netcdf 20031001_chilbolton_cloud-fraction-ecmwf-grid {
dimensions:
time = 24 ;
height = 60 ;
variables:
float horizontal_resolution ;
horizontal_resolution:units = "km" ;
horizontal_resolution:long_name = "Horizontal resolution of model" ;
float altitude ;
altitude:units = "m" ;
altitude:long_name = "Height of radar above mean sea level" ;
float forecast_time(time) ;
forecast_time:units = "hours" ;
forecast_time:long_name = "Time since initialization of forecast" ;
forecast_time:comments = "For each profile in the file this variable contains the time elapsed since the initialization time of the forecast from which it was taken. Note that the profiles in this file may be taken from more than one forecast." ;
forecast_time:missing_value = -999.f ;
forecast_time:_FillValue = -999.f ;
float rain_rate_threshold ;
rain_rate_threshold:long_name = "Rain rate threshold" ;
rain_rate_threshold:units = "mm hr-1" ;
rain_rate_threshold:comment = "Measurements above a surface rain rate of greater than this value were excluded due to the possibility of strong attenuation leading to an underestimate of cloud fraction." ;
float time(time) ;
time:units = "hours since 2003-10-01 00:00:00 +00:00" ;
time:long_name = "Hours UTC" ;
time:standard_name = "time" ;
time:axis = "T" ;
float height(time, height) ;
height:units = "m" ;
height:long_name = "Height above ground" ;
height:standard_name = "height" ;
height:comment = "The heights have been calculated using pressure, temperature and specific humidity." ;
height:C_format = "%.3f" ;
height:_FillValue = -999.f ;
height:missing_value = -999.f ;
height:axis = "Z" ;
float latitude ;
latitude:units = "degrees_north" ;
latitude:long_name = "Latitude of site" ;
latitude:standard_name = "latitude" ;
float longitude ;
longitude:units = "degrees_east" ;
longitude:long_name = "Longitude of site" ;
longitude:standard_name = "longitude" ;
float Cv(time, height) ;
Cv:long_name = "Observed cloud fraction by volume, 1 hour sampling" ;
Cv:units = "1" ;
Cv:missing_value = -999.f ;
Cv:_FillValue = -999.f ;
Cv:comment = "This variable is the observed cloud fraction, by volume, averaged onto the model grid with height, and 1 hour in time." ;
Cv:plot_range = 0.f, 1.f ;
Cv:plot_scale = "linear" ;
float Ca(time, height) ;
Ca:long_name = "Observed cloud fraction by area, 1 hour sampling" ;
Ca:units = "1" ;
Ca:missing_value = -999.f ;
Ca:_FillValue = -999.f ;
Ca:comment = "This variable is the observed cloud fraction, by area, averaged onto the model grid with height, and 1 hour in time." ;
Ca:plot_range = 0.f, 1.f ;
Ca:plot_scale = "linear" ;
float Cv_adv(time, height) ;
Cv_adv:long_name = "Observed cloud fraction by volume, 40km sampling" ;
Cv_adv:units = "1" ;
Cv_adv:missing_value = -999.f ;
Cv_adv:_FillValue = -999.f ;
Cv_adv:comment = "This variable is the observed cloud fraction, by volume, averaged onto the model grid with height, and over the time taken to advect the model\'s horizontal resolution (max 1 hour, min 10 minutes)." ;
Cv_adv:plot_range = 0.f, 1.f ;
Cv_adv:plot_scale = "linear" ;
float Ca_adv(time, height) ;
Ca_adv:long_name = "Observed cloud fraction by area, 40km sampling" ;
Ca_adv:units = "1" ;
Ca_adv:missing_value = -999.f ;
Ca_adv:_FillValue = -999.f ;
Ca_adv:comment = "This variable is the observed cloud fraction, by area, averaged onto the model grid with height, and over the time taken to advect the model\'s horizontal resolution (max 1 hour, min 10 minutes)." ;
Ca_adv:plot_range = 0.f, 1.f ;
Ca_adv:plot_scale = "linear" ;
float column_Ca(time) ;
column_Ca:long_name = "Total column cloud cover, 1 hour sampling" ;
column_Ca:units = "1" ;
column_Ca:missing_value = -999.f ;
column_Ca:_FillValue = -999.f ;
column_Ca:comment = "This variable is the total column cloud cover (by area), averaged over 1 hour." ;
column_Ca:plot_range = 0.f, 1.f ;
column_Ca:plot_scale = "linear" ;
float column_Ca_adv(time) ;
column_Ca_adv:long_name = "Total column cloud cover, 40km sampling" ;
column_Ca_adv:units = "1" ;
column_Ca_adv:missing_value = -999.f ;
column_Ca_adv:_FillValue = -999.f ;
column_Ca_adv:comment = "This variable is the total column cloud cover (by area), averaged over the time taken to advect the model\'s horizontal resolution (max 1 hour, min 10 minutes)." ;
column_Ca_adv:plot_range = 0.f, 1.f ;
column_Ca_adv:plot_scale = "linear" ;
float n(time, height) ;
n:long_name = "Number of radar pixels, 1 hour sampling" ;
n:units = "1" ;
n:missing_value = -999.f ;
n:_FillValue = -999.f ;
n:comment = "This variable is the number of radar pixels used to derive the cloud fractions by area and volume, for 1 hour sampling." ;
n:plot_range = 0.f, 1000.f ;
n:plot_scale = "linear" ;
float n_adv(time, height) ;
n_adv:long_name = "Number of radar pixels, 40km sampling" ;
n_adv:units = "1" ;
n_adv:missing_value = -999.f ;
n_adv:_FillValue = -999.f ;
n_adv:comment = "This variable is the number of radar pixels used to make the cloud fractions by area and volume, averaging over the time taken to advect 1 model grid box, using model winds." ;
n_adv:plot_range = 0.f, 1000.f ;
n_adv:plot_scale = "linear" ;
float model_Cv(time, height) ;
model_Cv:long_name = "Model cloud fraction" ;
model_Cv:units = "1" ;
model_Cv:missing_value = -999.f ;
model_Cv:_FillValue = -999.f ;
model_Cv:plot_range = 0.f, 1.f ;
model_Cv:plot_scale = "linear" ;
float model_iwc(time, height) ;
model_iwc:long_name = "Model ice water content" ;
model_iwc:units = "kg m-3" ;
model_iwc:units_html = "kg m-3" ;
model_iwc:missing_value = -999.f ;
model_iwc:_FillValue = -999.f ;
model_iwc:plot_range = 1.e-08f, 0.001f ;
model_iwc:plot_scale = "logarithmic" ;
float model_lwc(time, height) ;
model_lwc:long_name = "Model liquid water content" ;
model_lwc:units = "kg m-3" ;
model_lwc:units_html = "kg m-3" ;
model_lwc:missing_value = -999.f ;
model_lwc:_FillValue = -999.f ;
model_lwc:plot_range = 1.e-08f, 0.001f ;
model_lwc:plot_scale = "logarithmic" ;
float model_Cv_filtered(time, height) ;
model_Cv_filtered:long_name = "Model cloud fraction by volume with undetectable cirrus removed using best guess of radar sensitivity" ;
model_Cv_filtered:units = "1" ;
model_Cv_filtered:missing_value = -999.f ;
model_Cv_filtered:_FillValue = -999.f ;
model_Cv_filtered:comment = "This variable is model cloud fraction by volume, filtered to remove ice cloud deemed to be too tenuous to be detected by the radar.\n",
"The best guess of the radar sensitivity has been used, and the spread of IWC across the grid box assumed to be described by a gamma\n",
"distribution (Hogan and Illingworth 2003)." ;
model_Cv_filtered:plot_range = 0.f, 1.f ;
model_Cv_filtered:plot_scale = "linear" ;
float model_Cv_filtered_max(time, height) ;
model_Cv_filtered_max:long_name = "Model cloud fraction by volume with undetectable cirrus removed assuming radar 3 dB more sensitive than best guess" ;
model_Cv_filtered_max:units = "1" ;
model_Cv_filtered_max:missing_value = -999.f ;
model_Cv_filtered_max:_FillValue = -999.f ;
model_Cv_filtered_max:comment = "This variable is the same as \"model_Cv_filtered\" except that the sensitivity of the radar is taken to be 3 dB better.\n",
"It therefore provides an approximate estimate of the uncertainty associated with the removal of undetectable ice clouds from the model." ;
model_Cv_filtered_max:plot_range = 0.f, 1.f ;
model_Cv_filtered_max:plot_scale = "linear" ;
float model_Cv_filtered_min(time, height) ;
model_Cv_filtered_min:long_name = "Model cloud fraction by volume with undetectable cirrus removed assuming radar 3 dB less sensitive than best guess" ;
model_Cv_filtered_min:units = "1" ;
model_Cv_filtered_min:missing_value = -999.f ;
model_Cv_filtered_min:_FillValue = -999.f ;
model_Cv_filtered_min:comment = "This variable is the same as \"model_Cv_filtered\" except that the sensitivity of the radar is taken to be 3 dB worse.\n",
"It therefore provides an approximate estimate of the uncertainty associated with the removal of undetectable ice clouds from the model." ;
model_Cv_filtered_min:plot_range = 0.f, 1.f ;
model_Cv_filtered_min:plot_scale = "linear" ;
float model_iwc_filtered(time, height) ;
model_iwc_filtered:long_name = "Model ice water content with undetectable cirrus removed using best guess of radar sensitivity" ;
model_iwc_filtered:units = "kg m-3" ;
model_iwc_filtered:units_html = "kg m-3" ;
model_iwc_filtered:missing_value = -999.f ;
model_iwc_filtered:_FillValue = -999.f ;
model_iwc_filtered:comment = "This variable is model ice water content, filtered to remove ice cloud deemed to be too tenuous to be detected by the radar.\n",
"The best guess of the radar sensitivity has been used, and the spread of IWC across the grid box assumed to be described by a gamma\n",
"distribution (Hogan and Illingworth 2003)." ;
model_iwc_filtered:plot_range = 1.e-08f, 0.001f ;
model_iwc_filtered:plot_scale = "logarithmic" ;
float model_iwc_filtered_max(time, height) ;
model_iwc_filtered_max:long_name = "Model ice water content with undetectable cirrus removed assuming radar 3 dB more sensitive than best guess" ;
model_iwc_filtered_max:units = "kg m-3" ;
model_iwc_filtered_max:units_html = "kg m-3" ;
model_iwc_filtered_max:missing_value = -999.f ;
model_iwc_filtered_max:_FillValue = -999.f ;
model_iwc_filtered_max:comment = "This variable is the same as \"model_iwc_filtered\" except that the sensitivity of the radar is taken to be 3 dB better.\n",
"It therefore provides an approximate estimate of the uncertainty associated with the removal of undetectable ice clouds from the model." ;
model_iwc_filtered_max:plot_range = 1.e-08f, 0.001f ;
model_iwc_filtered_max:plot_scale = "logarithmic" ;
float model_iwc_filtered_min(time, height) ;
model_iwc_filtered_min:long_name = "Model ice water content with undetectable cirrus removed assuming radar 3 dB less sensitive than best guess" ;
model_iwc_filtered_min:units = "kg m-3" ;
model_iwc_filtered_min:units_html = "kg m-3" ;
model_iwc_filtered_min:missing_value = -999.f ;
model_iwc_filtered_min:_FillValue = -999.f ;
model_iwc_filtered_min:comment = "This variable is the same as \"model_iwc_filtered\" except that the sensitivity of the radar is taken to be 3 dB worse.\n",
"It therefore provides an approximate estimate of the uncertainty associated with the removal of undetectable ice clouds from the model." ;
model_iwc_filtered_min:plot_range = 1.e-08f, 0.001f ;
model_iwc_filtered_min:plot_scale = "logarithmic" ;
float model_snow_Cv(time, height) ;
model_snow_Cv:long_name = "Model cloud fraction including snow" ;
model_snow_Cv:units = "1" ;
model_snow_Cv:missing_value = -999.f ;
model_snow_Cv:_FillValue = -999.f ;
model_snow_Cv:comment = "The ECMWF model treats ice cloud and snow separately, with snow not contributing to cloud fraction or ice water content.\n",
"This variable is model cloud fraction but with the contribution of model snow added. See Hogan et al. (2001) for further discussion." ;
model_snow_Cv:plot_range = 0.f, 1.f ;
model_snow_Cv:plot_scale = "linear" ;
float model_snow_iwc(time, height) ;
model_snow_iwc:long_name = "Model ice water content including snow" ;
model_snow_iwc:units = "kg m-3" ;
model_snow_iwc:units_html = "kg m-3" ;
model_snow_iwc:missing_value = -999.f ;
model_snow_iwc:_FillValue = -999.f ;
model_snow_iwc:comment = "The ECMWF model treats ice cloud and snow separately, with snow not contributing to cloud fraction or ice water content.\n",
"This variable is model ice water content but with the contribution of model snow added. See Hogan et al. (2001) for further discussion." ;
model_snow_iwc:plot_range = 1.e-08f, 0.001f ;
model_snow_iwc:plot_scale = "logarithmic" ;
float model_snow_Cv_filtered(time, height) ;
model_snow_Cv_filtered:long_name = "Model cloud fraction by volume with snow added and undetectable cirrus removed using best guess of radar sensitivity" ;
model_snow_Cv_filtered:units = "1" ;
model_snow_Cv_filtered:missing_value = -999.f ;
model_snow_Cv_filtered:_FillValue = -999.f ;
model_snow_Cv_filtered:comment = "This variable is the same as \"model_Cv_filtered\" but with snow added in the same way as in \"model_snow_Cv\"." ;
model_snow_Cv_filtered:plot_range = 0.f, 1.f ;
model_snow_Cv_filtered:plot_scale = "linear" ;
float model_snow_Cv_filtered_max(time, height) ;
model_snow_Cv_filtered_max:long_name = "Model cloud fraction by volume with snow added and undetectable cirrus removed assuming radar 3 dB more sensitive than best guess" ;
model_snow_Cv_filtered_max:units = "1" ;
model_snow_Cv_filtered_max:missing_value = -999.f ;
model_snow_Cv_filtered_max:_FillValue = -999.f ;
model_snow_Cv_filtered_max:comment = "This variable is the same as \"model_Cv_filtered_max\" but with snow added in the same way as in \"model_snow_Cv\"." ;
model_snow_Cv_filtered_max:plot_range = 0.f, 1.f ;
model_snow_Cv_filtered_max:plot_scale = "linear" ;
float model_snow_Cv_filtered_min(time, height) ;
model_snow_Cv_filtered_min:long_name = "Model cloud fraction by volume with snow added and undetectable cirrus removed assuming radar 3 dB less sensitive than best guess" ;
model_snow_Cv_filtered_min:units = "1" ;
model_snow_Cv_filtered_min:missing_value = -999.f ;
model_snow_Cv_filtered_min:_FillValue = -999.f ;
model_snow_Cv_filtered_min:comment = "This variable is the same as \"model_Cv_filtered_min\" but with snow added in the same way as in \"model_snow_Cv\"." ;
model_snow_Cv_filtered_min:plot_range = 0.f, 1.f ;
model_snow_Cv_filtered_min:plot_scale = "linear" ;
float model_snow_iwc_filtered(time, height) ;
model_snow_iwc_filtered:long_name = "Model ice water content with snow added and undetectable cirrus removed using best guess of radar sensitivity" ;
model_snow_iwc_filtered:units = "kg m-3" ;
model_snow_iwc_filtered:units_html = "kg m-3" ;
model_snow_iwc_filtered:missing_value = -999.f ;
model_snow_iwc_filtered:_FillValue = -999.f ;
model_snow_iwc_filtered:comment = "This variable is the same as \"model_iwc_filtered\" but with snow added in the same way as in \"model_snow_iwc\"." ;
model_snow_iwc_filtered:plot_range = 1.e-08f, 0.001f ;
model_snow_iwc_filtered:plot_scale = "logarithmic" ;
float model_snow_iwc_filtered_max(time, height) ;
model_snow_iwc_filtered_max:long_name = "Model ice water content with snow added and undetectable cirrus removed assuming radar 3 dB more sensitive than best guess" ;
model_snow_iwc_filtered_max:units = "kg m-3" ;
model_snow_iwc_filtered_max:units_html = "kg m-3" ;
model_snow_iwc_filtered_max:missing_value = -999.f ;
model_snow_iwc_filtered_max:_FillValue = -999.f ;
model_snow_iwc_filtered_max:comment = "This variable is the same as \"model_iwc_filtered_max\" but with snow added in the same way as in \"model_snow_iwc\"." ;
model_snow_iwc_filtered_max:plot_range = 1.e-08f, 0.001f ;
model_snow_iwc_filtered_max:plot_scale = "logarithmic" ;
float model_snow_iwc_filtered_min(time, height) ;
model_snow_iwc_filtered_min:long_name = "Model ice water content with snow added and undetectable cirrus removed assuming radar 3 dB less sensitive than best guess" ;
model_snow_iwc_filtered_min:units = "kg m-3" ;
model_snow_iwc_filtered_min:units_html = "kg m-3" ;
model_snow_iwc_filtered_min:missing_value = -999.f ;
model_snow_iwc_filtered_min:_FillValue = -999.f ;
model_snow_iwc_filtered_min:comment = "This variable is the same as \"model_iwc_filtered_min\" but with snow added in the same way as in \"model_snow_iwc\"." ;
model_snow_iwc_filtered_min:plot_range = 1.e-08f, 0.001f ;
model_snow_iwc_filtered_min:plot_scale = "logarithmic" ;
float model_temperature(time, height) ;
model_temperature:units = "K" ;
model_temperature:long_name = "Temperature" ;
model_temperature:standard_name = "air_temperature" ;
model_temperature:C_format = "%.2f" ;
model_temperature:_FillValue = -999.f ;
model_temperature:missing_value = -999.f ;
float omega_500mb(time) ;
omega_500mb:units = "Pa s-1" ;
omega_500mb:long_name = "Vertical wind in pressure coordinates" ;
omega_500mb:standard_name = "omega" ;
omega_500mb:C_format = "%.6f" ;
omega_500mb:_FillValue = -999.f ;
omega_500mb:missing_value = -999.f ;
// global attributes:
:Conventions = "CF-1.0" ;
:title = "Cloud fractions by area and volume, as observed at Chilbolton, averaged to the ECMWF Integrated Forecast System (IFS) grid." ;
:location = "Chilbolton" ;
:day = 1s ;
:month = 10s ;
:year = 2003s ;
:history = "Cloud fraction on model grid history: 19 Oct 2010 12:46:49 - Generated from categorization data and ECMWF Integrated Forecast System (IFS) data by Ewan O\'Connor on pilvista\n",
"Categorization history: 19 Jan 2005 17:18:42 - Generated from level 1 data by Ewan O\'Connor \n",
"Radar history: Wed Feb 25 01:51:03 2004 - NetCDF generated from original data by Nicolas Gaussiat on hogwarts\n",
"Wed May 12 10:08:04 2004 - Recalibrated (-5.8 dB) by Nicolas Gaussiat on hogwarts\n",
"Wed May 12 11:31:20 2004 - Inserted incoherent reflectivity factor by radar on hogwarts\n",
"(Incoherent processing history: Wed Feb 25 00:54:30 2004 - NetCDF generated from original data by Nicolas Gaussiat on hogwarts\n",
"Wed May 12 10:34:18 2004 - Recalibrated (+0.5 dB) by Nicolas Gaussiat on hogwarts)\n",
"Lidar history: Thu Oct 2 04:24:21 2003 - NetCDF generated from original data by Ewan O\'Connor on hogwarts\n",
"Model history: Fri Sep 24 11:05:08 BST 2004 - NetCDF generated from original data by Ewan O\'Connor using cnmodel2nc on hogwarts\n",
"Fri Nov 12 17:36:14 2004 - Comments added by radar on hogwarts\n",
"Gauge history: Recorded using Microlink 3000 series DAQ\n",
"2003-11-10 13:53:59 : converted to netCDF from FORMAT5 using Matlab 6.5.0.180913a (R13) running on GLNX86\n",
"Microwave radiometer history: \n",
"2005-01-13 14:36:18 : Liquid and vapour vater path produced by Nicolas Gaussiat on hagrid\n",
"" ;
:source = "CloudNet categorization product (software version 0.9.2)\n",
"ECMWF Integrated Forecast System (IFS)" ;
:institution = "Data processed at the Department of Meteorology, University of Reading." ;
:software_version = "1.3" ;
:comment = "This dataset contains cloud fraction both from a forecast model and derived from the high-resolution observations on the grid of that model.\n",
"There are a number of different cloud fraction variables. In the case of the observations, cloud fraction has been calculated \"by volume\"\n",
"(i.e. the volume of a gridbox containing cloud) and \"by area\" (i.e. the area of the gridbox when viewed from above that is obscured by cloud).\n",
"It has also been calculated both from the time taken for the wind to advect 1 model grid-box of cloud across the site, and using a constant\n",
"1-hour sample window.\n",
"In the case of the model, the \"model_Cv\" variable contains cloud fraction taken directly from the model, while \"model_Cv_filtered\" contains\n",
"cloud fraction after filtering to remove tenuous ice clouds that are not believed to be likely to be detected by the radar. Generally the\n",
"observed values should be compared to \"model_Cv_filtered\", with \"model_Cv_filtered_min\" and \"model_Cv_filtered_max\" providing an estimate of\n",
"the range of uncertainty in the filtering procedure. Note that the problem of some ice cloud not being detected is limited to above around 8 km.\n",
"The filtering has been performed as discussed in Hogan et al. (2001, J. Appl. Meteorol., 40, 513-525), but accounting for sub-grid variability\n",
"as described by Hogan and Illingworth (2003, J. Atmos. Sci., 60, 756-767)." ;
}