Cloudnet level 3 products Robin Hogan Ewan OConnor

Cloudnet level 3 products Robin Hogan Ewan O’Connor

Cloudnet data levels • Level 2 a daily files – High-resolution meteorological products on the radar grid • Level 2 b daily files – Meteorological products averaged on to the grid of each particular model: separate dataset for each model and product – So far we have done cloud fraction and ice water content – Includes equivalent model values, both “raw” and “modified” to make necessary adjustments to allow unbiased comparison, e. g. • Remove high cirrus from model cloud fraction if not detectable • Flag model ice clouds above rain; would not be used in obs. • Level 3 files by month and year (& model version? ) – Statistics of a comparison between model and the observations – Observed, and raw & modified model means on same vert. grid – PDFs, skill scores, correlations, anything that might be useful!

$Cloud fraction Observations Met Office Mesoscale Model ECMWF Global Model Meteo. France ARPEGE Model$

Cloud fraction Observations Met Office Mesoscale Model ECMWF Global Model Meteo. France ARPEGE Model KNMI RACMO Model

$Monthly statistics • On model height grid – Mean obs & model fraction –$

Monthly statistics • On model height grid – Mean obs & model fraction – Frequency of occurrence and amount when present (thresholds 0. 05 -0. 95) • On regular 1 km grid for fair comparison between models – Contingency table, ETS, Q – Mean cloud fraction • In four height ranges (03, 3 -7, 7 -12, 12 -18 km) – PDFs of obs & model fraction • Height-independent – Contingency table, ETS, Q

Yearly statistics • Concatenation of monthly statistics to produce yearly file with exactly the same format – Skill scores etc. all much smoother • If modellers prefer, we could group together periods with forecasts from the same version of the model

Intercomparison • Parameters on universal 1 km grid can easily be compared between models

What can we do about high cloud? • All models see more cirrus than observed, and modification of model does not usually remove enough cloud to bring them into agreement – Are all models are wrong? – Does radar miss more IWC than it thinks due to small particles? – Just a symptom of models having plane-parallel clouds?