User’s Guide - Data Advisory Page

Release Date: 06-12-2018

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).

• Guidance On Excluding Affected Profiles (.pdf)
• Approximate South Atlantic Anomaly Boundaries (.txt)