The Ka-band ARM zenith radar (KAZR) remotely probes the extent and composition of clouds at millimeter wavelengths. The KAZR is a zenith-pointing Doppler radar that operates at a frequency of approximately 35 GHz. The main purpose of this radar is to determine the first three Doppler moments (reflectivity, vertical velocity, and spectral width) at a range resolution of approximately 30 meters from near-ground to nearly 20 km in altitude.
The KAZR replaces the millimeter wavelength cloud radar (MMCR) and utilizes a new digital receiver that provides higher spatial and temporal resolution than the MMCR. In addition, spectral artifacts in the data are significantly reduced in the KAZR, providing researchers the ability to study cloud dynamics to a much higher degree than with the MMCR. After the MMCR was upgraded, it was decided that it should be named differently as there were only 2 components from the original MMCR that were in the KAZR.
For more information on radar, please see General Information on radar
For more information see KAZR.
The DQ Office provides all the QC flags for the KAZR. These can sometimes be off, so do not trust the flags completely. We keep revising the limits as best we can. The RH and various temps will flag at times. There is also the twta_status_state that is flagged constantly as well. After viewing the metrics for a prolonged period of time, and something does change, that may be cause for further investigation.
Moderate Sensitivity Mode (MD)
This should have the same variables as the general mode, but is a little more sensitive.
High Sensitivity Mode (MD)
Depending on the location, this mode may only have the Co-Pol mode but will have the main variables listed above (Reflectivity, Doppler Velocity, Spectral Width, Signal-to-Noise Ratio).
There are a lot of components in a radar and there are many sensors used to monitor the system, so the diagnostic plots have a lot of data in them. They mostly include, temperatures, powers, noise, gains, calibration constants and transmit powers, see Fig. 2 and Fig. 3.
Noise Floor Comparison
Through some special processing, we are able to pull out the noise floor that the KAZR is measuring. This is plotted up over 14 days, normally with other vertically pointing radars. The data should be somewhat steady, there will be fluctuations. If the data are abnormally fluctuating over time, bring it to our attention.
Radar Lidar Comparison
Most 2D profiling instruments are plotted up on the same plot at a site to compare. Drop size distributions from the disdrometers are also plotted at the bottom. The white overlay is the cloud base height from the vceil25k. Blue overlays of when surface precipitation instruments are reporting precip are at the top of each profile plot.
Instrument is located at all sites.
Known issues for this instrument that MAY NOT need to be mentioned in your DQA's can be documented here.
Past problems for this instrument that DO need to be mentioned in your DQA's and possibly requiring a DQPR submittal:
Sometimes the transmitter will go out on the KAZR and the KAZR will not be able to detect clouds. The reflectivity will look like a clear day. The easiest way to determine this is by viewing the comparison plots. Please see DQR D110809.1
The channels were switched so that the Cross-Pol reflectivity was higher than the Co-Poll reflectivity. This can be seen when there is meteorological echoes and also in the LDR. The LDR should be negative, but when this problem occurs, the LDR becomes positive. Please see DQR D130813.1