CALIOP Instrument Anomaly Advisory: Low Energy Laser Shots
Dates Affected: September 01, 2016 - present
Applies to: CALIOP Level 1B and Level 2 Data Products, V4.10 and earlier
CALIOP (CALIPSO’s LIDAR instrument) is experiencing an elevated frequency of low energy laser shots within the South Atlantic Anomaly (SAA) region
due to decreased pressure inside the laser canister. The low energy laser shots began in September 2016 and have increased in frequency, particularly since
the second half of 2017 (Fig. 1). Science quality of affected profiles within the SAA is degraded and these profiles should be excluded from scientific
analyses. The document below provides guidance on how to identify affected profiles in CALIOP level 1B and level 2 products. Science quality of
profiles with nominal laser energies is unaffacted by this issue. The IIR (Imaging Infrared Radiometer) and the WFC (Wide Field Camera) instruments
are also unaffected.
Fig. 1 Monthly frequency of low energy laser shots (E532 < 80 mJ) from January 2016 to March 2018, globally and in the
SAA region (left). Spatial distribution of low energy shot frequency from October to December 2017 (right).