obs_seq_verify
reorders the observations from a forecast run of DART into a structure that is amenable for the evaluation of the forecast. The big picture is that the verification locations and times identified in the obsdef_mask.nc
and the observations from the forecast run (whose files must have an extension as in the following: obs_seq.forecast.YYYYMMDDHH
) are put into a netCDF variable that looks like this:obs_seq_verify
can read in a series of observation sequence files - each of the files must contain the entire forecast from a single analysis time. The extension of each filename is required to reflect the analysis time. Use ../../../assimilation_code/programs/obs_sequence_tool/obs_sequence_tool
to concatenate multiple files into a single observation sequence file if necessary. Only the individual ensemble members forecast values are used - the ensemble mean and spread (as individual copies) are completely ignored. The individual "prior ensemble member NNNN" copies are used. As a special case, the "prior ensemble mean" copy is used if and only if there are no individual ensemble members present (i.e. input.nml
&filter_nml:num_output_obs_members
== 0).Dimension | Explanation |
---|---|
analysisT | This is the netCDF UNLIMITED dimension, so it is easy to 'grow' this dimension. This corresponds to the number of forecasts one would like to compare. |
stations | The unique horizontal locations in the verification network. |
levels | The vertical level at each location. Observations with a pressure vertical coordinate are selected based on their proximity to the mandatory levels as defined in ../../../assimilation_code/programs/obs_seq_coverage/obs_seq_coverage . Surface observations or observations with undefined vertical coordinates are simply put into level 1. |
copy | This dimension designates the quantity of interest; the observation, the forecast value, or the observation error variance. These quantities are the ones required to calculate the evaluation statistics. |
nmembers | Each ensemble member contributes a forecast value. |
forecast_lead | This dimension relates to the amount of time between the start of the forecast and the verification. |
The USAGE section has more on the actual use of obs_seq_verify
.
This namelist is read from the file input.nml
. Namelists start with an ampersand '&' and terminate with a slash '/'. Character strings that contain a '/' must be enclosed in quotes to prevent them from prematurely terminating the namelist.
&obs_seq_verify_nml
obs_sequences = ''
obs_sequence_list = ''
station_template = 'obsdef_mask.nc'
netcdf_out = 'forecast.nc'
obtype_string = 'RADIOSONDE_TEMPERATURE'
print_every = 10000
verbose = .true.
debug = .false.
/
You can specify either obs_sequences
or obs_sequence_list
-- not both. One of them has to be an empty string ... i.e. ' '.
Item | Type | Description |
---|---|---|
obs_sequences | character(len=256), dimension(500) | Names of the observation sequence files - each of which MUST have an extension that defines the start of the forecast (the analysis time). The observation sequence filenames must be something like obs_seq.forecast.YYYYMMDDHH . If obs_sequences is specified, obs_sequence_list must be empty. |
obs_sequence_list | character(len=256) | Name of an ascii text file which contains a list of one or more observation sequence files, one per line. The observation sequence filenames MUST have an extension that defines the start of the forecast (the analysis time). The observation sequence filenames must be something like obs_seq.forecast.YYYYMMDDHH . obs_sequence_list can be created by any method, including sending the output of the 'ls' command to a file, a text editor, or another program. If obs_sequence_list is specified, obs_sequences must be empty. |
station_template | character(len=256) | The name of the netCDF file created by ../../../assimilation_code/programs/obs_seq_coverage/obs_seq_coverage that contains the verification network description. |
netcdf_out | character(len=256) | The base portion of the filename of the file that will contain the forecast quantities. Since each observation type of interest is processed with a separate run of obs_seq_verify , the observation type string is used to create a unique output filename. |
calendar | character(len=129) | The type of the calendar used to interpret the dates. |
obtype_string | character(len=32) | The observation type string that will be verified. The character string must match one of the standard DART observation types. This will be the name of the variable in the netCDF file, and will also be used to make a unique netCDF file name. |
print_every | integer | Print run-time information for every "print_every" n-th observation. |
verbose | logical | Print extra run-time information. |
debug | logical | Print a frightening amount of run-time information. |
assimilation_code/location/threed_sphere/location_mod.f90
assimilation_code/modules/assimilation/assim_model_mod.f90
models/your_model/model_mod.f90
assimilation_code/modules/observations/obs_kind_mod.f90
assimilation_code/modules/observations/obs_sequence_mod.f90
assimilation_code/modules/utilities/null_mpi_utilities_mod.f90
assimilation_code/modules/utilities/types_mod.f90
assimilation_code/modules/utilities/random_seq_mod.f90
assimilation_code/modules/utilities/time_manager_mod.f90
assimilation_code/modules/utilities/utilities_mod.f90
observations/forward_operators/obs_def_mod.f90
input.nml
is used for obs_seq_verify_nml- A netCDF file containing the metadata for the verification network. This file is created by
../../../assimilation_code/programs/obs_seq_coverage/obs_seq_coverage
to define the desired times and locations for the verification. (obsdef_mask.nc
is the default name) - One or more observation sequence files from
filter
run in forecast mode - meaning all the observations were flagged as evaluate_only. It is required/presumed that all the ensemble members are output to the observation sequence file (see num_output_obs_members). Each observation sequence file contains all the forecasts from a single analysis time and the filename extension must reflect the analysis time used to start the forecast. (obs_seq.forecast.YYYYMMDDHH
is the default name) - Every execution of
obs_seq_verify
results in one netCDF file that contains the observation being verified. Ifobtype_string = 'METAR_U_10_METER_WIND'
, andnetcdf_out = 'forecast.nc'
; the resulting filename will beMETAR_U_10_METER_WIND_forecast.nc
.
obs_seq_verify
is built in .../DART/models/your_model/work, in the same way as the other DART components.Once the forecast has completed, each observation type may be extracted from the observation sequence file and stuffed into the appropriate verification structure. Each observation type must be processed serially at this time, and each results in a separate output netCDF file. Essentially,
obs_seq_verify
sorts an unstructured, unordered set of observations into a predetermined configuration.In this example, the
obsdef_mask.nc
file was created by running ../../../assimilation_code/programs/obs_seq_coverage/obs_seq_coverage
with the namelist specified in the single 48hour forecast evaluated every 6 hours example. The obsdef_mask.txt
file was used to mask the input observation sequence files by ../../../assimilation_code/programs/obs_selection/obs_selection
and the result was run through ../filter/filter
with the observations marked as evaluate_only - resulting in a file called obs_seq.forecast.2008060818
. This filename could also be put in a file called verify_list.txt
.Just to reiterate the example, both namelists for
obs_seq_coverage
and obs_seq_verify
are provided below.&obs_seq_coverage_nml
obs_sequences = ''
obs_sequence_list = 'coverage_list.txt'
obs_of_interest = 'METAR_U_10_METER_WIND'
'METAR_V_10_METER_WIND'
textfile_out = 'obsdef_mask.txt'
netcdf_out = 'obsdef_mask.nc'
calendar = 'Gregorian'
first_analysis = 2008, 6, 8, 18, 0, 0
last_analysis = 2008, 6, 8, 18, 0, 0
forecast_length_days = 2
forecast_length_seconds = 0
verification_interval_seconds = 21600
temporal_coverage_percent = 100.0
lonlim1 = 0.0
lonlim2 = 360.0
latlim1 = -90.0
latlim2 = 90.0
verbose = .true.
/
&obs_seq_verify_nml
obs_sequences = 'obs_seq.forecast.2008060818'
obs_sequence_list = ''
station_template = 'obsdef_mask.nc'
netcdf_out = 'forecast.nc'
obtype_string = 'METAR_U_10_METER_WIND'
print_every = 10000
verbose = .true.
debug = .false.
/
The pertinent information from the obsdef_mask.nc
file is summarized (from ncdump -v experiment_times,analysis,forecast_lead obsdef_mask.nc) as follows:
verification_times = 148812.75, 148813, 148813.25, 148813.5, 148813.75,
148814, 148814.25, 148814.5, 148814.75 ;
analysis = 148812.75 ;
forecast_lead = 0, 21600, 43200, 64800, 86400, 108000, 129600, 151200, 172800 ;
There is one analysis time, 9 forecast leads and 9 verification times. The analysis time is the same as the first verification time. The run-time output of obs_seq_verify
and a dump of the resulting netCDF file follows:
[thoar@mirage2 work]$ ./obs_seq_verify |& tee my.verify.log
Starting program obs_seq_verify
Initializing the utilities module.
Trying to log to unit 10
Trying to open file dart_log.out
--------------------------------------
Starting ... at YYYY MM DD HH MM SS =
2011 3 1 10 2 54
Program obs_seq_verify
--------------------------------------
set_nml_output Echo NML values to log file only
Trying to open namelist log dart_log.nml
------------------------------------------------------
-------------- ASSIMILATE_THESE_OBS_TYPES --------------
RADIOSONDE_TEMPERATURE
RADIOSONDE_U_WIND_COMPONENT
RADIOSONDE_V_WIND_COMPONENT
SAT_U_WIND_COMPONENT
SAT_V_WIND_COMPONENT
-------------- EVALUATE_THESE_OBS_TYPES --------------
RADIOSONDE_SPECIFIC_HUMIDITY
------------------------------------------------------
find_ensemble_size: opening obs_seq.forecast.2008060818
location_mod: Ignoring vertical when computing distances; horizontal only
find_ensemble_size: There are 50 ensemble members.
fill_stations: There are 221 stations of interest,
fill_stations: ... and 9 times of interest.
InitNetCDF: METAR_U_10_METER_WIND_forecast.nc is fortran unit 5
obs_seq_verify: opening obs_seq.forecast.2008060818
analysis 1 date is 2008 Jun 08 18:00:00
index 6 is prior ensemble member 1
index 8 is prior ensemble member 2
index 10 is prior ensemble member 3
...
index 100 is prior ensemble member 48
index 102 is prior ensemble member 49
index 104 is prior ensemble member 50
QC index 1 NCEP QC index
QC index 2 DART quality control
Processing obs 10000 of 84691
Processing obs 20000 of 84691
Processing obs 30000 of 84691
Processing obs 40000 of 84691
Processing obs 50000 of 84691
Processing obs 60000 of 84691
Processing obs 70000 of 84691
Processing obs 80000 of 84691
METAR_U_10_METER_WIND dimlen 1 is 9
METAR_U_10_METER_WIND dimlen 2 is 50
METAR_U_10_METER_WIND dimlen 3 is 3
METAR_U_10_METER_WIND dimlen 4 is 1
METAR_U_10_METER_WIND dimlen 5 is 221
METAR_U_10_METER_WIND dimlen 6 is 1
obs_seq_verify: Finished successfully.
--------------------------------------
Finished ... at YYYY MM DD HH MM SS =
2011 3 1 10 3 7
--------------------------------------
[thoar@mirage2 work]$ ncdump -h METAR_U_10_METER_WIND_forecast.nc
netcdf METAR_U_10_METER_WIND_forecast {
dimensions:
analysisT = UNLIMITED ; // (1 currently)
copy = 3 ;
station = 221 ;
level = 14 ;
ensemble = 50 ;
forecast_lead = 9 ;
linelen = 129 ;
nlines = 446 ;
stringlength = 64 ;
location = 3 ;
variables:
char namelist(nlines, linelen) ;
namelist:long_name = "input.nml contents" ;
char CopyMetaData(copy, stringlength) ;
CopyMetaData:long_name = "copy quantity names" ;
double analysisT(analysisT) ;
analysisT:long_name = "time of analysis" ;
analysisT:units = "days since 1601-1-1" ;
analysisT:calendar = "Gregorian" ;
analysisT:missing_value = 0. ;
analysisT:_FillValue = 0. ;
int copy(copy) ;
copy:long_name = "observation copy" ;
copy:note1 = "1 == observation" ;
copy:note2 = "2 == prior" ;
copy:note3 = "3 == observation error variance" ;
copy:explanation = "see CopyMetaData variable" ;
int station(station) ;
station:long_name = "station index" ;
double level(level) ;
level:long_name = "vertical level of observation" ;
int ensemble(ensemble) ;
ensemble:long_name = "ensemble member" ;
int forecast_lead(forecast_lead) ;
forecast_lead:long_name = "forecast lead time" ;
forecast_lead:units = "seconds" ;
double location(station, location) ;
location:description = "location coordinates" ;
location:location_type = "loc3Dsphere" ;
location:long_name = "threed sphere locations: lon, lat, vertical" ;
location:storage_order = "Lon Lat Vertical" ;
location:units = "degrees degrees which_vert" ;
int which_vert(station) ;
which_vert:long_name = "vertical coordinate system code" ;
which_vert:VERTISUNDEF = -2 ;
which_vert:VERTISSURFACE = -1 ;
which_vert:VERTISLEVEL = 1 ;
which_vert:VERTISPRESSURE = 2 ;
which_vert:VERTISHEIGHT = 3 ;
which_vert:VERTISSCALEHEIGHT = 4 ;
double METAR_U_10_METER_WIND(analysisT, station, level, copy, ensemble, forecast_lead) ;
METAR_U_10_METER_WIND:long_name = "forecast variable quantities" ;
METAR_U_10_METER_WIND:missing_value = -888888. ;
METAR_U_10_METER_WIND:_FillValue = -888888. ;
int original_qc(analysisT, station, forecast_lead) ;
original_qc:long_name = "original QC value" ;
original_qc:missing_value = -888888 ;
original_qc:_FillValue = -888888 ;
int dart_qc(analysisT, station, forecast_lead) ;
dart_qc:long_name = "DART QC value" ;
dart_qc:explanation1 = "1 == prior evaluated only" ;
dart_qc:explanation2 = "4 == forward operator failed" ;
dart_qc:missing_value = -888888 ;
dart_qc:_FillValue = -888888 ;
// global attributes:
:creation_date = "YYYY MM DD HH MM SS = 2011 03 01 10 03 00" ;
:source = "$URL$" ;
:revision = "$Revision$" ;
:revdate = "$Date$" ;
:obs_seq_file_001 = "obs_seq.forecast.2008060818" ;
}
[thoar@mirage2 work]$
- the values of ASSIMILATE_THESE_OBS_TYPES and EVALUATE_THESE_OBS_TYPES are completely irrelevant - again - since
obs_seq_verify
is not actually doing an assimilation. - The analysis time from the filename is used to determine which analysis from
obsdef_mask.nc
is being considered, and which set of verification times to look for. This is important. - The individual
prior ensemble member
copies must be present! Since there are no observations being assimilated, there is no reason to choose the posteriors over the priors. - There are 221 locations reporting METAR_U_10_METER_WIND observations at all 9 requested verification times.
- The
METAR_U_10_METER_WIND_forecast.nc
file has all the metadata to be able to interpret the METAR_U_10_METER_WIND variable. - The analysisT dimension is the netCDF record/unlimited dimension. Should you want to increase the strength of the statistical results, you should be able to trivially
ncrcat
more (compatible) netCDF files together.
- none - but this seems like a good place to start: The Centre for Australian Weather and Climate Research - Forecast Verification Issues, Methods and FAQ