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Regional climate model simulation of the AMMA Special Observing Period #3 and the pre-Helene easterly wave

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Abstract

The study examines results of dynamic downscaling of two global analyses: the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis II and the Global Forecast System final analysis (FNL). Downscaling to a 0.5° grid over West Africa and the adjacent Atlantic Ocean is accomplished by each of two regional models, the Regional Model, version 3 (RM3) of the Center for Climate Systems Research and the Weather, Research and Forecasting model (WRF). Simulations are for September 2006, the African Monsoon Multidisciplinary Analysis (AMMA) Special Observing Period #3 (SOP-3). The aim of this study is to exploit the increased spatial detail in the simulations and representations of climate fields by the regional models to analyze meteorological systems within the SOP-3 area of interest and time frame. In particular, the paper focuses on the regional models’ representations of the structure and movement of a prominent easterly wave during September 10–13th, the precursor of Tropical Storm/Hurricane Helene. It describes the RM3 simulated structure of the developing storm in terms of circulation, precipitation, vertical motion, cumulus heating rates, and cross-sections of wind and geopotential height anomalies. Simulated cumulus heating rates within the wave’s main precipitation area imply a lowering of the bases of active cumulus in the transition from the African continent to the Atlantic, indicating that the ocean environment promotes greater upward latent heat flux that in turn intensifies overlying storms. RM3 circulation, precipitation patterns, and storm trajectory are reasonably consistent with observational evidence. Experiments show that precipitation rates near 6°N over the eastern North Atlantic are sensitive to vertical thermal stability, such that they are enhanced by warmer in situ sea-surface temperatures (SSTs) and diminished by colder SSTs. However, prescribing colder SST causes increases in precipitation north of 9°N within areas of large scale upward vertical motion where rainfall rates are less sensitive to in situ SSTs. The evaluation of WRF indicates that its storm propagation is too fast over West Africa, where associated WRF precipitation rates are exaggerated, but its performance is improved over the Atlantic.

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References

  • Brown D (2006) Tropical cyclone report, Hurricane Helene (AL082006). National Hurricane Center, NOAA, Miami, FL, p 12

    Google Scholar 

  • Chen F, Dudhia J (2001) Coupling an advanced land-surface/hydrology model with the Penn State/NCAR MM5 modeling system. Part I: model description and implementation. Mon Wea Rev 129:569–585

    Article  Google Scholar 

  • Chiang JCH, Kushnir Y, Giannini A (2002) Deconstructing Atlantic ITCZ variability: influence of the local cross-equatorial SST gradient, and remote forcing from the eastern equatorial Pacific. J Geophys Res 107(D1):4004. doi:10.1029/2000JD000307

    Article  Google Scholar 

  • Chou M-D, Suarez MJ (1994) An efficient thermal infrared radiation parameterization for use in general circulation models. NASA Tech Memo 104606 3:85

    Google Scholar 

  • Del Genio A, Yao M-S (1993) Efficient cumulus parameterization for long-term climate studies. The GISS scheme. In: Emanuel K, Raymond D (eds) Cumulus parameterization, vol 24. American Meteorology Society Monograph Series, Boston, pp 181–184

  • Del Genio A, Yao M-S, Kovari W, Lo K-W (1996) A prognostic cloud water parameterization for global climate models. J Clim 9:270–304

    Article  Google Scholar 

  • Diedhiou A, Janicot S, Viltard A, de Felice P, Laurent H (1999) Easterly wave regimes and associated convection over West Africa and tropical Atlantic: results from NCEP/NCAR and ECMWF reanalyses. Clim Dyn 15:795–822

    Article  Google Scholar 

  • Druyan L, Fulakeza M (2005) Mesoscale climate analysis over West Africa. CLIVAR Exch 10(20):34–35

    Google Scholar 

  • Druyan L, Fulakeza M, Lonergan P (2006) Mesoscale analyses of West African summer climate: focus on wave disturbances. Clim Dyn 27:459–481

    Article  Google Scholar 

  • Druyan L, Fulakeza M, Lonergan P (2008) The impact of vertical resolution on regional model simulation of the west African summer monsoon. Int J Climatol 28:1293–1314. doi:10.1002/joc.1636

    Article  Google Scholar 

  • Fritsch M, Carbone R (2004) Improving quantitative precipitation forecasts in the warm season. Bull Am Meteorol Soc 85:955–965

    Article  Google Scholar 

  • Futyan J, Del Genio A (2007) Deep convective system evolution over Africa and the tropical Atlantic. J Clim 20:5041–5060. doi:10.1175/JCLI4297.1

    Article  Google Scholar 

  • Hansen J et al (2002) Climate forcings in Goddard Institute for Space Studies SI2000 simulations. JGR 107:4347. doi:10.1029/200IJD001143

    Article  Google Scholar 

  • Kain, JS, Fritsch JM (1993) Convective parameterization for mesoscale models: The Kain-Fritcsh scheme. In: Emanuel KA, Raymond, DJ (eds) The representation of cumulus convection in numerical models. American Meteorology Society, p 246

  • Kanamitsu M, Ebisuzaki W, Woollen J, Yang SK, Hnilo JJ, Fiorino M, Potter GL (2002) NCEP-DOE AMIP-II reanalysis (R-2). Bull Am Meteorol Soc 83:1631–1643

    Article  Google Scholar 

  • Kiladis G, Thorncroft C (2008) Three-dimensional structure of easterly wave disturbances over Africa and tropical North Atlantic. 20th conference on climate variability and change, New Orleans. http://ams.confex.com/ams/88Annual/techprogram/paper_128178.htm. Accessed 21 Jan 2008

  • Mlawer EJ, Taubman SJ, Brown PD, Iacono MJ, Clough SA (1997) Radiative transfer for inhomogeneous atmosphere: RRTM, a validated correlated-k model for the long- wave. J Geophys Res 102(D14):16663–16682

    Article  Google Scholar 

  • Redelsperger JL, Thorncroft CD, Diedhiou A, Lebel T, Parker DJ, Polcher J (2006) African monsoon multidisciplinary analysis: An international research project and field campaign. Bull Am Meteorol Soc 87:1739–1746

    Article  Google Scholar 

  • Reed R, Klinker E, Hollingsworth A (1988) The structure and characteristics of African easterly wave disturbances as determined from the ECMWF operational analysis/forecast system. Meteorol Atmos Phys 38:22–33

    Article  Google Scholar 

  • Rosenzweig C, Abramopoulos F (1997) Land-surface model development for the GISS GCM. J Clim 10:2040–2054

    Article  Google Scholar 

  • Schmidlin FJ, Morrison BJ, Northam ET, Gerlach J (2007) Detailed observations of five African Easterly waves during NAMMA. Ppt presentation, NAMMA Science Team Meeting. Workshop, Baltimore, MD, May 2007

  • Skamarock WC et al (2005) A description of the advanced research WRF version 2. NCAR technical note, June 2005, Revised January 2005

  • Thorncroft C, Hodges K (2001) African easterly wave variability and its relationship to Atlantic tropical cyclone activity. J Clim 14:1166–1179

    Article  Google Scholar 

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Acknowledgments

This research was supported by National Science Foundation grant ATM-0652518, National Aeronautics and Space Administration (NAMMA) grant NNX07A193G, and by the National Aeronautics and Space Administration Climate and Earth Observing System Program. E. Noble is a Fellow of the National Aeronautics and Space Administration Graduate Student Researchers Program. Helpful discussion about cumulus heating rate profiles with Dr. A. Del Genio is acknowledged. We gratefully acknowledge assistance from the WRF help desk at the National Center for Atmospheric Research and helpful consultations concerning WRF with Dr. Jimy Dudhia. TRMM data used in this study were acquired using the GES-DISC Interactive Online Visualization and Analysis Infrastructure (Giovanni) as part of the NASA’s Goddard Earth Sciences (GES) Data and Information Services Center (DISC). NCEP reanalysis II data used in this study were obtained on-line from the National Oceanographic and Atmospheric Agency/Earth System Research Laboratory (Physical Sciences Division). FEWS data sets were created at the National Oceanographic and Atmospheric Agency Climate Prediction Center and made available on-line by the International Research Institute for Climate Prediction of Columbia University.

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Authors and Affiliations

  1. NASA/Goddard Institute for Space Studies, NYC and Center for Climate Systems Research, Columbia University, New York, USA

    Leonard M. Druyan, Matthew Fulakeza & Patrick Lonergan

  2. University of Colorado, Boulder, CO, USA

    Erik Noble

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  1. Leonard M. Druyan
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  2. Matthew Fulakeza
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  3. Patrick Lonergan
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  4. Erik Noble
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Correspondence to Leonard M. Druyan.

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Druyan, L.M., Fulakeza, M., Lonergan, P. et al. Regional climate model simulation of the AMMA Special Observing Period #3 and the pre-Helene easterly wave. Meteorol Atmos Phys 105, 191–210 (2009). https://doi.org/10.1007/s00703-009-0044-5

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  • DOI: https://doi.org/10.1007/s00703-009-0044-5

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