Improving the S-Shape Solar Radiation Estimation Method for Supporting Crop Models

Abstract EN

In line with the critical comments formulated in relation to the S-shape global solar radiation estimation method, the original formula was improved via a 5-step procedure.

The improved method was compared to four-reference methods on a large North-American database.

According to the investigated error indicators, the final 7-parameter S-shape method has the same or even better estimation efficiency than the original formula.

The improved formula is able to provide radiation estimates with a particularly low error pattern index (PIdoy) which is especially important concerning the usability of the estimated radiation values in crop models.

Using site-specific calibration, the radiation estimates of the improved S-shape method caused an average of 2.72±1.02 (α=0.05) relative error in the calculated biomass.

Using only readily available site specific metadata the radiation estimates caused less than 5% relative error in the crop model calculations when they were used for locations in the middle, plain territories of the USA.