AOPC/OOPC Mean Sea Level Pressure Working Group PDF

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AOPC/OOPC Mean Sea Level PressureWorking GroupDavid ParkerHadley Centre, Met Office, UKAOPC-IX, Asheville, North Carolina, USA June 23-27th2003100/XXXX Crown copyright

Presentation OutlineOverview of the Surface Pressure Group Workshop, Norwich 20th –21stNovember, 2002Current activities under the Group’s Terms of ReferenceUpcoming Events & Issues200/XXXX Crown copyright

Atmospheric Observation Panel for Climate (AOPC):Surface Pressure Group WorkshopNorwich 20th –21st November, 2002Present were representatives from France, Italy, Spain, UK, Chile, Switzerland,Germany, USA, Russia, Sweden, Netherlands, Canada. A number of theseparticipants stayed on from the EC-funded European and North Atlantic daily toMULtidecadal climATE variability (EMULATE) project start up meeting.Workshop outlineDay 1: Presentations on Historical MSLP data: compilations and qualitycontrolDay 2: Presentations on Historical MSLP: analyses and data extensions300/XXXX Crown copyright

Day 1: Presentations on Historical MSLP data: compilations and qualitycontrolDavid Wuertz : GHCN projectRob Allan: Hadley Centre MSLP data baseGil Compo: Comparison of ICOADS ship observations with US HistoricalWeather Maps 1899-1939Vicky Slonosky: Canadian historical MSLP data & future plansTheo Brandsma: Dutch & colonial (Indonesian & Japanese) historicalMSLPLars Barring: Historical MSLP data from Estonia & PolandVictor Lagun: Russian historic Antarctic surface pressure datamanagementPhil Jones: Summary of EMULATE meetingMaurizio Maugeri: Air pressure data in Italy400/XXXX Crown copyright

Day 2: Presentations on Historical MSLP: analyses and data extensionsAnders Moberg: Historical MSLP data from Norway, Sweden and FinlandGil Compo: Feasibility of reanalysis before the radiosonde eraShyh Chen: Surface pressure observation: a view from ReanalysisRob Allan (for Nathan Gillett): Trends in HadSLP and MSLP dataScott Woodruff: ICOADS dataTara Ansell: A new version of HadSLP using ICOADS data(A summary of each presentation is available on the Climatic Research Unit,University of East Anglia’s web site 00/XXXX Crown copyright

Current activities under the Group’s Terms of ReferenceInternational atmospheric pressure data base(Norwich Workshop 2002) Aim to set up an international monthly pressure data base for the globe.Also a separate data base of sub daily observations and, accordingly, the development ofa international operational pressure data base. David Wuertz and Gil Compo volunteered to be administrators of the monthly andoperational data bases respectively, with input from the Hadley Centre. No final decision was made about the inclusion of other variables such as wind speed anddirection in the data bases and it was agreed to keep this issue open for later discussions. The group agreed, if resources permit, it is better to digitise a number of variables at onetime, rather than just pressure. The need to adopt a uniform data format was recognised. We will work towards using theInternational Maritime Meteorological Archive (IMMA) format, or a variant thereof, and adaptthis to work with terrestrial pressure observations. It is however best suited for theoperational rather than monthly data base. Details of this format are now available as aseparate pdf document. 600/XXXX Crown copyright

Outstanding data issues(Norwich Workshop 2002)Need to compare various pressure holdings with the scanned images on the NOAA librarysite ( rescue home.html). There are some gaps in NOAAimages, and it would be desirable to fill in the missing years. Rob Allan and Tara Ansell will check for the Hong Kong daily records in the Met Office’slibrary. We have found some daily observations from 1853-1862, 1866-1886 since themeeting. We will keep searching! David Parker will investigate the Gordon Manley pressure records. Since the meetingDavid has been able to find evidence that Gordon Manley did indeed collate pressureobservations and there appears to be coverage for London from 1770. We have the potential to take the London and Paris records back to the 17th Century,possibly earlier. Phil Jones commented that despite their relatively close proximity, Londonand Paris are quite different series and actually provide a good measure of the NorthAtlantic Oscillation (NAO). Reanalysis fields(Norwich Workshop 2002)The group agreed to Phil Jones’ recommendation to write a formal letter, acting on behalf ofAOPC, to ECMWF requesting that their reanalysis data be made freely available. The coconvenors of the AOPC pressure working group will write the letter, to then be approved bythe members of AOPC and forwarded on to ECMWF by the head of AOPC.700/XXXX Crown copyright

Homogenisation of series(Norwich Workshop 2002)Phil Jones requested that series being homogenised should be done so according to thecurrent operating standard (i.e. observing hours and/or averaging scheme), therebypreventing the need for further adjustments when blending in current observations.Errors(Norwich Workshop 2002)One recommendation from the Boulder Workshop in 2002 was to produce, in time for the 4thIPCC assessment, grid box uncertainties and error covariance structures in gridded MSLPproducts. The group was asked to consider the following issues: Can we look simply at the number of observations per day? Are there any consistent errors, such as urbanisation effects with temperature? Any gross potential bias?Do we want to ignore / reject the very high altitude stations or how should we handlethem? This will be reviewed at follow-up meetings.Historical wind data(Boulder Meeting 2002)The Terms of Reference of the AOPC/OOPC MSLP Working Group should be expanded toinclude the homogenisation and analysis of surface winds, especially over the oceans, and8 00/XXXX Crown copyrighttheirconsistencywith surface pressure.

Upcoming Events & Issues Replacement of Ed Harrison as Co-convenor of the Group by Gil Compo.Proposal for an informal meeting of Group members who are attending the CLIMAR-IIWorkshop, Brussels, Belgium, 17-22nd November 2003. Atmospheric pressure sensors on drifting buoys, especially in the Southern Ocean.Formal approach to meteorological services to liaise with the Group on the construction,extension and quality control of long barometric pressure data series for the internationalatmospheric pressure data base. This would include hard copy records and digitised data,which would be quality controlled and ultimately fed back to these services and be availablethrough the international data base. 9Letter from AOPC to ECMWF concerning re-analysis data being made freely available.00/XXXX Crown copyright

David Parker will investigate the Gordon Manley pressure records. Since the meeting David has been able to find evidence that Gordon Manley did indeed collate pressure observations and there appears to be coverage for London from 1770. We have the potential to take the London and Paris records back to the 17th Century, possibly earlier.