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CIMO ET on Upgrading the Global Radiosonde Network – Geneva 3-7 November 2003

Upper Air Network UK National Report.

Tim Oakley & John Nash Met Office, Exeter, UK

 Network early 2001  8 ‘Core’ stations, manned 24/7  Defence and Boundary layer sites, when available 00/XXXX 2

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Current Upper-Air Network 2003

2 Manned Radiosonde Sites 4 Autosonde Sites Supplementary Radiosonde sites, ascents as required 5 Wind-Profiler Sites

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Upper-Air Network (Met Office)

Lerwick Camborne Castor Bay Albemarle Watnall Herstmonceux Larkhill(defence) Aberporth(defence) W.Freugh(defence) S.Uist(defence) Supplementary(8) Manned Manned Autosonde Autosonde Autosonde Autosonde Manned Manned Manned Manned Manned DigiCora III DigiCora III MW15 MW15 MW15 MW15 DigiCora III DigiCora III DigiCora III PC-Cora PC-Cora RS80H Loran 00 , 12 RS80H Loran 00 , 12 RS80H Loran 00 , 12 RS80H Loran 00 , 12 RS80H Loran 00 , 12 RS80H Loran 00 , 12 RS80H Loran IRREG RS80H Loran RS80H Loran RS80H Loran RS80H Loran IRREG IRREG IRREG IRREG    Gibraltar Falklands St Helena Manned Manned Manned Additional radiosonde ascents at the request of the National Met Centre.

DigiCora III DigiCora III DigiCora III RS80H GPS 00 , 12 RS80H GPS 00 , 12 RS80H GPS 12 00/XXXX 4

DigiCORA III - Ground System

 Operational from June 01  Able to interface with the continuing evolution of operational radiosondes & different wind finding.

 COTS Processor using Windows NT  Remote or local interrogation  Service Level Agreement with manufacturer 00/XXXX 5

Autosonde at 4 UK Sites

• Autosonde trialled for operationally feasible • Radiosondes Tested • Proved successful for operations at inland sites.

• From 2002 - operational at 4 Met. Office sites, UK • Plans to upgrade Autosondes to DigiCORA III during 03/04 00/XXXX 6

UK Radiosonde Trials 2002

 Jan 2002 - Radar v Graw v Sippican v Vaisala RS90 Test of GPS systems for both wind measurements & GPS heights as possible reference system to replace COSSOR radar.

 Feb 2002 – Vaisala RS90 v RS80 Comparison of alternative RS90 humidity measurements (i.e. cap/no cap)  May 2002 – Vaisala RS90 v RS80 v Snow-whites Continuing evaluation of the RS90 humidity measurements + comparison with Microwave Radiometer measurements .

 August 2002 – Radar v Graw v Sippican v Vaisala RS90 Final test for systems to replace the COSSOR radar.

 October 2002 – Vaisala RS92 (High Power) v RS80 First trials on DigiCORA III, comparisons with the operational ascent.

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UK Radiosonde Trials 2003

 May 2003 - Vaisala RS92 (Low Power) v RS80 First trials on DigiCORA III of the low power radiosonde + necessary hardware upgrades. Comparisons with the operational ascent.  July 2003 – Meteorlabor SPC/Snow-whites v RS80/RS92 Trial of complete Meteolabor system with Snow-whites as possible reference radiosonde system for 2004+.  October 2003 – Vaisala RS92 v RS80 Acceptance test for Pristina airport installation. Further evaluation of the RS92 GPS measurements.

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December 2003 – Vaisala RS80 v RS92 (L&H) v S/Whites Pre-acceptance test for the RS92 radiosonde.

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Next Generation Radiosonde

 RS80 radiosonde is considered obsolete by Vaisala, and production will gradually be reduced over 4 to 5 years.

 The radiofrequency transmitter is out of date and needs to be improved to meet requirements for reduced spectrum occupation and hence spectrum charges.

 The RS90 radiosonde had improved sensors, but the transmitter and internal electronics were not optimised.

 The RS90 relative humidity sensor package failed the Met Office acceptance test [ Sensor calibration errors, sensor instability and inadequate protection in cloud]

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Future RS92 work

 Vaisala are proposing that the Met Office use the newly developed RS92 radiosonde , built using dedicated ASIC’s not only for GPS winds but also for processing PTU information during flight and for digital data transmissions to the ground  The mechanical design of the RS92 has been changed to make the deployment of the temperature and relative humidity sensor exposure more reproducible, as suggested by Met Office.

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Future work [2]

 RS92 Acceptance testing 2003/04 Sensor performance ( i.e. humidity – pulse heating) Digital transmitter/receiver (low & high power) Complete ‘system’ acceptance test – Spring 04  Handover of RS92 to operations  Implementation of BUFR coding  Implementation of one software suite for Autosondes + DigiCora III

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BUFR Code

 DC III system has the capability to produce BUFR.

 Test and evaluate the BUFR. (Content, communications, storage)  Implement operationally.

Benefits  Transmission of complete Radiosonde archive  No need for manual editing of selected points  Inline with CBS recommendations to change to BUFR  Archive of high resolution data for verification/research

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BUFR findings to date.

 BUFR encoding on DigiCORA III has been tested to Met Office satisfaction. (Decoded successfully by operational database.)  Some inconsistencies between the encoded and decode data.

 Questions about the necessary level of data QC flagging.

 Concerns over the size of the BUFR message and the ability of the operational databases to archive/access the data.

 Project in Met Office tasked with delivering BUFR messages for the future.

Quality monitoring of RH sensor performance.

 12 year archive of ‘high resolution’ radiosonde measurements from 4 UK sites.

 Using surface observation to identify ascents that have passed through cloud.

 Monthly/annual statistics used to monitor the performance of the RH sensor.

 Information/results feedback to manufacturer.

 Used to detect changes from A & H Humicap , also batch performances and manufacture & calibration problems.

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Wind Profiler Network

 4 systems are operational components of the UK network.

 Wind data from these systems being assimilated into the UK NWP models.

 New 64MHz system under final acceptance and hand-over to operations.

 Collaboration with WINPROF (European network)

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GPS Water Vapour Network

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Network Configuration

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GPS Water Vapour Network

 Project has demonstrated the feasibility and usefulness of a ‘real-time’ GPS IWV network.

 Working with Nottingham University to develop a Met Office system to provide real-time IWV in < 2 hours from observation.

 Planned x10 increase in UK network by collaborations with other services.

 Aim to deliver an operational network of IWV measurements by 2005.

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Upper Air Networks – The Future.

 Further Automation.

 Integration.

 Increased use of high temporal & high resolution data.

 Use of other measurements ( i.e. Signal to Noise)

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Summary

 Integrated wind data already being used operationally and changing observing networks in the UK.

 Usefulness and potential benefits of IWV networks accepted by users and will be introduced into operations in next 2-3 years.

 Significant progress in exploiting the high resolution capabilities of remote sensing systems.  Progress in the techniques necessary to integrate different remote sensing system for temperature and humidity profiling.