SINGV: A convective‐scale weather forecast model for Singapore

Dipankar, Anurag; Webster, Stuart; Sun, Xiaoying; Sánchez, Claudio; North, Rachel; Furtado, Kalli; Wilkinson, Jonathan; Lock, A. P.; Vosper, Simon; Huang, Xiang‐Yu; Barker, Dale

doi:10.1002/qj.3895

Cited by 25 publications

(47 citation statements)

References 60 publications

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“…D01 and D02 use the model configuration described in Dipankar et al . (2020) and the references therein. Results used in the present study are from D03 that uses an urban version of SINGV (uSINGV) as described in Simón‐Moral et al (2020).…”

Section: Methodsmentioning

confidence: 99%

“…The rest of the model formulation is the same as SINGV and can be found in Dipankar et al . (2020). This modelling configuration has been shown to accurately represent the SEB and temperature above the urban canopy layer in an evaluation over Singapore presented in Simón‐Moral et al .…”

Section: Methodsmentioning

confidence: 99%

“…The model includes 80 vertical levels with the upper atmospheric level at 38.5 km in all the domains. D01 and D02 use the model configuration described in Dipankar et al (2020) and the references therein. Results used in the present study are from D03 that uses an urban version of SINGV (uSINGV) as described in Simón-Moral and Roth (2020).…”

Section: Usingv Modelmentioning

confidence: 99%

“…The Smith (1990) diagnostic cloud scheme is used with critical relative humidity set to unity on all the vertical levels (Simón-Moral et al, 2020). The rest of the model formulation is the same as SINGV and can be found in Dipankar et al (2020). This modelling configuration has been shown to accurately represent the SEB and temperature above the urban canopy layer in an evaluation over Singapore presented in Simón-Moral et al (2020).…”

Section: Usingv Modelmentioning

confidence: 99%

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Urban‐induced modifications to the diurnal cycle of rainfall over a tropical city

Doan

Dipankar

Simón-Moral

et al. 2021

Quart J Royal Meteoro Soc

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There is still no consensus on the mechanisms that modify precipitation over and around cities, especially for those located in the tropics where convective processes primarily drive rainfall. Here we contribute to the ongoing discussion about the urban-associated precipitation by investigating the urban effect on the diurnal cycle of rainfall over Singapore. We use the urban version of the numerical weather prediction system of the Meteorological Service Singapore (hereafter called uSINGV) at a 300 m horizontal resolution to simulate the rainfall conditions over Singapore and its surroundings during the inter-monsoon period between 2010 and 2014. Two simulations with different land surface conditions are conducted: one with urban areas (i.e. present conditions) and one without urban areas. uSINGV is shown to perform well for rainfall when compared to observations. Comparison between simulations reveals that the urban area is responsible for the formation of a rainfall "hot spot" over Singapore and Johor Bahru, located at the southern tip of the Malay Peninsula, and the urban effect is accountable for 20-30% of total rainfall during late afternoons and evenings, highlighting a strong urban effect on localized rainfall over a tropical city. Enhancement of convection due to the urban heat island effect, increased frictional convergence due to buildings' drag, the seaward shift of the sea-breeze front, and the increased inflow of boundary-layer moisture by the stronger sea breeze are suggested as most probable reasons for the increased rainfall in the urban area.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Usingv Modelmentioning

confidence: 99%

Section: Usingv Modelmentioning

confidence: 99%

See 2 more Smart Citations

Urban‐induced modifications to the diurnal cycle of rainfall over a tropical city

Doan

Dipankar

Simón-Moral

et al. 2021

Quart J Royal Meteoro Soc

Self Cite

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“…A similar reduction in intense rainfall rates with the RAL1-T configuration is found in other convective cases (Figure 4b). Dipankar et al (2020) showed that the reduction in intense rainfall rates (and subsequent reduction in domain-average precipitation) found with the RAL1-T configuration can be attributed to the moisture conservation scheme and the PC2 cloud scheme as both reduce the peak vertical velocity, which subsequently leads to a reduction in condensation. The same signal is seen in the simulations presented here, with the RAL1-T models having fewer grid points with vertical velocities exceeding 4 m⋅s −1 than the EA4-OP (Figure 5).…”

Section: Case-study Of Severe Convectionmentioning

confidence: 99%

Assessment of convection‐permitting versions of the Unified Model over the Lake Victoria basin region

Hanley

Pirret

Bain

et al. 2021

Quart J Royal Meteoro Soc

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The Met Office runs an operational high-resolution convection-permitting model over Tropical Africa to support National Meteorological Services across the continent. This article evaluates the prediction of convective storms in two convection-permitting versions of the Met Office Unified Model over the Lake Victoria basin region in East Africa. Two model configurations are compared for a case of severe convection: the first was tuned for tropical regions and the second was based on the operational UK model configuration. The tropical configuration compares better with satellite-derived rainfall observations in terms of domain-average rain-rate and the distribution of rain-rates is better, particularly for the more intense rain-rates. However, both configurations generally produce too much rain, too many small storms, and a lack of light rain, which is compensated for by heavy rain in the cores of the storms. The tropical configuration was then assessed over two rainy seasons. In both seasons, the onset time of night-time precipitation over Lake Victoria is delayed and the amount of precipitation is underestimated, which suggests the model may miss night-time storms that occur over the lake. During the first 12-24 hr of the simulations, the precipitation field is still spinning up from the lower-resolution global model fields used to initialise the convection-permitting model. This leads to large overestimates in the domain-average precipitation during this period and highlights the need to run convection-permitting models for at least two days to reduce the impact of cold-starting from a non-convective-permitting analysis. Despite the spin-up issues, fractions skill score analysis shows that forecast skill decreases with increasing lead time. This implies that there is inherent skill in the early stages of the model forecast and underlines that short-term forecast (0-48 hr) improvements in the model are likely to be achieved when using an improved analysis for initialisation. K E Y W O R D S convection, convection-permitting models, precipitationThis article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

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Confronting the convective gray zone in the global configuration of the Met Office Unified Model

Tomassini

Willett

Sellar

et al. 2022

Preprint

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In atmospheric models with kilometer-scale grids the resolution approaches the scale of convection. As a consequence the most energetic eddies in the atmosphere are partially resolved and partially unresolved. The modeling challenge to represent convection partially explicitly and partially as a subgrid process is called the convective gray zone problem. The gray zone issue has previously been discussed in the context of regional models, but the evolution in regional models is constrained by the lateral boundary conditions. Here we explore the convective gray zone starting from a defined global configuration of the Met Office Unified Model using initialized forecasts and comparing different model formulations to observations. The focus is on convection and turbulence, but some aspects of the model dynamics are also considered. The global model is run at nominal 5km resolution and thus contributions from both resolved and subgrid turbulent and convective fluxes are non-negligible. The main conclusion is that in the present assessment, the configurations which include scale-aware turbulence and a carefully reduced and simplified mass-flux convection scheme outperform both the configuration with fully parameterized convection as well as a configuration in which the subgrid convection parameterization is switched off completely. The results are more conclusive with regard to convective organization and tropical variability than extratropical predictability. The present study thus endorses the strategy to further develop scale-aware physics schemes and to pursue an operational implementation of the global 5km-resolution model to be used alongside other ensemble forecasts to allow researchers and forecasters to further assess these simulations.

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SINGV: A convective‐scale weather forecast model for Singapore

Cited by 25 publications

References 60 publications

Urban‐induced modifications to the diurnal cycle of rainfall over a tropical city

Urban‐induced modifications to the diurnal cycle of rainfall over a tropical city

Assessment of convection‐permitting versions of the Unified Model over the Lake Victoria basin region

Confronting the convective gray zone in the global configuration of the Met Office Unified Model

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