Sampling Strategies for the 404 MHz profilers
The following sampling strategy is used by the profilers.
1) The profiler uses two modes to collect data, the low mode and the high mode. The low mode collects data from 0.5-9.25 km above ground level (AGL) and the high mode collects from 7.5-16.25 km AGL. Note there is a region of overlap from 7.5-9.25 km AGL. The high mode is 16 dB more sensitive than the low mode. Note that the range gates are 250 m long. There are 36 range gates in each mode.
2) To measure the three dimensional winds, the antenna is electronically switched from the northward, vertical and eastward pointing beams. Each beam requires 2 minutes for data collection, one minute for each mode. Thus, a total of 6 minutes is required to complete data collection for one vertical profile of the horizontal and vertical winds. Horizontal winds are derived from the data collected in each of the three beams in a manner similar to the dual-Doppler technique.
3) Wind profiles are an hourly average of the profiles observed during the previous hour. Since each profile takes 6 minutes of obtain, a maximum of 10 profiles may be averaged together.
image
from NOAA
