Topic: IMS DSLO Product Algorithm Correction

Date/Time Issued: December 20, 2018 M-B2030 UTC

Product(s) or Data Impacted: M-BIMS DSLO GRIB2 products

Date/Time of Initial Impact: January 9, 2019 1800 UTC

Date/Time of Expected End: N/A

Length of Outage: See details below.

Details/Specifics of Change: M-BA correction to the Interactive Multisensor Snow and Ice Mapping System (IMS) M-bM-^@M-^\Days-Since-Last-ObservedM-bM-^@M-^] (DSLO) product algorithm will be implemented on January 9, 2019 at 1800 UTC.M-B This change will correct an ancillary product that has not updated since 2014.

The DSLO products are fields in some of the IMS output files. They are pixel maps with resolution and geometry coincident to the IMS snow/ice cover products. With the changes described below, the DSLO value at each pixel will be the lesser of the M-bM-^@M-^\days-since-last-updateM-bM-^@M-^] of the ASI (Automated Snow and Ice Mapping) product and M-bM-^@M-^\days-since-last-updateM-bM-^@M-^] by an IMS analyst.

Values for DLSO will only be computed where both the IMS and ASI M-bM-^@M-^\days-since-last-updatedM-bM-^@M-^] products overlap, which currently includes the portion of the Northern-Hemisphere above the 23rd North parallel. Areas outside the coverage region will be set to NaN or otherwise masked out.

The affected products have the following filenames and PDA product shortnames:

NIC.IMS_time_v3_YYYYJJJHH_1km.GRIB2.gz M-BM-BM-B NESDIS_IMS-V3_time_1km
NIC.IMS_snow_v3_YYYYJJJHH_4km.GRIB2.gz M-BM-B NESDIS_IMS-V3_snow_4km
NIC.IMS_ice_v3_YYYYJJJHH_4km.GRIB2.gz M-BM-BM-BM-BM-B NESDIS_IMS-V3_ice_4km