Reviewing operational and near operational progress in surface water flood forecasting for urban areas

2020 ◽  
Author(s):  
Linda Speight ◽  
Michael Cranston ◽  
Laura Kelly ◽  
Christopher White
Keyword(s):  
Surface Water ◽  
Urban Areas ◽  
Prediction Models ◽  
Rapid Development ◽  
Weather Prediction ◽  
Flood Forecasting ◽  
Water Flooding ◽  
Environment Protection ◽  
Probabilistic Forecasting ◽  
Protection Agency

<p>Surface water flooding is caused by intense rainfall before it enters rivers or drainage systems. As the climate changes and urban populations grow, the number of people around the world at risk of surface water flooding increases. Although it may not be possible to prevent such flooding, reliable and timely flood forecasts can help improve preparedness and recovery. Unlike river and coastal flooding where flood forecasting methods are well established, surface water forecasting techniques that address the challenges around predicting the location, timing and impact of events are still in their infancy.</p><p>Over the past five years there has been a rapid development of convection permitting numerical weather prediction models and probabilistic forecasting. Combined with an increase in computational ability, this has meant that it is potentially feasible to develop operational surface water forecasting systems for urban areas. The ability to make flood risk management decisions based on such forecasts depends on an interdisciplinary understanding of their strengths and limitations.</p><p>In 2019, the Scottish Environment Protection Agency (SEPA) commissioned a systematic review of UK and international surface water forecasting capabilities to inform the development of forecasting capabilities for Scotland (Speight et al, 2019). As part of the review process a literature review of international examples of operational surface water forecasting tools was conducted alongside discussion with a number of industry experts and leading academics to incorporate emerging capabilities.</p><p>This PICO will summarise the three approaches to surface water forecasting identified as part of this review; empirical based rainfall scenarios, hydrological forecasts linked to pre-simulated impact scenarios, and, real time hydrodynamic simulation. International examples of each type of approach will be presented along with discussion of their ability to meet the varying needs of decision makers. It will conclude by identifying ‘grand interdisciplinary challenges’ that still need to be addressed to provide effective solutions for reliable and timely surface water forecasts. For example although the emergence of new meteorological and hydrological capabilities is promising there is a scientific limit to the predictability of convective rainfall. To overcome this challenge re-thinking of the established role of flood forecasting is needed alongside developing interdisciplinary solutions for communicating uncertainty, making the best use of all available data and increasing preparedness.</p><p> </p><p><em>Speight, L., Cranston, M., Kelly, L. and White, C.J. (2019) Towards improved surface water flood forecasts for Scotland: A review of UK and international operational and emerging capabilities for the Scottish Environment Protection Agency. University of Strathclyde, Glasgow, pp 1-63, doi:10.17868/69416 Available online at https://strathprints.strath.ac.uk/69416/</em></p>

scholarly journals A Transformed Lagged Ensemble Forecasting Technique for Increasing Ensemble Size

2007 ◽  
Vol 135 (4) ◽  
pp. 1424-1438 ◽  
Author(s):  
Andrew R. Lawrence ◽  
James A. Hansen
Keyword(s):  
Prediction Models ◽  
Weather Prediction ◽  
Ensemble Forecast ◽  
Ensemble Forecasting ◽  
Limited Area ◽  
Ensemble Size ◽  
Probabilistic Forecasting ◽  
Ensemble Forecasts ◽  
Chaotic Model ◽  
The Impact

Abstract An ensemble-based data assimilation approach is used to transform old ensemble forecast perturbations with more recent observations for the purpose of inexpensively increasing ensemble size. The impact of the transformations are propagated forward in time over the ensemble’s forecast period without rerunning any models, and these transformed ensemble forecast perturbations can be combined with the most recent ensemble forecast to sensibly increase forecast ensemble sizes. Because the transform takes place in perturbation space, the transformed perturbations must be centered on the ensemble mean from the most recent forecasts. Thus, the benefit of the approach is in terms of improved ensemble statistics rather than improvements in the mean. Larger ensemble forecasts can be used for numerous purposes, including probabilistic forecasting, targeted observations, and to provide boundary conditions to limited-area models. This transformed lagged ensemble forecasting approach is explored and is shown to give positive results in the context of a simple chaotic model. By incorporating a suitable perturbation inflation factor, the technique was found to generate forecast ensembles whose skill were statistically comparable to those produced by adding nonlinear model integrations. Implications for ensemble forecasts generated by numerical weather prediction models are briefly discussed, including multimodel ensemble forecasting.

scholarly journals The role of urban boundary layer investigated by high resolution models and ground based observations in Rome area: a step for understanding parameterizations potentialities

2013 ◽  
Vol 6 (3) ◽  
pp. 5297-5344
Author(s):  
E. Pichelli ◽  
R. Ferretti ◽  
M. Cacciani ◽  
A. M. Siani ◽  
V. Ciardini ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Resolution ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Prediction ◽  
Sonic Anemometer ◽  
Lower Atmosphere ◽  
Area Of Interest ◽  
The Impact

Abstract. The urban forcing on thermo-dynamical conditions can largely influences local evolution of the atmospheric boundary layer. Urban heat storage can produce noteworthy mesoscale perturbations of the lower atmosphere. The new generations of high-resolution numerical weather prediction models (NWP) is nowadays largely applied also to urban areas. It is therefore critical to reproduce correctly the urban forcing which turns in variations of wind, temperature and water vapor content of the planetary boundary layer (PBL). WRF-ARW, a new model generation, has been used to reproduce the circulation in the urban area of Rome. A sensitivity study is performed using different PBL and surface schemes. The significant role of the surface forcing in the PBL evolution has been verified by comparing model results with observations coming from many instruments (LiDAR, SODAR, sonic anemometer and surface stations). The crucial role of a correct urban representation has been demonstrated by testing the impact of different urban canopy models (UCM) on the forecast. Only one of three meteorological events studied will be presented, chosen as statistically relevant for the area of interest. The WRF-ARW model shows a tendency to overestimate vertical transmission of horizontal momentum from upper levels to low atmosphere, that is partially corrected by local PBL scheme coupled with an advanced UCM. Depending on background meteorological scenario, WRF-ARW shows an opposite behavior in correctly representing canopy layer and upper levels when local and non local PBL are compared. Moreover a tendency of the model in largely underestimating vertical motions has been verified.

Convection is key to better polar low forecasts

2020 ◽  
Author(s):  
Matilda Hallerstig ◽  
Linus Magnusson ◽  
Erik Kolstad
Keyword(s):  
Prediction Models ◽  
Deterministic Model ◽  
Rapid Development ◽  
Weather Prediction ◽  
Model Performance ◽  
Horizontal Resolution ◽  
Added Value ◽  
Grid Spacing ◽  
Polar Lows ◽  
Polar Low

<p>ECMWF HRES and Arome Arctic are the operational Numerical Weather Prediction models that forecasters in northern Norway use to predict Polar lows in the Nordic and Barents Seas. These type of lows are small, but intense mesoscale cyclones with strong, gusty winds and heavy snow showers. They cause hazards like icing, turbulence, high waves and avalanches that threaten offshore activity and coastal societies in the area. Due to their small size and rapid development, medium range global models with coarser resolutions such as ECMWF have not been able to represent them properly. This was only possible with short range high resolution regional models like Arome. When ECMWF introduced their new HRES deterministic model with 9 km grid spacing, the potential for more precise polar low forecasts increased. Here we use case studies and sensitivity tests to examine the ability of ECMWF HRES to represent polar lows. We also evaluate what added value the Arome Arctic model with 2.5 km grid spacing gives. For verification, we use coastal meteorological stations and scatterometer winds. We found that convection has a greater impact on model performance than horizontal resolution. We also see that Arome Arctic produces higher wind speeds than ECMWF HRES. To improve performance during polar lows for models with a horizontal grid spacing less than 10 km, it is therefore more important to improve the understanding and formulation of convective processes rather than simply increasing horizontal resolution.</p>

scholarly journals Towards improving the simulation of meteorological fields in urban areas through updated/advanced surface fluxes description

2008 ◽  
Vol 8 (3) ◽  
pp. 523-543 ◽  
Author(s):  
A. Baklanov ◽  
P. G. Mestayer ◽  
A. Clappier ◽  
S. Zilitinkevich ◽  
S. Joffre ◽  
...  
Keyword(s):  
Air Pollution ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Prediction ◽  
Surface Fluxes ◽  
Surface Exchange ◽  
Urban Meteorology ◽  
Recent Developments ◽  
Urban Roughness ◽  
Meteorology And Air Pollution

Abstract. The increased resolution of numerical weather prediction models allows nowadays addressing more realistically urban meteorology and air pollution processes. This has triggered new interest in modelling and describing experimentally the specific features and processes of urban areas. Recent developments and results performed within the EU-funded project FUMAPEX on integrated systems for forecasting urban meteorology and air pollution are reported here. Sensitivity studies with respect to optimum resolution, parametrisation of urban roughness and surface exchange fluxes and the role of urban soil layers are carried out with advanced meso- or sub-meso meteorological models. They show that sensible improvements can be achieved by higher model resolution that is accompanied with better description of urban surface features. Recommendations, especially with respect to advanced urban air quality forecasting and information systems, are given together with an assessment of the needed further research and data.

scholarly journals Rapid surface water intervention performance comparison for urban planning

2018 ◽  
Vol 77 (8) ◽  
pp. 2084-2092 ◽  
Author(s):  
James L. Webber ◽  
Guangtao Fu ◽  
David Butler
Keyword(s):  
Surface Water ◽  
Urban Areas ◽  
Early Stage ◽  
Performance Comparison ◽  
Water Flooding ◽  
Surface Water Management ◽  
Management Interventions ◽  
Damage Costs ◽  
Performance Trends ◽  
High Level

Abstract Surface water flooding can be a significant source of damage and disruption in urban areas. The complexity of urban surfaces, the need for spatially disaggregated approaches and the multiplicity of interventions makes management challenging from a number of perspectives. This research responds to the challenge of selecting appropriate surface water management interventions by applying a fast assessment framework to generate evidence for comparing strategies at low resource cost during initial design. This is demonstrated by simulating flood dynamics and comparing damage costs in 144 flood scenarios. The main finding of this work is that a high-level quantitative assessment of large numbers of scenarios is capable of providing evidence to identify performance trends and consider resilience to extreme events at an early stage of planning.

scholarly journals Interactions Between the Nocturnal Low-Level Jets and the Urban Boundary Layer: A Case Study over London

2022 ◽  
Author(s):  
Aristofanis Tsiringakis ◽  
Natalie E. Theeuwes ◽  
Janet F. Barlow ◽  
Gert-Jan Steeneveld
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Prediction ◽  
Urban Boundary Layer ◽  
Limited Area ◽  
Low Level ◽  
Low Level Jets

AbstractUnderstanding the physical processes that affect the turbulent structure of the nocturnal urban boundary layer (UBL) is essential for improving forecasts of air quality and the air temperature in urban areas. Low-level jets (LLJs) have been shown to affect turbulence in the nocturnal UBL. We investigate the interaction of a mesoscale LLJ with the UBL during a 60-h case study. We use observations from two Doppler lidars and results from two high-resolution numerical-weather-prediction models (Weather Research and Forecasting model, and the Met Office Unified Model for limited-area forecasts for the U.K.) to study differences in the occurrence frequency, height, wind speed, and fall-off of LLJs between an urban (London, U.K.) and a rural (Chilbolton, U.K.) site. The LLJs are elevated ($$\approx $$ ≈ 70 m) over London, due to the deeper UBL, while the wind speed and fall-off are slightly reduced with respect to the rural LLJ. Utilizing two idealized experiments in the WRF model, we find that topography strongly affects LLJ characteristics, but there is still a substantial urban influence. Finally, we find that the increase in wind shear under the LLJ enhances the shear production of turbulent kinetic energy and helps to maintain the vertical mixing in the nocturnal UBL.

scholarly journals Urban surface water flood modelling – a comprehensive review of current models and future challenges

2020 ◽  
Author(s):  
Kaihua Guo ◽  
Mingfu Guan ◽  
Dapeng Yu
Keyword(s):  
Surface Water ◽  
Urban Areas ◽  
Scale Effects ◽  
Water Flooding ◽  
Urban Surface ◽  
Economic Losses ◽  
Intense Rainfall ◽  
Urban Flood ◽  
Comprehensive Review ◽  
Flood Modelling

Abstract. Urbanisation is an irreversible trend as a result of social and economic development. Urban areas, with high concentration of population, key infrastructure, and businesses are extremely vulnerable to flooding and may suffer severe socio-economic losses due to climate change. Urban flood modelling tools are in demand to predict surface water inundation caused by intense rainfall and to manage associated flood risks in urban areas. These tools have been rapidly developing in recent decades. In this study, we present a comprehensive review of the advanced urban flood models and emerging approaches for predicting urban surface water flooding driven by intense rainfall. The study explores the advantages and limitations of existing model types, highlights the most recent advances and identifies major challenges. Issues of model complexities, scale effects, and computational efficiency are also analysed. The results will inform scientists, engineers, and decision-makers of the latest developments and guide the model selection based on desired objectives.

scholarly journals An Overview of the Performance and Operational Applications of the MRMS and FLASH Systems in Recent Significant Urban Flash Flood Events

2021 ◽  
pp. 1-29
Author(s):  
ALAN GERARD ◽  
STEVEN M. MARTINAITIS ◽  
JONATHAN J. GOURLEY ◽  
KENNETH W. HOWARD ◽  
JIAN ZHANG
Keyword(s):  
Urban Areas ◽  
Situational Awareness ◽  
Prediction Models ◽  
Flash Flood ◽  
Spatial Scales ◽  
Weather Prediction ◽  
Small Time ◽  
Severe Weather ◽  
Flood Events ◽  
The Public

AbstractThe Multi-Radar Multi-Sensor (MRMS) system is an operational, state-of-the-science hydrometeorological data analysis and nowcasting framework that combines data from multiple radar networks, satellites, surface observational systems, and numerical weather prediction models to produce a suite of real-time, decision-support products every two minutes over the contiguous United States and southern Canada. The Flooded Locations and Simulated Hydrograph (FLASH) component of the MRMS system was designed for the monitoring and prediction of flash floods across small time and spatial scales required for urban areas given their rapid hydrologic response to precipitation. Developed at the National Severe Storms Laboratory in collaboration with the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) and other research entities, the objective for MRMS and FLASH is to be the world’s most advanced system for severe weather and storm-scale hydrometeorology, leveraging the latest science and observation systems to produce the most accurate and reliable hydrometeorological and severe weather analyses. NWS forecasters, the public and the private sector utilize a variety of products from the MRMS and FLASH systems for hydrometeorological situational awareness and to provide warnings to the public and other users about potential impacts from flash flooding. This article will examine the performance of hydrometeorological products from MRMS and FLASH, and provide perspectives on how NWS forecasters use these products in the prediction of flash flood events with an emphasis on the urban environment.

Distributed urban drag parameterization in the sub-kilometre scale London Model

2021 ◽  
Author(s):  
Birgit Sützl ◽  
Gabriel Rooney ◽  
Anke Finnenkoetter ◽  
Sylvia Bohnenstengel ◽  
Sue Grimmond ◽  
...  
Keyword(s):  
High Resolution ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Forecasting ◽  
Weather Prediction ◽  
Urban Environments ◽  
Internal Boundary ◽  
Average Height ◽  
High Rise ◽  
London Model

<p>Urban environments in numerical weather prediction models are currently parameterised as part of the atmosphere-surface exchange at ground-level. The vertical structure of buildings is represented by the average height, which does not account for heterogeneous building forms at the subgrid-level. The use of city-scale models with sub-kilometre resolutions and growing number of high-rise buildings in cities call for a better vertical representation of urban environments.</p><p>We present the use of a newly developed, height-distributed urban drag parameterization with the London Model, a high-resolution version of the Met Office Unified Model over Greater London and surroundings at approximately 333 m resolution. The distributed drag parameterization requires vertical morphology profiles in form of height-distributed frontal area functions, which capture the full extent and variability of building-heights. These morphology profiles were calculated for Greater London and parameterised by an exponential distribution with the ratio of maximum to mean building-height as parameter.</p><p>A case study with the high-resolution London Model and the new drag parameterization appears to capture more realistic features of the urban boundary layer compared to the standard parameterization. The simulation showed increased horizontal spatial variability in total surface stress, identifying a broad range of morphology features (densely built-up areas, high-rise building clusters, parks and the river). Vertical effects include heterogeneous wind profiles, extended building wakes, and indicate the formation of internal boundary layers. This study demonstrates the potential of height-distributed urban parameterizations to improve urban weather forecasting, albeit research into distribution of heat- and moisture-exchange is necessary for a fully distributed parameterization of urban areas.</p>

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