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Start Over Author "Kiladis, George N." Journal monthly weather review
19 results on '"Kiladis, George N."'

3. CORRIGENDUM

Author

Kiladis, George N., primary, Dias, Juliana, primary, Straub, Katherine H., primary, Wheeler, Matthew C., primary, Tulich, Stefan N., primary, Kikuchi, Kazuyoshi, primary, Weickmann, Klaus M., primary, and Ventrice, Michael J., primary

Published
2020
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4. Tropical Origins of Weeks 2–4 Forecast Errors during the Northern Hemisphere Cool Season.

Author

Dias, Juliana, Tulich, Stefan N., Gehne, Maria, and Kiladis, George N.

Subjects
MADDEN-Julian oscillation, PRECIPITATION anomalies, FORECASTING, LEAD time (Supply chain management), NUMERICAL weather forecasting
Abstract

A set of 30-day reforecast experiments, focused on the Northern Hemisphere (NH) cool season (November–March), is performed to quantify the remote impacts of tropical forecast errors on the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS). The approach is to nudge the model toward reanalyses in the tropics and then measure the change in skill at higher latitudes as a function of lead time. In agreement with previous analogous studies, results show that midlatitude predictions tend to be improved in association with reducing tropical forecast errors during weeks 2–4, particularly over the North Pacific and western North America, where gains in subseasonal precipitation anomaly pattern correlations are substantial. It is also found that tropical nudging is more effective at improving NH subseasonal predictions in cases where skill is relatively low in the control reforecast, whereas it tends to improve fewer cases that are already relatively skillful. By testing various tropical nudging configurations, it is shown that tropical circulation errors play a primary role in the remote modulation of predictive skill. A time-dependent analysis suggests a roughly 1-week lag between a decrease in tropical errors and an increase in NH predictive skill. A combined tropical nudging and conditional skill analysis indicates that improved Madden–Julian oscillation (MJO) predictions throughout its life cycle could improve weeks 3–4 NH precipitation predictions. [ABSTRACT FROM AUTHOR]

Published
2021
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18. The Southern Oscillation. Part VII: Meteorological Anomalies over the Indian and Pacific Sectors Associated with the Extremes of the Oscillation

Author

Kiladis, George N. and van Loon, Harry

Abstract

AbstractComposite surface pressure, temperature, and precipitation anomalies are mapped over the Indian and Pacific sectors during the various stages of Warm and Cold Events in the Southern Oscillation. In the year before the development of positive sea surface temperature anomalies in the central and eastern equatorial Pacific (Year–1 of a Warm Event), a strong South Pacific High is associated with below normal surface pressure over Australia and the Indian Ocean. This occurs concurrently with a poleward displacement of the Pacific convergence zones, with above normal air temperature and precipitation over the subtropical Pacific, and opposite conditions along the equator. By the next year (Year 0) of the Warm Event, thew anomalies have the opposite sign. The sequence of anomalies during a Cold Event is inverse to that during a Warm Event but otherwise the anomaly patterns are remarkably similar.It appears that enhanced convection and low surface pressure within the Pacific convergence zones contribute to the observed westerly wind anomalies in the western equatorial Pacific at the end of Year–1, which are in turn tied to the onset of above normal equatorial SST in the following year. The observed reversal in atmospheric anomalies over the Indian and Pacific oceans daring Warm Events is an extreme manifestation of a general biennial tendency in these anomalies, with Cold Events occupying the opposite extreme.

Published
1988
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