A gap filling method for active surface heat balance structure

Jacek Leśny,Monika Panfil,W Zielinski,A Michalski,L Kuchar,B Kazmierczak

doi:10.1051/itmconf/20182300023

Jacek Leśny, Monika Panfil + Show 4 more

Open Access

https://doi.org/10.1051/itmconf/20182300023

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Abstract

The paper describes gap filling procedures for active surface heat balance structure data recorded for fields of rape, maize, spring and winter wheat and an apple orchard. The balance components were determined based on the Bowen ratio requiring direct measurements of net radiation, soil heat flux, temperature and water vapour pressure profiles. The latter is used to determine vertical gradients and the Bowen ratio, with sensible and latent heat fluxes calculated from the heat balance equation. Missing data are filled in from regression dependencies between individual balance components at various measurement sites. The regression data set comprised results recorded over 24 h, before the gap in measurements and after 24 h. Multiple regressions were determined from a 48-h measurement set. Regression was applied to establish missing values of net radiation (Rn), soil heat flux (G) and latent heat (LE), while sensible heat was calculated from the active surface heat balance equation. Relatively the greatest differences were found for latent heat and soil fluxes, with both estimated values deviating by 13% from the measured daily average, for net radiation the relative difference was 10% and for sensible heat – 6%. This method successfully filled gaps in measured heat balance data from April to September.

Highlights

Requiring field measurements, we need to assume that for various reasons errors or gaps in measurements will appear in data series
Mean daily values of heat balance components determined on the basis of their estimated fluctuations were close to measured values (Table 2)
In the presented examples the greatest relative differences were found between values of latent heat fluxes and the soil flux

Summary

Introduction

Requiring field measurements, we need to assume that for various reasons errors or gaps in measurements will appear in data series. Analysis of collected data series was possible only after the missing information had been supplemented For this purpose we used equations of regression taking place between values of individual heat balance components at various measurement sites. For individual hours of measurements these differences were occasionally much greater It needs to be stated here all the heat balance components for the active surface in the adopted notation (equation 5) in the 24-h course may take both positive and negative values.

Discussion

Summary