qa4ecv wp4: an ecv algorithm for fapar & lai · qa4ecv mid-term review meeting, mssl, 14-16...

QA4ECV Mid-Term Review Meeting, MSSL, 14-16 June 2016

QA4ECV WP4: an ECV algorithm forfAPAR & LAI

Simon Blessing, Ralf Giering


D4.3 ATBD for FAPAR & LAI from albedo

- internally reviewed

- delivered via EUMETSAT

- description of data flow through TIP5D-LUTs

- description of error propagation and budget

- guidance on suitable usage of FAPAR and LAI


Progress on ATBD for FAPAR & LAI from albedo


The Two-Stream inversion package

Optimisation:- find 2-stream parameters matching BHRVIS and BHRNIR

Error Propagation:- use 2nd derivative at optimum to determine posterior covariances

TIP-Tables:process is tabulated over observation space for performance

From Covariances:uncertainties onLAI and fAPAR

At Optimum:- optimal LAI- simulated VIS- absorption in canopy is fAPAR


TIP 5D Table Construction96 TIP look-up-tables for 5D generated for

● NIR, VIS uncertainty levels 0%-5%, 5%-7%, 7%-10%,>10%, respectively,● NIR/VIS correlation levels <-0.5, -0.5% – 0.5%, >0.5%,● snow and no snow prior conditions.

● Tables resolve albedo differences of 10-3.● TIP inversions are trusted for typically observed albedos.● Flag table extended to hold necessary 5D information.● Tables contain posterior uncertainty of each inversion.

Final cost function for no snow (left) and snow (right) using 5 % albedo uncertainty


Performance of Re-Processing with GA-BHRs

● In preparation for the “real” data, simple5D was applied to GA-BHRs● FAPAR/LAI from GlobAlbedo BHRs processed for 1998-2011,

8-daily, global, 1km resolution● Processing on CEMS' LOTUS cluster took two working days,

including rescheduling of interrupted jobs

histogram of job durations in cpu

seconds

histogram of job durations in cpu

seconds

x: max. memoryy: cpu seconds

x: max. memoryy: cpu seconds

x: max. swapy: cpu seconds

x: max. swapy: cpu seconds


FAPAR/LAI from GlobAlbedo BHRs processed for 1998-2011, 8daily, global, 1km resolution

global snapshot:



fapar/LAI from GlobAlbedo BHRs processed for 1998-2011, 8daily, global, 1km resolution

From: Pinty B., N. Gobron: Land Surface Albedo Dynamics, in State of the Climate 2014, Special Supplement to BAMS Vol. 96, 2015



ΔFAPAR ΔσFAPAR

● comparsion at site-level to 2D-processing re-run for all GA-verification sites



How do TIP-5D and TIP-2D results differ for a tile, e.g. h18v03?

=> Small increase in value, reduced uncertainty.

FAPARFAPAR σFAPAR

σFAPAR



● comparsion at site-level

ΔFAPAR

ΔσFAPAR



input BHRs

input BHRs

resulting FAPAR

resulting FAPAR


Summary

● ATBD D4.3 for fapar and LAI delivered

● TIP-5D LUT generated

● GlobalAlbedo 1998-2011 reprocessed with TIP-5D

● processing of daily,1km VIS+NIR BHR (1998-2015)expected to take ~10days on CEMS

● new fapar and LAI have a slightly reduced uncertainty

qa4ecv wp4: an ecv algorithm for fapar & lai · qa4ecv mid-term review meeting, mssl, 14-16...

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