Bug report

Bug was reported to COSP users on 01 Feb 2018  and to the simulation group on 28 Feb 2018.

Dear COSP users —  
    
    We are writing to notify you of an error in MODIS simulator output affecting COSP 
    versions 1 and 2 prior to 29 Nov 2017.  
    
    In COSP 1.4 and 1.4.1 and COSP 2.0 all MODIS simulator variables are affected by an error manifest only 
    when clouds with both liquid and ice visible from space. In CESM the impacts are quite small 
    (https://www.esrl.noaa.gov/psd/people/dustin.swales/COSP/v1.4.2/cosp_quicklooksV1.4.2.html). 
    
    In COSP 1.4.1 variables jpdftaureliqmodis and jpdftaureicemodis are further affected by an 
    error in initialization. We expect that when these errors are manifest the data will be nonsensical. 
    
    For future projects we encourage you to use COSP 1.4.2 or COSP 2.0.1 or later.  
    
    The attached file, which was sent to the modeling groups intending to submit to CMIP6, provides 
    more detail including the diagnostics affected and github links for the code changes.
    
    ---
    Robert Pincus and Dustin Swales 
    University of Colorado/NOAA Earth System Research Lab
    http://cires.colorado.edu/researcher/robert-pincus	

Attached file summarizing affected diagnostics for various version of COSP:

Plan

• Because bug was reported approximately one month after the start of DECK simulations, it was too late to incorporate the bug fix.
• Bug fix will be incorporated in future versions of E3SM (PR #2097).
• COSP variables impacted should not be released or used for analysis.

Bug fix

• Incorporated with PR #2097. To maintain backward BFB results with DECK simulations, the bug fix must be activated with a CPP directive APPLY_POST_DECK_BUGFIXES.