Skip to main content

Volume 61 Supplement 4

Special Issue: Coupling Processes in the Equatorial Atmosphere (CPEA)

Diurnal and intraseasonal variation of UTLS vertical wind disturbance in the equatorial region and its relation to tropospheric convective activities


Vertical wind variations in the Upper Troposphere and Lower Stratosphere (UTLS) measured by the Equatorial Atmosphere Radar (EAR) at Kototabang, Sumatra, between 2003 and 2005 but mainly in 2004, have been statistically analyzed to study the characteristics of wind variances associated with convective activity, which is related to gravity wave generation and propagation. The analyses are intended to characterize relatively short period disturbances of less than 12 hours and an energy propagation direction of a relatively high elevation angle, and to relate vertical wind variations to convective activity close to the EAR. Correlation analyses between vertical wind variations and rainfall show that the wind variances have a clear diurnal variation indicating probable effects of tropospheric convection. They also show some intraseasonal variation. However, there are no significant correlations with the Out-going Long-wave Radiation (OLR) anomaly. The correlations between variances at UT and LS suggest that the UTLS coupling of vertical wind variation through upward propagation of gravity wave is similarly evident in the afternoon during both the active and the inactive phase of OLR that is a proxy of large-scale convective activity.


  • Alexander, M. J. and J. R. Holton, A Model study of zonal forcing in the equatorial stratosphere by convectively induced gravity waves, J. Atmos. Sci., 54, 408–419, 1997.

    Article  Google Scholar 

  • Alexander, M. J., J. R. Holton, and D. R. Durran, The gravity wave response above deep convection in a squall line simulation, J. Atmos. Sci., 52, 2212–2226, 1995.

    Article  Google Scholar 

  • Alexander, M. J., H. H. Bares, and L. Pfister, Tropical stratospheric gravity wave activity and relationship to clouds, J. Geophys. Res., 105, 22,299–22,309, 2000.

    Article  Google Scholar 

  • Alexander, M. J., P. T. May, and J. H. Beres, Gravity waves generated by convection in the Darwin area during the Darwin Area Wave Experiment, J. Geophys. Res., 109, doi:10.1029/2004JD004729, 2004.

  • Alexander, S. P., T. Tsuda, J. Furumoto, T. Shimomai, T. Kozu, and M. Kawashima, A statistical overview of convection during the first CPEA campaign, J. Meteor. Soc. Jpn., 84A, 57–93, 2006.

    Article  Google Scholar 

  • Alexander, S. P., T. Tsuda, Y. Shibagaki, and T. Kozu, Seasonal gravity wave activity observed with the Equatorial Atmosphere Radar and its relation to rainfall information from the Tropical Rainfall Measuring Mission, J. Geophys. Res., 113, D02104, doi:10.1029/2007JD008777, 2008.

    Google Scholar 

  • BMRC,, 2008.

  • Dhaka, S. K., M. Takahashi, Y. Kawatani, S. Malik, Y. Shibagaki, and S. Fukao, Observations of deep convective updrafts in tropical convection and their role in the generation of gravity waves, J. Meteor. Soc. Jpn., 81, 1185–1199, 2003.

    Article  Google Scholar 

  • Dhaka, S. K., M. K. Yamamoto, Y. Shibagaki, H. Hashiguchi, M. Yamamoto, and S. Fukao, Convection-induced gravity waves observed by the Equatorial Atmosphere Radar (0.20°S, 100.32°E) in Indonesia, Geophys. Res. Lett., 32, L14820, doi:10.1029/2005GL022907, 2005.

    Article  Google Scholar 

  • Doviak, R. J. and D. S. Zrnic, Doppler Radar and Weather Observations, 562 pp., Academic Press, 1993.

    Google Scholar 

  • Dutta, G., B. Bapiraju, P. Balasubrahmanyam, and H. A. Basha, VHF radar observations of gravity waves at a low latitude, Ann. Geophys., 17, 1012–1019, 1999.

    Article  Google Scholar 

  • Dutta, G., T. Tsuda, P. V. Kumar, M. C. A. Kumar, S. P. Alexander, and T. Kozu, Seasonal variation of short-period (<2 h) gravity wave activity over Gadanki, India (13.5°N, 79.2°E), J. Geophys. Res., 113, D14103, doi:10.1029/2007JD009178, 2008.

    Article  Google Scholar 

  • Fovell, R., D. Durran, and J. R. Holton, Numerical simulations of convectively generated stratospheric gravity waves, J. Atmos. Sci., 49, 1427–1442, 1992.

    Article  Google Scholar 

  • Fukao, S., Copupling Processes in the Equatorial Atmosphere (CPEA): A project overview, J. Meteor. Soc. Jpn., 84A, CPEA Special Issue, 1–18, 2006.

    Article  Google Scholar 

  • Fukao, S., H. Hashiguchi, M. Yamamoto, T. Tsuda, T. Nakamura, M. K. Yamamoto, T. Sato, M. Hagio, and Y. Yabugaki, The Equatorial Atmosphere Radar (EAR): System description and first results, Radio Sci., 38, 1053, doi:10.1029/2002RS002767, 2003.

    Article  Google Scholar 

  • Kawashima, M., Y. Fujiyoshi, M. Ohi, T. Honda, T. Kozu, T. Shimomai, and H. Hashiguchi, Overview of Doppler radar observations of precipitating cloud systems in Sumatera Island during the first CPEA campaign, J. Meteor. Soc. Jpn., 84A, CPEA Special Issue, 33–56, 2006.

    Article  Google Scholar 

  • Kodama, Y.-M., M. Tokuda, and F. Murata, Convective activity over the Indonesian Maritime Continent during CPEA-I as evaluated by lightning activity and Q1 and Q2 profiles, J. Meteor. Soc. Jpn., 84A, CPEA Special Issue, 133–149, 2006.

    Article  Google Scholar 

  • Kozu, T., T. Shimomai, Z. Akramin, Marzuki, Y. Shibagaki, and H. Hashiguchi, Intraseasonal variation of raindrop size distribution at Koto Tabang, West Sumatra, Indonesia, Geophys. Res. Lett., 32, L07803, doi:10.1029/2004GL022340, 2005.

    Article  Google Scholar 

  • Kozu, T., K. K. Reddy, S. Mori, M. Thurai, J. T. Ong, D. N. Rao, and T. Shimomai, Seasonal and diurnal variations of raindrop size distribution in Asian monsoon region, J. Meteor. Soc. Jpn., 84A, CPEA Special Issue, 195–209, 2006.

    Article  Google Scholar 

  • Madden, R. A. and P. R. Julian, Observations of the 40–50-day tropical oscillation—A review, Mon. Wea. Rev., 122, 814–837, 1994.

    Article  Google Scholar 

  • Mori, S., J.-I. Hamada, Y. I. Tauhid, M. D. Yamanaka, N. Okamoto, F. Murata, N. Sakurai, H. Hashiguchi, and T. Sribimawati, Diurnal land-sea rainfall peak migration over Sumatera Island, Indonesian maritime continent observed by TRMM satellite and intensive rawinsonde soundings, Mon. Wea. Rev., 132, 2021–2039, 2004.

    Article  Google Scholar 

  • Morita, J., Y. N. Takayabu, S. Shige, and Y. Kodama, Analysis of rainfall characteristics of the Madden-Julian oscillation using TRMM satellite data, Dyn. Atmosph. Ocea., 42, 107–126, 2006.

    Article  Google Scholar 

  • Shibagaki, Y., T. Shimomai, T. Kozu, S. Mori, Y. Fujiyoshi, H. Hashiguchi, M. K. Yamamoto, S. Fukao, and M. D. Yamanaka, Multi-scale aspects of convective systems associated with an intraseasonal oscillation over the Indonesian Maritime Continent, Mon. Wea. Review, 134, 1682–1696, 2006.

    Article  Google Scholar 

  • Tsuda, T., Y. Murayama, H. Wiryosumarto, S. B. Harijono, and S. Kato, Radiosonde observations of equatorial atmosphere dynamics over Indonesia, 2, characteristics of gravity waves, J. Geophys. Res., 99, 10,507–10,516, 1994.

    Article  Google Scholar 

  • Wheeler, M. and G. N. Kiladis, Convectively coupled equatorial waves: Analysis of clouds and temperature in the wavenumber-frequency domain, J. Atmos. Sci., 56, 374–399, 1999.

    Article  Google Scholar 

  • Yamamoto, M. K., N. Nishi, T. Horinouchi, M. Niwano, and S. Fukao, Vertical wind observation in the tropical upper troposphere by VHF wind profiler: A case study, Radio Sci., 42, doi:10.1029/2006RS003538, 2007.

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Toshiaki Kozu.

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit

Reprints and permissions

About this article

Cite this article

Kozu, T., Kodama, YM., Shibagaki, Y. et al. Diurnal and intraseasonal variation of UTLS vertical wind disturbance in the equatorial region and its relation to tropospheric convective activities. Earth Planet Sp 61, 535–544 (2009).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Key words