LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Krishnamurti, T. N.; Gadgil, Sulochana (2011)
Publisher: Co-Action Publishing
Journal: Tellus A
Languages: English
Types: Article
Subjects:
6 vertical levels of the entire 365-day global FGGE Illb analysis for 5 variables are subjected to a time-series analysis and a frequency filter to investigate the structure of the 30- to 50-day mode. This study isolates regions where the amplitude of these low-frequency oscillations are large; the vertical structures across these large amplitude regions are also presented. The seasonal variation of the maximum 30–50 day filtered wind in the lower troposphere is highlighted. The major results for the FGGE year show that the 30- to 50-day mode has its largest amplitude in the upper troposphere of polar latitudes and in the summer monsoon region. During the northern winter, active regions are also located over the equatorial belt of the central Pacific ocean. The phase propagation on the pressure surfaces are examined simply from an analysis of a time sequence of low-frequency weather maps. The vertical phase propagation is illustrated by pressure-time plots of the low-frequency data sets at individual locations. This analysis suggests vertical propagation over convective areas and a lack of it over most other regions. A highlight of this study is a phenomenon we have labelled as “low-frequency storms”. Here we illustrate long-lasting, low-frequency, weather systems that propagate meridionally (1) over the summer monsoon regions from the equator to the Himalayas and (2) over the eastern Pacific ocean from the equator northwards during the northern winter season. An example of such a long-lasting system is traced to 60° N; subsequently, it appears to move zonally from the gulf of Alaska across the Canadian Arctic, north Atlantic, and Europe prior to its dissipation over Siberia. The potential for interactions between these low-frequency systems and polar front cyclones is another interesting aspect of this investigation. The low-frequency oscillations and motions are considered important since their amplitude in the troposphere is large (8 ms-1) and they are well-defined within their scales of motion (on the order of 4000 km or larger).DOI: 10.1111/j.1600-0870.1985.tb00432.x
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • Y O E Chang, Chih-Pei 1977. Viscous internal gravity waves and low-frequency oscillations in the tropics. J . Atmos. Sci. 34,901-910.
    • Dunkerton, T. J. 1983. A nonsymmetric equatorial inertial instability. J . Atmos. Sci. 40, 807-8 13.
    • Endlich, R. M., Singleton, R. C. and Kaufman, J. W. 1969. Analysis of detailed vertical wind speed profiles. J. Atmos. Sci. 26, 1030-1041.
    • Guillemin, E. A. 1957. Synthesis of passive networks. Wiley, 571 pp.
    • Hayashi, Y. 1972. A method of analyzing transient waves by space-time cross spectra. J . Appl. Meteorol. 12,404-408.
    • Krishnamurti, T. N. and Bhalme, H. N. 1976. Oscillations of a monsoon system. Part I: Observational aspects. J . Atrnos. Sci. 33, 1937-1953.
    • Krishnamurti, T. N. and Subrahmanyam, D. 1982. The 30-50 day mode at 850 mb during MONEX. J. Atmos. Sci. 39,2088-2095.
    • Krishnamurti, T. N., Jayakumar, P. K., Sheng, J., Surgi, N. and Kumar, A. 1985. Divergent circulations on the 30- to 50-day time scale. J . Atmos. Sci. 00, 000-000.
    • Lorenc, C. 1980. A global three-dimensional multivariate statistical interpolation scheme. Mon. Wea. Rev. 109,701-721.
    • Lorenc, C . 1984. The evolution of planetary scale 200 mb divergences during the F G G E year. Meteorological office Technical note No. II/210, pp. 1-23. Available from Dynamical Climatology Branch, Meteorological Office, London Road, Bracknell, Berkshire, England.
    • Madden, R. A. and Julian, P. R. 1971. Detection of a 40-50 day oscillation in the zonal wind in the tropical Pacific. J. Atrnos. Sci. 28, 702-708.
    • Madden, R. A. and Julian, P. R. 1972. Description of global-scale circulations cells in the tropics with a 40-50 day period. J. Atrnos. Sci. 29, 1109-1 123.
    • Murakami, M. 1979. Large-scale aspects of deep convective activity over the G A T E area. Mon. Wea. Rev. 107,994-1013.
    • Murakami, M. 1983. Analysis of the deep convective activity over the western Pacific and southeast Asia. Part I: Diurnal variation. J . Meteorol. SOCJ.apan 61, 6&76.
    • Murakami, M. 1984. Analysis of deep convective activity over the western Pacific and Southeast Asia. Part 11. J . Meteorol. SOCJ.apan 62,88-108.
    • Murakami, T., Nakazawa, T. and Jin Hai He 1983. 40-50 day oscillations during the 1979 Northern Hemisphere summer. Technical Report No. UHMET 83-02. Department of Meteorology, University of Hawaii, Honolulu, Hawaii.
    • Quah, Leong-Chuan 1983. On the 30-50 day tropospheric oscillation during the 1978-79 Northern Winter. Masters Thesis, Department of Meteorology, Florida State University, Tallahassee, Florida, 32306.
    • Shanks, J. C 1967. Recursion filters for digital processing. Geophysica 32, 33-5 1.
    • Sikka, D. R. and Gadgil, S. 1980. On the maximum cloud zone and the ITCZ over Indian Longitudes during the southwest monsoon. Mon. Wea. Rev. 108, 1840-1853.
    • Simmons, A. J.. Wallace, J. M., Branslator, G . W. 1983. Barotropic wave instability and atmospheric teleconnection patterns. J. A m o s . Sci. 40, 1363-1 392.
    • Stevens, D. E. 1983. On symmetric stability and instability of zonal mean flows near the equator. J . Atmos. Sci. 40, 882-908.
    • Webster, P. J. 1983. Mechanisms of monsoon lowfrequency variability: surface hydrological effects. J . Atmos. Sci. 40, 2 I 1&2 124.
    • Yasunari, T. 1981. Structure of an Indian summer monsoon system with around 40-day period. J. Meteorol. SOCJ.apan 59,336-354.
    • Yasunari, T. 1980. A quasi-stationary appearance of 30- to 40-day period in the cloudiness fluctuations during the summer monsoon over India. J. Meteorol. Soc. Japan 58,225-229.
    • Zangvil, A. 1977. On the presentation and interpretation of spectra of large-scale disturbances. Mon. Wea. Rev. 105, 1469-1472.
  • No related research data.
  • Discovered through pilot similarity algorithms. Send us your feedback.

Share - Bookmark

Cite this article

Collected from