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
 Hydrology and Remote Sensing Laboratory: Beltsville, MD
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Northeast Area Beltsville, Maryland (BARC) Beltsville Agricultural Research Center Hydrology and Remote Sensing Laboratory 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
- People
- Research Sites
- Pesticide Volatilization
- Watershed Modeling
- Climate Change
- Soil Moisture
- Drought and ET
- HRSL Brochure

Title:   Author  item
                                            Alfieri, Josephitem
                                            Kustas, William

                                                         - *Bill*item
                                            Prueger, Johnitem
                                            HIPPS, L.E. - Utah State University
  Submitted to: Meeting Abstract
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 5/5/2016
                                    Publication  Date: N/A
                                    Citation: N/AInterpretive Summary:
                                Technical Abstract: Due to their highly-structured canopy, turbulent characteristics within and above vineyards, may not conform to those typically exhibited by other agricultural and natural ecosystems. Using data collected as a part of the Grape Remote sensing and Atmospheric Profiling and Evapotranspiration Experiment (GRAPEX), an ongoing multi-institution field project conducted in the Central Valley of California, this study evaluated the spectral characteristics of 12 one-hour periods spanning the 2014 growing season to investigate vertical variations in the turbulent structure over vineyards. Focusing on unstable daytime conditions when the surface boundary layer was well developed, the study compared the turbulent structure at three above-canopy heights: 2.5 m, 3.75 m, and 8 m, agl using both traditional and wavelet-based spectral analysis. Fourier-based spectral analysis of the wind velocity components indicates a strong tendency for the spectral peak to broaden and shift toward lower frequencies as the measurement height increases. Also, beginning with the highest-frequency eddies, the turbulent structure at differing heights become increasingly decoupled as the separation distance between the measurements increases indicating the eddies contributing to the measurements at one height act independently of similarly sized eddies measured at another height. As a result, the overall correlation between the turbulent flows measured at differing heights decreases exponential with increasing separation distance. Additionally, wavelet analyses showed the intensity of the turbulent mixing fluctuated significantly over each of the hourly measurement periods with intermittent periods of strong turbulent activity interspersed between intervals of relative calm. While these effects were evident for all of the hourly periods considered, the magnitude of the effects appears to vary in response to the direction of the wind relative to the orientation of the vineyard rows.


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