48, 60, 72

The timestamps used by the data assimilation within CORe is confusing because there
is the data assimilation time cycle, and forecast times.  CORe then selects
two of the forecast times to be the CORe analysis times.  So you have three
different times.  This is illustrated in the bfg_grb2 files.


bfg_grb2/YYYYMMDDHH/bfg.yyyymmddhh_fhrN_memMMM.grb
         YYYYMMDDHH assimination cycle, observations +/- 3 hours
         yyyymmddhh forecast cycle, YYYYMMDDHH + 6 hours
         fhr03 used as an analysis by CORe
         fhr06 used as an analysis by CORe
         fhr09 used as an forecast by CORe
	 There is an assimilation cycle every 6 hours.
	 Two CORe analyses are generated by one short range forecast.
         The forecast consists of the first part being "forced" by
	   the incremental update.  The second part is a "free" forecast.
	   The CORe analyses are from the free portion of the forecast.

         The timing of the bfg_grb2 are the nemsio files generated by
	 the forecast step.

Comments: Wanqui.Wang@noaa.gov cc: Arun.Kumar@noaa.gov Wesley.Ebisuzaki@noaa.gov