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Level 3 Cloudnet product:

Evaluation statistics of SMHI RCA model liquid water content

Data Home | Overview of Cloudnet products | Product list | Quicklooks | Conditions of use

Summary

Designation
lwc-adiabatic-smhi-rca-grid-stats
Level
3
Algorithm design/Product maintainer
Institute
University of Reading and the Swedish Meteorological and Hydrological Institute (SMHI)
Description
This product consists of evaluation statistics for the liquid water content of the SMHI Rossby Centre Regional Atmospheric Model (RCA), 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 SMHI RCA model liquid water content, which was produced by the University of Reading and the Swedish Meteorological and Hydrological Institute (SMHI) using measurements from [SITE].

Dataset contents

Sample NetCDF file: 200304_chilbolton_lwc-adiabatic-smhi-rca-grid-stats.nc
Header of sample NetCDF file in ASCII: 200304_chilbolton_lwc-adiabatic-smhi-rca-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 SMHI RCA liquid water content at Chilbolton during Apr 2003

This dataset contains statistics on the performance of SMHI RCA 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:Department of Meteorology, University of Reading.

Dimensions and coordinate variables

height
Height above ground
    Units:m
    Type:single-precision floating-point vector
height_raw
Mean height of model levels above ground
    Units:m
    Type:single-precision floating-point vector
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:m
    Type:single-precision floating-point vector
height_coarse_max(height_coarse)
Height above ground of the top of each range used for PDFs
    Units:m
    Type:single-precision floating-point vector
time_resolution
Temporal resolution of model
    Units:hours
    Type:single-precision floating-point scalar
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-2
    Type:single-precision floating-point vector
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:kg m-2
    Type:single-precision floating-point vector
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:hours
    Type:single-precision floating-point scalar
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:hours
    Type:single-precision floating-point scalar
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:kg m-3
    Type:single-precision floating-point vector
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:dimensionless
    Type:single-precision floating-point array
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:dimensionless
    Type:single-precision floating-point array
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:dimensionless
    Type:single-precision floating-point array
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:dimensionless
    Type:single-precision floating-point array
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:dimensionless
    Type:single-precision floating-point array
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:dimensionless
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-3
    Type:single-precision floating-point array
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:kg m-2
    Type:single-precision floating-point vector
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:kg m-2
    Type:single-precision floating-point vector
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:kg m-2
    Type:single-precision floating-point vector
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:dimensionless
    Type:signed two-byte integer vector
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:dimensionless
    Type:signed two-byte integer vector
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:dimensionless
    Type:signed four-byte integer vector
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:dimensionless
    Type:signed two-byte integer vector
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:dimensionless
    Type:signed two-byte integer vector
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:dimensionless
    Type:signed four-byte integer vector
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:dimensionless
    Type:signed four-byte integer scalar
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:dimensionless
    Type:signed two-byte integer array
B(height, lwc_bin)
Number of samples with cloud in model but not observations

    See the comment of the "A" variable.

    Units:dimensionless
    Type:signed two-byte integer array
C(height, lwc_bin)
Number of samples with cloud in observations but not model

    See the comment of the "A" variable.

    Units:dimensionless
    Type:signed two-byte integer array
D(height, lwc_bin)
Number of samples with cloud in neither model nor observations

    See the comment of the "A" variable.

    Units:dimensionless
    Type:signed two-byte integer array
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:dimensionless
    Type:single-precision floating-point array
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:dimensionless
    Type:single-precision floating-point array
ETS_all(lwc_bin)
Equitable threat score for all heights

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

    Units:dimensionless
    Type:single-precision floating-point vector
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:dimensionless
    Type:single-precision floating-point vector

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