Calculation Procedure and Application of the Pseudo- atmospheric Transmittance based on the Month and Weather in Shimonoseki

Abstract

The calculation procedure of “pseudo-atmospheric transmittance” based on the month and weather in a particular location is described in this paper. The pseudo-atmospheric transmittance with regard to the month and weather in Shimonoseki was calculated based on the hourly data of total solar radiation on the horizontal plane of the Shimonoseki Local Meteorological Observatory in 2021. As an example of the application of the pseudo-atmospheric transmittance, the hourly total solar radiation was predicted using the pseudo-atmospheric transmittance, the calculated position of the sun, and the weather forecast. The hourly total solar radiation in the western part of Yamaguchi Prefecture (including Shimonoseki City) from March 13 (Sun) to March 19 (Sat), 2022 was predicted by using the weather forecast texts announced by the Shimonoseki Local Meteorological Observatory at 17:00 on the days before the forecast target days. The accuracy of the predicted solar radiation largely depends on the weather forecast information. On March 15, 16, and 18, when the real weather was almost as forecasted, the errors in the predicted total daily solar radiation were -8.0, -5.0, and -0.9%, respectively. On the contrary, on March 13, when the difference in the real and forecasted weather occurred, the error in the predicted total solar radiation was 74.0%. The weather forecast information with a high spatiotemporal resolution is required to improve the prediction accuracy.