Short-Term Forecast of Satellite-Derived Solar Irradiance in corporation with Numerical Weather Prediction over the Korean Peninsula
Authors: Kim Chang , Kim Hyun-Goo , Oh Myeonchan , Kang Yong-Heack 
Published: June 2022

&lt;p&gt;The great increase of penetration rate in the photovoltaic (PV) system into electricity grid requires renewable energy management system (REMS) which is usually made by the power forecast at the various time scales; 15 minutes ahead, 3 hours ahead, same day and 24 hours ahead. cloud moving vector which is derived by two consecutive satellite imagery in general. In this study, however, horizontal wind fields are taken from the Unified Model Local Data Assimilation and Prediction System (UM &amp;#8211; LDAPS) that is operated by Korea Meteorological Administration.&amp;#160; The horizontal resolution of UM &amp;#8211; LDAPS is 1.5 km and forecast horizon is 48 hours per each initialization. Wind speed at the level where the relative humidity, averaged over the domain, is largest is incorporated into the advection module that produces the cloud or clear sky index displacement. Solar irradiance from the satellite imagery is derived by the University of Arizona Solar Irradiance Based on Satellite &amp;#8211; Korea Institute of Energy Research model (Kim et al., 2017). The temporal and spatial resolution of satellite imagery are 15 minutes and 1 km, respectively. Finally, solar irradiance at a cloudy pixel displaced after the forecasted time, will be recalculated where the clear sky index and solar zenith angle. The smart persistent model is employed for the reference model at the evaluation. The investigation period is from January to December, 2018. Forecasts by cloud moving vector are produced every hour but forecast at 09 LST is only employed here to compare with persistent model. &amp;#160;Below is the example from the 1 hour ahead forecasted and observed GHI. Cloud clusters are similar between forecast and observation but small clouds over the Korean Peninsula disappeared in the observed imagery. The solar irradiance forecast based on cloud moving vector assumes that the clouds do not form nor dissipated for the forecasting horizon. That is why the discrepancy between forecast and observation exists.&amp;#160; The relative root mean square error (rRMSE) between observed and forecasted GHI during the investigation period. In the intra-hour ahead forecast, the persistent model is better than the forecast by cloud moving vector. However, the rRMSE does not show that cloud moving vector forecast performs better than the persistent model for the forecasting horizon exceeding 2 &amp;#8211; 3 hours. That is due to the microphysical characteristics of clouds that will be affected to cloud moving vector and solar irradiance itself. We will show the major results in detail in the upcoming conference.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.29c657329b5265738610561/sdaolpUECMynit/2202SME&amp;app=m&amp;a=0&amp;c=eca60c2ecc0cd78a93d3e997732fa54d&amp;ct=x&amp;pn=gnp.elif&amp;d=1&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&lt;p&gt;Acknowledgement&lt;/p&gt;&lt;p&gt;This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry &amp; Energy (MOTIE) of the Republic of Korea (No. 2019371010006B).&lt;/p&gt;