Height of convective cloud top (HCCT) is a new output parameter introduced with cycle 43r1. HCCT gives the height in metres (m) of the clouds produced by all three forms of parametrized convection:
- shallow convection which is surface-based and produces thin clouds (up to 200 hPa in depth);
- deep moist convection (DMC) which originates from the boundary layer and the resulting cloud is thicker than 200 hPa;
- elevated (mid-level) convection occurs in the presence of large-scale ascent and sufficiently moist air (relative humidity above 80%), e.g. warm fronts of extratropical cyclones.
Since HCCT includes all forms of convection mentioned above, sometimes high convective cloud tops can be related to mid-level convection that produces relatively thin high-level clouds. To check whether this is the case one can use HCCT in conjunction with the cloud base height (CBH) in order to obtain cloud depth as it is shown in one of the plots below. On that plot these clouds will appear to be quite thin.
Looking globally we can notice quite widespread coverage of convective clouds. This is due to the fact that the convective detrainment is the main source of clouds in the model.
HCCT represents instantaneous values and as such the field itself could be quite noisy. It can happen that cloudless grid boxes where DMC has not been triggered yet are surrounded by very high and thick convective clouds produced by DMC, shallow and mid-level convection.