MODAPS PCR VNP 23-004
| PCR Number | VNP 23-004 |
|---|---|
| Date | 2023-09-13 |
| Initiator | Sudipta Sarkar, Carol Davidson, Huilin Gao |
| Abstract | PGE687 2.0.2, PGE688 2.0.2, PGE698 2.0.2 Changes includes: |
| Problem Statement | Revised for J1 and NPP to improve identification of water and estimation of evaporation volume |
| Description of Change | Changes includes: Use of the same monthly composite method with MODIS; provide the contamination fraction values for each lake; update the lake evaporation volume equation by using the open water surface area; update percentile files; and added terrain shadow mask and use them for classifying VIIRS images. |
| Products Affected | VNP28C2, VNP28C3, VJ128C2, and VJ128C3 |
| Software Affected | PGE687 2.0.2, PGE688 2.0.2, PGE698 2.0.2 |
| Processing String to Receive the Change | S-NPP Forward Processing. S-NPP Reprocessing. J1 Forward Processing. J1 Reprocessing. |
| Downstream Product Effects | SNPP VIIRS Land products, including VNP28C2/C3 and VJ128C2/C3 |
| Data Granules to be Used for Science Testing | Science test has been executed to assess the performance of these revisions. All results have been duly reviewed and confirmed by the science team and LDOPE, before final approval. |
| Justification | After adding terrain shadow masks, the water area estimation has been improved, especially for those lakes located in mountain regions. Taking Lake Hawea (GWR ID 131) for instance, the VNP28C3 reservoir surface area is more accurate compared to MOD28C3 in which such masks are not implemented (Figs. 1&2). Regardless, the SNPP/ J1 reservoir products agree well with the MODIS product as only a few locations are affected by the terrain shallow notably. The R[squared] values of 8-day area between SNPP/ JPSS-1 and MODIS are 0.99. Furthermore, the R[squared] values between the MODIS and VIIRS-based monthly evaporation rates are 0.89 for VJ1 and 0.90 for VNP. |
| Effective Date for Implementation of Change | PGEs noted in this document went into production, as part of the C2 reprocessing the week of Sept 5, 2023 for SNPP and JPSS1. |
| Status | Major algorithm development completed. Sadashiva Devadiga approved 09/21/2023. Sudipta Sarkar approved 09/13/2023. |
