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
 Crops Pathology and Genetics Research: Davis, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Outreach Events
                        UC Davis Picnic Day
                                    Kinders go to College
                                    STEM Girls
                                    Future Scientist Program
                                    Agriculture Future of America
                                    Wallace-Carver Fellowship
                                    Young Scholars Program
                                    Annual Awards Banquet
                    About Us
                        About Us
                                    Our Mission
                                    Principal InvestigatorsSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Davis, California Crops Pathology and Genetics Research 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
- Etiology and Biology of Tree Crop Diseases
- Rice Genetics
- Sustainable Floriculture
- Sustainable Viticulture

Title:   Author  item
                                            SHAPLAND, THOMAS - University Of Californiaitem
                                            McElrone, Andrewitem
                                            SNYDER, RICHARD - University Of Californiaitem
                                            PAW U, K.T. - University Of California
  Submitted to: Boundary Layer Meteorology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 8/25/2011
                                    Publication  Date: 6/27/2012
                                    Citation: Shapland, T.M., Mcelrone, A.J., Snyder, R.L., Paw U, K. 2012. Structure function analysis of two-scale Scalar Ramps. Part I: Theory and Modeling. Boundary Layer Meteorology. DOI: 10.1007/s10546-012-9742-5.Interpretive Summary: In these paired studies, we describe the theoretical basis (part 1) and practical application (part 2) of a new mathematical method to determine heat and water exchange from crop surfaces obtained from surface renewal (SR) energy balance measurements. The SR technique uses measurements of sensible (i.e. the temperature rise when an air parcel is heated) and soil heat fluxes and net irradiance at the ground or crop canopy surface to estimate latent energy exchange (i.e. heat flux from the Earth’s surface to the atmosphere associated with evaporation or transpiration of water from a crop surface). To date SR has been unable to serve as a stand-alone technique capable of describing energy exchange process above agricultural surfaces (i.e. crop fields, vineyards, orchards).  The new method described here works well over bare ground and short canopies under unstable conditions, and should form the foundation for analysis over taller and more complex surfaces.  The advances reported here should enable SR to become a widely used and relatively inexpensive technique for better quantifying water flux and irrigation needs for crop land across the region.
                                Technical Abstract: Structure functions are used to study the dissipation and inertial range scales of turbulent energy, to parameterize remote turbulence measurements, and to characterize ramp features in the turbulent field. The ramp features are associated with turbulent coherent structures, which dominate energy and mass fluxes in the atmospheric surface layer. The analysis of structure functions for indentifying the ramp characteristics is used in surface renewal methods. It is unclear how different scales of coherent structures (i.e., smaller ramps embedded in larger ramps) that are commonly observed in data influence structure function analysis. In this paper, we examine the effects of multiple ramp scales on structure functions and their analysis by using both artificially generated multi-scale ramp series and high frequency temperature observations from above bare ground and two types of short plant canopies. We used structure function lags ranging in scale from isotropic to larger than the characteristic turbulent coherent structures and special analysis of structure functions to detect different scales of coherent structures. The frequencies of the coherent structure scales increase with mean wind shear, but the size of the scales relative to one another is fairly constant. The new objective method reported here for obtaining surface renewal-based scalar exchange works well over bare ground and short canopies under unstable conditions, and should form the foundation for analysis over taller and more complex surfaces.


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