Numerical Approach for Air Temperature, Soil Temperature and the Difference between Them with Julian Date under Napa Cabbage

Abstract

The main objective of this study was to develop the estimation models for air temperature (Ta), soil temperature (Ts) at 15 cm depth and the difference (dT = Ta -Ts) in Sandy Loam under Napa Cabbage cultivation. The verification process was based on the error analysis criteria. Results indicated a positive correlation between Ta and Ts, with higher Ta corresponding to higher Ts. The estimation models for Ta and Ts according to Julian date were developed as a log functions (log model for Ta, LMTa; log model for Ts, LMTs) judged ｢Fit｣ and ｢Fit well｣, respectively. The linear regressions for Ts and dT as the LRMTs (linear regression model for Ts) and LRMdT (linear regression model for dT) judged ｢Fit｣ and ｢Unfit｣, respectively. Furthermore, an analysis revealed that higher Ta, combined with lower water content, led to an increase in dT. A double regression model for dT, considering both Ta and Qv (double regression model for dT, DRMdT), was found to be a good fit for the dataset. In summary, this study successfully developed estimation models for Ta, Ts, and dT, employing both logarithmic and linear regression approaches. The models were rigorously evaluated using error analysis criteria, providing valuable insights into temperature dynamics in Sandy Loam during Napa Cabbage cultivation.