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Phenology Land Product Validation Workshop LPV Phenology Subgroup; Status Following on the Dublin meeting 2010, aim is to develop a plan on how to effectively use ground- to airborne-level phenological measurements to validate satellite-based land surface phenology products internationally-coordinated remote sensing land surface phenology validation and inter-comparison activity Around 80 members in the mailing list from different parts of the world
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Phenology Land Product Validation Workshop LPV Phenology Subgroup; Status What terminology we should use? Email was sent to the list server for input into the AGU poster Led on to the Semantics of Phenology Different scale, processes, sensors.. Leaf phenology, Vegetation/ canopy phenology, Lands surface phenology/ seasonality, Landscape phenology … Overall the agreement was on ‘Land surface phenology’ http://vip.arizona.edu/VIP_LSP_Semantics.php Land surface phenology refers to the type of products that seek to quantify and summarize the dynamics of the vegetated land surface at temporal scales from annual to seasonal. Products should clearly mention about the sensor/ method ……
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Phenology Land Product Validation Workshop LPV Phenology Subgroup; Status In the context of LPV validation Stage 1 Validation Product accuracy is assessed from a small (typically < 30) set of locations and time periods by comparison with in-situ or other suitable reference data. Product Vs Ground Stage 2 Validation significant set of locations and time periods by comparison with reference in situ or other suitable reference data. Spatial and temporal consistency of the product and with similar products has been evaluated over globally representative locations and time periods. Product vs Product vs (more) Ground Stage 3 Validation Uncertainties are characterized in a statistically robust ………. more(product) vs (more) ground Stage 4 Validation systematically updated ………
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Phenology Land Product Validation Workshop LPV Phenology Subgroup; Status Normal LPV activity Most often algorithm development groups collect field data Strength for us (phenology) Two groups ( ground data & Satellite data) Challenge for us (phenology) How to combine?
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Phenology Land Product Validation Workshop Agenda and Objectives Review of available data: Remote Sensing Phenology Products Camera & In situ Networks Ground/Citizen Measurements & Networks Core Site Selection based on data availability Panel led Discussion: Satellite and in situ data scaling issues, utility of citizen science for product assessment, address major questions and concerns… Define Pilot Projects: Review of Sites - Preparation and Distribution of Data Bundles Structure and Timeline of Projects Responsible Parties Workshop Review: Did we meet the workshop objectives? Publication of meeting results. Schedule an informal meeting at AGU 2012 for status update on Data Distribution and Pilot Projects?
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Remote Sensing data product Contribution from data providers/algorithm development team
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Data from many moderate resolution remote sensing sensor, mainly vegetation indices at a compositing period We broadly follow three steps to derive phenological matrices Data filtering Temporal smoothing (many methods) Derived matrices ( many method and many matrices) JÖNSSON and EKLUNDH, 2004
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MODIS NACP Phenology Products Retrieved Phenology Metrics 1.Beginning of season 2.End of season 3.Length of season 4.Base VI value 5.Peak time 6.Peak value 7.Amplitude 8.Left derivative 9.Right derivative 10.Integral over season - absolute 11.Integral over season - scaled 12.Maximum value 13.Minimum value 14.Mean value 15.RMSE of fitting
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MODIS NACP Phenology Products Availability and Status Availability: From http://accweb.nascom.nasa.gov/http://accweb.nascom.nasa.gov/ Products: phenology metrics derived from LAI/EVI/NDVI, and original, smooth/gap-filled LAI, FPAR, EVI & NDVI. Temporal Coverage: From 2001 to 2010. Spatial Coverage: Full North America, partially South America. Asia is under processing. Online data services: Subset by geographic area Subset by data layer Reproject Mosaic Aggregation Re-format (to GeoTIFF).
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MCD12Q2 C5 Product Global database –Annual since 2001, 500-m Includes 7 metrics –Onset of EVI increase –Onset of EVI maximum –Onset of EVI decrease –Onset of EVI mimimum –Min EVI –Max EVI –Sum of growing season EVI Validation: –Opportunistic, largely in New England –Current focus on PhenoCam Data Timing Annual Metrics Mark Friedl
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USGS EROS Vegetation Dynamics Availability: From http://phenology.cr.usgs.gov//http://phenology.cr.usgs.gov// Products: Nine annual remote sensing phenological indicators (served as raster data sets) are available at two spatial resolutions (1000 m2 and 250 m2) based on NDVI Temporal Coverage: AVHRR (1989-2011) MODIS (2001-2011) Spatial Coverage: conterminous U.S. Method : Delayed Moving Average (DMA) method (Reed et al., 1994). Considerable QA checking done on USGS phenological data Jesslyn Brown
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Phenological metrics available at multiple resolutions Jesslyn Brown
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Phenological metrics available at multiple resolutions Jesslyn Brown
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The “VGT4Africa” phenology product Algorithm developed by the Joint Research Centre (European Commission) Product generated by VITO (Belgium) Based on the processing of a moving time-window of 1.5 year of NDVI from the VEGETATION instrument Updated within 3 days after every 10-day period (“dekad”) Covers the whole African continent Provides dekad dates for “start of growth”, “max NDVI” and “half-senescence” Availability: from VITO through ftp and EUMETCast, jan 2007 until present Product description: Combal B. & Bartholomé E. 2006: Phenology. In: Bartholomé edit: VGT4Africa user manual 1st edition, European Commission ref EUR 22344 EN: 165-212 Method: Combal B. & Bartholomé E. 2010: Retrieving phenological stages from low resolution Earth observation data. In: Maselli & al.: Remote Sensing Optical Observations of Vegetation Properties, Research Signpost, Kerala, India, 115-129. Bartholomé
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Start dates as observed on 3rd dekad of Dec 2011 (note: actual time resolution of the product is the dekad, not the month)
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VIP Data Explorer:30 Years of Multi-Sensor VI and Phenology Data Availability: From vip.arizona.edu/viplab_data_explorer.php Products: Vegetation index and phenology from AVHRR, VEGETATION, MODIS (Sensor independent) Temporal Coverage: 30+ Spatial Coverage: Global Spatial resolution : 0.05 deg Considerable data quality assessment Kamel Didan
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PHAVEOS – the Phenology And Vegetation EO Service A service to provide: Vegetation maps of several biophysical variables relevant to models of bio-geochemical cycles Leaf Area Index (LAI) fraction of Absorbed Photosynthetically Active Radiation (fAPAR) MERIS Terrestrial Chlorophyll Index (MTCI) fraction of green land cover (fCover) Continuous time series to support phenology studies and monitoring Visualisation of individual maps and phenology curves for individual locations Thomas Lankester
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MERIS / MODIS Sentinel 3 Sentinel 2 (LDCM) Biophysical processing and mapping Data sources HiProGen and Overland Daily Level 3 and Level 4 data dissemination WebServer Web client on user PC
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Level 3 daily product examples fCover LAIfAPAR
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ftp://l3-server.infoterra.co.uk/pub/SNL/MTCI_L4_2009-2010_comparison.gif Spring 2009 – 2010 comparison
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Phenology Land Product Validation Workshop Core Site Selection Original Sites (2010 Dublin Workshop): Do we keep the original sites? Are more sites needed? What are the essential variables and is it necessary for every site to offer the same set of core variables/instruments? Site NameCountryCover TypeLatLonMETFLUXPheno Camera Radiometer PARPheno Observations Torgnon – TellinodItalyGrassland45.827.56XXXXX Torgnon – TronchaneyItalyLarch Forest45.827.56XXXXX Park FallsUSADeciduous Broadleaf45.95-90.27XXX HyytialaFinlandBoreal Conifer61.8524.29XXXXX HarvardUSAMixed Forest42.54-72.17XXXX BartlettUSAMixed Forest44.06-71.29XXX HowlandUSABoreal Hardwood Trans45.2-68.74XXX TakayamaJapanDeciduous Broadleaf36.15137.42XXXX TakayamaJapanEvergreen Coniferous36.14137.37XXXX BarraxSpainCropland39.05-2.09 Hubbard BrookUSADeciduous Hardwood43.93XXXX Vaira RanchUSAGrassland38.41-120.95XXXX …other suggestions? particularly Asian or Southern Hemisphere locations.
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Phenology Land Product Validation Workshop Panel Discussion Working across scales: Are site specific nested datasets (in-situ, phenocam, RS) and validation results applicable to validation of continental/global RS phenology products? Do PhenoCams need to be validated with in-situ observations? What standards need to be set for Phenology LPV: Are standardized definitions needed for metrics? – Start of Season, End of Season Are standardized methods needed to calculate metrics? – Curve fitting, Derivative peaks, etc. What do we mean by Phenology Validation? Is it setting a realistic offset/error range between phenocam or in-situ and RS metrics? Is this application specific? What are best practices for LPV using in-situ data?
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Phenology Land Product Validation Workshop Pilot Project Definition Core Sites Selection and Considerations: Do we agree upon the site selections? Is all data freely available? Creation of formal data sharing agreement. Data Collections/Bundles: RS products – size of subset over each site, 100km? Centralized Storage and Access Ground/In Situ Site Data – centralized storage? Project Objectives: Do we allow for a flexible structure and let researchers dictate site by site analysis OR do all projects follow a set protocol? Timeline – What is a realistic expectation? The LPV 5yr Plan states Validation Protocol established by 2013. Responsible Parties: Data Collections/Bundles – must be available by…? Who will conduct the research? PhD Students, Post-Docs, Staff Scientists.
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Phenology Land Product Validation Workshop Workshop Review Did we meet our objectives? Provide a synopisis of the majority available data sets. Review and discuss validation methods, current limitations and concerns. Selection of Core Sites. Agreement on data subsets, storage and access. Define Pilot Projects. Set a course for future Land Surface Phenology Validation For the future: Do responsible parties understand their tasks (providing data, analysis, etc.) Write up of a Meeting Summary Publication – EOS. Summary Poster for AGU – Jadu and Matt with input from committee. Informal Meeting at AGU 2012 to discuss progress.
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