Date/Time Issued: February 27, 2018 1725 UTC
Product(s) or Data Impacted: GOES-16 Cloud Optical Depth L2 Data
Date/Time of Initial Impact: February 22, 2018 at 2215 UTC
Date/Time of Expected End: M-BN/A
Length of Event: M-BN/A
Details/Specifics of Change: The GOES-R Peer/Stakeholder Product Validation Review (PS-PVR) for ABI L2+ Cloud Optical and Microphysical Properties (COMP) Provisional Maturity was held on February 22, 2018. As a result of this review, the PS-PVR panel recommended that the ABI Cloud Optical Depth (COD) product be declared Provisional. This was accomplished at approximately 2215 UTC on February 22, 2018. At the same time, the PS-PVR panel recommended that the ABI Cloud Particle Size (CPS) transition to Provisional be delayed.
The ABI L2+ Cloud Optical Depth product assigns each earth-navigated cloudy pixel a value. Non-cloudy pixels or those for which the retrieval was not successful receive fill values. For pixels with solar zenith angles less than or equal to 82M-BM-: (daytime), valid COD values can range from 0.5 to 50.0 while pixels with solar zenith angles greater than 82M-BM-: (nighttime) will have valid COD values ranging from 1.0 to 8.0. COD values outside those ranges are considered less accurate and their usage is not recommended. Similarly, pixels with solar zenith angles between 65M-BM-: and 90M-BM-: should be considered less accurate and do not meet the product specifications. Daytime COD values are derived using visible and near-infrared channels while the nighttime COD values are derived from near-infrared and infrared channels. The COD product is generated for every ABI Full Disk (FD) of the Earth and Continental United States (CONUS) region.
Provisional maturity, by definition, means that:
Validation activities are ongoing and the general research community is now encouraged to participate;
Severe algorithm anomalies are identified and under analysis. Solutions to anomalies are in development and testing.
Incremental product improvements may still be occurring;
Product performance has been demonstrated through analysis of a small number of independent measurements obtained from select locations, periods, and associated ground truth or field campaign efforts;
Product analysis is sufficient to communicate product performance to users relative to expectations (Performance Baseline);
Documentation of product performance exists that includes recommended remediation strategies for all anomalies and weaknesses. Any algorithm changes associated with severe anomalies have been documented, implemented, tested, and shared with the user community;
Testing has been fully documented; and
Product is ready for operational use and for use in comprehensive cal/val activities and product optimization.
Provisional users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized. Persons desiring to use the GOES-16 ABI Provisional maturity Cloud Optical Depth products for any reason, including but not limited to scientific and technical investigations, are encouraged to consult the NOAA algorithm working group (AWG) scientists for feasibility of the planned applications. This product is sensitive to upstream processing, such as the quality of the calibration, navigation and the other cloud algorithms (mask, type/phase, height).
Known issues at the Provisional validation stage include:
Missing values occur randomly due to upstream L1b issues;
The upstream cloud algorithms can lead to clear regions being assigned a cloud optical depth or cloudy regions being classified as clear sky, hence receiving no COD value;
Issues in the NWP products can cause upstream cloud algorithms to misidentify cloudy pixels as M-Bnon-cloudy so COD retrievals are not performed;
Optically thin cirrus clouds are sometimes misclassified as liquid water, supercooled liquid water or mixed phase, which impacts COD values;
The risk of misclassifying liquid water clouds as ice is greatest in regions with broken cumulus clouds, hence COD values are impacted in those situations; M-B
The ability to correctly identify clouds that have both liquid water and ice within the portion of the cloud influencing the measured ABI radiances is limited.
Any past or future calibration changes to channels involved in the day or night COD retrievals can impact the COD retrievals.
Due to several reasons the CPS wonM-bM-^@M-^Yt be transitioned to Provisional at this moment. It is likely that retrieval will be adjusted, which may be also have an impact to COD product.
Contact for further information: OSPO User Services at SPSD.UserServices@noaa.gov
Contacts for specific information on the ABI L2 COD product:
Jaime Daniels email@example.com
Wayne MacKenzie firstname.lastname@example.org
Andrew Heidinger email@example.com