The seasonality of circumnavigation Madden–Julian Oscillation (MJO) events is examined using 42 years observations, reanalysis, and global model simulations. MJO are most likely to propagate across the Atlantic Ocean, Africa back equatorial Indian Ocean relatively unweakened during March–April–May a lesser extent September–October–November. During these seasons, referred as “long-rain” “short-r...

Abstract Based on the database of Subseasonal to Seasonal (S2S) Prediction project World Weather Research Programme (WWRP) / Climate (WCRP), influence North Atlantic Oscillation (NAO) Madden- Julian (MJO) and its forecast skill is investigated. It found that most models can capture MJO phase changes following positive negative NAO events. About 20 days after initialized with a (negative) NAO, a...

Possible sources of the observed modulation tropical Madden-Julian oscillation (MJO) by stratospheric quasi-biennial (QBO) and 11-year solar cycle are investigated using 41 years reanalysis data archived climate model data. Larger upward fluxes extratropical planetary-scale waves, leading in some cases to sudden warmings (SSWs), late fall early winter during easterly phase QBO than westerly (th...

The atmospheric moisture and temperature profiles from the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit on the NASA Aqua mission, in combination with the precipitation from the Tropical Rainfall Measuring Mission (TRMM), are employed to study the vertical moist thermodynamic structure and spatial–temporal evolution of the Madden–Julian oscillation (MJO). The AIRS data in...

AMERICAN METEOROLOGICAL SOCIETY | 425 W eather prediction is typically concerned with lead times of hours to days, while seasonal-tointerannual climate prediction is concerned with lead times of months to seasons. Recently, there has been growing interest in “subseasonal” forecasts—those that have lead times on the order of weeks (e.g., Schubert et al. 2002; Waliser et al. 2003; Waliser et al. ...

A significant sign reversal in the meridional potential vorticity gradient was found during the summer of 1991 on the 310-K isentropic surface (near 700 mb) over the Caribbean Sea. The Charney–Stern necessary condition for instability of the mean flow is met in this region. It is speculated that the sign reversal permits either invigoration of African waves or actual generation of easterly wave...

The effect of the Madden–Julian oscillation (MJO) in the eastern Pacific on the North American monsoon is documented using NCEP–NCAR reanalysis and daily mean precipitation data from 1958 to 2003. It is found that positive zonal wind anomalies in the eastern tropical Pacific lead to above-normal precipitation in northwest Mexico and Arizona from several days to over a week later. This connectio...

Internal gravity waves influence a variety of phenomena in Earth’s stratosphere and upper troposphere, including aviation weather turbulence and circulations that set high-altitude distributions of ozone and greenhouse gases. Here coupling between the dominant mode of subseasonal variability of the equatorial atmosphere—the Madden-Julian oscillation (MJO)—and subtropical stratospheric gravity w...

The variability of rainfall and drop size distributions (DSDs) as a function of large-scale atmospheric conditions and storm characteristics is investigated using measurements from the Atmospheric Radiation Measurement Program (ARM) facility at Darwin, Australia. Observations are obtained from an impact disdrometer with a near continuous record of operation over five consecutive wet seasons (20...