Level 3 Cloudnet product:

Evaluation statistics of DWD Lokal Modell liquid water content

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Summary

Designation: lwc-adiabatic-dwd-lm-6-17-grid-stats
Level: 3
Algorithm design/Product maintainer
Institute: University of Reading and the Deutscher Wetterdienst (DWD)
Description: This product consists of evaluation statistics for the liquid water content of the DWD Lokal Modell (LM), including means, PDFs and skill scores.
Documentation: None yet available
Relevant publication(s): Pending
Quicklooks: http://www.met.rdg.ac.uk/radar/cloudnet/quicklooks/
Suggested acknowledgement: We acknowledge the Cloudnet project (European Union contract EVK2-2000-00611) for providing the evaluation statistics of DWD Lokal Modell liquid water content, which was produced by the University of Reading and the Deutscher Wetterdienst (DWD) using measurements from [SITE].

Dataset contents

Sample NetCDF file: 200404_chilbolton_lwc-adiabatic-dwd-lm-6-17-grid-stats.nc
Header of sample NetCDF file in ASCII: 200404_chilbolton_lwc-adiabatic-dwd-lm-6-17-grid-stats.cdl

The following is a description of the variables in this product, produced automatically from the metadata in the sample file (using the nc2html unix utility):

Dataset title: Evaluation of DWD Lokal Modell liquid water content at Chilbolton during Apr 2004

This dataset contains statistics on the performance of DWD Lokal Modell liquid water content, including means as a function of height, probability density function, skill scores and the contingency table to allow other skill scores to be calculated.

Institution:

Dimensions and coordinate variables

height
Height above ground

Units:

Type:

height_raw
Mean height of model levels above ground

Units:

Type:

height_coarse
(No coordinate variable)

lwc_bin
(No coordinate variable)

lwp_bin
(No coordinate variable)

Variables

height_coarse_min(height_coarse)
Height above ground of the bottom of each range used for PDFs

Units:

Type:

height_coarse_max(height_coarse)
Height above ground of the top of each range used for PDFs

Units:

Type:

time_resolution
Temporal resolution of model

Units:

Type:

lwc_bin_min(lwc_bin)
Liquid water content bin minimum

This variable provides the liquid water content thresholds for the contingency tables and the skill scores, and the minimum of the bins used in the liquid water content probability density functions.

Units:

^-3

Type:

lwc_bin_nominal_centre(lwc_bin)
Liquid water content nominal bin centre

This variable provides the nominal centres of the bins used in the liquid water content probability density functions, evenly spread in logarithmic space. It therefore does not strictly correspond to the centre of the first bin (which has a minimum at 0) or the last bin (which has a maximum at infinity).

Units:

^-3

Type:

lwp_bin_min(lwp_bin)
Liquid water path bin minimum

This variable provides the liquid water path minimum of the bins used in the liquid water path probability density functions.

Units:

^-2

Type:

lwp_bin_nominal_centre(lwp_bin)
Liquid water path nominal bin centre

This variable provides the nominal centres of the bins used in the liquid water path probability density functions, evenly spread in logarithmic space. It therefore does not strictly correspond to the centre of the first bin (which has a minimum at 0) or the last bin (which has a maximum at infinity).

Units:

^-2

Type:

forecast_time_min
Minimum time since forecast initialization

The hourly model forecasts evaluated in this file are from a range of different forecast lead times. This variable is the minimum forecast lead time.

Units:

Type:

forecast_time_max
Maximum time since forecast initialization

The hourly model forecasts evaluated in this file are from a range of different forecast lead times. This variable is the maximum forecast lead time.

Units:

Type:

mean_observed_lwc(height)
Mean observed liquid water content

This variable is the mean liquid water content versus height as determined by using radar and lidar to identify the liquid cloud base and top in each profile, using the model temperature and pressure to calculate the adiabatic liquid water content in each cloud layer, and then using dual-wavelength microwave radiometers to scale the liquid water content values to yield the correct liquid water path. Only data coincident with the model were used, and measurements above any surface rain were not used due to the possibility of an incorrect estimate of liquid water content by the microwave radiometers. A missing value indicates that in this height range there were no simultaneous model and observational data.

Units:

^-3

Type:

mean_observed_lwc_th(height)
Mean observed liquid water content (tophat)

This variable is the mean liquid water content versus height as determined by the radar and lidar only, assuming a tophat distribution. Only data coincident with the observations for mean_observed_lwc were used. A missing value indicates that in this height range there were no simultaneous model and observational data.

Units:

^-3

Type:

mean_observed_lwc_adiabatic(height)
Mean observed adiabatic liquid water content

This variable is the mean liquid water content versus height as determined by the radar and lidar only, using the adiabatic assumption. Only data coincident with the observations for mean_observed_lwc were used. A missing value indicates that in this height range there were no simultaneous model and observational data.

Units:

^-3

Type:

mean_model_lwc(height)
Mean model liquid water content

This variable is the mean model liquid water content versus height. Only data with coincident observations were used, and data above any observed surface rain have not been used due to the possibility of bias in the observations leading to an unfair comparison. A missing value indicates that in this height range there were no simultaneous model and observational data.

Units:

^-3

Type:

mean_obs_lwc_adiabatic_inc_all(height)
Mean observed adiabatic liquid water content including when no reliable microwave radiometer observations were available

This variable is the mean liquid water content versus height as determined by the radar and lidar only, using the adiabatic assumption. Only data coincident with the model were used, and data above any surface rain have not been used due to the uncertainty in cloud boundaries. A missing value indicates that in this height range there were no simultaneous model and observational data.

Units:

^-3

Type:

mean_model_lwc_inc_all(height)
Mean model liquid water content including when no reliable microwave radiometer observations were available

This variable is the same as mean_model_lwc except that data coincident with the observations for mean_obs_lwc_adiabatic_inc_all were used, and data above any observed surface rain have not been used due to the possibility of bias in the observations leading to an unfair comparison. A missing value indicates that in this height range there were no simultaneous model and observational data.

Units:

^-3

Type:

mean_observed_lwc_raw(height_raw)
Mean observed liquid water content on model grid

This variable is the same as mean_observed_lwc except that it was calculated on the original model grid.

Units:

^-3

Type:

mean_observed_lwc_th_raw(height_raw)
Mean observed liquid water content (tophat) on model grid

This variable is the same as mean_observed_lwc_th except that it was calculated on the original model grid.

Units:

^-3

Type:

mean_observed_lwc_adiabatic_raw(height_raw)
Mean observed adiabatic liquid water content on model grid

This variable is the same as mean_observed_lwc_adiabatic except that it was calculated on the original model grid.

Units:

^-3

Type:

mean_model_lwc_raw(height_raw)
Mean model liquid water content on model grid

This variable is the same as mean_model_lwc except that it was calculated on the original model grid.

Units:

^-3

Type:

mean_obs_lwc_adiab_inc_all_raw(height_raw)
Mean adiabatic liquid water content on model grid including when no reliable microwave radiometer observations were available

This variable is the same as mean_obs_lwc_adiabatic_inc_all except that it was calculated on the original model grid.

Units:

^-3

Type:

mean_model_lwc_inc_all_raw(height_raw)
Mean model liquid water content on model grid including when no reliable microwave radiometer observations were available

This variable is the same as mean_model_lwc_inc_all except that it was calculated on the original model grid.

Units:

^-3

Type:

foo_observed_raw(height_raw, lwc_bin)
Mean observed frequency of occurrence on model grid

This variable is the mean observed frequency of occurrence of liquid water contents above a range of different values, as indicated by the lwc_bin_min variable.

Units:

Type:

foo_model_raw(height_raw, lwc_bin)
Mean model frequency of occurrence on model grid

This variable is the mean model frequency of occurrence of liquid water contents above a range of different values, as indicated by the lwc_bin_min variable.

Units:

Type:

foo_observed_th_raw(height_raw, lwc_bin)
Mean observed frequency of occurrence on model grid for tophat distribution

This variable is the mean observed frequency of occurrence of liquid water contents (assuming a tophat distribution) above a range of different values, as indicated by the lwc_bin_min variable.

Units:

Type:

foo_observed_adiabatic_raw(height_raw, lwc_bin)
Mean observed frequency of occurrence on model grid for adiabatic assumption

This variable is the mean observed frequency of occurrence of adiabatic liquid water contents above a range of different values, as indicated by the lwc_bin_min variable.

Units:

Type:

foo_observed_adiabatic_inc_all_(height_raw, lwc_bin)
Mean observed frequency of occurrence for adiabatic assumption on model grid including when no reliable microwave radiometer observations were available

This variable is the mean observed frequency of occurrence of adiabatic liquid water contents above a range of different values, as indicated by the lwc_bin_min variable. The adiabatic assumption has been used in estimating liquid water content.

Units:

Type:

foo_model_inc_all_raw(height_raw, lwc_bin)
Mean model frequency of occurrence on model grid including when no reliable microwave radiometer observations were available

This variable is the mean model frequency of occurrence of liquid water contents above a range of different values, as indicated by the lwc_bin_min variable.

Units:

Type:

awp_observed_raw(height_raw, lwc_bin)
Mean observed amount when present on model grid

This variable is the mean observed liquid water content when it exceeds a range of different values, as indicated by the lwc_bin_min variable.

Units:

^-3

Type:

awp_model_raw(height_raw, lwc_bin)
Mean model amount when present on model grid

This variable is the mean model liquid water content when it exceeds a range of different values, as indicated by the lwc_bin_min variable.

Units:

^-3

Type:

awp_observed_th_raw(height_raw, lwc_bin)
Mean observed amount for tophat distribution when present on model grid

This variable is the mean observed liquid water content (assuming a tophat distribution) when it exceeds a range of different values, as indicated by the lwc_bin_min variable.

Units:

^-3

Type:

awp_observed_adiabatic_raw(height_raw, lwc_bin)
Mean observed amount for adiabatic assumption when present on model grid

This variable is the mean observed adiabatic liquid water content when it exceeds a range of different values, as indicated by the lwc_bin_min variable.

Units:

^-3

Type:

awp_obs_adiabatic_inc_all_raw(height_raw, lwc_bin)
Mean observed amount for adiabatic assumption when present on model grid including when no reliable microwave radiometer observations were available

This variable is the mean adiabatic liquid water content when it exceeds a range of different values, as indicated by the lwc_bin_min variable.

Units:

^-3

Type:

awp_model_nolwp_raw(height_raw, lwc_bin)
Mean model amount when present on model grid including when no reliable microwave radiometer observations were available

This variable is the mean model liquid water content when it exceeds a range of different values, as indicated by the lwc_bin_min variable.

Units:

^-3

Type:

mean_model_lwc_gridscale(height)
Mean model grid-scale liquid water content

This variable is the same as mean_model_lwc, except that the sub-grid-scale contribution to water content was not included.

Units:

^-3

Type:

foo_model_gridscale_raw(height_raw, lwc_bin)
Mean model grid-scale frequency of occurrence on model grid

This variable is the same as foo_model_raw, except that the sub-grid-scale contribution to water content was not included.

Units:

Type:

awp_model_gridscale_raw(height_raw, lwc_bin)
Mean model grid-scale amount when present on model grid

This variable is the same as awp_model_raw, except that the sub-grid-scale contribution to water content was not included.

Units:

^-3

Type:

pdf_observed_lwc(height_coarse, lwc_bin)
PDF of observed liquid water content

This variable is the probability density function of observed liquid water content in four height ranges, with bin minima indicated by the lwc_bin_min variable. Only data with coincident model and observations were used, and missing values indicate height ranges where no such data were available.

Units:

^-3

Type:

pdf_observed_lwc_th(height_coarse, lwc_bin)
PDF of observed liquid water content (tophat)

This variable is the same as pdf_observed_lwc, except that a tophat distribution was assumed.

Units:

^-3

Type:

pdf_observed_lwc_adiabatic(height_coarse, lwc_bin)
PDF of observed adiabatic liquid water content

This variable is the same as pdf_observed_lwc, except that the adiabatic assumption was made and the liquid water path from dual-wavelength microwave radiometers was not used to constrain the liquid water content.

Units:

^-3

Type:

pdf_model_lwc(height_coarse, lwc_bin)
PDF of model liquid water content

This variable is the probability density function of model liquid water content in four height ranges, with bin minima indicated by the lwc_bin_min variable. Only data with coincident model and observations were used, and missing values indicate height ranges where no such data were available.

Units:

^-3

Type:

pdf_obs_lwc_adiabatic_inc_all(height_coarse, lwc_bin)
PDF of observed adiabatic liquid water content including when no reliable microwave radiometer observations were available

This variable is the same as pdf_observed_lwc, except that the adiabatic assumption was made and the liquid water path from dual-wavelength microwave radiometers was either not present or not used to constrain the liquid water content.

Units:

^-3

Type:

pdf_model_lwc_inc_all(height_coarse, lwc_bin)
PDF of model liquid water content including when no reliable microwave radiometer observations were available

This variable is the same as pdf_model_lwc, except that data coincident with pdf_obs_lwc_adiabatic_inc_all have been included.

Units:

^-3

Type:

pdf_model_lwc_gridscale(height_coarse, lwc_bin)
PDF of model grid-scale liquid water content

This variable is the same as pdf_model_lwc, except that the sub-grid-scale contribution to water content was not included.

Units:

Type:

pdf_observed_lwp(lwp_bin)
PDF of observed liquid water path

This variable is the probability density function of observed liquid water path (where the mean wind speed was calculated from the mean of model winds in the grid boxes in the profile that contain liquid water), with bin minima indicated by the lwp_bin_min variable. Only data with coincident model and observations were used, and missing values indicate where no such data were available.

Units:

^-2

Type:

pdf_observed_lwp_3km(lwp_bin)
PDF of observed liquid water path using mean winds from 0 to 3 km

This variable is the probability density function of observed liquid water path (where the mean wind speed was calculated from the mean of the magnitude of the model winds from 0 to 3 km in the vertical), with bin minima indicated by the lwp_bin_min variable. Only data with coincident model and observations were used, and missing values indicate where no such data were available.

Units:

^-2

Type:

pdf_model_lwp(lwp_bin)
PDF of model liquid water path

This variable is the probability density function of model liquid water path, with bin minima indicated by the lwp_bin_min variable. Only data with coincident model and observations were used, and missing values indicate where no such data were available.

Units:

^-2

Type:

pdf_model_lwp_gridscale(lwp_bin)
PDF of model grid-scale liquid water path

This variable is the same as pdf_model_lwp, except that the sub-grid-scale contribution to liquid water path was not included.

Units:

^-2

Type:

num_samples(height)
Number of samples used

This variable contains the number of samples at each height used in calculating the contingency table and the skill scores. Each sample is one hour apart in the original data.

Units:

Type:

num_samples_raw(height_raw)
Number of samples used for variables on model grid

This variable contains the number of samples at each height used in calculating the contingency table and skill scores reported on the model grid. Each sample is one hour apart in the original data.

Units:

Type:

num_samples_coarse(height_coarse)
Number of samples used for PDFs

This variable contains the number of samples in the four coarse height ranges used in calculating the probability density functions of liquid water content.

Units:

Type:

num_inc_all_samples(height)
Number of samples used under adiabatic assumption including when no reliable microwave radiometer observations were available

This variable contains the number of samples at each height used in calculating the contingency table and the skill scores. Each sample is one hour apart in the original data.

Units:

Type:

num_inc_all_samples_raw(height_raw)
Number of samples used for variables on model grid under adiabatic assumption including when no reliable microwave radiometer observations were available

This variable contains the number of samples at each height used in calculating the contingency table and skill scores reported on the model grid. Each sample is one hour apart in the original data.

Units:

Type:

num_inc_all_samples_coarse(height_coarse)
Number of samples used for PDFs under adiabatic assumption including when no reliable microwave radiometer observations were available

This variable contains the number of samples in the four coarse height ranges used in calculating the probability density functions of liquid water content.

Units:

Type:

num_lwp
Number of samples used for liquid water path PDFs

This variable contains the number of samples used in calculating the probability density functions of liquid water path.

Units:

Type:

A(height, lwc_bin)
Number of samples with cloud in model and observations

This variable is used with "B", "C" and "D" to calculate various skill scores. It has been calculated for the full range of liquid water content thresholds (indicated by the lwc_bin_min variable). Thus for a threshold of 1e-08 kg m-3, this variable is the number of samples with liquid water content greater than 1e-08 kg m-3 simultaneously in the model and the observations. Skill scores for multiple months should be calculated by first summing the values of A, B, C and D for those months.

Units:

Type:

B(height, lwc_bin)
Number of samples with cloud in model but not observations

See the comment of the "A" variable.

Units:

Type:

C(height, lwc_bin)
Number of samples with cloud in observations but not model

See the comment of the "A" variable.

Units:

Type:

D(height, lwc_bin)
Number of samples with cloud in neither model nor observations

See the comment of the "A" variable.

Units:

Type:

ETS(height, lwc_bin)
Equitable threat score

This variable is a measure of the skill of the liquid water forecasts calculated as ETS=(A-E)/(A+B+C-E), where E is the number of hits that occurred by chance, given by E=(A+B)*(A+C)/(A+B+C+D). A perfect forecast would have an ETS of 1 and a random forecast an ETS of 0.

Units:

Type:

Q(height, lwc_bin)
Yule's Q skill score

This variable is a measure of the skill of the liquid water forecasts calculated as Q=(A*D-B*C)/(A*D+B*C). It is closely related to the odds ratio, but ranges from -1 to 1.

Units:

Type:

ETS_all(lwc_bin)
Equitable threat score for all heights

This variable is calculated from A, B, C and D at all heights.

Units:

Type:

Q_all(lwc_bin)
Yule's Q skill score for all heights

This variable is calculated from A, B, C and D at all heights.

Units:

Type:

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