Abstract
The latest version of the International Centre for Theoretical Physics (ICTP) regional climate model (RegCM4) is used in this study to examine the East African climate, focusing on October to December (OND) rainfall and the circulation mechanisms associated with extreme wet and dry events over the period 1991–2008. Grell convection scheme with Fritsch-Chappell closure assumption is used. The experiment was performed with the initial and lateral boundary conditions obtained from ERA-interim gridded reanalysis at a 1.5° resolution. The simulation period was 1990–2008 at a resolution of 50 km. Results show that the model realistically simulates the annual cycle, the OND mean seasonal rainfall, and its interannual variability over the East African region, where the simulated rainfall tends to underestimate the observed rainfall. There is however a significant positive correlation between the simulated rainfall and the rainfall datasets used to evaluate the model performance. Further analysis revealed that, the model captures well the observed circulation anomaly patterns, with divergence at low level and convergence at upper level during dry years, and for wet years, convergence (divergence) was simulated at low (upper) level, especially over the western Indian Ocean and the study area. Dry years are hence characterized by sinking motion as oppose to wet years which depict rising motion. These were corroborated by the pressure vertical velocity (omega), which showed positive (negative) anomalies over the region during dry (wet) years. The findings from this study provide insight into the circulation anomaly associations with wet and dry events in the region. The observed biases indicate that the ability of the model in simulating the East African climate is still a significant challenge. Therefore, future work needs to focus on improving the performance of the model in climate research over the region.
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Abiodun BJ, Pal JS, Afiesimama EA, Gutowski WJ, Adedoyin A (2007) Simulation of West African monsoon using RegCM3 part II: impacts of deforestation and desertification. Theor Appl Climatol 93:245–261
Adeniyi MO (2013) Sensitivity of different convection schemes in RegCM4.0 for simulation of precipitation during the Septembers of 1989 and 1998 over West Africa. Theor Appl Climatol. doi:10.1007/s00704-013-0881-5
Anthes RA (1977) A cumulus parameterization scheme utilizing a one-dimensional cloud model. Mon Weather Rev 105:1423–1438
Anthes RA, Hsie EY, Kuo YH (1987) Description of the Penn State/NCAR Mesoscale Model Version 4 (MM4), National Center for Atmospheric Research Tech Note TN-282 + STR. NCAR, Boulder
Anyah RO, Semazzi FHM (2004) Simulation of the sensitivity of Lake Victoria basin climate to lake surface temperatures. Theor Appl Climatol 79:55–69
Anyah RO, Semazzi FHM (2007) Variability of East African rainfall based on multiyear RegCM3 simulations. Int J Climatol 27:357–371
Ata H, Afzaal M (2006) Simulation of winter-2000 rainfall over Pakistan using two different domains with RegCM3. Pak J Meteorol 3(6):57–74
Barry RG, Chorley RJ (2003) Atmosphere, weather and climate, 8thedition, 462 pp.
Bretherton CS, McCaa JR, Grenier H (2004) A new parameterization for shallow cumulus convection and its application to marine subtropical cloud-topped boundary layers. I. Description and 1D results. Mon Weather Rev 132:864–882
Davis N, Bowden J, Semazzi FHM, Xie L (2009) Customization of RegCM3 Regional Climate Model for Eastern Africa and a Tropical Indian Ocean Domain. J Clim 22:3595–3616
Dee DP, Uppala SM, Simmons AJ, Berrisford P, Poli P, Kobayashi S, Andrae U, Balmaseda MA, Balsamo G, Bauer P, Bechtold P, Beljaars A, van de Berg L, Bidlot J, Bormann N, Delsol C, Dragani R, Fuentes M, Geer AJ, Haimberger L, Healy S, Hersbach H, Holm EV, Isaksen L, Kallberg P, Koehler M, Matricardi M, McNally AP, Monge-Sanz BM, Morcrette JJ, Peubey C, de Rosnay P, Tavolato C, Thepaut JN, Vitart F (2011) The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q J R Meteorol Soc 137:553–597
Diallo I, Sylla MB, Camara M, Gaye AT (2013) Interannual variability of rainfall over the Sahel based on multiple regional climate models simulations. Theor Appl Climatol 113:351–362. doi:10.1007/s00704-012-0791-y
Diallo I, Giorgi F, Sukumaran S, Stordal F, Giuliani G (2014) Evaluation of RegCM4 driven by CAM4 over Southern Africa: mean climatology, interannual variability and daily extremes of wet season temperature and precipitation. Theor Appl Climatol. doi:10.1007/s00704-014-1260-6
Dickinson RE, Henderson SA, Kennedy P (1993) Biosphere–atmosphere transfer scheme (BATS) version 1e as coupled to the NCAR community climate model. Tech Rep, National Center for Atmospheric Research Tech Note NCAR.TN-387 + STR. NCAR, Boulder
Diro GT, Rauscher SA, Giorgi F, Tompkins AM (2012) Sensitivity of seasonal climate and diurnal precipitation over Central America to land and sea surface schemes in RegCM4. Clim Res 52:31–48. doi:10.3354/cr01049
Emanuel KA (1991) A scheme for representing cumulus convection in large-scale models. J Atmos Sci 48:2313–2335
Emanuel KA, Zivkovic-Rothman M (1999) Development and evaluation of a convection scheme for use in climate models. J Atmos Sci 56:1766–1782
Folland CK (1983) Regional-scale interannual variability of climate. A north-west European perspective. Meteorol Mag 12:163–187
Gao XJ, Xu Y, Zhao ZC, Pal JS, Giorgi F (2006) On the role of resolution and topography in the simulation of East Asia precipitation. Theor Appl Climatol 86:173–185
Giorgi F, Anyah RO (2012) The road towards RegCM4. Clim Res 52:3–6. doi:10.3354/cr01089
Giorgi F, Marinucci MR, Bates GT, DeCanio G (1993a) Development of a second generation regional climate model (RegCM2). Part II: convective processes and assimilation of lateral boundary conditions. Mon Weather Rev 121:2814–2832
Giorgi F, Marinucci MR, Bates GT (1993b) Development of a second generation regional climate model (RegCM2), part I: boundary-layer and radiative transfer processes. Mon Weather Rev 121(10):2794–2813
Giorgi F, Huang Y, Nishizawa K, Fu C (1999) A seasonal cycle simulation over eastern Asia and its sensitivity to radiative transfer and surface processes. J Geophys Res 104:6403–6423
Giorgi F, Francisco R, Pal JS (2003) Effects of a sub-grid scale topography and landuse scheme on surface climate and hydrology. I. Effects of temperature and water vapor disaggregation. J Hydrometeor l 4:317–333
Giorgi F, Bi X, Pal JS (2004) Mean interannual variability and trends in a regional climate change experiment over Europe. I. Present-day climate (1961–1990). Clim Dyn 22:733–756
Giorgi F, Coppola E, Solmon F, Mariotti L, Sylla MB, Bi X, Elguindi N, Diro GT, Nair V, Giuliani G, Turuncoglu UU, Cozzini S, Guttler I, O’Brien TA, Tawfik AB, Shalaby A, Zakey AS, Steiner AL, Stordal F, Sloan LC, Brankovic C (2012) RegCM4: model description and preliminary tests over multiple CORDEX domains. Clim Res 52:7–29
Grell GA (1993) Prognostic evaluation of assumptions used by cumulus parameterization. Mon Weather Rev 121:764–787
Grell G, Dudhia J, Stauffer DR (1994) A description of the fifth generation Penn State/NCAR Mesoscale Model (MM5), National Center for Atmospheric Research Tech Note NCAR/TN-398 + STR. NCAR, Boulder
Grenier H, Bretherton CS (2001) A moist PBL parameterization for large scale models and its application to subtropical cloud-topped marine boundary layers. Mon Weather Rev 129:357–377
Harris I, Jones PD, Osborn TJ, Lister DH (2014) Updated high-resolution grids of monthly climatic observations. In press, Int J Climatol 34(3):623–642
Holtslag A, DeBruijn E, Pan HL (1990) A high resolution air mass transformation model for short-range weather forecasting. Mon Weather Rev 118:1561–1575
Indeje M, Semazzi FHM, Ogallo LJ (2000) ENSO signals in East African rainfall and their prediction potentials. Int J Climatol 20:19–46
Ininda JM (1995) Numerical simulation of the influence of sea surface temperature anomalies on the East African seasonal rainfall. PhD. thesis, Department of Meteorology, University of Nairobi, Kenya
Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, White G, Woollen J, Zhu Y, Leetmaa A, Reynolds B, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Jenne R, Joseph D (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteorol Soc 77:437–470
Kiehl JT, Bonan GB, Boville BA, Briegleb BP, Williamson DL, Rasch PJ (1996) Description of the NCAR Community Climate Model (CCM3). NCAR Technical Note NCAR TN-420 + STR, pp 152
Kok JF (2011) A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle. Proc Natl Acad Sci U S A 108:1016–1021
Laurent B, Marticorena B, Bergametti G, Leon JF, Maho-wald NM (2008) Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database. J Geophys Res 113:D14218. doi:10.1029/ 2007 JD009484
Mutemi JN, Ogallo LA, Krishnamurti TN, Mishra AK, Vijaya KTSV (2007) Multimodel based superensemble forecasts for short and medium range NWP over various regions of Africa. Meteorol Atmos Phys 95:87–113
Ogallo L, Oludhe C (2009) Climate information in decision making in the greater horn of Africa: lessons and experiences. WMO Bull 58(3):184–187
Ogwang BA, Guirong T, Haishan C (2012) Diagnosis of September-November drought and the associated circulation anomalies over Uganda. Pak J Meteorol 9(17):11–24
Ogwang BA, Chen H, Li X, Gao C (2014) The influence of topography on East African October to December climate: sensitivity experiments with RegCM4. doi:10.1155/2014/143917
Ogwang BA, Chen H, Li X, Gao C (2015) Evaluation of the capability of RegCM4.0 in simulating East African climate. Theor Appl Climatol. doi:10.1007/s00704-015-1420-3
Okoola RE (1999) Mid-tropospheric circulation patterns associated with extreme dry and wet episodes over equatorial Eastern Africa during the northern hemisphere spring. J Appl Meteorol 38:1161–1169
Oleson KW, Dai Y, Bonan G, Bosilovich M, Dickinson R, Dirmeyer P, Hoffman F, Levis S, Niu GY, Thornton P, Vertenstein M, Yang ZL, Zeng X (2004) Technical description of the Community Land Model. National Center for Atmospheric Research Tech Note NCAR/TN-461 + STR. NCAR, Boulder
Oleson KW, Niu GY, Yang ZL, Lawrence DM, Thornton PE, Lawrence PJ, Stockli R, Dickinson RE, Bonan GB, Levis S, Dai A, Qian T (2008) Improvements to the Community Land Model and their impact on the hydrologic cycle. J Geophys Res 113:G01021. doi:10.1029/2007JD000563
Otieno VO, Anyah RO (2012) Effects of land use changes on climate in the Greater Horn of Africa. Clim Res 52:77–95. doi:10.3354/cr01050
Owiti Z, Zhu W (2012) East African rainfall seasonality based on modulated annual cycle (MAC). Int J Phys Sci 7(24):3050–3061. doi:10.5897/IJPS12.240
Ozturk T, Altinsoy H, Türke M, Kurnaz ML (2012) Simulation of temperature and precipitation climatology for the Central Asia CORDEX domain using RegCM 4.0. Clim Res 52:63–76
Pal J, Small E, Eltahir E (2000) Simulation of regional-scale water and energy budgets: representation of subgrid cloud and precipitation processes within RegCM. J Geophys Res-Atmos 105(D24):29579–29594
Pal JS, Giorgi F, Bi X, Elguindi N, Solmon F, Gao X, Francisco R, Zakey A, Winter J, Ashfaq M, Syed F, Bell JL, Diffanbaugh NS, Kamacharya J, Konare A, Martinez D, da Rocha RP, Sloan LC, Steiner A (2007) The ICTP RegCM3 and RegCNET: regional climate modeling for the developing world. Bull Am Meteorol Soc 88:1395–1409
Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Clim 15:1609–1625
Rudolf B, Becker A, Schneider U, Meyer A, Ziese M, Finger P, Stender P, Heller A, Breidenbach JN (2011) New GPCC Full Data Reanalysis Version 5 provides high-quality gridded Monthly precipitation data. GEWEX News 21(2):4–5
Schreck CJ, Semazzi FHM (2004) Variability of the recent climate of Eastern Africa. Int J Climatol 24:681–701
Seth A, Giorgi F (1998) The effects of domain choice on summer precipitation simulation and sensitivity in a regional climate model. J Clim 11(10):2698–2712
Solmon F, Giorgi F, Liousse C (2006) Aerosol modeling for regional climate studies: application to anthropogenic particles and evaluation over a European/African domain. Tellus Ser B Chem Phys Meterol 58:51–72
Steiner AL, Pal JS, Rauscher SA, Bell JL, Diffenbaugh NS, Boone A, Sloan LC, Giorgi F (2009) Land surface coupling in regional climate simulations of the West African monsoon. Clim Dyn 33:869–892
Sun L, Semazzi FHM, Giorgi F, Ogallo LJ (1999a) Application of the NCAR regional climate model to Eastern Africa. Part I: simulation of the short rains of 1988. J Geophys Res 104:6529–6548
Sun L, Semazzi FHM, Giorgi F, Ogallo LJ (1999b) Application of the NCAR regional climate model to eastern Africa. Part II: simulation of interannual variability of short rains. J Geophys Res 104:6549–6562
Sylla MB, Coppola E, Mariotti L, Giorgi F, Ruti PM, Dell’Aquila A, Bi X (2010) Multiyear simulation of the African climate using a regional climate model (RegCM3) with the high resolution ERA-interim reanalysis. Clim Dyn 35:231–247. doi:10.1007/s00382-009-0613-9
Tan G-R, Li H, Ren H-L, Chen H (2014) Quantifying synoptic eddy feedback onto the low-frequency flow associated with anomalous temperature events in January over China. Int J Climatol. doi:10.1002/joc.4135
Tawfik AB, Steiner AL (2011) The role of soil ice in land-atmosphere coupling over the United States: a soil moisture precipitation winter feedback mechanism. J Geophys Res 116:D02113. doi:10.1029/2010JD014333
Uppala S, Dee D, Kobayashi S, Berrisford P, Simmons A (2008) Towards a climate data assimilation system: status update of ERA-Interim. ECMWF Newsl 115:12–18
Wilks DS (2006) Statistical methods in the atmospheric sciences, 2nd edn. Academic, London, 627 pp
Zakey AS, Solmon F, Giorgi F (2006) Implementation and testing of a desert dust module in a regional climate model. Atmos Chem Phys 6:4687–4704
Zakey AS, Giorgi F, Bi X (2008) Modeling of sea salt in a regional climate model: fluxes and radiative forcing. J Geophys Res 113:D14221. doi:10.1029/2007JD009209
Zeleke T, Giorgi F, Tsidu GM, Diro GT (2013) Spatial and temporal variability of summer rainfall over Ethiopia from observations and a regional climate model experiment. Theor Appl Climatol 111(3–4):665–681
Zeng X, Beljaars A (2005) A prognostic scheme of sea surface skin temperature for modeling and data assimilation. Geophys Res Lett 32:L14605. doi:10.1029/2005 GL023030
Zeng X, Zhao M, Dickinson RE (1998) Inter comparison of bulk aerodynamic algorithms for the computation of Sea surface fluxes using TOGA COARE and TAO data. J Clim 11:2628–2644
Zhi X-F (2001) Interannual variability of the Indian summer monsoon and its modeling with zonally symmetric 2D-Model. Shaker Verlag, Aachen, 151 pp
Zou L, Zhou T (2013a) Improve the simulation of western North Pacific summer monsoon in RegCM3 by suppressing convection. Meteorol Atmos Phys 121(1–2):29–38
Zou L, Zhou T (2013b) Near future (2016-40) summer precipitation changes over China as projected by a regional climate model (RCM) under the RCP8.5 emissions scenario: comparison between RCM downscaling and the driving GCM. Adv Atmos Sci 30(3):806–818
Acknowledgments
We thank the NOAA for providing the OISST data, the ECMWF for providing the ERA-interim reanalysis data, and the University of East Anglia Climatic Research Unit for the data used in this study. We also thank the Chinese Scholarship Council (CSC) for the financial support and the Nanjing University of Information Science and Technology for providing the required facilities for data analysis and for all other forms of support.
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Ogwang, B.A., Chen, H., Tan, G. et al. Diagnosis of East African climate and the circulation mechanisms associated with extreme wet and dry events: a study based on RegCM4. Arab J Geosci 8, 10255–10265 (2015). https://doi.org/10.1007/s12517-015-1949-6
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DOI: https://doi.org/10.1007/s12517-015-1949-6