Local identification of equatorial Kelvin waves in real-time operational forecasts

João B. Cruz; José M. Castanheira; Carlos C. DaCamara

doi:10.1002/qj.4717

Local identification of equatorial Kelvin waves in real-time operational forecasts

João B. Cruz, José M. Castanheira^*, Carlos C. DaCamara

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Equatorial Kelvin waves (KWs) are associated with a variety of equatorial atmospheric phenomena, namely, tropical convection, cloud and precipitation variability, tropical cyclogenesis, the onset of monsoon season over Africa and India, and even the quasi-biennial oscillation and the Madden–Julian oscillation. As such, if operational forecasts are to improve near the Tropics, it is important that they correctly represent KWs. This article aims at developing a novel methodology for identifying KWs in real-time operational forecasts at specific longitudes using only the meridional structures of the solutions to the free Laplace tidal equations, known as Hough vector functions. The main advantages of this newly proposed methodology are that (a) it can identify KWs at a specific longitude and (b) very low computational cost is needed to apply it to real-time operational forecasts. The application of the method to 2015–2017 European Centre for Medium-range Weather Forecasts (ECMWF) analysis and operational forecast data reveals a systematic bias in the representation of KWs by the ECMWF operational forecast model.

Original language	English
Pages (from-to)	2440-2457
Number of pages	18
Journal	Quarterly Journal of the Royal Meteorological Society
Volume	150
Issue number	761
Early online date	8 Apr 2024
DOIs	https://doi.org/10.1002/qj.4717
Publication status	Published - Apr 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.

Funding

This work was supported by IDL (UIDB/50019/2020) and CESAM (UIDP/50017/2020+UIDB/50017/2020+ LA/P/0094/2020) through national funds by Funda\u00E7\u00E3o para a Ci\u00EAncia e Tecnologia I.P./MCTES (FCT), Portugal. Thanks are due to Huib E. de Swart and Aarnout van Delden (IMAU, Department of Physics, Utrecht University) for their valuable guidance, comments, and insights. Finally, we thank Rita M. Cardoso (IDL, Faculty of Sciences, University of Lisbon) for her indispensable help and patience in retrieving the ECMWF data.

Funders	Funder number
Fundação para a Ciência e a Tecnologia
Ministério da Ciência, Tecnologia e Ensino Superior
Centro de Estudos Ambientais e Marinhos, Universidade de Aveiro
Instituto Dom Luiz, Universidade de Lisboa	UIDB/50019/2020

Keywords

equatorial waves
Kelvin waves
operational forecasts
tropical dynamics

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10.1002/qj.4717Licence: CC BY-NC-ND

Quart J Royal Meteoro Soc - 2024 - Cruz - Local identification of equatorial Kelvin waves in real‐time operationalFinal published version, 19.9 MBLicence: CC BY-NC-ND

Cite this

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title = "Local identification of equatorial Kelvin waves in real-time operational forecasts",

abstract = "Equatorial Kelvin waves (KWs) are associated with a variety of equatorial atmospheric phenomena, namely, tropical convection, cloud and precipitation variability, tropical cyclogenesis, the onset of monsoon season over Africa and India, and even the quasi-biennial oscillation and the Madden–Julian oscillation. As such, if operational forecasts are to improve near the Tropics, it is important that they correctly represent KWs. This article aims at developing a novel methodology for identifying KWs in real-time operational forecasts at specific longitudes using only the meridional structures of the solutions to the free Laplace tidal equations, known as Hough vector functions. The main advantages of this newly proposed methodology are that (a) it can identify KWs at a specific longitude and (b) very low computational cost is needed to apply it to real-time operational forecasts. The application of the method to 2015–2017 European Centre for Medium-range Weather Forecasts (ECMWF) analysis and operational forecast data reveals a systematic bias in the representation of KWs by the ECMWF operational forecast model.",

keywords = "equatorial waves, Kelvin waves, operational forecasts, tropical dynamics",

author = "Cruz, {Jo{\~a}o B.} and Castanheira, {Jos{\'e} M.} and DaCamara, {Carlos C.}",

note = "Publisher Copyright: {\textcopyright} 2024 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.",

year = "2024",

month = apr,

doi = "10.1002/qj.4717",

language = "English",

volume = "150",

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AU - Cruz, João B.

AU - Castanheira, José M.

AU - DaCamara, Carlos C.

PY - 2024/4

Y1 - 2024/4

N2 - Equatorial Kelvin waves (KWs) are associated with a variety of equatorial atmospheric phenomena, namely, tropical convection, cloud and precipitation variability, tropical cyclogenesis, the onset of monsoon season over Africa and India, and even the quasi-biennial oscillation and the Madden–Julian oscillation. As such, if operational forecasts are to improve near the Tropics, it is important that they correctly represent KWs. This article aims at developing a novel methodology for identifying KWs in real-time operational forecasts at specific longitudes using only the meridional structures of the solutions to the free Laplace tidal equations, known as Hough vector functions. The main advantages of this newly proposed methodology are that (a) it can identify KWs at a specific longitude and (b) very low computational cost is needed to apply it to real-time operational forecasts. The application of the method to 2015–2017 European Centre for Medium-range Weather Forecasts (ECMWF) analysis and operational forecast data reveals a systematic bias in the representation of KWs by the ECMWF operational forecast model.

AB - Equatorial Kelvin waves (KWs) are associated with a variety of equatorial atmospheric phenomena, namely, tropical convection, cloud and precipitation variability, tropical cyclogenesis, the onset of monsoon season over Africa and India, and even the quasi-biennial oscillation and the Madden–Julian oscillation. As such, if operational forecasts are to improve near the Tropics, it is important that they correctly represent KWs. This article aims at developing a novel methodology for identifying KWs in real-time operational forecasts at specific longitudes using only the meridional structures of the solutions to the free Laplace tidal equations, known as Hough vector functions. The main advantages of this newly proposed methodology are that (a) it can identify KWs at a specific longitude and (b) very low computational cost is needed to apply it to real-time operational forecasts. The application of the method to 2015–2017 European Centre for Medium-range Weather Forecasts (ECMWF) analysis and operational forecast data reveals a systematic bias in the representation of KWs by the ECMWF operational forecast model.

KW - equatorial waves

KW - Kelvin waves

KW - operational forecasts

KW - tropical dynamics

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ER -

Local identification of equatorial Kelvin waves in real-time operational forecasts

Abstract

Bibliographical note

Funding

Keywords

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