MODAPS PCR 16-002
| PCR Number | 16-002 |
|---|---|
| Date | 2016-01-07, Updated 2016-02-17, 2016-03-01, 2016-03-22 |
| Initiator | George Riggs |
| Abstract | PGE07 v6.0.26: Replaced binary snow map and snow fraction with NDSI based snow cover. Removed some of the older screens and introduced new snow tests based on surface height, surface temperature, reflectance, solar angle, and NDSI values. Changed the surface temperature calculation to use Band 31 BT instead of the IST algorithm. Changed the definition of QA bits. PGE12 v6.0.13, PGE13 v6.0.32, PGE14 v6.0.6: L2G process updated to work with changes in L2. PGE13 updated to generate the L2G-lite product MxD10GA work with a new snow specific sorting scheme. PGE43 v6.0.11, 45 v6.0.2: L3 daily and 8-day PGEs updated to work with the L2G-lite input and new science changes made in L2. PGE46 v6.0.6, PGE67 v6.0.2, PGE88 v6.0.4: Distinguish inland water from Ocean and further separate inland water bodies into clear view open water, clear view lake ice, or cloud obscured water body in CMG products. |
| Problem Statement | Reprocess the Snow suite of products using the science team recommended changes in the C6 snow suite of algorithms, and C6 version of inputs and ancillaries. |
| Description of Change | Discontinue generation of snow cover binary map and snow fraction, instead report NDSI and NDSI snow cover as the fundamental science parameter. Refine the reflectance and thermal band tests and use the elevation data to improve on the snow commission and omissions, especially over mountains. Use Band 31 to estimate the surface temperature screen instead of using IST. Refine the QA flags. Update the L2G and L3 processes to propagate the changes in the L2 snow product to L3 daily and multi-day composite gridded tiled and CMG products. Use same spectral bands and science algorithm for processing of Aqua and Terra, by use of Quantitative Image Restoration algorithm to reconstruct band 6 in Aqua. Distinguish between inland water and ocean in the L4 CMG snow products. PGE07 6.0.23 (2-17-2016):Added HDF-compress to L2 products. PGE07 6.0.24 (3-23-2106):Added grace exit for cases where no valid data found for destriping. PGE07 6.0.25 (3-23-2106):Integrated the SDP Toolkit QIR tool as a process of PGE0 - no output effected. PGE07 6.0.26 (3-23-2106):Fix for SNOWCOVERPERCENT calculation to avoid erroneous negative values. PGE13 6.0.32 (2-17-2016):Updated to allow LSR processing for tiles where no MCDLCHKM input are available. PGE43 6.0.11 (3-01-2016):To generate MxD10A1C. |
| Products Affected | MOD10_L2, MOD10GA, MOD10A1/A2, MOD10C1/C2/CM, MYD10_L2, MYD10GA, MYD10A1/A2/ MYD10C1/C2/CM |
| Software Affected | PGE07 v6.0.26; PGE12 v6.0.13; PGE13 v6.0.32; PGE14 v6.0.6; PGE43 v6.0.11; PGE45 v6.0.2; PGE46 v6.0.6; PGE67 v6.0.2; PGE88 v6.0.4 Process: MOD_PR10xx (L2, A1, A2, C1, C2, CM), MOD_PRMGR, MOD_PR13 |
| Processing String to Receive the Change | Terra Reprocessing, Aqua Reprocessing |
| Downstream Product Effects | None. |
| Data Granules to be Used for Science Testing | Series of science tests run and test results evaluated for deliveries with incremental changes. Science test generated global products from two 16-day periods, summer and winter of 2003, and also for 3-month winter period of 2003.2010-059 |
| Justification | Snow cover binary map and snow fraction provided as the fundamental science parameters in the C5 products were largely misinterpreted and misused by the users and so is no longer included in the C6 version of the products. Instead the C6 product includes both the raw NDSI, which is the normalized snow index that users can use to derive their own snow fraction product, and the science team provided "NDSI Snow Cover", which is the raw NDSI layer that is filtered based on different screens to maximize the confidence in detected snow. Additional quality flags are also included indicating the outcome of some of the spectral and thermal tests. Under clear sky conditions the snow cover algorithm is near 100% accuracy at snow cover detection. Snow omission errors are rare with significant improvement for snow commission over high mountain regions. Snow commission errors associated with clouds could still be present, primarily on the fringes of clouds, where the cloud contamination causes a pixel to appear similar to snow. Errors associated with cloud/snow confusion appear to be static and occur most commonly in situations where the cloud cover is scattered popcorn, shaped and with ice content. Under all such cases, appropriate QA bits have been provided in C6 to help users make a proper judgment. |
| Effective Date for Implementation of Change | Completed. |
| Status | Major algorithm development completed. Sadashiva Devadiga approved on 01/07/2016. Michael King approved on 01/19/2016. Sadashiva Devadiga updated 02/17/2016. Gang Ye updated 03/01/2016. Gang Ye update 03/22/2016. |
