Dual-wavelength humidity profiles and liquid water content retrievals using S-PolKa During the DYNAMO Field Campaign

The NCAR scanning, S- and Ka-band dual-wavelength, dual-polarimetric, radar (S-PolKa) makes simultaneous S-band and Ka-band measurements with 1 degree beamwidth and nominal range resolution of 150 m. Both radars have dual-polarization and Doppler measurement capabilities. The S-PolKa radar is a national resource as part of the NSF Deployment Pool and has been deployed for atmospheric studies around the world. The dual-wavelength and dual-polarization capabilities of S-PolKa enable the estimation of humidity profiles in the lower troposphere and liquid water content (LWC). Using the LWC estimates and making some reasonable assumptions results in mass weighted diameter (D0) estimates.

The S-PolKa system was deployed in the Maldives for 4.5 months during the Dynamics of the Madden Julian Oscillation (DYNAMO) field campaign. The humidity retrievals showed a large spatial and temporal variability that was also reflected in the sounding data. The S-PolKa retrieved humidity is verified against the 3 hourly sounding data using only data that was very close in time and space in order to minimize the impact of the natural variability and the sampling differences. The retrievals are then used to investigate the variability of the humidity in the tropical DYNAMO domain.

The LWC/ D0 retrievals are performed on the native radar resolution. While difficult to verify, the errors of the LWC estimates are currently being investigated using collocated microwave radiometer measurements collocated with S-PolKa during DYNAMO. The latest results will be presented.