Performance of aerosol optical depth forecasts over the Middle East:
Multi-model analysis and validation
Abstract
A primary source of error for predictions of solar irradiance in
clear-sky conditions is the total aerosol optical depth (AOD). Dust
aerosol loading can also be significant in arid regions such as the
Middle East, thus considerably decreasing the solar resource while
increasing the detrimental effects of soiling on collectors at solar
power plants, particularly during dust storms. Many photovoltaic (PV)
and concentrated solar power (CSP) plants have been or will be
constructed in the Middle East, making AOD forecasting a pressing issue
for plant and grid operators. In this study we present a climatological
analysis of 1–3-day AOD forecasts from a two-year period (2018–2019)
from three operational models: the NASA Goddard Earth Observing System
Model, Version 5 (GEOS-5), the NEMS GFS Aerosol Component (NGAC) model,
and the Copernicus Atmosphere Monitoring Service (CAMS) Near-Real-Time
(NRT) model. AOD predictions from these models are validated against
daily-average observations from 20 Aerosol Robotic Network (AERONET)
stations across the Middle East. It is found that GEOS-5 is the best
model on average, with the smallest fractional gross error and near-zero
modified normalized mean bias. CAMS NRT is the next-best model, while
NGAC, which has the coarsest grid spacing of the three models examined
here, generally performs poorly. In addition to standard error metrics
to characterize the overall performance of the models, a multi-site time
series analysis is performed to assess how well these models represent
significant dust storm events in the UAE in July 2018 and in Kuwait in
April 2018.