Cold pools – a first step in representing convective organization in GCMs
|Anthony D. Del Genio — National Aeronautics and Space Administration||Jingbo Wu — Columbia University|
|Audrey B. Wolf — NASA - Goddard Institute for Space Studies||—|
- Initiation of convective downdrafts that inject cold air into the boundary layer
- Formation of cold pools that spread over time and remain distinct from ambient air
- Regeneration of convection by lifting of ambient air at the gust front
- Initiation of a stratiform cloud and rain region by detrained convective condensate
- Development and evolution of mesoscale updrafts and downdrafts.
Initial GCM tests indicate that parameterized cold pools are ~1–2 km deep and are deeper over land than over ocean; have cold anomalies of ~0.5–2 K or more, with the largest values over drier continental areas; and usually have dry anomalies of ~0–1.5 g/kg, although cold pools at the edges of the continental Intertropical Convergence Zone (ITCZ) tend to be slightly wetter than ambient air. Although these characteristics qualitatively resemble those seen in field experiments and cloud-resolving models (CRMs), the frequency of occurrence (~0.5% globally) and duration (2 hours or less) of cold pools is not sufficient to shift the phase of the diurnal cycle of convection. We are performing SCM tests of the Midlatitude Continental Convective Clouds Experiment (MC3E) field campaign data to try to understand how this limitation of the parameterization might be mitigated.