Aspects of the 40–50 Day Oscillation during the Northern Summer as Inferred from Outgoing Longwave Radiation

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Abstract
Intraseasonal variability Of tropical convection over the Indian Ocean/Pacific region during northern summer is studied using outgoing longwave radiation (OLR). OLR anomalies are found to propagate eastward along the equator from the Indian 0cean to the western Pacific and northward towards the Indian subcontinent and southern China. It is found that the dominant mode of tropical convection consists of a dipole with centers located over the Indian 0cean and the western Pacific/South China Set. This dipole undergoes complex structural changes over a broad period range centered around 40–50 days. During a typical oscillation, an anomaly first develops over the equatorial Indian Ocean. This anomaly then extends eastward to the equatorial western and central Pacific to form an elongated convection zone, while its center is displaced progressively northward from the Indian Ocean into the Indian subcontinent by an anomaly of the opposite sign. The elongated convection zone over the western Pacific then... Abstract Intraseasonal variability Of tropical convection over the Indian Ocean/Pacific region during northern summer is studied using outgoing longwave radiation (OLR). OLR anomalies are found to propagate eastward along the equator from the Indian 0cean to the western Pacific and northward towards the Indian subcontinent and southern China. It is found that the dominant mode of tropical convection consists of a dipole with centers located over the Indian 0cean and the western Pacific/South China Set. This dipole undergoes complex structural changes over a broad period range centered around 40–50 days. During a typical oscillation, an anomaly first develops over the equatorial Indian Ocean. This anomaly then extends eastward to the equatorial western and central Pacific to form an elongated convection zone, while its center is displaced progressively northward from the Indian Ocean into the Indian subcontinent by an anomaly of the opposite sign. The elongated convection zone over the western Pacific then...