[Back to Detailed Agenda]
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| Chairs: Simon Hook, Marc Imhoff
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Discussion Questions:
- What new space-based measurement capabilities should Terrestrial Ecology, Biodiversity, and Applied Sciences be pursuing and advocating? Are the ones on the legacy roadmap still valid?
- What types of mission studies (to assess alternative technological /scientific approaches to a measurement, to assess readiness and risk, and to estimate mission cost and complexity) and other types of preparation are needed?
- How do we set priorities for ourselves; what should we tell the Carbon Cycle and Ecosystems Management and Operations Working Group (CC&E MOWG), how should we plan to respond to the NRC's Decadal Survey?
- How do we engage the involvement and support of the much larger ecological, biogeochemistry, biodiversity, and applications communities?
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--- Please forward any additional comments to the relevant Program Manager at NASA Headquarters. ---
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In response to the comment by Jim Collatz: Jim makes an excellent point that both top down and bottom up approaches to ecosystem carbon budgets are desirable. CO2 profiles ALONE are "not optimal" to quote my original comment. However, they provide valuable information for closing budgets and validating models as Jim points out. In an ideal scientific world we would make all measurements at once. Today, in our far from ideal world, we may need to support a phased approach based on available budgets and mature technologies.
– submitted by Michael Keller at 2006-08-24 16:04:35 |
There is a need to have the canopy structure (lidar, radar, BRDF) measurements acquired simultaneously with the biochemistry (hyperspectral imager) to increase accuracy of data and value for modeling. I think including a thermal imager on the same platform would further increase accuracy of physiolgical measurements for estimating carbon and water fluxes.
– submitted by Susan Ustin at 2006-08-24 15:23:47 |
In the first bullet under recommendations for this breakout, under Vegetation 3-D Structure, the phrase "vegetation height profiles" is used. May I suggest we change this to "vegetation density as a function of height above the ground"? This is a little more precise, though we must also define what we mean by "density"! Note that lidar (e.g. Drake et al. 2002) and InSAR (e.g. Treuhaft et al. 2003) are beginning to suggest that moments of the density distribution—e.g. vegetation standard deviations, height of mean energy—may produce the most accurate biomass results, more accurate than height alone. (I understand that the original wording of this bullet was completely consistent with what I'm suggesting, but I prefer the more explicit wording).
– submitted by Robert Treuhaft at 2006-08-24 11:05:51 |
I disagree with statements that co2 lidar technology is not optimal for
understanding ecosystem function and that only detailed studies (bottom
up?) will yield such understanding. What happened to the paradigm of
top-down/bottom up reconciliation approaches? That philosophy is based on
the idea that detailed bottom up studies may work great on the little patch of earth on which they are centered but may not answer the questions that focus on terrestrial sources and sinks of carbon at regional to global scales. This problem of extrapolation applies at all scales of investigation. For instance, one could measure photosynthesis of a leaf and put a chamber over the soil and extrapolate those measured fluxes to the canopy. Why run expensive eddy flux towers? This is done because leaf and soil measurements are not directly scalable to local canopy fluxes. Eddy covariance measurements allow us to study the relationship between chamber measurements and whole canopy fluxes. Similarly local studies of ecosystem function may not be easily or accurately scaled to the region and the globe. If we don’t have good measurements at these larger scales to reconcile with local measurements how do we know the extrapolations are robust? Another example can be made of the WLEF regional study. The multiple local tower flux measurements do not explain the regional fluxes measured from the tall tower.
To argue that atmospheric measurements of co2 are in the purview of some other science program at NASA is to misunderstand the scientific value of these measurements. Climate modelers interested in co2 radiative forcing need only Mona Loa records. so why should they be interested in addressing the processes responsible for sources and sinks
for carbon from terrestrial surfaces except to predict the future? For that they are relying on ecosystem/biogeochemistry expertise to provide the understanding. Measurements of atmospheric co2 are not necessary to understand atmospheric circulation (but may be used to correct temperature profile measurements), most aspects of atmospheric chemistry and physics, and aerosols. Measurements of atmospheric co2 tell us about photosynthesis, respiration, fires/disturbance and, unrelated to ecosystems processes, fossil fuel burning and physical exchange with the oceans.
I agree that atmospheric co2 measurements using lasers is immature technology. I also agree that OCO should be useful though there are important holes not filled by passive approaches. I believe more accurate regional and seasonal measurements of CO2 in the lower troposphere will provide useful information about regional to global sources and sinks for carbon, regional productivity, and ecosystem health.
– submitted by George (Jim) Collatz at 2006-08-24 08:58:51 |
In the plenaries, the need for water stress information at the tower footprint scale (on the order of 100s of m) has been mentioned several times - to improve ET/carbon assimilation estimates under stressed conditions at scales that can be verified with tower flux data. While microwave-based soil moisture estimates are too coarse (10s of km), Landsat-scale thermal IR data provide valuable information about moisture stress at the sub-100m scale (the MODIS land surface temperature product, at 1km resolution, is significantly less optimal). We face a potential looming gap in our ability to collect global high-resolution thermal data - after Landsat 5 and ASTER there are no new missions on the horizon. While a 120m thermal imager is listed as an “optional capability” for the LDCM, its prospects for inclusion appear tenuous due to budgetary issues. Support for continuity of thermal data collection at <100m resolution should be a high priority for the ecosystem flux community…currently there is no mention in the Decadal Survey.
– submitted by Martha Anderson at 2006-08-23 16:17:27 |
Is there a gap in our recommendations wrt future polar-orbiting instruments for land (Physiology/Function category)? I can conceive of a wide-swath (daily global coverage), 100-200 m resolution, (explicit) multi-angle imaging spectrometer (progammable a la CHRIS/Proba: we don't need spectra over open ocean). I.e., do we have to have another across-track scanning instrument a la AVHRR/MODIS/VIIRS? What about a WFIS-type instrument (an Orbital Sci. instrument incubator instrument that seems to have disappeared). Or a POLDER-like approach?
– submitted by Mark Chopping at 2006-08-22 17:06:47 |
The Kimes et al. paper came out in February (Volume 100, Number 4, Predicting lidar measured forest vertical structure from multi-angle spectral data • Pages 503-511.
– submitted by Michael Keller at 2006-08-22 16:57:52 |
Multiangle is under-represented in these dicsussions. The USP is additional canopy measurements at high temporal resolution (monthly) at moderate spatial resolution (100m is optimal); fits between lidar/SAR and polar-orbiting solar wl instruments. See Kimes et al., RSE, January 2006.
– submitted by Mark Chopping at 2006-08-22 15:25:28 |
http://esto.nasa.gov/conferences/igarss03/papers/TU091340_Hildebrand.pdf#search=%22Earth%20observation%20requirements%20biomass%22
The above link is a paper summarizing envisioned needs for Global Earth Observation.
– submitted by Josef Kellndorfer at 2006-08-22 14:58:57 |
One mission being discussed based on the Decadal Survey is a carbon budget mission possibly using CO2 Lidar technology. While atmospheric carbon dioxide budgets are interesting for testing ecological models, they are not optimal for understanding ecosystems and terrestrial ecology research. Building understanding requires detailed knowledge of ecosystem structure and function.
– submitted by Michael Keller at 2006-08-22 14:45:29 |
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