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Full-Text Articles in Physical Sciences and Mathematics
Changing Fields: Agricultural Land Use Changes In Nebraska 1925-1974, Donald A. Wilhite
Changing Fields: Agricultural Land Use Changes In Nebraska 1925-1974, Donald A. Wilhite
Drought Mitigation Center: Faculty Publications
The series of graphs and maps which follow illustrate agricultural land use changes in Nebraska from 1925 to 1974. With these graphs and maps, the major agronomic crops of corn (dryland and irrigated), wheat, sorghum and soybeans are analyzed. The purpose of this analysis is to provide a pictorial history of Nebraska's ever-changing cropping system and, hopefully, to stimulate ideas and discussion with regard to trends and future directions. The Nebraska Water Resources Center is deeply interested in both the past and the future of Nebraska's agriculture because of the demands which agriculture places on the state's water resources. An …
Turbulence Spectra Above A Vegetated Surface Under Conditions Of Sensible Heat Advection, Raymond P. Motha, Shashi B. Verma, Norman J. Rosenberg
Turbulence Spectra Above A Vegetated Surface Under Conditions Of Sensible Heat Advection, Raymond P. Motha, Shashi B. Verma, Norman J. Rosenberg
Drought Mitigation Center: Faculty Publications
Spectra of vertical and horizontal velocity, air temperature and humidity fluctuations were analyzed from measurements made over a well-watered alfalfa crop under conditions of sensible heat advection. Vertical velocity and air temperature spectra as well as cospectra of momentum, sensible heat and water vapor were found to be dependent on atmospheric thermal stratification. These spectra and cospectra were shifted toward higher frequencies under advective as compared to lapse conditions. These results indicate that the predominant eddy sizes are relatively smaller under advective conditions. Humidity spectra, on the other hand, were independent of daytime thermal stratification conditions but were influenced by …