NASA Global Ecosystem Dynamics Investigation …cci.esa.int/sites/default/files/D1_S1_T5_Armston.pdfGlobal Ecosystem Dynamics Investigation High Resolution Laser Ranging of the Earth’s

NASA Global Ecosystem Dynamics Investigation (GEDI)

Update and Potential Collaboration

GEDI Science Definition Team

1st CCI Biomass User Workshop – September 25-26, 2018 – Paris

Presentation Outline

• Science Goals, Questions and Objectives• Current Mission Status• L1 Science Requirements• Science Approach and Data Products• Biomass Cal/Val Activities• Summary


Global Ecosystem Dynamics Investigation

High Resolution Laser Ranging of the Earth’s Forests and

Topography


Science Questions and Objectives

Carbon Cycle Biodiversity

GEDI Goal: Advance our ability to characterize the effects of changing climate and land use on ecosystem

structure and dynamics


Current Mission Status

• Currently in Phase D• TVAC completed Sunday• Oct TBD – KDP-D/E• Oct 13th – Ship Date• Nov 27th – LRD


GEDI Lidar Measurements

GEDI’s sole observable is the lidar waveform which provides ground

elevation, canopy height, cover and various profiles and metrics.

GEDI makes up to 10 billion observations of forest and

land surface structure over its nominal two-year mission

Amplitude

RH

75

RH

50

RH25

Normalized Cumulative Return Energy

110

120

130

140

150

1600.25 0.5 0.75 1.00

0 50 100 150 200

WGS

84 e

leva

tion

(m)

Elevation of center of lowest mode

Highest reflecting surfaceelevation

Lowest reflecting surfaceelevation

25 m


• Acquire lidar canopy vertical profile data required to estimate aboveground woody carbon density for the Earth’s global tropical and temperate forests within the ISS orbital coverage at ≤ 1 km resolution. At the end of two years after on-orbit checkout, at least 80% of the 1 km cells will meet an accuracy within 20% standard error, or 20 Mg/ha whichever is greater, subject to instrument availability.

• Acquire transects (that is, near contiguous, along-track laser footprint observations) of tropical & temperate forest canopy vertical profiles from the top of canopy to the ground. Instrument performance must be sufficient to acquire profiles in conditions of up to about 95% canopy cover for all beams. Additionally, at least one laser beam must have sufficient power to acquire profiles in conditions of up to 98% canopy cover.

• Record, validate, publish, and deliver science data records (L0-L1B) and validated data products and model outputs (L2-L4) to the DAACs designated by NASA for use by the scientific community.

8

Baseline Requirements

80% of 1 km cells meet a biomass accuracy of 20% SE or 20 Mg/ha

Acquire transects of canopy profiles in conditions of up to 95%/98% cover


• Previously: 1 power and 2 coverage lasers ® 3 lasers, 5 beams, 10 tracks• Now: 2 power and 1 coverage laser ® 3 lasers, 4 beams, 8 tracks

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Science Changes – New Mission Configuration

5.4 km

There is no impact to Level 1 Science Requirements


• GEDI measurement is the waveform (Level 1B)- Waveform is used to derive height and profile metrics using established algorithms (Level

2 & Level 3)

• GEDI produces biomass (Level 4) empirically at footprint and gridded level - Other L4 products produced only for selected areas as demonstrations

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Science Approach and Data Products


GEDI Science Data Products

Product/ Data File Description Source

First Data Delivery After

IOC

DataLatency

ArchiveSite

GEDI00_B Level 0B Instrument Products (Sci, GPS, ST) MOC Within 24 hours of receipt

at GSFC Within 24 hours of receipt at GSFC LPDAAC

GEDI01_A Level 1A Waveform Fitted Parameters SOC First 2 months of L1

released at 6 months4 months in monthly intervals LPDAAC

GEDI01_B Level 1B Geolocated Waveforms SOC First 2 months of L1


GEDI02_ALevel 2A Footprint Elevation and Height Metrics

SOC First 2 months of L2 released at 6 months

4 months in monthly intervals LPDAAC

GEDI02_B Level 2B Footprint Cover and Profile Metrics SOC First 2 months of L2


GEDI03 Level 3A Gridded Land Surface Metrics SOC

Populated with first 2 months of L2 data at 6 months

4 months in monthly intervals ORNLDAAC

GEDI04_A Level 4A Footprint Aboveground Biomass SOC First 12 months of L3 data

at 17 months

6 months after global sampling required to meet L1 requirement

ORNLDAAC

GEDI04_B Level 4B Gridded Aboveground Biomass SOC First 12 months of L3 data

at 17 months

6 months after global sampling required to meet L1 requirement

ORNLDAAC


• GEDI relies on crowd-sourced field and airborne lidar data• Pre-launch calibration allows us to exploit a vast array of past and present

field studies

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Pre-Launch Calibration for Biomass

GEDI Forest StructureData Base

GEDI PerformanceTool


• GEDI relies on crowd-sourced field and airborne lidar data• Pre-launch calibration allows us to exploit a vast array of past and present

field studies

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Pre-Launch Calibration for Biomass

GEDI Forest StructureData Base

GEDI PerformanceTool

CoverageStrong


• Complex effort spanning many different organizations • Common framework required to standardize existing field and airborne lidar

data• Every plot has associated small footprint lidar data as well as field data

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GEDI Forest Structure Database (July 2018)

Number of plots Number of simulated GEDI footprints (0.0625 ha)

1,448,033 trees in 4,823 plots (native resolution) from 95 projects


• Candidate models selected - ATBD designed with flexibility to easily modify/change models

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GEDI Footprint Biomass Models

Footprint-level biomass models are built from existing coincident ALS/field data

Systematic comparison of model performance based on cross-validation and geographic transferability

Stratification of modelsPlant Functional Type (PFT)Continental Region

OLS Regression

RMSE = 55.8%Stratified by PFT and Region


• CEOS Land Product Validation Biomass Focus Area- GEDI team co-leading validation protocol development- >50 international biomass experts writing document for well vetted product

validation- GEDI team will follow CEOS protocol for post-launch biomass product validation

• Multi-Mission Analysis Platform- NASA/ESA activity for increased data sharing, open code and algorithm

development on upcoming missions (NISAR, BIOMASS, GEDI)- NASA MAP will ingest GEDI field and lidar data to bolster consistent cal/val

activities

• Multi-Mission Biomass Cal/Val Subgroup- Members of GEDI, ICESat-2, NISAR and ESA’s BIOMASS have monthly meetings to

discuss cal/val- Ensure consistent cal/val approaches (following CEOS)- Coordinate new field and airborne collections

GEDI Cal/Val Partnerships and Collaboration


• GEDI is scheduled for launch on November 27, 2018• Data products are clearly defined and based on mature algorithms

- GEDI L4 biomass gridding (Sean Healey) is next!

• Pre- and post-launch calibration and validation approaches are in place and final details being formalized

• GEDI continues to leverage activities across other NASA missions and programs, as well as international activities to both provide additional cal/val margins and to extend data products

• The GEDI team are working closely with CEOS groups, the NASA-ESA Multi-Mission Analysis Platform, and other missions teams on data sharing and coordinated cal/val- Laura Duncanson, 8:45AM Wednesday- New opportunities with CCI+ Biomass

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Summary


NASA Global Ecosystem Dynamics Investigation …cci.esa.int/sites/default/files/D1_S1_T5_Armston.pdfGlobal Ecosystem Dynamics Investigation High Resolution Laser Ranging of the Earth’s

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