
Level 3 Cloudnet product:Evaluation statistics of Met Office Global model liquid water contentData Home  Overview of Cloudnet products  Product list  Quicklooks  Conditions of useSummary
Dataset contentsSample NetCDF file: 200304_chilbolton_lwcadiabaticmetofficeglobalgridstats.nc 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 Met Office global liquid water content at Chilbolton during Apr 2003This dataset contains statistics on the performance of Met Office global 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.
Dimensions and coordinate variablesheightHeight above ground
Type:singleprecision floatingpoint vector Mean height of model levels above ground
Type:singleprecision floatingpoint vector (No coordinate variable) lwc_bin (No coordinate variable) lwp_bin (No coordinate variable) Variablesheight_coarse_min(height_coarse)Height above ground of the bottom of each range used for PDFs
Type:singleprecision floatingpoint vector Height above ground of the top of each range used for PDFs
Type:singleprecision floatingpoint vector Temporal resolution of model
Type:singleprecision floatingpoint scalar 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:hoursType:singleprecision floatingpoint scalar 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:hoursType:singleprecision floatingpoint scalar 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 dualwavelength 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:dimensionlessType:singleprecision floatingpoint array 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:dimensionlessType:singleprecision floatingpoint array 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:dimensionlessType:singleprecision floatingpoint array 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:dimensionlessType:singleprecision floatingpoint array 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:dimensionlessType:singleprecision floatingpoint array 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:dimensionlessType:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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 dualwavelength microwave radiometers was not used to constrain the liquid water content. Units:kg m^{3}Type:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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 dualwavelength microwave radiometers was either not present or not used to constrain the liquid water content. Units:kg m^{3}Type:singleprecision floatingpoint array 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:singleprecision floatingpoint array 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:singleprecision floatingpoint vector 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:dimensionlessType:signed twobyte integer vector 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:dimensionlessType:signed twobyte integer vector 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:dimensionlessType:signed fourbyte integer vector 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:dimensionlessType:signed twobyte integer vector 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:dimensionlessType:signed twobyte integer vector 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:dimensionlessType:signed fourbyte integer vector 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:dimensionlessType:signed fourbyte integer scalar 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 1e08 kg m3, this variable is the number of samples with liquid water content greater than 1e08 kg m3 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:dimensionlessType:signed twobyte integer array Number of samples with cloud in model but not observations See the comment of the "A" variable. Units:dimensionlessType:signed twobyte integer array Number of samples with cloud in observations but not model See the comment of the "A" variable. Units:dimensionlessType:signed twobyte integer array Number of samples with cloud in neither model nor observations See the comment of the "A" variable. Units:dimensionlessType:signed twobyte integer array Equitable threat score This variable is a measure of the skill of the liquid water forecasts calculated as ETS=(AE)/(A+B+CE), 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:dimensionlessType:singleprecision floatingpoint array Yule's Q skill score This variable is a measure of the skill of the liquid water forecasts calculated as Q=(A*DB*C)/(A*D+B*C). It is closely related to the odds ratio, but ranges from 1 to 1. Units:dimensionlessType:singleprecision floatingpoint array Equitable threat score for all heights This variable is calculated from A, B, C and D at all heights. Units:dimensionlessType:singleprecision floatingpoint vector Yule's Q skill score for all heights This variable is calculated from A, B, C and D at all heights. Units:dimensionlessType:singleprecision floatingpoint vector These pages are maintained by . 