National Weather Service United States Department of Commerce

MES0-SAILS TEST: New Radar Technology

     The NWS Cleveland WSR-88D Doppler Weather Radar, KCLE, was recently upgraded.  With this upgrade, the KCLE radar began participation in a field test of the Multiple Elevation Scan Option (MESO) for SAILS (Supplemental Addaptive Intra-Volume Scan).  The field test will continue for about 1 year.  The SAILS function allows for one addtional low level scan (0.5 degree elevation angle) per volume scan.  MESO-SAILS enables the radar operator to select either 1, 2, or 3, supplemental low level scans per volume scan.  This new scan is inserted into the “middle” of the volume scan to evenly space, as close as possible, the time intervals between low-level data updates. When the MESO-SAILS 3 Scan Option is active, the 0.5 degree updates will be available every 75 to 90 seconds.  SAILS as well as MESO-SAILS is only available when the radar is in VCP (Volume Coverage Pattern) 12 or 212.

Regular SAILS Option

depiction of the scan strategy when using SCAN

The regular SAILS option begins the scan strategy at elevation 0.5 and advances upward to 3.1 (first chart on the left).  It then returns to swipe an addiitonal 0.5 scan (second second chart) before returning to complete (third chart) the rest of the elevations (4.0 to 19.5, for example).






































table describing the elevation scan strategy for SAILS, SAILSX2, and SAILSX3The table on the left shows the elevation scan pattern that can be expected when in SAILS (exactly like the above description) and for the additional SAILSX2 and SAILSX3 options.  It also shows the amount of time to comple each scan.

The first SAILS (additional) scan takes place after the 3.1 scan for SAILS, after the 1.8 scan for SAILSX2, and after the 1.3 scan for SAILSX3.  The SAILSX2 and SAILSX3 get additional 0.5 scans after the 6.4 slice and 4.0 slice, respectively.  The final additional 0.5 scan of SAILSX3 takes place after the 8.0 scan.


The primary advantage to utilizing this feature is to get more frequent scans of the lowest elevation in order to interrogate critical features such as possible rotation and tornado formation (among other storm-scale features).