A Climatology of Tropical Synopical Scale Behavior From Tovs-Estimated Precipitable Water
Abstract
Tropical synoptic scale behavior is examined using 3 to 8 day filtered precipitable water (PW) estimated from TOVS operational satellite observations for 24 three-month seasons. Zonally-oriented tropical convergence zones and regions of enhanced synoptic variance are quantified and found to be poorly correlated with each other. Time-longitude plots (Hovmoller format) identify spatially coherent PW anomalies that can often be tracked around the globe. The strongest and most consistent signal is of eastward propagation across northern hemisphere Africa. Other regions demonstrate both eastward or westward propagation according to season and location. A general shift from eastward to westward propagation occurs between 20 deg and 30 deg latitude in each hemisphere. Hovmoller composites suggest an additional eastward propagating mode between 5 deg N and 12.5 deg N during SON across the entire Pacific Ocean. Seven tropical regions are chosen to perform climatological studies of synoptic scale behavior. Hovmoller composites reveal 10 m/s westward propagation across the North Atlantic (zonal wavelength is 6,000 km) and 7 m/s eastward propagation of over Sahel Africa (zonal wavelength is 2,500-3,000 km). Composites over the southern Indian Ocean suggest westward motion, while propagation in the ITCZ, SPCZ, west Pacific warm pool, and Amazon basin shows little preference of zonal direction.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 09, 1997
- Accession Number
- ADA320428
Entities
People
- Morgan D. Mackey
Organizations
- Air Force Institute of Technology