Met Office Unified Model Tropical Cyclone Performance Following Major Changes to the Initialization Scheme and a Model Upgrade

Julian T. Heming Met Office, Exeter, Devon, United Kingdom

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Abstract

The Met Office has used various schemes to initialize tropical cyclones (TCs) in its numerical weather prediction models since the 1980s. The scheme introduced in 1994 was particularly successful in reducing track forecast errors in the model. Following modifications in 2007 the scheme was still beneficial, although to a lesser degree than before. In 2012 a new trial was conducted that showed that the scheme now had a detrimental impact on TC track forecasts. As a consequence of this, the scheme was switched off. The Met Office Unified Model (MetUM) underwent a major upgrade in 2014 including a new dynamical core, changes to the model physics, an increase in horizontal resolution, and changes to satellite data usage. An evaluation of the impact of this change on TC forecasts found a positive impact both on track and particularly intensity forecasts. Following implementation of the new model formulation in 2014, a new scheme for initialization of TCs in the MetUM was developed that involved the assimilation of central pressure estimates from TC warning centers. A trial showed that this had a positive impact on both track and intensity predictions from the model. Operational results from the MetUM in 2014 and 2015 showed that the combined impact of the model upgrade and new TC initialization scheme was a dramatic cut in both TC track forecast errors and intensity forecast bias.

Corresponding author address: Julian T. Heming, Met Office, FitzRoy Road, Exeter, Devon, EX1 3PB, United Kingdom. E-mail: julian.heming@metoffice.gov.uk

Abstract

The Met Office has used various schemes to initialize tropical cyclones (TCs) in its numerical weather prediction models since the 1980s. The scheme introduced in 1994 was particularly successful in reducing track forecast errors in the model. Following modifications in 2007 the scheme was still beneficial, although to a lesser degree than before. In 2012 a new trial was conducted that showed that the scheme now had a detrimental impact on TC track forecasts. As a consequence of this, the scheme was switched off. The Met Office Unified Model (MetUM) underwent a major upgrade in 2014 including a new dynamical core, changes to the model physics, an increase in horizontal resolution, and changes to satellite data usage. An evaluation of the impact of this change on TC forecasts found a positive impact both on track and particularly intensity forecasts. Following implementation of the new model formulation in 2014, a new scheme for initialization of TCs in the MetUM was developed that involved the assimilation of central pressure estimates from TC warning centers. A trial showed that this had a positive impact on both track and intensity predictions from the model. Operational results from the MetUM in 2014 and 2015 showed that the combined impact of the model upgrade and new TC initialization scheme was a dramatic cut in both TC track forecast errors and intensity forecast bias.

Corresponding author address: Julian T. Heming, Met Office, FitzRoy Road, Exeter, Devon, EX1 3PB, United Kingdom. E-mail: julian.heming@metoffice.gov.uk
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  • Clayton, A. M., Lorenc A. C. , and Barker D. M. , 2013: Operational implementation of a hybrid ensemble/4D-Var global data assimilation system at the Met Office. Quart. J. Roy. Meteor. Soc., 139, 14451461, doi:10.1002/qj.2054.

    • Search Google Scholar
    • Export Citation
  • Davies, T., Cullen M. J. P. , Malcolm A. J. , Mawson M. H. , Staniforth A. , White A. A. , and Wo N. , 2005: A new dynamical core for the Met Office’s global and regional modelling of the atmosphere. Quart. J. Roy. Meteor. Soc., 131, 17591782, doi:10.1256/qj.04.101.

    • Search Google Scholar
    • Export Citation
  • Dvorak, V., 1975: Tropical cyclone intensity analysis and forecasting from satellite imagery. Mon. Wea. Rev., 103, 420430, doi:10.1175/1520-0493(1975)103<0420:TCIAAF>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Dvorak, V., 1984: Tropical cyclone intensity analysis using satellite data. NOAA Tech. Rep. NESDIS 11, 47 pp. [Available from NOAA/NESDIS, 5200 Auth Rd., Washington, DC 20233.]

  • Gross, J., 1996: 1995 National Hurricane Center forecast verification. National Hurricane Center, Miami, FL, 14 pp. [Available online at http://www.nhc.noaa.gov/verification/pdfs/Verification_1995.pdf.]

  • Heming, J. T., 2009: Evaluation of and improvements to the Met Office tropical cyclone initialisation scheme. Meteor. Appl., 16, 339351, doi:10.1002/met.129.

    • Search Google Scholar
    • Export Citation
  • Heming, J. T., 2012: Tropical cyclone predictions from the Met Office and ECMWF global models - Relative performance and error diagnosis. Proc. 30th Conf. on Hurricanes and Tropical Meteorology, Ponte Vedra Beach, FL, Amer. Meteor. Soc., 4A.6. [Available online at https://ams.confex.com/ams/30Hurricane/webprogram/Paper205026.html.]

  • Heming, J. T., 2014: The impact on tropical cyclone predictions of a major upgrade to the Met Office Global Model. Proc. 31st Conf. on Hurricanes and Tropical Meteorology, San Diego, CA, Amer. Meteor. Soc., 11A.3. [Available online at https://ams.confex.com/ams/31Hurr/webprogram/Paper243428.html.]

  • Heming, J. T., 2016: The method used to verify the forecast tracks of tropical cyclones in Met Office numerical weather prediction models. Meteor. Appl., in press.

    • Search Google Scholar
    • Export Citation
  • Heming, J. T., and Radford A. M. , 1998: The performance of the United Kingdom Meteorological Office global model in predicting the tracks of Atlantic tropical cyclones in 1995. Mon. Wea. Rev., 126, 13231331, doi:10.1175/1520-0493(1998)126<1323:TPOTUK>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Heming, J. T., Chan J. C. L. , and Radford A. M. , 1995: A new scheme for the initialisation of tropical cyclones in the UK Meteorological Office global model. Meteor. Appl., 2, 171184, doi:10.1002/met.5060020211.

    • Search Google Scholar
    • Export Citation
  • Knaff, J. A., and Zehr R. M. , 2007: Reexamination of tropical cyclone pressure–wind relationships. Wea. Forecasting, 22, 7188, doi:10.1175/WAF965.1.

    • Search Google Scholar
    • Export Citation
  • Lander, M. A., 2014: Super Typhoon Haiyan’s 170 kt peak intensity: Has Super Typhoon Tip been dethroned? Proc. 31st Conf. on Hurricanes and Tropical Meteorology, San Diego, CA, Amer. Meteor. Soc., 9C.8. [Available online at https://ams.confex.com/ams/31Hurr/webprogram/Paper245225.html.]

  • Met Office, 2014: ENDGame: A new dynamical core for seamless atmospheric prediction. [Available online at http://www.metoffice.gov.uk/research/news/2014/endgame-a-new-dynamical-core.]

  • Morgerman, J., 2014: iCyclone chase report: Super Typhoon HAIYAN in Tacloban City & Leyte, Philippines. iCyclone.com Chase Rep., 47 pp. [Available online at http://www.icyclone.com/upload/chases/haiyan/iCyclone_HAIYAN_in_Tacloban_City_040314.pdf.]

  • Neumann, C. J., 1972: An alternative to the HURRAN tropical cyclone forecast system. Mon. Wea. Rev., 100, 245255, doi:10.1175/1520-0493(1972)100<0245:PAOTHT>2.3.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wood, N., and Coauthors, 2014: An inherently mass-conserving semi-implicit semi-Lagrangian discretization of the deep-atmosphere global non-hydrostatic equations. Quart. J. Roy. Meteor. Soc., 140, 15051520, doi:10.1002/qj.2235.

    • Search Google Scholar
    • Export Citation
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