Visit to the SPolKa

Published: 3 November 2011

SPol_and_radiometer_lowres — The SPolKa radar at the wharf site. The large radar dish is the S-band antenna while the much smaller dish in the lower corner is the K-band antenna. In the right foreground of the image, mounted on the stone platform, is the scanning radiometer.

On Wednesday, October 19, I journeyed up the Atoll to see where our DYNAMO colleagues spend their days—at the SPolKa radar site.

The SPolKa is a dual-wavelength (10-cm S band and 0.8-cm Ka bands) polarimetric radar. The S-band radar will detect all of the precipitating and many of the non-precipitating clouds, and with its polarimetric capabilities will provide information on particle type (snow, ice, graupel, rain) to give better rain estimates. The Ka- and S-band radars are beam-matched, meaning that the same cloud volume is observed at both wavelengths, allowing dual-wavelength retrievals. Given the fact that the Ka-band is much more strongly attenuated by water vapor than the S-band, if a cloud is seen by both bands then examining the difference in reflectivity at the two wavelengths will provide information on the amount of water vapor between the radar and the cloud. These water vapor retrievals will provide important information about the humidity structure in the lower atmosphere during the MJO initiation.

Scott_SPol_lowres — Hiroyuki Yamada and Scott Ellis at the SPol site.

A guest instrument, a multi-wavelength scanning radiometer run by Paquita Zuidema of University of Miami, is also installed at the SPolKa site to provide additional water vapor measurements.

Scott Ellis of NCAR gave me and a visiting scientist, Hiroyuki Yamada, a tour of the SPolKa. Yamada is from JAMSTEC (the Japan Agency for Marine-Earth Science and Technology) and had spent the last few weeks launching radiosondes on Male (the capital of the Maldives) as part of the CINDY/DYNAMO/AMIE campaigns.

SPol_clouds_lowres — A typical cloud field observed from the SPol site. If you have sharp eyes, you might be able to spot the SACR antenna in the far distance of the picture—it is just peeking between the two big cement barriers at the northern end of the wharf site.

The SPolka radar site is the nerve center of the DYNAMO campaign and is usually quite busy during the day. The SPolka hosts work space for the SPol radar technicians, several scientists from NCAR and University of Washington who are working with the SPol data, the chief scientist for the SMART-R, several graduate students, and a visiting scientist or two. All in all, it is a great place to spend the morning talking about radar, clouds, and the MJO.

— Sally McFarlane

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The ARM Climate Research Facility is a DOE Office of Science user facility. The ARM Facility is operated by nine DOE national laboratories, including .