Abstract
A rotating coordinate frame of reference is used to analyze the propagation of high brightness temperature (Tb) anomalies resembling episodes of the Madden-Julian waves confined to the tropical oceans. Looking within the 37 GHz horizontally polarized frequency band of the Special Sensor Microwave Imager (SSM/I) aboard the F10 and F11 satellites, high Tb features identical to an intraseasonal oscillation in the tropics have been observed. Hovmoeller and Pentad Mean Anomaly (PMA) diagrams showed separate events of these features propagating over the equatorial Indian/Western Pacific Ocean basins. The composite Tb anomalies show a five-stage morphology process: initiation east of equatorial Africa, intensification when propagating through the Indian Ocean, fully mature stage in the maritime continent, and a weakening over the western Pacific followed by dissipation near the International Date Line. These Tb anomalies demonstrate longitudinal, temporal and latitudinal dependence as the features propagate. The dominant feature is observed over the Indo-pacific ocean basin propagating eastward at a phase speed of approximately 5 deg / day. A model was then developed where these Tb anomalies were placed in a rotating coordinate frame at speeds within the vicinity of 5 deg / day in an attempt to produce frozen features of Madden-Julian Oscillations (MJO's). With this method (freezing the propagating event), analyses were performed on the anomalies without blurring the feature. The averaged lifetime of each event was around 30 to 40 days.
Dossen, Josephus (1999). Investigation of Madden-Julian waves using a rotating coordinate frame from microwave radiometric measurements. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1999 -THESIS -D679.