A description of these quick prepbufrobs_assim text files is given below.

Size: px

Start display at page:

Download "A description of these quick prepbufrobs_assim text files is given below."

Julian Fields
5 years ago
Views:

1 The 20 th Century Reanalysis (20CR) Project Ensemble Filter data assimilation system produces ASCII text files containing the surface and sea level pressure observations used in the assimilation, essential metadata, and the feedback information on those observations. Feedback information includes quality control flags, the difference between the observation and the first guess, the uncertainty in the first guess, the difference between the analysis and the observations, and the uncertainty in the analysis. All of these fields are intended to be joined with the more complete metadata contained in the International Surface Pressure Databank Hierarchical Data Format 5 files. A description of these quick prepbufrobs_assim text files is given below. G. Compo 8 September 2012 Corrects an error in the description of entries 20 and Timestamp 2 This field describes the year, month, day, hour, and minute of the observation in the form YYYYMMDDHHMM. Unique Observation Number Code Length 7 Character Minimum: Maximum: A unique number assigned to each observation at the same observation time (year, month, day, hour, minute). Combing with Year, month, day, hour, minute forms a unique ID of each observation. E.g., the second observation in the Data Bank for February GMT has field 9 = , and a unique observation code of In 20CR version2, some minutes set to missing (99) in the HDF5 were converted to 00, resulting in duplication of the unique observation number code. This will be corrected in the HDF5 files. 2. NCEP Observation Type Code Length 3 Integer This field is designated for NCEP observation type code. Numbers above 193 are unique to ISPD. 120 Radiosonde Observation Data 132 Dropsonde Observation 180 Marine Observation Data 181 Station Observation Data 183 Station Observation only reporting sea level pressure

2 193 Digitized Mea SEA-LEVEL PRESSUREBOGUS 3x0 Synoptic (0,6,12,18UTC) Central Pressure from a tropical cyclone best track dataset 3x1-3x5 Synoptic (0,6,12,18UTC) Central Pressure for a category 1-5 tropical cyclone from a tropical cyclone best track dataset 4x0 Non-synoptic Central Pressure from a tropical cyclone best track dataset 5x0 Bogus Central pressure for a tropical depression derived from tropical cyclone best track wind dataset. 5x1-585 Bogus Central Pressure for a category 1-5 tropical cyclone derived from a tropical cyclone best track wind dataset. Second digits of the NCEP observation type code for tropical cyclones are designated for the regional codes based on the basin/sub-basins classifications by National Climatic Data Center Global Tropical Cyclone Stewardship. 1. Eastern North Pacific (sub-basin: Central Pacific) 2. Eastern North Pacific 3. North Atlantic 4. North Indian 5. South Indian 6. South Pacific (sub-basin: Eastern Australia) 7. South Pacific 8. West Pacific Missing: Variable Type character P = pressure 4. Longitude Length 6 The longitude coordinate of a geophysical observation ( ) Max: Latitude The latitude coordinate of a geophysical observation ( ) Min: Max: 90.00

3 6. Elevation Length 4 Integer The elevation of a geophysical point observation relative to Mean Sea Level (meters) Min: -400 Max: 8850 Missing: Elevation of the Model Surface Integer The elevation of a geophysical point observation, vertically interpolated to the model surface. Missing: Time offset of observation time from analysis time Min: Max: 2.99 Missing: Modified Observed Pressure after bias correction Length 7 The atmospheric surface pressure observation (if type 120 or 181) or the observed sea level pressure observation at the indicated elevation (hectopascals) after applying any bias adjustment (hectopascals) Min: Max: Missing: Modified Observed Pressure after Vertically Interpolating to Model Surface Double This field is designated for the Observed Pressure with orography adjustment to the elevation of the model surface and after applying any bias adjustment (hectopascals). Min: Max: Missing: Observed Sea Level Pressure Length 7 The atmospheric sea level pressure observation (hectopascals)

4 Min: Max: Missing: Bias Length 5 This field is allocated for difference between the observation and first guess averaged over the past sixty days. 13. Observation Error in Observed Surface Pressure Specified Observation Error in the observed pressure Missing: Observation Error in Observed Pressure vertically Interpolated to Model Surface This field is designated for the specified Observation Error in the Observed Pressure with orography adjustment. Missing: Assimilation indicator This field indicates whether the observation was assimilated 0 the observation was not assimilated 1 the observation was assimilated 16. Usability Check for Reanalysis This field is designated for the 20 th Century Reanalysis usage check Observations passing quality control may still not be assimilated in regions of dense observations. 0 not usable 1 usable 9 missing 17. Quality Control Indicator

5 This field indicates whether the observation was rejected. 1 the observation was rejected 0 the observation was accepted 18. QC Background check flag indicator The field indicates whether the observation failed a check against the ensemble background 0 the observation is within the ensemble spread plus observation error limits 1 the observation is outside of the ensemble spread plus observation error limits 19. Buddy flag indicator The field indicates whether the observation significantly improves the fit of the first guess to the neighboring observations up to distance 1000 km away. 0 improves the fit to the neighbors 1 degrades the fit to the neighbors 20. Ensemble Mean First Guess Pressure minus Modified Observation Pressure This field is designated for the Ensemble Mean Guess Pressure minus the Modified Observation Pressure minus at the observation location. Min: Max: Missing: 9.9E Standard Deviation of Ensemble Guess Pressure This field is designated for the Standard Deviation of the Ensemble First Guess Pressure at the observation location. Missing: 9.95E Ensemble Mean Analysis Pressure minus Modified Observation Pressure This field is designated for the Ensemble Mean Analysis Pressure minus the

6 Modified Observation Pressure at the observation location. Min: Max: Missing: 9.9E Standard Deviation of Ensemble Analysis Pressure This field is designated for the Standard Deviation of the Ensemble Analysis Pressure at the observation location. Min: Missing: 9.95E Name of ships or stations Length 30 Character Name of Ships or Stations from source record or station library table Missing: 9 x 29 For source ICOADS data in International Marine Meteorological Archive format, ID Indicator and Identification/Call Sign information will be used for this field. 25. Observation (Station) ID 3 Character This field is designated for an identifier that represents a fixed station for land data. It represents a marine call sign or other marine identifier when present. Missing: 9 x 12 Fortran format statement that wrote the data write(159,9802) statid(nob),stattype(nob),obtype(nob),rtod*oblocx(nob),rtod*oblocy(nob),& nint(zob(nob)),nint(zfgob(nob)),obtime(nob),oborig(nob),ob(nob),slpob(nob),bi as(nob),stdevorig(nob),stdev(nob),& iassim(nob),iuseob(nob),ibadob(nob),ifailbg(nob),ifailbud(nob),& theobfit_prior,theobsprd_prior,theobfit_post,theobsprd_post,statname(nob),obid (nob) end if enddo

7 9802 format(a19,1x,i3,1x,a1,1x,f7.2,1x,f6.2,1x,i5,1x,i5,1x,f6.2,1x,f7.1,1x,f7.1,1x,& f7.1,1x,e10.3,1x,f5.2,1x,f5.2,5(1x,i1),4(1x,e10.3),1x,a30,1x,a13) Example lines of data from the assimilation of version 1 January 1, UTC: P E E E E E+00 Alice Springs P E E E E E+00 Port Lincoln P E E E E E+00 Robe P E E E E E+00 CHARLOTTETOWN

Coupled data assimilation for climate reanalysis

Coupled data assimilation for climate reanalysis Dick Dee Climate reanalysis Coupled data assimilation CERA: Incremental 4D-Var ECMWF June 26, 2015 Tools from numerical weather prediction Weather prediction