Attention for Data Usage
- Lack of Data
This archive lacks a lot of observation data. Long-term lacked observations were caused by trouble of radar, repair of the radar or transfer to the other site. Lacked observations for a few days were caused by mistakes of exchange of recording media, damage of recording media or stops with extraordinary action of radar. Clear air echo in upper height range is frequently too weak to detect its doppler shift.
- Quality Control
Quality control hasn't been made in this database such as excluding erroneous data using continuity of wind velocity in height and time. We will make quality control and improve the data quality in future.
- Vertical Wind
UHF radar cannot measure vertical velocities in the case of strong rain, because the echo from rain is too strong compared with the echo from clear air.
Downward winds exceeding 1 m/s are inferred as rainfall, and are removed in this database. However, echoes from weak rain and snow are sometimes mistaken as downward wind.
- Ground Clutter
Ground clutter is an echo from ground surface object caused by the upward beam's sidelobe in the horizontal direction. Its doppler velocity is zero. When surface wind speed is high, the spectral width of clutter broadens out. Wind measurement errors sometimes occur by clutter's overlapping with clear air echo.
To avoid clutter contamination, zero velocity horizontal winds in the lower height range are excluded in this database.
We are developing new data processing method to detect atmospheric echo even under ground clutter contamination.
- Other Source of Wind Measurement Error
A part of wind measurement error is caused by echo from an airplane, a bird and by sharp fluctuations of rain.
Back to Data Archive
Created by Yuichi Ohno (ohno@crl.go.jp)
Ver. 2.1 : Apr 2002