1. Spatial Model-Data Comparison Project Conclusions Forward models are very different and do not agree on timing or spatial distribution of C sources/sinks. Examination of NEE shows GPP is largest component of discrepancies. Why?

2. Tower-Based Spectral Measures of LUE, GPP Provide Independent Data at Meter-Scale and Minute-Scale Resolution

3. Adding Spectral Measures of Vegetation Light Use Efficiency to Existing Towers and Tower Sites Gap-Filler for Tower Measurements Diagnostics For Process Models Scaling to Landscape, Region Globe??

4. Spectral Measures of Surface-Atmosphere Energy, Water, Carbon Exchange Latent heat LE =  C p [e*- e a ] g c g a  g c +g a Models compute g c g c = g c * x f( [e*- e a ],T a, soil moisture) 0≤f≤ 1 g c * = max g c f is a non-linear function of soil moisture Soil moisture is difficult to model Precipitation & soil properties variability Soil Moisture diffcult to measure in the presence of dense vegetation. Carbon Assimilation Rate Directly From Satellite A = par x fapar x LUE radiative xfer NDVI PRI g c = Ah/c

5. Xanthophyll Band 531 nm Reference Band 570 nm            PRI = As LUE decreases   and PRI decrease. Photochemical Reflectance Index A Normalized Difference Reflectance Index (NDRI) Gamon et al. 1992, 1993, 1997, Gamon & Surfus 1999 At the landscape scale       are also sensitive to variations in other pigments and conditions other than LUE; beta-carotene, lutein, variations in soil, litter background.

6. ab Figure 3: (a) A dual channel radiometer is mounted on the DF49 Fluxnet tower with a vertical zenith angle (VZA) of 62°. A motor moves the canopy sensor 360 o every 15 minutes. Data are recorded every 5 seconds, year round. (b) The instrument on the Fluxnet Canada Douglas fir research site Fluxnet Canada Doug Fir British Columbia

7. Measured Components For Douglas Fir

8. Slope of PRI vs LUE Doug Fir LUE ≈ (∂PRI/∂SF-0.21)/0.05

9. COMBINING MODEL, TOWER AND REMOTE SENSING MEASUREMENTS Remote sensing estimates of LUE, in combination with process model estimates and tower-based estimates form a powerful set of independent measures for cross-validation of these independent methodologies. Process models calculate –components of gross primary production, e.g. LUE, GPP –autotrophic and heterotrophic respiration, NEP Compare process model predictions to spectral and eddy covariance (EC) measures of same –compare model outputs of these quantities to the minute-scale tower and remote sensing-inferred values –Spectral measures can help gap-fill tower EC flux data –flag and help diagnose problems in any of the methods when the diurnal or longer-term values diverge. Aircraft and satellite landscape-scale measures (available only under clear-sky conditions) could be compared with similar estimates from process models –examine divergences over the landscape –flag and diagnose problems remote sensing algorithm variables used by the process models such as soil texture, soil moisture, nutrient levels etc. –data assimilation

11. What needs to be added to the existing Canadian, U.S., European and International network of flux towers?

12. Scaling to Landscape Aircraft Spectral Measurements - Missions of opportunity? NASA AVIRIS, the Canadian CASI, EO-1, NASA LVIS Lidar, other Canadian Lidar flights and the NASA airborne SLICER instrument (an aircraft Lidar flown during BOREAS), ASAS, multi-angle along-track hyperspectral flown during BOREAS Scaling to Region and Globe -- Not Global yet, but… Chris Proba, EO-1, MERIS MODIS Tower Spectral Measurement Instruments Costs of sensors range from 25K$ as in the AMSPEC from Hilker et al, to a full spectrum CCD at about 6-10K$ - (350-1500 nm), to a simple PRI sensor using a light sensor and interference filter for about 2K$ (which could be handmade).