title: Modeling apple surface temperature dynamics based on weather data.
abstract: The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST) dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed) was recorded for seven hours between 11:00-18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of "Fuji" apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management.
authors.affiliation: School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China. hudiepianpianlilei@hotmail.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Center for Precision & Automated Agricultural Systems, Washington State University, 24106 North Bunn Rd., Prosser, WA 99350, USA. troy_peters@wsu.edu.
authors.forename: Troy
authors.initials: T
authors.lastname: Peters
authors.affiliation: Center for Precision & Automated Agricultural Systems, Washington State University, 24106 North Bunn Rd., Prosser, WA 99350, USA. qinzhang@wsu.edu.
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Center for Precision & Automated Agricultural Systems, Washington State University, 24106 North Bunn Rd., Prosser, WA 99350, USA. jj.zhang@wsu.edu.
authors.forename: Jingjin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China. danfenggrace@gmail.com.
authors.forename: Danfeng
authors.initials: D
authors.lastname: Huang
mesh_terms: D003198:Computer Simulation; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods*; D005638:Fruit / Q000502:physiology*; D006813:Humidity; D027845:Malus / Q000502:physiology*; D008954:Models, Biological; D012621:Seasons; D013696:Temperature; D013817:Thermography / Q000379:methods*; D014887:Weather