Assessment techniques for the ARM cloud radars

The Atmospheric Radiation Measurement (ARM) program operates millimeter cloud radars continuously at each of its sites. These radars form a key component of the ARM measurement set so it is important to keep the instruments functioning properly including maintenance of calibration. However, the cloud radars are probably the most complicated instruments at the ARM sites and are subject to a variety of failure modes. Keeping these instruments operating optimally at remote locations is a challenging task. We are developing a range of techniques for diagnosing radar instrument issues including failed components and calibration shifts in order to minimize instrument down-time and maximize usability of the data. These techniques include tracking distributions of radar reflectivity with altitude and tracking the relationship between reflected power and the Doppler velocity.