| NSF Org: |
EF Emerging Frontiers |
| Recipient: |
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| Initial Amendment Date: | February 14, 2013 |
| Latest Amendment Date: | February 14, 2013 |
| Award Number: | 1241531 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Timothy Kratz
EF Emerging Frontiers BIO Directorate for Biological Sciences |
| Start Date: | February 15, 2013 |
| End Date: | January 31, 2016 (Estimated) |
| Total Intended Award Amount: | $255,181.00 |
| Total Awarded Amount to Date: | $255,181.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3227 CHEADLE HALL SANTA BARBARA CA US 93106-0001 (805)893-4188 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1832 Ellison Hall Santa Barbara CA US 93106-4060 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | MacroSysBIO & NEON-Enabled Sci |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.074 |
ABSTRACT
Temperature exerts a primary environmental control on biological systems and processes at a range of scales in space and time. Its influence is fundamental, ranging from controls on the reaction rates of enzymes, ecosystem biogeochemical reactions, and large-scale distributions of plant and animal species. Temperature is also a fundamental characteristic of climate. Indeed, much of the concern about the impact of climate warming is motivated by the pervasive influence of temperature on organisms. Although most focus is usually on air temperature, the skin temperature of an organism, such as a plant, is actually more relevant in many cases. However, until now measurements of organismal temperature using thermal images taken from some distance away have been challenging because of sensor and computational limitations. This research project addresses this gap in understanding through three goals: (1) to assess the use of thermal imaging measurements for ecological and agricultural studies, such as monitoring the response of plant canopies to heat and drought stress; (2) to demonstrate the continuous deployment of robust thermal cameras for continuous canopy imaging for a range of ecosystems; and (3) to develop scaling algorithms to relate sparse measurements at individual canopy sites to the patterns observed at regional scales by sensors on aircraft and satellites. The work will combine temperature observations at a range of spatial resolutions with synthesis activities in an innovative manner. The results will enhance our understanding of how ecosystem structure and function are related to skin temperature patterns.
This project will introduce new technology and infrastructure for long-term thermal data collection that could have a large impact on our understanding of ecological functioning across multiple scales. It will combine the diverse interdisciplinary expertise of researchers at different stages in their careers in fields including plant physiology, remote sensing, biogeography, and statistics. Results will directly inform questions concerning the link between leaf temperatures and carbon assimilation by ecosystems and the response of natural and agricultural ecosystems to drought stress. It will address scaling of properties and processes related to temperature, as is required for predicting responses to climate change. Particular focus will be on the responses of ecosystems to drought and heat waves. More tangible outcomes will be advances in understanding of plant-temperature interactions in natural and managed ecosystems, as well as the establishment of canopy thermal imaging equipment at three long-term monitoring sites. Finally, this project will integrate research and teaching through the training of post-doctoral researchers, mentoring of undergraduate students, and development of laboratory modules based on the concepts and data generated by this project for undergraduate and graduate courses in geography, earth science, ecology, and environmental science.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Temperature is a primary environmental control on physiological and environmental processes at a range of temporal and spatial scales, influencing rates of photosynthesis and respiration and modifying rates of evaporation, transpiration and heat exchange between the surface and lower atmosphere as some examples. While air temperature is often used as a measure of environmental temperature, surface temperature may be more appropriate in many cases.
Remote sensing has played a critical role in providing measures of surface temperature, and a number of standard land surface temperature (LST) products exist. However, the retrieved temperature of an object depends on the efficiency at which it emits radiation (called emissivity) and the proportion of measured radiation emitted, vs reflected from the object. Remote sensing products attempt to correct for these effects by making various assumptions about a surface. For example, in the case of a perfect emitter (blackbody), LST can be directly retrieved from emitted radiance from a surface and the only additional corrections required are to account for atmospheric effects between the sensor and surface. However, very few objects are blackbodies, and thus actual LST retrievals require knowledge of surface emissivity as well as downwelling atmospheric emission.
In this project, we focused on quantifying the impact of errors in emissivity estimation on retrieved surface temperatures at multiple scales. We also focused on improved understanding of thermal measurements through the development of software and field and laboratory activities targeted at undergraduates. We worked with data collected using a handheld imaging thermal sensor developed by FLIR as well as aircraft and satellite data. Tangible research outcomes included a demonstration of the importance of changes in surface emissivity on temperature retrievals due to changes in fractional cover. For example, at field scales we demonstrated that temperature estimates were highly dependent on the proportion of senesced material in the field of view. Assuming all surfaces behaved as black bodies generated an underestimate of temperature that increased linearly with increased senescence, reaching 2 C in a grassland ecosystem. Use of a FLIR default emissivity of 0.95 was more nuanced, leading to an overestimate when green leaves dominated the scene and an underestimate for senesced surfaces.
Similar patterns were observed at coarser scales. For example, when comparing fine scale estimates of LST from aircraft, to coarser resolution data from MODIS, aircraft and MODIS observations were similar at high green cover, but MODIS estimates showed increasingly larger errors as green cover declined. This is highly significant, in that MODIS LST has become a core data set used to observe plant stress, or mortality due to drought, yet the temperature observed will be adversely impacted by changes in surface cover in response to stress. We also developed an improved method for retrieving LST based on estimates of fractional cover from an airborne imaging spectrometer, demonstrating that differences between the modeled and measured temperatures were consistent with surface cooling due to shadows, and canopy warming due to stress.
Last Modified: 06/03/2016
Modified by: Dar A Roberts
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