U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Kustas, William

                                                         - *Bill*item
                                            Anderson, Marthaitem
                                            NORMAN, JOHN - UNIVERSITY OF WISCONSINitem
                                            Li, Fuqin
  Submitted to: Boundary Layer Meteorology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 8/8/2006
                                    Publication  Date: 10/16/2006
                                    Citation: Kustas, W.P., Anderson, M.C., Norman, J.M., Li, F. 2006. Utility of radiometric-aerodynamic temperature relations for heat flux estimation. Boundary Layer Meteorology. DOI 10.1007/s10546-006-9093.Interpretive Summary: In many models using remotely sensed land surface temperature observations for estimating soil and vegetation water and energy exchanges, results have not have been generally satisfactory.  This is due in part to the non-unique relationship between the so-called aerodynamic temperature, which in model formulations represents the efficiency of heat exchange between the land surface and overlying atmosphere, and a surface temperature measurement from a thermal-infrared radiometer, which largely corresponds to a weighted soil and canopy temperature as a function of radiometer sensor viewing angle.  Recent efforts with experimental data have empirically related radiometric-aerodynamic temperature differences to solar radiation and leaf area or the amount of canopy cover.  In this study, simulations by a detailed soil-plant-environment model, Cupid, which considers both radiative and turbulent exchanges across the soil-canopy-air interface, are used to explore the radiometric-aerodynamic temperature relations for a semi-arid shrubland ecosystem under a range of leaf area/canopy cover, soil moisture and meteorological conditions.  The results indicate that while solar radiation and leaf area both strongly affect the magnitude of the radiometric-aerodynamic temperature differences, the linear relationships are non unique.  These simulations show that soil-canopy temperature differences are highly correlated with variations in the radiometric-aerodynamic temperature differences, with the slope being primarily a function of leaf area.  The results suggest developing models that can reliably estimate component soil and canopy temperatures and associated resistances are better able to define the radiometric-aerodynamic relation for a range in vegetated canopy cover conditions than are simple, empirically-based schemes.
                                Technical Abstract: In many land surface models using bulk transfer (one-source) approaches, the application of radiometric surface temperature observations in energy flux computations has given mixed results.  This is due in part to the non-unique relationship between the so-called aerodynamic temperature, which relates to the efficiency of heat exchange between the land surface and overlying atmosphere, and a surface temperature measurement from a thermal-infrared radiometer, which largely corresponds to a weighted soil and canopy temperature as a function of radiometer viewing angle.  Recent efforts with experimental data have empirically related radiometric-aerodynamic temperature differences to solar radiation and leaf area or canopy cover.  In this study, simulations by a detailed soil-plant-environment model, Cupid, which considers both radiative and turbulent exchanges across the soil-canopy-air interface, are used to explore the radiometric-aerodynamic temperature relations for a semi-arid shrubland ecosystem under a range of leaf area/canopy cover, soil moisture and meteorological conditions.  The results indicate that while solar radiation and leaf area both strongly affect the magnitude of the radiometric-aerodynamic temperature differences, the linear relationships are non unique, with slopes varying by two orders of magnitude depending on local conditions.  These simulations show that soil-canopy temperature differences are highly correlated with variations in the radiometric-aerodynamic temperature differences, with the slope being primarily a function of leaf area.  The results suggest that two-source schemes that can reliably estimate component soil and canopy temperatures and associated resistances are better able to define the radiometric-aerodynamic relation for a range in vegetated canopy cover conditions than are simple, empirically-based one-source schemes.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov