Effects of stability functions in a dynamic model convective boundary layer simulation

Bopape, Mary-Jane M.; Plant, Robert S.; Coceal, Omduth; Efstathiou, Georgios A.; Valdivieso, Maria

doi:10.1002/asl.1008

Cited by 1 publication

(1 citation statement)

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“…It is associated with a diurnal cycle [72], and its value is influenced by the turbulence representation used. For example, in large-eddy simulations its value, and the boundary layer temperature profile, were found to differ between the Smagorinky and the dynamic Smagorinsky model, during both the morning transition [73] and CBL equilibrium stage [74]. The evolution of the PBL height as simulated by different configurations of WRF is shown for the 17 April 2019 case in Figure 12a.…”

Section: The Planetary Boundary Layer Heightmentioning

confidence: 99%

Sensitivity of Simulations of Zambian Heavy Rainfall Events to the Atmospheric Boundary Layer Schemes

Bopape

Waitolo

Plant

et al. 2021

Climate

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Weather forecasting relies on the use of numerical weather prediction (NWP) models, whose resolution is informed by the available computational resources. The models resolve large scale processes, while subgrid processes are parametrized. One of the processes that is parametrized is turbulence which is represented in planetary boundary layer (PBL) schemes. In this study, we evaluate the sensitivity of heavy rainfall events over Zambia to four different PBL schemes in the Weather Research and Forecasting (WRF) model using a parent domain with a 9 km grid length and a 3 km grid spacing child domain. The four PBL schemes are the Yonsei University (YSU), nonlocal first-order medium-range forecasting (MRF), University of Washington (UW) and Mellor–Yamada–Nakanishi–Niino (MYNN) schemes. Simulations were done for three case studies of extreme rainfall on 17 December 2016, 21 January 2017 and 17 April 2019. The use of YSU produced the highest rainfall peaks across all three cases; however, it produced performance statistics similar to UW that are higher than those of the two other schemes. These statistics are not maintained when adjusted for random hits, indicating that the extra events are mainly random rather than being skillfully placed. UW simulated the lowest PBL height, while MRF produced the highest PBL height, but this was not matched by the temperature simulation. The YSU and MYNN PBL heights were intermediate at the time of the peak; however, MYNN is associated with a slower decay and higher PBL heights at night. WRF underestimated the maximum temperature during all cases and for all PBL schemes, with a larger bias in the MYNN scheme. We support further use of the YSU scheme, which is the scheme selected for the tropical suite in WRF. The different simulations were in some respects more similar to one another than to the available observations. Satellite rainfall estimates and the ERA5 reanalysis showed different rainfall distributions, which indicates a need for more ground observations to assist with studies like this one.

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Section: The Planetary Boundary Layer Heightmentioning

confidence: 99%