|
|
vol. 12, nr. 1 (2008)
|
Possibilities and accuracy of estimation of heat flux into soil during a day on the basis of meteorological data
|
|
|
Jan Kossowski
|
|
| (get PDF )
|
|
|
Institute of Agrophysics, Polish Academy of Sciences, ul. Doświadczalna 4, 20-290 Lublin |
|
|
vol. 12 (2008), nr. 1,
pp. 125-140
|
|
|
abstract:
The paper is concerned with the influence of weather conditions on heat exchange by soil surface, and in particular – on the sum of heat flux into soil during daylight. The observational materials were collected during 42 days without precipitation in several May-July periods on experimental fields with bare soil at Felin near Lublin. The regression equations describing relations of the daily sums of heat flux into soil with meteorological data, as treated separately and together (various combinations contained from 2 to 12 of the data, at variants without and with daily sum of solar radiation), including the determination coefficients and the significance level of variables were established. Moreover, the values of standard and relative errors of estimation of the daily sums of soil heat flux using the equations were calculated. Analysis of all the parameters permitted to select the best (optimal) regression equations, i.e. with the smallest errors of estimation of the daily sums of heat flux into soil on the basis of minimum number of meteorological data. The equation recommended as most favourable to use contained seven variables (daily sum of solar radiation, daily mean of wind speed, air temperature daily amplitude, mean and maximum air temperatures, differences of mean and maximum air temperatures between a given and previous day), but only three of them (radiation, wind speed and air temperature) are required to be measured. By using this equation it is possible to estimate daily heat flux sums into soil with accuracy as follows: standard error about 0.47 MJ m-2, mean and maximal relative errors 11% and above 30%, respectively.
|
|
keywords:
soil heat flux, estimation, meteorological data
|
|
original in:
Polish
|
|
|
|
|
|
