MOSAC-17 Olympics 2012 - showcasing weather science - Brian Golding

MOSAC-17

       14-16 November 2012

           PAPER 17.16

     Olympics 2012 –
showcasing weather science
         Brian Golding

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1. Introduction

As part of the Met Office’s contribution to the running of the 2012 London Olympic Games, several
aspects of leading edge weather forecasting science were showcased on the Met Office web site.
The presentation was designed to be accessible to the public, but also to provide access to real-
time outputs, enabling colleagues in other National Met Services to assess the performance of the
new capabilities.

Operational Context

The Edgemoor agreement defined two types of forecasting service: a fully automated generic
service, delivered primarily through web products, and a high value advisory service based on
expert interpretation of automated products in the context of the customer’s specific sensitivities.

During the Olympics, the primary service to the Olympic organisers and to civil protection
authorities was of the second, advisory, type. However, at the same time, an enhanced set of
generic products was delivered to the general public and business based on the standard 5000
sites automated forecasts, enhanced with new capabilities. The science showcase demonstrated
next-generation capabilities in short-range forecasting that will improve the quality of the
underpinning automated forecasts used in the generic service and as primary input to the advisory
services. During the Games, the showcase products were used as additional guidance by the
forecasting teams in Exeter and at the Games venues.

As described to MOSAC 16, the underpinning strategy for short range weather forecasting has two
pillars: (1) taking the basic convection-permitting model that has been delivered in the UKV and
improving its accuracy, primarily through improved observation processing, data assimilation &
ensemble forecasting techniques; (2) developing the next generation convection-permitting
modelling system with coupled coastal ocean, terrestrial hydrology and atmospheric composition.
In this context, the capabilities chosen for showcasing were as follows:
      Convective-scale probability forecasts:
             o 2.2km UK grid, 6 hourly update, 12 member ensemble, 36hr forecast
      NWP nowcast :
             o 1.5km grid, hourly update, deterministic, 12hr forecast
      Very high resolution wind & wave forecasts for Weymouth Bay:
             o 333m atmosphere grid, daily update, deterministic, 36hr forecast
             o 250m wave grid, daily update, deterministic, 36hr forecasts
      Air quality forecasts:
             o 12km grid, twice daily update, deterministic, 5-day forecasts

International Context

The World Weather Research Programme of the WMO sponsors a range of activities to facilitate
technology transfer, especially to developing countries. Forecasting Demonstration Projects
(FDPs) are the principal model for these, and have more recently been joined by Research &
Development Projects (RDPs). The first FDP was held in Sydney in 2000 to accompany the
Sydney Olympic Games and was built on the application of a wide range of international
nowcasting methods to the greatly enhanced observational capabilities implemented for those
Games. The S2000 FDP was tremendously successful and was succeeded by another very
successful FDP/RDP at the Beijing Olympics in 2008 and a FDP at the Whistler Winter Olympics
2010. Planning for a FDP/RDP at the Sochi winter games in 2014 is already well advanced.

Shortly after the Beijing 2008 FDP, the UK was asked if it would hold a London 2012 FDP. Careful
consideration was made as to whether the conditions were right for the Met Office to host such an

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event. It was noted that successful FDPs involved major investment in new observing facilities,
implementation of database capabilities accessible to the participating institutes, a means of
communicating the experimental forecasts to the operational forecasts while clearly differentiating
them as experimental, comprehensive comparative verification facilities, and a socio-economic
impact project.

It was concluded that the Met Office was not in a position to host an FDP for several reasons:
     Little new observation capability was planned
     Security restrictions would make external access difficult to provide
     It would be difficult to justify the investment as a contribution to the PWS

Instead, it was decided to run an internal FDP with the following aims
     Deliver additional operational capabilities needed by Games forecasters
     Expedite delivery of new severe weather forecasting capabilities
     Demonstrate our leading edge facilities to international colleagues
     Demonstrate our scientific capabilities to the UK & International public

The investment cost was limited to creation of the web pages themselves.

Success of the internal FDP depended on three key achievements:
    Successful completion of the science
    Development of the required web pages
    Communication of the plans to our international colleagues

The achievement of these plans was seriously affected by delays in implementation of the
supercomputer upgrade, which was originally expected to be live in September 2011. In the end,
access to the new P7 was only achieved in April 2012, and operational acceptance had to be
delayed until after the Olympics.

2. Web page structure

Due to delays in access to Doppler radar data and to the new P7 supercomputer, and taking
account of the limited web development resources available, it became evident early in 2012 that it
would be very difficult to achieve delivery of real-time nowcasts to a web page.

The main web page structure was therefore designed to deliver the remaining three showcase
products. For the duration of the Games, the Public Website was given an additional tab
specifically for Games information. The top level page summarised Met Office involvement in the
Olympics and Paralympics, with links to information on individual sports and events.

One link from this page went to “Enhanced Weather Capability”. This page (Fig. 1) contained a
summary of the areas of science being showcased, with links to explanatory pages introducing
each of the new capabilities. Finally, the real-time products were available through links from the
explanatory pages or from the summary page. An alternative access to the real-time products
could be obtained direct from the Invent tab on the public home page. The real-time products page
also included a feedback form, enabling visitors to assess the value of the showcase products.

For the NWP nowcast, a set of explanatory pages was created and linked from the Research News
page on the Research partition of the website. Some expanded material was also provided on the
Collaboration Wiki page under password protection. Password access was provided to a wide
range of UK and international colleagues.

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Figure 1: Top Level Web Page for Extended Weather Capability

3. Communicating with international colleagues

The WMO Executive Council in May 2012 was taken as the first opportunity to inform international
colleagues of the Met Office’s intention to provide a showcase for next generation NWP
capabilities.

Once the ensemble products were available on the website, Ken Mylne informed the WMO expert
group on ensemble forecasting, together with a large number of contacts in the ensemble and
probabilistic forecasting communities.

Once the nowcasting pages were available on the website, I informed the WWRP Joint Steering
Committee and members of its working groups on nowcasting research and mesoscale forecasting
research, together with all delegates to the 2012 WMO Symposium on Nowcasting. The
Symposium took place in the second week of the Olympic Games and I was able to present
preliminary results from each of the showcase capabilities, as well as to advertise the web links.

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4. The Showcase Capabilities

MOGREPS-UK 2.2km ensemble
It has been recognised from the first introduction of convective-scale NWP models, that although
the forecast convective features are remarkably realistic, there is often little skill in their timing or
location. Building on the use of ensembles to address this issue at larger scales in the medium
range, it was a logical step to seek to implement an ensemble of convective-scale forecasts. Partial
funding for the development of this capability was provided by defra as a contribution to delivering
the rainfall forecasting improvements recommended in the Pitt Review into the 2007 floods.

Experience with MOGREPS-R, the regional 18km ensemble that is currently operational, indicated
much of the uncertainty was likely to come from the larger scale structure driven through the
boundary conditions. This experience also indicated that problems could arise if there was
inconsistency between the initial state perturbations in the interior and in the forecast driving the
boundaries. The initial implementation of MOGREPS-UK therefore relies entirely on the
perturbations generated in the global MOGREPS-G, interpolated down, through MOGREPS-R, to
the initial and boundary perturbations of the UK model. MOGREPS-UK is initially implemented on a
2.2km grid, solely because of inadequate computer power to support an ensemble with the 1.5km,
UKV gridlength. In order to achieve a 6-hourly update frequency, the ensemble size has also been
restricted to 12 members. Recognising that this is inadequate for probabilistic product generation,
post-processing is carried out using the last two runs, introducing a lagged aspect to the products
and increasing the ensemble size to 24. Forecasts are currently run to T+36hrs.

Considerable effort was put into designing a set of probabilistic products that would address
specific needs of those using the showcase site. Map products were provided for rain (both
intensity and persistence), high temperatures and wind (sustained high & low speeds & gusts)
thresholds, while site-specific wind forecasts were provided for the Games venues in meteogram
and wind rose formats. Finally a specialist product was provided showing probabilities of tailwinds
and crosswinds for the rowing venue at Eton Dorney.

This showcase is seen as a pre-operational trial of a capability that is expected to become
operational in 2013.

Forecaster feedback from the ensemble output has been very positive, and some individual cases
during the June floods were exceptionally good. Anecdotal feedback on the products has also
been positive. Further study is underway to look at the summer’s heavy precipitation events in
more detail, and feedback from the website will be analysed.

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Figure 2: Example of Wind Rose probabilistic wind forecast for Wimbledon

       Figure 3: Example of Wind forecast for Eton Dorney rowing venue

Nowcasting Demonstration Project
The science of nowcasting was initially developed in 1980-2000, focussed on the use of real-time
radar images for flood and severe weather forecasting. Creation of the UK radar network and the
implementation of Nimrod in 1996 created a world class facility based on Lagrangian extrapolation
of the radar-based actual, blended with NWP model output. Following its demonstration in the
S2000 Olympics FDP, several countries have developed Nimrod-like nowcasting systems. In the
UK, we have upgraded Nimrod in collaboration with the Australian Bureau of Meteorology, to use
the STEPS approach, based on a multiplicative scale cascade. An alternative approach, based on

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identification of specific storm and pre-storm characteristics, has come from the USA, and is also
widely copied where severe storms are prevalent. However, it has been evident for many years,
that these nowcasting systems all have severe limitations in capturing storm development. As a
result, and following the extension of NWP to convective scale, attention is shifting to the
application of NWP in nowcasting. This is a very demanding objective, requiring major advances in
data assimilation to achieve a close match between the NWP initial fields and the observed radar
precipitation. Partial funding for the development of this capability was provided by defra as a
contribution to delivering the rainfall forecasting improvements recommended in the Pitt Review
into the 2007 floods.

The showcase demonstrated a first implementation of this capability, using the 1.5km model in an
hourly update cycle called the Nowcasting Demonstration Project (NDP). It was restricted to the
southern part of the UK, due to computer power limitations. Consistently with the focus on data
assimilation, the NDP used 4D-Var data assimilation and included Doppler radar winds from five
radars together with other sub-hourly observation sources, in addition to the observations available
to the operational UKV 3D-Var assimilation. Assimilation was performed in a one-hour window,
centred on the hour. Observations were received up to 15 minutes after the end of the window, and
the 12-hour forecast was available shortly after the hour, i.e. 30 minutes after the observation
window. Error covariances were re-tuned to focus on the convective scale detail.

There was very strong interest in this showcase from international colleagues, who see the UK as
trail blazers in this area. The case studies presented on the website and at the Symposium were
seen as evidence supporting the UK strategy of moving towards an operational NWP nowcast. The
reception by forecasters was less enthusiastic. This was partly due to a technical issue that
resulted in different products being made available from the two supercomputers running in
parallel. In addition there were a few occasions when the NDP failed to pick up convection
correctly forecast by a previous UKV run, or in which successive NDP runs differed in their
guidance. On the other hand, there were several cases in which the NDP picked up a convective
development earlier or more precisely than the UKV, and this is supported by verification statistics
that suggest a gain of about one hour’s predictability in the early stages of the forecast.

A comprehensive assessment of the whole summer period is currently under way, with a target of
delivering a report early in 2013. It is anticipated that a successor system will be made operational
for the whole UK following the next supercomputer upgrade, currently scheduled for 2015. Given
the chaotic nature of convective scale weather, it is likely that lagged post-processing will form a
feature of the resulting nowcasting system.

Weymouth Bay models
Unlike the first two showcases, the implementation of very high resolution models for Weymouth
Bay was an operational requirement to support the Weymouth forecasting team. The requirement
arose principally due to the influence of the Island of Portland on both the wind and the waves in
the Bay. The existing operational 1.5km atmospheric model was unable to properly resolve the
impact of Portland on the winds, while the operational 12km wave model did not resolve Portland
at all. Prior to the Games, a 333m configuration of the Unified Model had been used to estimate
the wind climatology of the Bay and this was implemented in real-time to provide guidance on
small-scale wind structure. A 250m configuration of the SWAN wave model was implemented to
capture the influence of Portland and inshore bathymetry on the wave field, including the focussing
effects of the Shambles bank on swell approaching Chesil Bank. This model used wind forecasts
from the 1.5km UKV to reduce the complexity of the showcase suite, recognising that the local
wind influence on the waves would be minimal.

There has been very substantial feedback on this showcase, especially on the atmospheric
component – perhaps reflecting the communities to which the showcasing was advertised. A
concern of international colleagues was the absence of in situ observations that could be used to
verify the forecasts. However, feedback from the Weymouth team was extremely positive, noting

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especially the useful guidance that the model provided on the low wind days. The overall service
for Weymouth has been widely praised by the Games organisers and the participating teams, and
it appears that a substantial part of this praise can be attributed to the availability of the 333m
model guidance. An evaluation of the wave model is in preparation based on feedback from the
sailing teams.

Looking to the future, an aspiration for the next generation coupled UK convective-scale model is
to use unstructured grids in the near-shore region that will enable that model to achieve the
benefits of running SWAN, but along the whole of the UK coastline. Coupled with a similar inshore
resolution for the shelf-seas model it will provide a substantial step forward in coastal flood
forecasting, amongst other applications.

There are currently no plans to implement a sub-km atmospheric model before 2020. However, the
evidence from this showcase, taken together with increasing evidence of the capability of models
of this resolution in boundary layer forecasting, may force us to reconsider priorities for the 2015
supercomputer upgrade.

Air Quality Model
The Met office has been running a 12km grid North-West European configuration of the Unified
Model with UKCA chemistry and Classic aerosols for nearly two years, and it recently obtained
operational status, delivering air quality forecasts to the BBC, in place of the previous service using
the NAME dispersion model. The performance of this model has recently been reviewed by the
team that compared several models for defra in 2010. Their conclusion was that it was now best in
class. The object of this showcase was to advertise this capability at the same time as introducing
its forecasts to the standard site-specific forecasts on the public website.

The showcase provided an animation of daily forecast maps of air quality index for the UK. In the
event there were only two short periods of elevated index values, neither of which reached the
“poor air quality” level, so the capability was not severely tested. A problem which became evident
soon after implementation was excessive index levels over the sea, due to accumulation of marine
emissions in a very shallow boundary layer. This was screened out to avoid conveying misleading
forecasts, though there remained a few occasions when these high values moved over France and
Eastern England.

Anecdotal feedback was generally positive, apart from criticism of the nomenclature (high index
corresponds to low air quality) which derives from defra. Routine verification will be scrutinised for
the period, and is expected to confirm earlier results indicating that ozone prediction is generally
good, while particulates need more work. Research is continuing, particularly to improve the
representation of emissions in the model. The long terms plan is for the next generation coupled
UK convective-scale model to include sufficient chemistry and aerosol to provide air quality
forecasts as well as the feedbacks into the meteorology.

5. Summary

The Met Office science showcase for the Olympic and Paralympic Games successfuly
demonstrated next generation capabilities that are world leading. A layered web access enabled
public appreciation of the science while also delivering real-time products of interest to international
collaborators. International feedback indicates that the showcase was appreciated and that it
enhanced the perception of Met Office capability in the areas concerned.

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