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Domec, Jean-Christophe

Publications and source records attributed to Domec, Jean-Christophe.

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

AmeriFlux FLUXNET-1F US-NC3 NC_Clearcut#3

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-NC3 NC_Clearcut#3. This is the FLUXNET version of the carbon flux data for the site US-NC3 NC_Clearcut#3 produced by applying the standard ONEFlux (1F) software. Site Description - The North Carolina Clearcut site #3 was set up to complement NC2, and continue in place of NC1. The previous rotation of loblolly pine was harvested in the spring of 2012, the site was prepared and replanted with 2-yr old seedlings in the winter of 2012/2013. Measurements were terminated in 2021 due to trees outgrowing the tower and infrastructure capability.

Noormets, Asko↗
DOE OSTI2023

Merging flux-variance with surface renewal methods in the roughness sublayer and the atmospheric surface layer

In this article, Two micrometeorological methods utilizing high-frequency sampled air temperature were tested against eddy covariance (EC) sensible heat flux (𝐻) measurements at three sites representing agricultural, agro-forestry, and forestry systems. The two methods cover conventional and newly proposed forms of the flux-variance (FV) and surface renewal (SR) schemes of differing complexities. The sites represent measurements in surface, roughness, and roughness to surface transitional layers. Regression analyzes against EC show that the most reliable FV and SR forms estimate 𝐻 with slopes within ±10% from unity and coefficient of determination 𝑅2 > 0.9 across all the three sites. The best performance of both FV and SR was found at the agricultural site with measurements well within the surface layer, while the worst was found for the tall forest with measurements within the roughness sublayer where its thickness needed to be additionally estimated. The main variable driving 𝐻 in FV is the temperature variance, whereas in SR, it is the geometry of ramp-like structures. Since these structures are also responsible for most of the temperature variance, a novel FV-SR approach emerging from combining the methods is proposed and evaluated against EC measurements and conventional FV and SR schemes. The proposed FV-SR approach requiring only a single fast response thermocouple is potentially independent of calibration and ameliorates some of the theoretical objections that arise when combining ramp statistics with similarity arguments. The combination of methods also provides new insights into the contribution of coherent structures to the temperature variance and its dependence on atmospheric stratification. Other potential utility of the new method is to include it in multi-tool assessments of surface energy fluxes, since a convergence or divergence of the results has a high diagnostic value.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Sucrose transport inside the phloem: Bridging hydrodynamics and geometric characteristics

In plants, the delivery of the products of photosynthesis is achieved through a hydraulic system labeled as phloem. This semi-permeable plant tissue consists of living cells that contract and expand in response to fluid pressure and flow velocity fluctuations. The Münch pressure flow theory, which is based on osmosis providing the necessary pressure gradient to drive the mass flow of carbohydrates, is currently the most accepted model for such sucrose transport. When this hypothesis is combined with the conservation of fluid mass and momentum as well as sucrose mass, many simplifications must be invoked to mathematically close the problem and to resolve the flow. Here this study revisits such osmotically driven flows by developing a new two-dimensional numerical model in cylindrical coordinates for an elastic membrane and a concentration-dependent viscosity. It is demonstrated that the interaction between the hydrodynamic and externally supplied geometrical characteristic of the phloem has a significant effect on the front speed of sucrose transport. These results offer a novel perspective about the evolutionary adaptation of plant hydraulic traits to optimize phloem soluble compounds transport efficiency.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

AmeriFlux FLUXNET-1F US-NC1 NC_Clearcut

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-NC1 NC_Clearcut. This is the FLUXNET version of the carbon flux data for the site US-NC1 NC_Clearcut produced by applying the standard ONEFlux (1F) software. Site Description - The North Carolina Clearcut site is located in a pine plantation amongst the mixed forests of the North Carolina lower coastal plain. Owned by the Weyerhaeuser Company, the plantation is managed for the purpose of commercial logging. In 2004, 70 ha of 75 year old native hardwoods was harvested. Following the clearcut, the stand was bedded and planted with loblolly pine seedlings. The only significant natural disturbances during the measurement period was a severe drought that lasted from summer of 2007 through 2008. Consequently, the 2007 total amount of precipitation was 486 mm below the 30-year norm.

Noormets, Asko↗
DOE OSTI2022

AmeriFlux FLUXNET-1F US-NC4 NC_AlligatorRiver

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-NC4 NC_AlligatorRiver. This is the FLUXNET version of the carbon flux data for the site US-NC4 NC_AlligatorRiver produced by applying the standard ONEFlux (1F) software. Site Description - The North Carolina Alligator River site was established to provide core measurements for understanding carbon cycling in natural coastal forested wetlands. It serves as a reference for NC1, NC2 and NC3, representing an ecosystem type that dominated the area prior to European settlement.

Noormets, Asko↗