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Models for estimation of hourly soil temperature at 5 cm depth and for degree-day accumulation from minimum and maximum soil temperature


Horton, B, Models for estimation of hourly soil temperature at 5 cm depth and for degree-day accumulation from minimum and maximum soil temperature, Soil Research, 50, (6) pp. 447-454. ISSN 1838-675X (2012) [Refereed Article]

Copyright Statement

Copyright 2012 CSIRO

DOI: doi:10.1071/SR12165


A model has been developed for the daily variation in soil temperature at 5 cm depth, for use where both the minimum and maximum temperatures are known or can be estimated. The model is based on data from three Australian sites with minute-by-minute data over 3–7 years. The model uses two sine curves; one for the increase from minimum to maximum and another for the relatively rapid decrease in temperature immediately after the maximum. An exponential decay function is used for the slower decrease in temperature until the minimum is reached.

The time of the minimum soil temperature is primarily determined by the time of sunrise and therefore varies depending on the day of the year, whereas the time of the maximum temperature is influenced primarily by the time of the middle of the day (midpoint between sunrise and sunset). The time of the transition point between the maximum and the next minimum is related to the time of sunset. Therefore, the model uses latitude, longitude, and the day of the year to determine the time of sunrise and sunset to adjust the shape of the temperature profile throughout the day.

The model has been validated using 3-hourly soil temperature data for 35 other sites in Australia, with a correlation of 0.993 between actual 3-hourly temperatures and those predicted. Its use for degree-day calculations has been validated using hourly data from a site in Victoria, where the model’s estimates of degree-days differ <0.7% from the value based on individual hourly temperatures, whereas methods that assume a symmetrical change from maximum to minimum temperature overestimate degree-days by 6–7%.

Item Details

Item Type:Refereed Article
Keywords:daily temperature profile, air temperature
Research Division:Environmental Sciences
Research Group:Soil sciences
Research Field:Soil physics
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Soils
UTAS Author:Horton, B (Dr Brian Horton)
ID Code:75573
Year Published:2012
Web of Science® Times Cited:9
Deposited By:Agricultural Science
Deposited On:2012-02-05
Last Modified:2013-05-13

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