An overview of the NCAR S-PolKa radar operations during DYNAMO

The National Center for Atmospheric Research (NCAR) S- and K_a-band dual-wavelength and dual-polarimetric ground-based research weather radar (S-PolKa) was recently deployed for 3.5 months during the Dynamics of the Madden Julian Oscillation (DYNAMO) field experiment on Addu Atoll, Maldives. The S-PolKa radar on Addu was part of a radar “super-site” that consisted of scanning and vertical incident radars at various wavelengths and resolutions. The radar measurements taken on Addu Atoll during DYNAMO constitute an unprecedented data set in the Indian Ocean region observing the cloud life cycle from shallow non-precipitating cumulus to the development of deep convection and the resultant anvil clouds. The S-band wavelength of S-PolKa suffers very little attenuation and is therefore well-suited for precipitation studies. It is also sensitive enough to see non-precipitating clouds and the Bragg scatter associated with moist-layers and cloud formation. The dual-polarimetric S-band capability enables improved estimates of rainrate and rain amount compared with conventional radars. Also bulk estimates of hydrometeor type are routinely made using the S-band data and a temperature profile, typically from a proximity sounding. Detailed analysis of the microphysics of clouds and precipitation is possible using the numerous vertical scans of the radar.

The K_a-band wavelength measurements of the S-PolKa system are simultaneous with the S-band. The addition of these simultaneous measurements at the attenuating K_a-band wavelength provides the capability to measure the lower tropospheric humidity and the total cloud liquid water content (cloud +rain).

The long period of operations and the remote location presented unique challenges for this deployment. This presentation will provide an overview of the operation of, and the data collected by, the S-PolKa radar during the DYNAMO field deployment.