Dew duration and amount on corn leaves as determined from measurements during SMEX05 and simulation using the ALEX model

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Kabela, Erik
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The Department of Agronomy seeks to teach the study of the farm-field, its crops, and its science and management. It originally consisted of three sub-departments to do this: Soils, Farm-Crops, and Agricultural Engineering (which became its own department in 1907). Today, the department teaches crop sciences and breeding, soil sciences, meteorology, agroecology, and biotechnology.

The Department of Agronomy was formed in 1902. From 1917 to 1935 it was known as the Department of Farm Crops and Soils.

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  • Department of Farm Crops and Soils (1917–1935)

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Dew plagues crop producers in many facets of agriculture. Many studies have been done on the effects of dew in terms of pest formation and diseases on crops. Although the formation of dew is significant on a micro-scale, satellite projects such as SMOS aim to measure soil moisture on a meso or synoptic scale. The presence of dew has been found to decrease soil brightness temperature, which in turn effects soil moisture readings. The purpose of the dew collection portion of SMEX05 was to manually measure dew so that the effect could be studied on measurements made by remotely sensed soil moisture readings. The use of physical models for atmoshphere-land interactions can provide a great benefit to remote satellite measurements of soil moisture. Although physical measurements of dew are important to satellite remote sensing, spatial coverage of manual measurements are at a minimum. Due to this, atmosphere-land models will need to be used to estimate amounts of dew. Also, by using models, manual measurements of dew can be validated. The purpose of this paper is to determine if manual dew measurements obtained during the Soil Moisture Experiment in 2005 (SMEX05) are accurately modeled by the atmosphere-land exchange model, ALEX. Dew measurements were taken during SMEX05 from June 16 to July 3, 2005 in corn, soybean, and alfalfa fields south of Ames, Iowa. Collection usually began at approximately 6:45 CDT and commenced at approximately 9:00 CDT each morning. My hypothesis for this paper is that dew amount and duration collected from SMEX05 are predicted accurately by the atmosphere-land exchange (ALEX) model. Accuracy for dew amount is defined as an amount within 0.05 to 0.1 mm of manual measurements. Accuracy for dew duration is defined as 0.5 hours within automated observations from leaf wetness sensors deployed in various fields within the Walnut Creek Watershed. I found that dew amount is accurate for light, moderate, and heavy dew events, while dew duration is predicted within 0.5 to 1 hours.

Sun Jan 01 00:00:00 UTC 2006