background
Following previous work done by Bresch and Rizvi for KMA project and ASR project.
basic PREPBUFR features
- observations are separated into wind reports and mass reports
- each file contains data within 6-hour time window
- missing obs error for surface land reports
- reported variables
- sea level pressure
- pressure/height
- U-component-relative-to-earth
- V-component-relative-to-earth
- virtual temperature when q available
- temperature when q is not available
- specific humidity
- quality markers 0 - 15
See http://www.emc.ncep.noaa.gov/mmb/data_processing/prepbufr.doc/table_7.htm for definitions.
Currently, quality markers 0, 1, 2, and 3 are considered OK obs. - observation types
See http://www.emc.ncep.noaa.gov/mmb/data_processing/prepbufr.doc/table_6.htm for details.
status
mass and wind reports merged
fix the problems of double-counting of observation numbers and double-usage of pressure field.
thinning
Two new namelist variables for thinning are introduced in wrfvar4 record.
&wrfvar4
thin_conv = .true.
thin_mesh_conv = 20.0, 20.0, 20.0, ...
Thinning is mandatory as time-duplicate data are "thinned" within thinning routine,
however, thin_conv can be set to .false. in the namelist for debugging purpose.
Thinning mesh of each observation type is specified through a namelist variable
&wrfvar4 thin_mesh_conv. The unit is km and default values are 20km.
Each observation type can set its thinning mesh and the index/order follows the
definition in WRFDA/var/da/da_control/da_control.f90
integer, parameter :: sound = 1
integer, parameter :: synop = 2
integer, parameter :: pilot = 3
integer, parameter :: satem = 4
integer, parameter :: geoamv = 5
integer, parameter :: polaramv = 6
integer, parameter :: airep = 7
integer, parameter :: gpspw = 8
integer, parameter :: gpsref = 9
integer, parameter :: metar = 10
integer, parameter :: ships = 11
integer, parameter :: ssmi_rv = 12
integer, parameter :: ssmi_tb = 13
integer, parameter :: ssmt1 = 14
integer, parameter :: ssmt2 = 15
integer, parameter :: qscat = 16
integer, parameter :: profiler = 17
integer, parameter :: buoy = 18
integer, parameter :: bogus = 19
integer, parameter :: pseudo = 20
integer, parameter :: radar = 21
integer, parameter :: radiance = 22
integer, parameter :: airsr = 23
integer, parameter :: sonde_sfc = 24
integer, parameter :: mtgirs = 25
time window checking
only obs between time_window_min and time_window_max will be used.
&wrfvar21 time_window_min = '2007-08-15_10:00:00.0000
&wrfvar22 time_window_max = '2007-08-15_14:00:00.0000
assign u,v,t,q obs errors for synop and metar
u%err = 1.1 (m/s)
v%err = 1.1 (m/s)
t%err = 2.0 (degree)
q%err = 10%
assign pw obs errors for gpspw
pw%err = 0.2 (cm)
new feature as of Apr 4, 2009 - read in ob errors from an external ob error table (obs_errtable) if it exists.
The external ob error table follows the format of prepobs_errtable.nam from GSI.
If using external ob error table, ob errors for synop, metar, gpspw will be from the table as well. If the ob error of an ob type is missing (with a value of 0.1E10) in the ob error table, default large values of u%err=10(m/s), v%err=10(m/s), t%err=5(degree), p%err=200(Pa), q%err=10% will be used.
observation grouping
From http://www.emc.ncep.noaa.gov/mmb/data_processing/prepbufr.doc/table_6.htm
Report Type Definition 11 Fixed land RAOB and PIBAL by block and station number 12 Fixed land RAOB and PIBAL by call letters 13 Mobile land RAOB, including CLAS soundings 22 Ship RAOB with name 23 Ship RAOB without name (report id set to "SHIP") 31 Reconnaissance aircraft or dropwinsonde 41 Aircraft flight-level (all types) 61 Satellite soundings/retrievals/radiances 63 Satellite-derived winds 65 SSM/I total precipitable water (ocean) product 66 SSM/I rain rate product 68 SSM/I brightness temperatures 69 SSM/I cloud water (ocean) product 71 NOAA Profiler Network (NPN) Profiler winds 72 NEXRAD Vertical Azimuth Display (VAD) winds 73 Wind profiler originating in PIBAL bulletins (tropical and European) 74 GPS-IPW (Integrated Precipitable Water) 75 Multi-Agency Profiler (MAP) Profiler winds 76 Japanese Meteological Agency (JMA) profiler winds 77 NOAA Profiler Network (NPN) or Multi-Agency Profiler (MAP) RASS temperatures 511 Land surface by block and station number (synoptic, both unrestricted & restricted WMO Res. 40) 512 Land surface by call letters (METAR) 514 Mobile land surface (synoptic) 522 Ship with name 523 Ship without name (report id set to "SHIP") 531 C-MAN platform 532 Tide gauge report 540 Mesonet surface 551 Sea-level pressure bogus 561 Fixed buoy 562 Drifting buoy 571 SSM/I wind speed (ocean) product 573 SSM/I soil moisture product 574 SSM/I snow depth product 575 SSM/I additional products (surface tag, ice concentration, ice age, ice edge, calculated surface type) 576 SSM/I surface (skin) temperature product 577 SSM/I sea surface temperature product 581 ERS scatterometer winds 582 QuikSCAT scatterometer winds 583 WindSAT scatterometer winds (Navy- or NESDIS- produced) 584 ASCAT scatterometer winds
In WRF-Var:
11,12,13,22,23,31 - sound and pilot 41 - airep 522,523 - ship 531,532,561,562 - buoy 511,514 - synop 512 - metar 63 - geoamv 582,583 - qscat 74 - gpspw 71,73,75,76,77 - profiler 571,65 - ssmi_rv
MPI-ready
Previous unstable problem is fixed in revision 3828 (April 24, 2009).
A patch tar file can be download from WRFDA users site (posted April 30, 2009) for the released V3.1 code (which is based on revision 3818).