Location: Crops Pathology and Genetics Research
2012 Annual Report
Significant progress has also been made on revisiting the theoretical calculations (i.e. Van Atta equations) that drive Surface Renewal estimates of water flux from agricultural surfaces. Until now, surface renewal relied on Eddy Co-Variance for calibration and our updated theoretical calculations have all but eliminated the need for this calibration. We recently published two invited manuscripts in a special issue of Boundary Layer Meteorology (Shapland et al. 2012a &2012b). Two additional manuscripts are nearing completion and will be submitted to the journals by October 2012.
Over the past few months, we made excellent progress in calibrating SR for the use of more sturdy (thicker gauge) thermocouples under field conditions. The fine gauge thermocouples, originally used in for SR, are highly responsive and work well for tracking the air temperature fluctuations at high frequency, however, they are fragile and required much maintenance. We successfully calibrated fine gauge thermocouples against heavier gauge (more sturdy) ones. The surface renewal sensible heat flux estimates from the heavier thermocouples (76 micron diameter wire) are strongly correlated with those of the 13 micron diameter (fine gauge) thermocouples. We established SR fields stations at two weighing lysimeter sites (Wheat in Davis and Thompson Seedless grapevines in Parlier) to compare results against the water loss estimates from the weighing lysimeters.