From Proba-V to Proba-MVA

Transcription

1 From Proba-V to Proba-MVA Fabrizio Niro ESA Sensor Performances Products and Algorithm (SPPA) ESA UNCLASSIFIED - For Official Use

2 Proba-V extension in the Copernicus era Proba-V was designed with the main objective to bridge the gap from SPOT- VGT to S3 for Land; in this respect, the mission was successful, ensuring continuity to CGLS for the provision of a large set of biophysical variables By the end of 2019 Sentinel-3 A+B will take over the task of providing data to CGLS for continuing the SPOT-VGT data record Similarly, the Sentinel-2 A+B 10m data at 5 days revisit will address most applications needs (both for land and coastal/inland water)

3 Thinking out-of-the-box: end-of-life experiment In the context of a mission extension beyond 2019, under the assumption that there are no delay in S3 B deployment and operations the constraints of an operational global daily mission will be released for Proba-V this will give the freedom to explore new opportunities to operate the satellite, such as a new mission concept and a completely new observation scenario A similar approach was successfully implemented in the past, toward mission end-of-life, in order to collect valuable data for addressing specific scientific question or for preparing new mission (e.g., ERS-2, GOCE, SPOT-Take5) Special dataset covering the 20 days of GOCE re-entry phase Image Credits: ESA Example of SPOT-Take5 dataset used to simulate Sentinel-2 5-days revisit time series Image Credits: CESBIO

4 Proba-Multiple View Angle (MVA) Proba-1 CHRIS multi-viewing angle observation geometry Image Credits: ESA What about if we tilt the platform along the orbit imaging a given area from multiple viewing angles? We could repeat the manoeuvre along the orbit or focus on special events and target areas Proba-1-CHRIS (same platform) already supports such observation scenario but for small areas (14x14km2), with Proba-V we could cover much bigger areas (full 2200km swath or 500km central camera) to study mesoscale atmospheric processes Among existing MVA sensors: SLSTR (2 views), PARASOL-3MI (the most sophisticated with >14 views and polarizers), the MISR (9 views) seems the most appropriate to be used as a model

5 NASA-MISR on board Terra Launched in 1999 aboard Terra platform to operate until fall 2020 Specs: Swath: 380 km Coverage: global in 9 days Spatial Resolution: 275 m MISR geometry of observation Image Credits: NASA 9 cameras: 1 nadir, 4 forward, 4 backward 4 bands: Blue, Green, Red, NIR Applications: Clouds, Aerosol, Surface MISR observing temporal evolution of solar eclipse and of a volcano's eruption Image Credits: NASA

6 Proba-MVA Specs Vs. MISR MISR Proba-MVA Analysis Coverage Global in 9 days Fragmented, on-request Viewing angles 70, 60, 45, 26, 0, -26, - 45, -60, -70 Across track Swath Spatial Resolution Spectral coverage 70, 55, 0, -55, -70 (TBD) 380 km 2200 km (500km central camera) 275 m 100 m (central camera) Blue, Green, Red, NIR Blue, Red, NIR, SWIR PV-MVA should focus on special events or target areas PV-MAV with 5 viewing angles should provide similar capabilities for aerosol/surface PV- MVA larger swath, though unfavorable illumination condition in the anti-sun camera PV-MVA providing better spatial resolution PV-MVA bands are borader, spurious molecular signature Calibration On-board diffuser Vicarious PV-MVA 5% radiometric accuracy

7 Proba-MVA acquisitions Along-track acquisition (100 km) Proba-V has linear CCD arrays and imaging are built using platform movement (pushbroom) If we simulate a MVA acquisition with 5 viewing angles (70, 55, 0, -55, -70) we should account for the time for acquisition along-track and the remaining time for manoeuvre Along-track acquisition (500 km) The need is to cover an along-track stretch large enough in order to study mesoscale processes in the atmosphere Ideally 500km along track would guarantee to image an area of 500x500km 2 at 100m spatial resolution, which will allow to have a synoptic view of large events (smoke, fires, clouds)

8 Opening the door for new applications: Stereoscopic retrieval of cloud/aerosol top height Stereoscopic view of Etna s plume Stereoscopic retrieval of cloud and aerosol plume height with MISR. The MVA allows for purely geometric retrieval of height, independent on errors in radiometry, it has been largely validated with MODIS cloud top height.

9 Opening the door for new applications: Retrieval of wind vectors Tracking Hurricane Wilma across Caribbean Retrieval of multi-levels wind vectors over Hurricane Earl

10 Opening the door for new applications: Retrieval of aerosol optical and micro-physical properties Retrieving size of dust and smoke aerosol particles with MISR. MVA capabilities are key to retrieve aerosol optical and microphysical properties since they allow to sample phase functions at different scattering angles. Sever air pollution in New Delhi

11 Opening the door for new applications: Retrieving canopy height and vegetation parameters Mapping canopy height with MISR LAI and FPAR maps from MISR

12 Initial thoughts about Proba-MVA implementation Duration Mission concept Calibration Processing Exploitation Proposal Starting Nov 2019 (as long as CGLS will be ready for the transition to S3) for 1-2 years Planning could be on request for target areas and special events or autonomous for sequential stripes along the orbit Calibration should be continued using the current vicarious methods Operational processing limited to co-registered and fully calibrated Level 1 MVA images at TOA Level 2 could be ESA-supported science products developed within the Proba-V MEP QWG should be revised to include scientists of aerosol/clouds/3drtm; MISR and 3MI scientists should be involved as well Action TBD internally To be verified with REDU/ESTEC To be verified with VITO To be discussed internally

13 Conclusion Considering the availability of Sentinel-3 A+B constellation, it is difficult to justify the continuation of Proba-V mission beyond 2019 as-it-is The proposal is to have a paradigm shift from an operational to an Earth- Explorer-type mission for a limited 1-2 years period Proba-MVA can have a number of benefits: Provide justifications for a future ESA operational MVA mission Stimulate new science, e.g., for retrieval of aerosol and clouds properties, for improving 3D RTM of coupled canopy/atmosphere Aggregating a new science community (Land and Atmosphere) around the Proba-V MEP for developing new algorithms, sharing ideas Foster synergy with current and planned EO missions such as S2 and S3, and with in-situ network of aerosol/cloud observations

14 Back-up slides ESA UNCLASSIFIED - For Official Use

15 The orbital drift Orbital drift is known to have significant impact on longterm data record of satellite products, as demonstrated for AVHRR-NOAA derived products (e.g., J. R. Nagol et al., Remote Sens., 2014); The current prediction of Proba-V LTDN evolution are: 9:40 Nov 2019, 9:00 end of 2020; This will worsen environmental conditions for optical imagery (especially in anti-sun side-view camera) and introduce spurious trends in long-term analysis; While BRDF correction, C2 baseline, will partly cure this effect by providing nadir-normalized reflectances, the continuity requirement of the mission could be questionable considering that an operational stable mission (Sentinel-3) will be fully functional at that time;