The structure and characteristics of African easterly wave disturbances as determined from the ECMWF operational analysis/forecast system

Reed, Richard J.; Klinker, E.; Hollingsworth, A.

doi:10.1007/bf01029944

Cited by 99 publications

(113 citation statements)

References 18 publications

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“…The AEJ is much stronger than the climatological average value of 15 m s _1 often quoted and also located about 5° of latitude equatorward of the expected latitude for August (cf. Reed et al 1977). Newell and Kidson (1984) and more recently Grist and Nicholson (2001) suggest that the AEJ is stronger and equatorward of its mean position during dry Sahelian years.…”

Section: Meteorological Situation During the Experimentmentioning

confidence: 99%

“…Operational forecasters are forced to combine the outputs from deficient NWP models with crude empirical rules. Our knowledge of the AEWs is dominated by three sources: the GATE data (e.g., Reed et al 1977), NWP analyses (e.g., Reed et al 1988;Diedhiou et al 1999), and theoretical models (e.g., Thorncroft and Hoskins 1994a,b;Paradis et al 1995). While Reed et al (1977) provided us with a valuable description of AEWs, our view is dominated by the composite analyses close to the West African coast.…”

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confidence: 99%

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The JET2000 Project: Aircraft Observations of the African Easterly Jet and African Easterly Waves

Thorncroft¹,

Parker²,

Burton³

et al. 2003

Bull. Amer. Meteor. Soc.

103

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Section: Meteorological Situation During the Experimentmentioning

confidence: 99%

mentioning

confidence: 99%

The JET2000 Project: Aircraft Observations of the African Easterly Jet and African Easterly Waves

Thorncroft¹,

Parker²,

Burton³

et al. 2003

Bull. Amer. Meteor. Soc.

103

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“…Various studies based on ECMWF analyses or reanalysis have indicated a circulation north of the AEJ (Nitta et al, 1985;Reed et al, 1988;Pytharoulis and Thorncroft, 1999;Fink et al, 2004). Different from the southern waves that have maximum amplitude at the jet level (600-700 hPa), the northern waves are usually confined below 850 hPa (Reed et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

Modulation of the African easterly jet by a mesoscale convective system

Wang

Elsberry

2010

Atmospheric Science Letters

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The modulation of the African easterly jet (AEJ) by a mesoscale convective system (MCS) is examined in a numerical simulation. An AEJ with a strong and confined core is simulated before the formation of the MCS north of the AEJ axis, and the jet is 'split' with two separate cores after the passage of the MCS. Our diagnosis suggests that the MCS may be triggered by a wave propagating south of the AEJ axis. A momentum budget analysis indicates that the meridional circulation associated with the MCS weakens the jet to its south and forms the secondary jet to its north.

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“…Druyan et al [3] also found positive bias in seasonal simulations of precipitation with the model used here and three other regional models. Reed et al [4] evaluated the structure and characteristics of African easterly wave disturbances in earlier ECMWF operational analyses and forecasts, but not simulated precipitation.…”

Section: Introductionmentioning

confidence: 99%

Regional Model Nesting within GFS Daily Forecasts Over West Africa

Druyan

Fulakeza²,

Lonergan³

et al. 2010

TOASCJ

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Abstract:The study uses the RM3, the regional climate model at the Center for Climate Systems Research of Columbia University and the NASA/Goddard Institute for Space Studies (CCSR/GISS). The paper evaluates 30 48-hour RM3 weather forecasts over West Africa during September 2006 made on a 0.5° grid nested within 1° Global Forecast System (GFS) global forecasts. September 2006 was the Special Observing Period #3 of the African Monsoon Multidisciplinary Analysis (AMMA). Archived GFS initial conditions and lateral boundary conditions for the simulations from the US National Weather Service, National Oceanographic and Atmospheric Administration were interpolated four times daily. Results for precipitation forecasts are validated against Tropical Rainfall Measurement Mission (TRMM) satellite estimates and data from the Famine Early Warning System (FEWS), which includes rain gauge measurements, and forecasts of circulation are compared to reanalysis 2. Performance statistics for the precipitation forecasts include bias, root-mean-square errors and spatial correlation coefficients. The nested regional model forecasts are compared to GFS forecasts to gauge whether nesting provides additional realistic information. They are also compared to RM3 simulations driven by reanalysis 2, representing "high potential skill" forecasts, to gauge the sensitivity of results to lateral boundary conditions. Nested RM3/GFS forecasts generate excessive moisture advection toward West Africa, which in turn causes prodigious amounts of model precipitation. This problem is corrected by empirical adjustments in the preparation of lateral boundary conditions and initial conditions. The resulting modified simulations improve on the GFS precipitation forecasts, achieving time-space correlations with TRMM of 0.77 on the first day and 0.63 on the second day.

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The structure and characteristics of African easterly wave disturbances as determined from the ECMWF operational analysis/forecast system

Cited by 99 publications

References 18 publications

The JET2000 Project: Aircraft Observations of the African Easterly Jet and African Easterly Waves

The JET2000 Project: Aircraft Observations of the African Easterly Jet and African Easterly Waves

Modulation of the African easterly jet by a mesoscale convective system

Regional Model Nesting within GFS Daily Forecasts Over West Africa

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