Abstract. Effective numerical weather forecasting is vital in arid regions like the
United Arab Emirates (UAE) where extreme events like heat waves, flash
floods, and dust storms are severe. Hence, accurate forecasting of
quantities like surface temperatures and humidity is very important. To
date, there have been few seasonal-to-annual scale verification studies with
WRF at high spatial and temporal resolution. This study employs a convection-permitting scale (2.7 km grid scale)
simulation with WRF with Noah-MP, in daily forecast mode, from 1 January to
30 November 2015. WRF was verified using measurements of 2 m air temperature
(T2 m), 2 m dew point (TD2 m), and 10 m wind speed (UV10 m) from 48 UAE
WMO-compliant surface weather stations. Analysis was made of seasonal and
diurnal performance within the desert, marine, and mountain regions of the
UAE. Results show that WRF represents temperature (T2 m) quite adequately during
the daytime with biases ≤+1 ∘C. There is, however, a
nocturnal cold bias (−1 to −4 ∘C), which increases during hotter
months in the desert and mountain regions. The marine region has the
smallest T2 m biases (≤-0.75 ∘C). WRF performs well regarding
TD2 m, with mean biases mostly ≤ 1 ∘C. TD2 m over the marine
region is overestimated, though (0.75–1 ∘C), and nocturnal
mountain TD2 m is underestimated (∼-2 ∘C). UV10 m
performance on land still needs improvement, and biases can occasionally be
large (1–2 m s−1). This performance tends to worsen during the hot
months, particularly inland with peak biases reaching ∼ 3 m s−1. UV10 m is better simulated in the marine region (bias ≤ 1 m s−1). There is an apparent relationship between T2 m bias and UV10 m
bias, which may indicate issues in simulation of the daytime sea breeze.
TD2 m biases tend to be more independent. Studies such as these are vital for accurate assessment of WRF nowcasting
performance and to identify model deficiencies. By combining sensitivity
tests, process, and observational studies with seasonal verification, we can
further improve forecasting systems for the UAE.