Cold domes over the warm pool: a study of the properties of cold domes produced by mesoscale convective systems during TOGA COARE

Abstract

Mesoscale convective systems (MCSs) are known to cool the subcloud layer by the introduction of penetrative downdrafts to the surface, resulting in the formation of cold domes (also known as cold pools). Five MCSs sampled during the Tropical Ocean-Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) are analyzed to relate properties of the cold domes to those of the inflow environments. Data from two NOAA P3 aircraft are used to determine the mean temperature, specific humidity, and wind speeds in the cold domes. Unique to this project is that low-level altitude flight legs ranged from 35 m to 300 m. Composite soundings of the inflow environment were constructed using flight level data from the NOAA P3s, the NCAR Electra and the NASA DC-8 aircraft, as well as dropsonde data from the DC-8 and rawinsonde data from nearby island and ship sites. All the MCSs examined produced cold domes that were accompanied by increases in wind speed. These changes in temperature and wind speed between the cold dome and the inflow environments led to significant increases in the sensible heat flux that is dependent on these two variables. Changes in the specific humidity were not as consistent. The majority of the cases display a decrease in specific humidity within their cold domes. As a result, increases in the latent heat fluxes observed in the cold domes were more dependent on the increases in wind speed. Stronger cold domes (cool, dry and strong winds) were associated with squall line MCSs, while non-squall line MCSs produced weaker cold domes (cool, weak to moderate winds), that were not necessarily less moist than the inflow environment.