Search

Your search keyword '"Running, S. W"' showing total 144 results
Start Over Author "Running, S. W"
144 results on '"Running, S. W"'

2. Reconciling carbon-cycle concepts, terminology, and methods

Author

Chapin, F. S., Woodwell, G. M., Randerson, J. T., Rastetter, E. B., Lovett, G. M., Baldocchi, D. D., Clark, D. A., Harmon, M. E., Schimel, D. S., Valentini, R., Wirth, C., Aber, J. D., Cole, J. J., Goulden, M. L., Harden, J. W., Heimann, M., Howarth, R. W., Matson, P. A., McGuire, A. D., Melillo, J. M., Mooney, H. A., Neff, J. C., Houghton, R. A., Pace, M. L., Ryan, M. G., Running, S. W., Sala, O. E., Schlesinger, W. H., and Schulze, E.

Subjects
net ecosystem production, net ecosystem carbon balance, gross primary production, ecosystem respiration, autotrophic respiration, heterotrophic respiration, net ecosystem exchange, net biome production, net primary production
Abstract

Recent projections of climatic change have focused a great deal of scientific and public attention on patterns of carbon (C) cycling as well as its controls, particularly the factors that determine whether an ecosystem is a net source or sink of atmospheric carbon dioxide (CO2). Net ecosystem production (NEP), a central concept in C-cycling research, has been used by scientists to represent two different concepts. We propose that NEP be restricted to just one of its two original definitions-the imbalance between gross primary production (GPP) and ecosystem respiration (ER). We further propose that a new term-net ecosystem carbon balance (NECB)-be applied to the net rate of C accumulation in (or loss from [negative sign]) ecosystems. Net ecosystem carbon balance differs from NEP when C fluxes other than C fixation and respiration occur, or when inorganic C enters or leaves in dissolved form. These fluxes include the leaching loss or lateral transfer of C from the ecosystem; the emission of volatile organic C, methane, and carbon monoxide; and the release of soot and CO2 from fire. Carbon fluxes in addition to NEP are particularly important determinants of NECB over long time scales. However, even over short time scales, they are important in ecosystems such as streams, estuaries, wetlands, and cities. Recent technological advances have led to a diversity of approaches to the measurement of C fluxes at different temporal and spatial scales. These approaches frequently capture different components of NEP or NECB and can therefore be compared across scales only by carefully specifying the fluxes included in the measurements. By explicitly identifying the fluxes that comprise NECB and other components of the C cycle, such as net ecosystem exchange (NEE) and net biome production (NBP), we can provide a less ambiguous framework for understanding and communicating recent changes in the global C cycle.

Published
2006

4. Carbon and energy fluxes in cropland ecosystems : a model-data comparison

Author

Lokupitiya, E., Denning, A. S., Schaefer, K., Ricciuto, D., Anderson, R., Arain, M. A., Baker, I., Barr, A. G., Chen, G., Chen, J. M., Ciais, P., Cook, D. R., Dietze, M., Maayar, M. El, Fischer, M., Grant, R., Hollinger, D., Izaurralde, C., Jain, A., Kucharik, C., Li, Z., Liu, S., Li, L., Matamala, R., Peylin, P., Price, D., Running, S. W., Sahoo, A., Sprintsin, M., Suyker, A. E., Tian, H., Tonitto, C., Torn, M., Verbeeck, Hans, Verma, S. B., and Xue, Y.

Published
2016

5. Within-season crop monitoring at continental scale utilizing new gap-filled Landsat temporal series.

Author

Rajadel-Lambistos, C., Izquierdo-Verdiguier, E., Moreno-Martínez, A., Maneta, M. P., Begueria, S., Kimball, J. S., Clinton, N., Atzberger, C., Camps-Valls, G., and Running, S. W.

Abstract

Timely and accurate crop acreage information is essential for food security and the informed decision-making by governmental bodies and stakeholders in the agro-economic system. Surveys and fieldwork are expensive and time consuming, and the information is usually only released after the cropping season. Remote sensing technology is inexpensive, scales well for large areas, and offers the opportunity to gather within-season information. However, environmental and technical constraints complicate model applications to larger scales. For example, clouds and snow introduce data gaps, and the weather-driven crop development creates highly variable spectral-temporal signatures. This study determines the earliest possible month that permits the accurate classification of the major crops in the CONUS using gap-filled data, transfer learning, and cloud computing technology. The resulting within-season, annual crop classifications are generated with precision rates of up to 80%, presented as annual crop maps and county-level area statistics. The crop classification products presented in this work are unique, in that they were created with shorter records for the first time, using data within a concise time-range (i.e. a few months) and at a 30-meter spatial resolution, while covering continental scale. This novel prospect allows for potential new applications in forecasting regional crop productions. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

16. The Hydrosphere State (Hydros) Satellite Mission: An Earth System Pathfinder for Global Mapping of Soil Moisture and Land Freeze/Thaw

Author

Entekhabi, D, Njoku, E. G, Spencer, M, Kim, Y, Smith, J, McDonald, K. C, vanZyl, J, Houser, P, Dorion, T, Koster, R, O'Neill, P. E, Girard, R, Belair, S, Crow, W, Jackson, T. J, Kerr, Y. H, Kimball, J. S, Running, S. W, Pultz, T, Shi, J, and Wood, E

Subjects
Earth Resources And Remote Sensing
Abstract

The Hydrosphere State Mission (Hydros) is a pathfinder mission in the National Aeronautics and Space Administration (NASA) Earth System Science Pathfinder Program (ESSP). The objective of the mission is to provide exploratory global measurements of the earth's soil moisture at 10-km resolution with two- to three-days revisit and land-surface freeze/thaw conditions at 3-km resolution with one- to two-days revisit. The mission builds on the heritage of ground-based and airborne passive and active low-frequency microwave measurements that have demonstrated and validated the effectiveness of the measurements and associated algorithms for estimating the amount and phase (frozen or thawed) of surface soil moisture. The mission data will enable advances in weather and climate prediction and in mapping processes that link the water, energy, and carbon cycles. The Hydros instrument is a combined radar and radiometer system operating at 1.26 GHz (with VV, HH, and HV polarizations) and 1.41 GHz (with H, V, and U polarizations), respectively. The radar and the radiometer share the aperture of a 6-m antenna with a look-angle of 39 with respect to nadir. The lightweight deployable mesh antenna is rotated at 14.6 rpm to provide a constant look-angle scan across a swath width of 1000 km. The wide swath provides global coverage that meet the revisit requirements. The radiometer measurements allow retrieval of soil moisture in diverse (nonforested) landscapes with a resolution of 40 km. The radar measurements allow the retrieval of soil moisture at relatively high resolution (3 km). The mission includes combined radar/radiometer data products that will use the synergy of the two sensors to deliver enhanced-quality 10-km resolution soil moisture estimates. In this paper, the science requirements and their traceability to the instrument design are outlined. A review of the underlying measurement physics and key instrument performance parameters are also presented.

Published
2004
Full Text
View/download PDF

17. Using the Space-Borne NASA Scatterometer (NSCAT) to Determine The Frozen and Thawed Seasons of a Boreal Landscape

Author

Frolking, S, McDonald, K. C, Kimball, J. S, Way, J. B, Zimmermann, R, and Running, S. W

Subjects
Earth Resources And Remote Sensing
Abstract

We hypothesize that the strong sensitivity of radar backscatter to surface dielectric properties, and hence to the phase (solid or liquid) of any water near the surface, should make space-borne radar observations a powerful tool for large-scale spatial monitoring of the freeze/thaw state of the land surface, and thus ecosystem growing season length.

Published
1998

25. Global products of vegetation leaf area and fraction absorbed PAR from year one of MODIS data

Author

Myneni, R. B., Hoffman, S., Knyazikhin, Y., Privette, J. L., Glassy, J., Tian, Y., Wang, Y., Song, X., Zhang, Y., Smith, G. R., Lotsch, A., Friedl, M., Morisette, J. T., Votava, P., Nemani, R. R., Running, S. W., Myneni, R. B., Hoffman, S., Knyazikhin, Y., Privette, J. L., Glassy, J., Tian, Y., Wang, Y., Song, X., Zhang, Y., Smith, G. R., Lotsch, A., Friedl, M., Morisette, J. T., Votava, P., Nemani, R. R., and Running, S. W.

Abstract

An algorithm based on the physics of radiative transfer in vegetation canopies for the retrieval of vegetation green leaf area index (LAI) and fraction of absorbed photosynthetically active radiation (FPAR) from surface reflectances was developed and implemented for operational processing prior to the launch of the moderate resolution imaging spectroradiometer (MODIS) aboard the TERRA platform in December of 1999. The performance of the algorithm has been extensively tested in prototyping activities prior to operational production. Considerable attention was paid to characterizing the quality of the product and this information is available to the users as quality assessment (QA) accompanying the product. The MODIS LAI/FPAR product has been operationally produced from day one of science data processing from MODIS and is available free of charge to the users from the Earth Resources Observation System (EROS) Data Center Distributed Active Archive Center. Current and planned validation activities are aimed at evaluating the product at several field sites representative of the six structural biomes. Example results illustrating the physics and performance of the algorithm are presented together with initial QA and validation results. Potential users of the product are advised of the provisional nature of the product in view of changes to calibration, geolocation, cloud screening, atmospheric correction and ongoing validation activities.

Published
2002

26. Remote sensing of the leaf area index of temperate coniferous forests

Author

Spanner, M. A, Acevedo, W, Teuber, K. W, Running, S. W, Peterson, D. L, Card, D. H, and Mouat, D. A

Subjects
Earth Resources And Remote Sensing
Abstract

To estimate the one-sided leaf area index (LAI) of temperate coniferous forests using data acquired from the Daedalus Airborne Thematic Mapper, an empirical model is developed. The study area follows an environmental gradient across west-central Oregon, where leaf development varies in response to temperature and moisture. The relationship between the ratio of thematic-mapper simulator channels four and three and the leaf area index for selected closed canopy or fully stocked forest stands along the gradient is analyzed. Results show that a good relationship exists between the LAI and the IR/red ratio for conifers and that a conifer species-independent asymptotic relationship is observed between LAI and near IR/red reflectance, with near radiometric saturation occurring at an LAI of about 7-8.

Published
1984

Catalog

Books, media, physical & digital resources
See catalog results