CLSATO

AMF3 CloudSat Overpasses

1 March 2017 - 30 May 2017

Lead Scientist: Sergey Matrosov

Observatory: AMF (ARM Mobile Facility 3) - OLI

Synergy between ground-based and satellite radar observations of clouds and precipitation is important for refining the algorithms to retrieve hydrometeor microphysical parameters, improvements in the retrieval accuracy and better understanding the advantages and limitations of different retrieval approaches. The new dual-frequency (Ka - and W-band, 35 GHz and 94 GHz) fully polarimetric Scanning ARM cloud radars (SACRs-2) are advanced sensors aimed to significantly enhance remote sensing capabilities. One of these radars is deployed as part of the third ARM Mobile Facility (AMF3) at Oliktok Point, Alaska (70.495o N, 149.886oW). The CloudSat satellite, which is part of the polar-orbiting A-train satellite constellation passes over the vicinity of the AMF3 location (typically within 0-7 km depending on a particular overpass) on a descending orbit every 16 days on approximately 13.21 UTC. The nadir pointing W-band CloudSat cloud profiling radar (CPR) provides vertical profiles of reflectivity which are then used for retrievals of hydrometeor parameters. The CloudSat and SACR-2-based ARM radar variable measurements and cloud and precipitation microphysical retrievals can be approximately matched in space in time during satellite overpasses, particularly if special SACR-2 scanning procedures are applied for several minutes during an A-train overpass. Availability of approximately matched ARM and CloudSat measurements/retrievals will allow for intercomparisons and validation activities which could lead to improved remote sensing results from both ground-based and satellite cloud radars. It will also provide data for maintaining the radar absolute calibration. An important benefit of scanning the SACR-2 approximately along the orbital track of CloudSat will also be maximizing the comparison data set for examining cloud and precipitation structure. It will allow for an independent evaluation of the extent of the SACR-2 spatial coverage under different conditions. The primary activity for this campaign will include performing special scanning routines for the SACR-2 at near the time of CloudSat overpasses. Special scans will include hemispheric range-height indicator (RHI) scans in the direction, which is parallel to CloudSat overpasses (i.e., RHI in the azimuthal direction of about 26.3o), and several additional RHI scans in the directions that would intercept the CloudSat ground track. The total duration of special SACR-2 scans during one overpass will be around 10 minutes. The SACR-2 special scans will be performed at the time of overpasses occurring during the three month period starting on 5 March 2017. The dates of the overpasses during this period are March 5 and 21, April 6 and 22, and May 8 and 24. Relevancy to the ARM mission: This IOP is relevant to the ARM mission since the proposed activities and expected data sets, which will be obtained during the CloudSat/A-train overpasses, will complement measurements from AMF3 and support calibration efforts thus enhancing cloud and precipitation retrievals. It will also support the use of combined AMF3 and satellite-based measurements to upscale AMF3 observations to a regional scale.