VIIRS Geolocation (GEO) Sensor Data Record (SDR) - Nasa

JPSS VIIRS CAL & GEO SDR OAD 474-00090
Effective Date: October 09, 2012
Revision B
Page 67
2.3.6 Computational Precision Requirements
The VIIRS SDR CAL routine outputs two structures for each band in the Moderate (750m)
resolution, and Imagery (375m) resolution: a scaled version and a non-scaled version of the SDR.
The scaled versions of the bands are identified for long term storage, and the non-scaled full
floating point versions are used for immediate processing of EDRs and Ips. These full floating
point versions are removed by the storage system after an amount of time, post creation.
2.3.7 Algorithm Support Considerations
The DMS and INF must be running before the algorithm is executed.
2.3.8 Assumptions and Limitations
2.3.8.1 I/O Timeliness
Dual gain bands require calibration space view data from the previous granule and next granule.
From this, one-granule latency occurs for the dual gain bands.
2.3.8.2 Sci2Ops Issues
The CAL code expects that the Verified VIIRS RDR data follows the “product order” convention
for detector numbering, which requires that the highest number detector in scan N lies adjacent to
detector number 1 in scan N+1 (see Section 2.2.2.3 of the ATBD, 474-00027).
2.3.8.3 Numerical Computation Considerations
The scientific SDR and EDR algorithms must be convertible into operational code that is
compatible with data latency requirements. This essentially means that most EDRs must be
completely processed from VIIRS raw data, including CAL and georeferencing, within 28 minutes
from the time the raw data are available. The complexity of the calculations used for VIIRS
radiometric CAL is similar to those in routine MODIS processing and are therefore expected to
perform within a reasonable allocation of the operational timeline.
Here are optimization considerations. The current version of the operational algorithm is deemed
to fall within acceptable processing timeline. Should it become necessary then additional
optimization can be achieved by threading the algorithm to multiprocess each scan, or
multiprocess each CAL step (Reflective, Emissive, DayNight).
2.3.8.4 Additional Assumptions
It is assumed that Verified RDR data are provided in correct time sequence and that complete
scans are provided (missing data within a scan is to be filled). It is also assumed that RDR data
are reconstructed to remove any coding, compression, and band referencing that was performed
on-board.
Check the JPSS MIS Server at https://jpssmis.gsfc.nasa.gov/frontmenu_dsp.cfm to verify that this is the correct version prior to use.