A Systemic Analysis of Multiscale Deep Convective Variability over the Tropical Pacific

نویسندگان

  • WEN-WEN TUNG
  • MITCHELL W. MONCRIEFF
  • JIAN-BO GAO
چکیده

The multiscale tropical deep convective variability over the Pacific Ocean is examined with the 4-month highresolution deep convection index ( ) derived from satellite imagery. With a systemic view, the complex ITBB phenomenon is described with succinct parameters known as generalized dimensions associated with the correlation structures embedded in the observed time series, with higher-order dimensions emphasizing extreme convective events. It is suggested that convective activities of lifetimes ranging from 1 h to ;21 days have interdependence across scales that can be described by a series of power laws; hence, a spectrum of generalized dimensions, that is, the time series is multifractal. The spatiotemporal features of the time series is I I T T BB BB preliminarily examined by changing the spatial domain from 0.18 3 0.18 to 258 3 258. The multifractal features are weakened with increasing strength of spatial averaging but cannot be eliminated. Furthermore, the data ITBB has the property of long-range dependency, implying that its autocorrelation function decays with a power law in contrast to the zero or exponentially decaying autocorrelation functions for white and commonly used red noise processes generated from autoregressive models. Physically, this means that intensified convection tends to be followed by another intensified event, and vice versa for weakened events or droughts. Such tendency is stronger with larger domain averaging, probably due to more complete inclusion of larger-scale variability that has more definite trends, such as the supercloud clusters associated with the Madden–Julian oscillation (MJO). The evolution of cloud clusters within an MJO event is studied by following the MJO system across the analysis domain for ;21 days. Convective activities along the front, center, and rear parts of the MJO event continuously intensify while approaching the date line, indicating multifractal features in the range of 1 h to about 5–10 days. Convective activity along the front and rear edges of the MJO event are more intermittent than in the center. The multifractal features of the time series can be approximated by the random multiplicative cascade ITBB processes, suggesting likely mechanisms for the multiscale behavior and casting concern on the predictability time scale of the observed phenomena.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

The Tropical–Extratropical Interaction between High-Frequency Transients and the Madden–Julian Oscillation

The interaction between high-frequency transient disturbances and convection, and the Madden–Julian Oscillation (MJO), is investigated using NCEP–NCAR reanalysis and satellite outgoing longwave radiation data for 15 northern winters. During the phase of the MJO with enhanced convection over the East Indian Ocean and Indonesia, and suppressed convection over the South Pacific convergence zone, b...

متن کامل

The influence of convective outflow on water vapor mixing ratios in the tropical upper troposphere An analysis based on UARS MLS measurements

The source of increased water vapor mixing raregions of convective outflow. These studies dealt with varitios over the central and eastern tropical Pacific region during ations in relative humidity over a broad region of the tropthe 1992 E1 Nifio event is examined using measurements of ical upper troposphere (i.e., 200-500 hPa). Presently, it is upper tropospheric water vapor provided by the Mi...

متن کامل

Detection of tropical deep convective clouds from AMSU-B water vapor channels measurements

[1] Methods to detect tropical deep convective clouds and convective overshooting from measurements at the three water vapor channels (183.3 ± 1, 183.3 ± 3, and 183.3 ± 7 GHz) of the Advanced Microwave Sounding Unit-B (AMSU-B) are presented. Thresholds for the brightness temperature differences between the three channels are suggested as criterion to detect deep convective clouds, and an order ...

متن کامل

Tropical Intraseasonal Variability in Version 3 of the GFDL Atmosphere Model

Tropical intraseasonal variability is examined in version 3 of the Geophysical Fluid Dynamics Laboratory AtmosphereModel (AM3). In contrast to its predecessor AM2, AM3 uses a new treatment of deep and shallow cumulus convection and mesoscale clouds. The AM3 cumulus parameterization is a massflux-based scheme but also, unlike that in AM2, incorporates subgrid-scale vertical velocities; these pla...

متن کامل

Extreme Convection of the Near-Equatorial Americas, Africa, and Adjoining Oceans as seen by TRMM

This study documents the preferred location and diurnal cycle of extreme convective storms that occur in the tropical band containing the east Pacific Ocean, Central and South America, the Atlantic Ocean, and northern Africa. Data from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar show three types of convective-stratiform structures that constitute extreme convective events...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2003