Verification of operational numerical weather prediction model forecasts of precipitation using satellite rainfall estimates over Africa

Wang, Yan; Gueye, M.; Greybush, Steven J.; Greatrex, Helen; Whalen, Andrew J.; Ssentongo, Paddy; Zhang, Fuqing; Jenkins, Gregory S.

doi:10.1002/met.2112

Cited by 4 publications

(4 citation statements)

References 89 publications

(109 reference statements)

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“…We remap conservatively to 1 • × 1 • resolution and daily accumulations from 0600 UTC to 0600 UTC, and we refer to this forecast as ENS. As Wang et al (2023) demonstrate, ECMWF forecasts outperform National Centers for Environmental Prediction-Global Forecast System (NCEP-GFS) forecasts of precipitation over Africa.…”

Section: Observational Data and Ecmwf Ensemble Forecastsmentioning

confidence: 95%

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Sources of predictability of synoptic‐scale rainfall during the West African summer monsoon

Rasheeda Satheesh,

Knippertz,

Fink

et al. 2023

Quart J Royal Meteoro Soc

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Numerical model‐based forecasts of precipitation exhibit poor skill over northern tropical Africa when compared to climatology‐based forecasts and to other tropical regions. However, as recently demonstrated by Vogel et al. (2021), purely data‐driven forecasts based on spatio‐temporal dependencies inferred from gridded satellite rainfall estimates show promise for the prediction of 24‐hour precipitation occurrence rate in this region. The present work explores this potential further by advancing the statistical model and providing meteorological interpretations of the performance results. Advances include (a) the use of a recently developed correlation metric, the Coefficient of Predictive Ability (CPA), to identify predictors, (b) forecast evaluation with robust reliability diagrams and score decompositions, (c) a study domain over tropical Africa nested in a considerably enlarged spatio‐temporal domain to identify coherent propagating features and, (d) the introduction of a novel coherent‐linear‐propagation factor to quantify the coherence of propagating signals. The statistical forecast is compared with a climatology‐based benchmark, the European Centre for Medium‐Range Weather Forecasts (ECMWF) operational ensemble forecast, and a statistically post‐processed ensemble forecast. All methods show poor skill within the main rainbelt over northern tropical Africa, where differences in Brier scores between the different approaches are hardly statistically significant. However, the data‐driven forecast outperforms the other methods along the fringes of the rainbelt, where meridional rainfall gradients are large. The coherent‐linear‐propagation factor, in concert with metrics of convective available potential energy and convective instability, reveals that high stochasticity in the rainbelt limits predictability. At the fringes of the rainbelt, the data‐driven approach leverages coherent precipitation features associated with propagating tropical weather systems such as African easterly waves.This article is protected by copyright. All rights reserved.

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Section: Observational Data and Ecmwf Ensemble Forecastsmentioning

confidence: 95%

“…As Wang et al . (2023) demonstrate, ECMWF forecasts outperform National Centers for Environmental Prediction–Global Forecast System (NCEP–GFS) forecasts of precipitation over Africa.…”

Section: Methodsmentioning

confidence: 99%

Sources of predictability of synoptic‐scale rainfall during the West African summer monsoon

Rasheeda Satheesh,

Knippertz,

Fink

et al. 2023

Quart J Royal Meteoro Soc

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“…Similarly, numerical weather prediction models generally have large rainfall errors in East Africa (e.g. Wang et al ., 2022). Indeed even computationally expensive convection‐permitting ensembles have less skill over East Africa than is typical for midlatitudes (Cafaro et al ., 2021).…”

Section: Introductionmentioning

confidence: 99%

Convective systems and rainfall in East Africa

Hill

Stein

Cafaro

2023

Quart J Royal Meteoro Soc

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East Africa is particularly vulnerable to weather extremes, with severe weather linked to thousands of deaths per year. Improved forecasts of convective events in this region are urgently needed, from both nowcasting and numerical weather prediction models. Improving these forecasts requires further knowledge of convection in this region. This study aims to improve understanding of convective events in East Africa, based on a six‐year climatology of convective life cycles and the associated precipitation. Convective systems are identified as contiguous areas of cold cloud in geostationary satellite measurements over East Africa. A tracking algorithm is used to trace the evolution of the properties of these systems through time and space. Matching the systems to surface precipitation obtained from satellite microwave observations provides insight into how the life cycles of these systems relate to precipitation at the surface. Over the region as a whole, 59% of the accumulated precipitation can be attributed to the tracked convective systems. The majority (81%) of heavy precipitation events (10 mmhr−1) are attributable to convective systems, while light rainfall events (1 mmhr−1) are not (1.8%). Most of the tracked convective systems have an area less than 400 km2 and last for less than an hour. However, the less frequent larger longer‐lived systems produce the majority of the regional accumulated precipitation. Composite life cycles of the tracked systems show rapid intensification and the heaviest precipitation initially, followed by a steady increase in area and weakening in intensity before the system decays. Finally, the Madden–Julian oscillation, which plays a key role in intraseasonal rainfall variability in the region, is also linked to the amount of rainfall due to convective systems through changes in the frequency and properties of these systems.

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“…Several methods have been employed to improve the interpolation results, such as graph neural networks (GNNs) [19,20] and graph for spatial interpolation (GSI) [21]. Additionally, various numerical weather prediction (NWM) models are used to achieve high spatial resolution in rainfall data [22]. For example, the Weather Research and Forecasting (WRF) model has a proven potential in depicting the spatial distribution of rainfall [23].…”

Section: Introductionmentioning

confidence: 99%

The WRF-Driven Grid-Xin’anjiang Model and Its Application in Small and Medium Catchments of China

Gong,

Hu,

Yao

et al. 2023

Water

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The distributed Grid-Xin’anjiang (Grid-XAJ) model is very sensitive to the spatial and temporal distribution of data when used in humid and semi-humid small and medium catchments. We used the successive correction method to merge the gauged rainfall with rainfall forecasted by the Weather Research and Forecasting (WRF) model to enhance the spatiotemporal accuracy of rainfall distribution. And we used the Penman–Monteith equation to calculate the potential evapotranspiration (PEPM). Then, we designed two forcing scenarios (WRF-driven rainfall (Wr) + PEPM, WRF-merged rainfall (Wm) + PEPM) to drive the Grid-XAJ model for flood forecasting. We found the WRF-driven Grid-XAJ model held significant potential in flood forecasting. The Grid-XAJ model provided only an approximation of flood hygrographs when driven by scenario Wr + PEPM. The results in scenario Wm + PEPM showed a high degree-of-fit with observed floods with mean Nash–Sutcliffe efficiency coefficient (NSE) values of 0.94 and 0.68 in two catchments. Additionally, scenario Wm + PEPM performed better flood hygrographs than scenario Wr + PEPM. The flood volumes and flow peaks in scenario Wm + PEPM had an obvious improvement compare to scenario Wr + PEPM. Finally, we observed that the model exhibited superior performance in forecasting flood hydrographs, flow peaks, and flood volumes in humid catchments compared with semi-humid catchments.

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Verification of operational numerical weather prediction model forecasts of precipitation using satellite rainfall estimates over Africa

Cited by 4 publications

References 89 publications

Sources of predictability of synoptic‐scale rainfall during the West African summer monsoon

Sources of predictability of synoptic‐scale rainfall during the West African summer monsoon

Convective systems and rainfall in East Africa

The WRF-Driven Grid-Xin’anjiang Model and Its Application in Small and Medium Catchments of China

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