Hindcast skill improvement in Climate Forecast System (CFSv2) using modified cloud scheme
Corresponding Author
Samir Pokhrel
Indian Institute of Tropical Meteorology, Pune, India
Correspondence
Samir Pokhrel, Indian Institute of Tropical Meteorology, NCL Post, Pashan, Pune 411008, India.
Email: [email protected]
Search for more papers by this authorAnupam Hazra
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorHemantkumar S. Chaudhari
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorSubodh K. Saha
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorFebin Paulose
Cochin University of Science and Technology, Kochi, India
Search for more papers by this authorSujith Krishna
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorPhani Murli Krishna
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorSuryachandra A. Rao
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorCorresponding Author
Samir Pokhrel
Indian Institute of Tropical Meteorology, Pune, India
Correspondence
Samir Pokhrel, Indian Institute of Tropical Meteorology, NCL Post, Pashan, Pune 411008, India.
Email: [email protected]
Search for more papers by this authorAnupam Hazra
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorHemantkumar S. Chaudhari
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorSubodh K. Saha
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorFebin Paulose
Cochin University of Science and Technology, Kochi, India
Search for more papers by this authorSujith Krishna
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorPhani Murli Krishna
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorSuryachandra A. Rao
Indian Institute of Tropical Meteorology, Pune, India
Search for more papers by this authorAbstract
Two sets of CFSv2 retrospective forecast experiments are performed to check the model's fidelity for operational forecast usage for the prediction of Indian summer monsoon rainfall (ISMR). The first experiment (Exp1) is identical to the present operational mode of the model. The second experiment (Exp2) includes major changes in terms of the different cumulus parameterization scheme, modified cloud microphysics scheme and the variable critical relative humidity. These changes have already shown enhancement in the seasonal viability of the model in the free-run mode. This study has carried out exclusive hindcast experiments by combining the above mentioned major changes. There is a marked improvement in the spatial distribution of the precipitation and the amplitude of the annual cycle of ISMR. The underestimation of the peak of the annual cycle of ISMR in Exp1 is enhanced by 23% in Exp2. Because of better simulations of clouds and tropospheric temperature gradient, the point of maximum precipitation has migrated northwards from equator (Exp1) to 20°N (Exp2). These improvements also impress upon all the other aspect of the ocean–atmosphere coupled interaction, namely planetary-scale Hadley circulation, air–sea interactions and most of the facets of monsoon teleconnections. The skill of extended Indian monsoon rainfall region (65°–95°E, 5°–35 N) has increased from 0.50 in Exp1 to 0.67 in Exp2 and the same holds true for other regions as well. The skill of Niño3.4 index enhances from 0.58 in Exp1 to 0.67 in Exp2. The dynamical wind shear based monsoon performance indices also show the surge in the skill score. The significant improvement of seasonal skill scores across all the variables clearly shows the dynamical consistency and at the same time establishes the superiority of the Exp2 for seasonal forecast. This work will add new dimension to develop a new genre of monsoon forecasting model.
REFERENCES
- Abhilash, S., Sahai, A.K., Pattnaik, S., Goswami, B.N. and Kumar, A. (2014) Extended range prediction of active-break spells of Indian summer monsoon rainfall using an ensemble prediction system in NCEP Climate Forecast System. International Journal of Climatology, 34, 98–113.
- Adler, R.F., Huffman, G.J., Chang, A., Ferraro, R., Xie, P., Janowiak, J., Rudolf, B., Schneider, U., Curtis, S., Bolvin, D., Gruber, A., Susskind, J., Arkin, P. and Nelkin, E. (2003) The version 2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979–present). Journal of Hydrometeorology, 4, 1147–1167.
- Ashok, K., Guan, Z.Y. and Yamagata, T. (2001) Impact of the Indian Ocean Dipole on the relationship between the Indian monsoon rainfall and ENSO. Geophysical Research Letters, 28, 4499–4450.
- Bretherton, C.S., Smith, C. and Wallace, J.M. (1992) An intercomparison of methods for finding coupled patterns in climate data. Journal of Climate, 5, 541–560.
- Charney, J.G. (1969) The intertropical convergence zone and the Hadley circulation of the atmosphere. In: Proceedings of WMO/IUCG Symposium on Numerical Weather Prediction, Vol. III. Tokyo: Japanese Meteorological Agency, pp. 73–79.
- Chattopadhyay, R., Phani, R., Sabeerali, C.T., Dhakate, A.R., Salunke, K.D., Mahapatra, S., Rao, A.S. and Goswami, B.N. (2015) Influence of extratropical sea-surface temperature on the Indian summer monsoon: an unexplored source of seasonal predictability. Quarterly Journal of the Royal Meteorological Society, 141, 2760–2775.
- Chattopadhyay, R., Suryachandra, A., Rao, S.C.T., George, G., Rao Nagarjuna, D., Dhakate, A. and Salunke, K. (2016) Large-scale teleconnection patterns of Indian summer monsoon as revealed by CFSv2 retrospective seasonal forecast runs. International Journal of Climatology, 36, 3297–3313. https://doi.org/10.1002/joc.4556.
- Chaudhari, H.S., Hazra, A., Saha, S.K., Dhakate, A. and Pokhrel, S. (2016a) Indian summer monsoon simulations with CFSv2: a microphysics perspective. Theoretical and Applied Climatology, 125, 253–269.
- Chaudhari, H.S., Pokhrel, S., Kulkani, A., Hazra, A. and Saha, S.K. (2016b) Clouds–SST relationship and interannual variability modes of Indian summer monsoon in the context of clouds and SSTs: observational and modelling aspects. International Journal of Climatology, 36, 4723–4740.
- Chaudhari, H.S., Pokhrel, S., Mohanty, S. and Saha, S.K. (2013) Seasonal prediction of Indian summer monsoon in NCEP coupled and uncoupled model. Theoretical and Applied Climatology, 114, 459–477.
- Chaudhari, H.S., Pokhrel, S., Rahman, H., Dhakate, A., Saha, S.K., Pentakota, S. and Gairola, R.M. (2016c) Influence of upper ocean on Indian summer monsoon rainfall: studies by observation and NCEP Climate Forecast System (CFSv2). Theoretical and Applied Climatology, 125, 413–426.
- Clough, S.A., Shephard, M.W., Mlawer, E.J., Delamere, J.S., Iacono, M.J., Cady-Pereira, K., Boukabara, S. and Brown, P.D. (2005) Atmospheric radiative transfer modeling: a summary of the AER codes. Journal of Quantitative Spectroscopy & Radiative Transfer, 91, 233–244.
- De, S., Hazra, A. and Chaudhari, H.S. (2016) Does the modification in critical relative humidity of NCEP CFSv2 dictate Indian mean summer monsoon forecast?: evaluation through thermodynamical and dynamical aspects. Climate Dynamics, 46, 1197–1222. https://doi.org/10.1007/s00382-015-2640-z.
- Dee, D.P., Uppala, S.M., Simmons, A.J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M.A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A.C.M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A.J., Haimberger, L., Healy, S.B., Hersbach, H., Hólm, E.V., Isaksen, L., Kiallberg, P., Köhler, M., Matricardi, M., McNally, A.P., Monge-Sanz, B.M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N. and Vitart, F. (2011) The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Quarterly Journal of the Royal Meteorological Society, 137, 553–597.
- Delsole, T. and Shukla, J. (2010) Model fidelity versus skill in seasonal forecasting. Journal of Climate, 23, 4794–4806.
- Ek, M.B., Mitchell, K.E., Lin, Y., Rogers, E., Grunmann, P., Koren, V., Gayno, G. and Tarpley, J.D. (2003) Implementation of Noah land surface model advances in the National Centers for Environmental Prediction operational mesoscale Eta model. Journal of Geophysical Research, 1089, 8851. https://doi.org/10.1029/2002JD003296.
- Ferrier, B.S., Lin, Y., Black, T., Rogers, E. and DiMego, G. (2002) Implementation of a new grid-scale cloud and precipitation scheme in the NCEP Eta model. In: 15th Conference on Numerical Weather Prediction. San Antonio, TX: American Meteorological Society, pp. 280–283.
- Gadgil, S. and Gadgil, S. (2006) The Indian monsoon, GDP and agriculture. Economic and Political Weekly, XLI, 4887–4895.
- Gadgil, S., Joseph, P.V. and Joshi, N.V. (1984) Ocean–atmosphere coupling over monsoon regions. Nature, 312, 141–143.
- Gadgil, S., Rajeevan, M. and Nanjundiah, R. (2005) Monsoon prediction—Why yet another failure? Current Science, 88, 1389–1400.
- Gadgil, S. and Srinivasan, J. (2011) Seasonal prediction of the Indian monsoon. Current Science, 100, 343–353.
- Gadgil, S., Vinayachandran, P.N., Francis, P.A. and Gadgil, S. (2004) Extremes of the Indian summer monsoon rainfall, ENSO and equatorial Indian Ocean oscillation. Geophysical Research Letters, 31, L12213. https://doi.org/10.1029/2004GL019733.
- Ganai, M., Mukhopadhyay, P., Phani Murali Krishna, R. and Mahakur, M. (2015) Impact of revised simplified Arakawa–Schubert convection parameterization scheme in CFSv2 on the simulation of the Indian summer monsoon. Climate Dynamics, 45, 881–902. https://doi.org/10.1007/s00382-014-2320-4.
- Goswami, B.N., Krishnamurthy, V. and Annamalai, H. (1999) A broad-scale circulation index for the interannual variability of the Indian summer monsoon. Quarterly Journal of the Royal Meteorological Society, 125, 611–633.
- Goswami, B.N. and Xavier, P.K. (2005) Dynamics of internal interannual variability of the Indian summer monsoon in a GCM. Journal of Geophysical Research, 110, D24104. https://doi.org/10.1029/2005JD006042.
- Griffies, S.M., Harrison, M.J., Pacanowski, R.C. and Rosati, A. (2004) A technical guide to MOM4 (GFDL Ocean Group Technical Report No. 5, 337 pp.). Washington, D. C.: NOAA/Geophysical Fluid Dynamics Laboratory.
- Halley, E. (1686) An historical account of the trade winds and monsoons observable in the seas between and near the Tropics with an attempt to assign a physical cause of the said winds. Philosophical Transactions of the Royal Society of London, 16, 153–168.
10.1098/rstl.1686.0026 Google Scholar
- Han, J. and Pan, H.-L. (2011) Revision of convection and vertical diffusion schemes in the NCEP global forecast system. Weather and Forecasting, 26, 520–533. https://doi.org/10.1175/WAF-D-10-05038.1.
- Hazra, A., Chaudhari, H.S. and Dhakate, A. (2016) Evaluation of cloud properties in the NCEP CFSv2 model and its linkage with Indian summer monsoon. Theoretical and Applied Climatology, 124, 31–41.
- Hazra, A., Chaudhari, H.S., Rao, S.A., Goswami, B.N., Dhakate, A., Pokhrel, S. and Saha, S.K. (2015) Impact of revised cloud microphysical scheme in CFSv2 on the simulation of the Indian summer monsoon. International Journal of Climatology, 35, 4738–4755.
- Hazra, A., Chaudhari, H.S., Saha, S.K., Pokhrel, S. and Goswami, B.N. (2017a) Progress towards achieving the challenge of Indian summer monsoon climate simulation in a coupled ocean–atmosphere model. Journal of Advances in Modeling Earth Systems, 9, 2268–2290. https://doi.org/10.1002/2017MS000966.
- Hazra, A., Chaudhari, H.S., Saha Subodh, K. and Pokhrel, S. (2017b) Effect of cloud microphysics on Indian summer monsoon precipitating clouds: a coupled climate modeling study. Journal of Geophysical Research, 122, 1–20. https://doi.org/10.1002/2016JD026106.
- Hoerling, M.P. and Kumar, A. (2002) Atmospheric response patterns associated with tropical forcing. Journal of Climate, 15, 2184–2203.
- Hong, S.Y. and Pan, H.L. (1998) Convective trigger function for a mass-flux cumulus parameterization scheme. Monthly Weather Review, 126, 2599–2620.
- Hu, Z.Z., Wu, R., Kinter, J.L. and Yang, S. (2005) Connection of summer rainfall variations in South and East Asia: role of El Niño-Southern Oscillation. International Journal of Climatology, 25, 1279–1289.
- Iacono, M.J., Mlawer, E.J., Clough, S.A. and Morcrette, J.-J. (2000) Impact of an improved longwave radiation model, RRTM, on the energy budget and thermodynamic properties of the NCAR Community Climate Model, CCM3. Journal of Geophysical Research, 105, 14873–14890.
- Jiang, X., Waliser, D.E., Li, J.L. and Woods, C. (2011) Vertical cloud structures of the boreal summer intraseasonal variability based on CloudSat observations and ERA-Interim reanalysis. Climate Dynamics, 36, 2219–2232.
- Kim, Y.J. and Arakawa, A. (1995) Improvement of orographic gravity wave parameterization using a meso-scale gravity wave model. Journal of the Atmospheric Sciences, 52, 1875–1902.
- Koteswaram, P. (1958) Easterly jet stream in the Tropics. Tellus A, 10, 43–57.
- Kripalani, R.H. and Kulkarni, A. (1999) Climatology and variability of historical Soviet snow depth data: some new perspectives in snow-Indian monsoon teleconnections. Climate Dynamics, 15, 475–489.
- Kripalani, R.H., Oh, J.H., Kulkarni, A., Sabade, S.S. and Chaudhari, H.S. (2007) South Asian summer monsoon precipitation variability: coupled climate model simulations and projections under IPCC AR4. Theoretical and Applied Climatology, 90, 133–159.
- Krishna Kumar, K., Hoerling, M. and Rajagopalan, B. (2005) Advancing dynamical prediction of Indian monsoon rainfall. Geophysical Research Letters, 32, L08704. https://doi.org/10.1029/2004GL021979.
- Kumar, A., Jha, B. and L’Heureux, M. (2010) Are tropical SST trends changing the global teleconnection during La Niña? Geophysical Research Letters, 37, L12702. https://doi.org/10.1029/2010GL043394.
- Lott, F. and Miller, M.J. (1997) A new subgrid-scale orographic drag parametrization: its formulation and testing. Quarterly Journal of the Royal Meteorological Society, 123, 101–127.
- Moorthi, S. and Suarez, M.J. (1992) Relaxed Arakawa–Schubert: a parameterization of moist convection for general circulation models. Monthly Weather Review, 120, 978–1002.
- Nanjundiah, R.S. (2009) A quick look into assessment of forecasts for the Indian summer monsoon rainfall in 2009 (CAOS Report No. 2009- AS-2). Bangalore: CAOS.
- Parthasarathy, B., Munot, A.A. and Kothawale, D.R. (1995) All India monthly and seasonal rainfall series: 1871–1993. Theoretical and Applied Climatology, 49, 217–224.
- Pokhrel, S., Chaudhari, H.S., Saha, S.K., Dhakate, A., Yadav, R.K., Salunke, K., Mahapatra, S. and Rao, S.A. (2012a) ENSO, IOD and Indian summer monsoon in NCEP Climate Forecast System. Climate Dynamics, 39, 2143–2165.
- Pokhrel, S., Dhakate, A., Chaudhari, H.S. and Saha, S.K. (2013) Status of NCEP CFS vis-a-vis IPCC AR4 models for the simulation of Indian summer monsoon. Theoretical and Applied Climatology, 111, 65–78.
- Pokhrel, S., Rahaman, H., Parekh, A., Saha, S.K., Dhakate, A., Chaudhari, H.S. and Gairola, R.M. (2012b) Evaporation–precipitation variability over Indian Ocean and its assessment in NCEP Climate Forecast System (CFSv2). Climate Dynamics, 39, 2585–2608.
- Pokhrel, S., Saha, S.K., Dhakate, A., Chaudhari, H.S., Salunke, K., Rahman, H., Hazra, A., Sujith, K. and Sikka, D.R. (2016) Seasonal prediction of Indian summer monsoon rainfall in NCEP CFSv2: forecast and predictability error. Climate Dynamics, 46, 2305–2326. https://doi.org/10.1007/s00382-015-2703-1.
- Preethi, B., Kripalani, R.H. and Kumar, K.K. (2010) Indian summer monsoon rainfall variability in global coupled ocean–atmosphere models. Climate Dynamics, 35, 1521–1539.
- Rajeevan, M. and Nanjundiah, R.S. (2009) Coupled model simulations of twentieth century climate of the Indian summer monsoon. In: N. Mukunda (Ed.) Current Trends in Science – Platinum Jubilee Special. Bangalore: Indian Academy of Sciences, pp. 537–567.
- Rajeevan, M., Pai, D.S. and Thapliyal, V. (1998) Spatial and temporal relationships between global land surface air temperature anomalies and Indian summer monsoon rainfall. Meteorology and Atmospheric Physics, 66, 157–171.
- Rajeevan, M., Rohini, P., Niranjan Kumar, K., Srinivasan, J. and Unnikrishnan, C.K. (2013) A study of vertical cloud structure of the Indian summer monsoon using CloudSat data. Climate Dynamics, 40, 637–650.
- Rajeevan, M., Unnikrishnan, C.K. and Preethi, B. (2012) Evaluation of the ENSEMBLES multi-model seasonal forecasts of Indian summer monsoon variability. Climate Dynamics, 38, 2257–2274.
- Ramu, D.A., Sabeerali, C.T., Chattopadhyay, R. and Rao, D.N. (2016) Indian summer monsoon rainfall simulation and prediction skill in the CFSv2 coupled model: impact of atmospheric horizontal resolution. Journal of Geophysical Research: Atmospheres, 121(5), 2205–2221. https://doi.org/10.1002/2015JD024629.
- Rao, D.N., George, G., Sabeerali, C.T., Ramu, D.A. and Rao, A.S. (2015) Changing relationship between the tropical easterly jet and the Indian summer monsoon rainfall: role of Indian Ocean warming. Indian Journal of Geo-Marine Sciences, 44(11), 1678–1683.
- Rowell, D.P. (2013) Simulating SST teleconnections to Africa: what is the state of the art? Journal of Climate, 26(15), 5397–5418.
- Sabeerali, C.T., Dandi, A.R., Dhakate, A., Salunke, K., Mahapatra, S. and Rao, S.A. (2013) Simulation of boreal summer intraseasonal oscillations in the latest CMIP5 coupled GCMs. Journal of Geophysical Research, 118, 4401–4420. https://doi.org/10.1002/jgrd.50403.
- Saha, K. (1970) Zonal anomaly of sea surface temperature in equatorial Indian Ocean and its possible effect upon monsoon circulation. Tellus A, 22(4), 403–409.
10.1111/j.2153-3490.1970.tb00506.x Google Scholar
- Saha, S., Moorthi, S., Pan, H.-L., Wu, X., Wang, J., Nadiga, S., Tripp, P., Kistler, R., Woollen, J., Behringer, D., Liu, H., Stokes, D., Grumbine, R., Gayno, G., Wang, J., Hou, Y.T., Chuang, H.Y., Juang, H.-M.H., Sela, J., Iredell, M., Treadon, R., Kleist, D., Delst, P.V., Keyser, D., Derber, J., Ek, M., Meng, J., Wei, H., Yang, R., Lord, S., Dool, H.V.D., Kumar, A., Wang, W., Long, C., Chelliah, M., Xue, Y., Huang, B., Schemm, J.K., Ebisuzaki, W., Lin, R., Xie, P., Chen, M., Zhou, S., Higgins, W., Zou, C.Z., Liu, Q., Chen, Y., Han, Y., Cucurull, L., Reynolds, R.W., Rutledge, G. and Goldberg, M. (2010) The NCEP Climate Forecast System reanalysis. Bulletin of the American Meteorological Society, 91, 1015–1057.
- Saha, S., Moorthi, S., Wu, X., Wang, J., Nadiga, S., Tripp, P., Behringer, D., Hou, Y.T., Chuang, H.Y., Iredell, M., Ek, M., Meng, J., Yang, R., van den Mendez, Zhang, H., Wang, W., Chen, M. and Becker, E. (2014a) The NCEP Climate Forecast System version 2. Journal of Climate, 27, 2185–2208.
- Saha, S.K., Pokhrel, S. and Chaudhari, H.S. (2013) Influence of Eurasian snow on Indian summer monsoon in NCEP CFSv2 free run. Climate Dynamics, 41, 1801–1815.
- Saha, S.K., Pokhrel, S., Chaudhari, H.S., Dhakate, A., Shewale, S., Sabeer Ali, C.T., Salunke, K., Hazra, A., Mahapatra, S. and Rao, A.S. (2014b) Improved simulation of Indian summer monsoon in latest NCEP Climate Forecast System (CFSv2) free run. International Journal of Climatology, 34, 1628–1641.
- Saha, S.K., Pokhrel, S., Salunke, K., Dhakate, A., Chaudhari, H.S., Rahman, H., Sujith, K., Hazra, A. and Sikka, D.R. (2016) Potential predictability of Indian summer monsoon rainfall in NCEP CFSv2. Journal of Advances in Modeling Earth Systems, 8, 96–120. https://doi.org/10.1002/2015MS000542.
- Sahai, A.K., Chattopadhyay, R., Joseph, S., Mandal, R., Dey, A., Abhilash, A., Krishna, R.P.M. and Borah, N. (2015) Real-time performance of a multi-model ensemble based extended range forecast system in predicting the 2014 monsoon season based on NCEP-CFSv2. Current Science, 109, 1802–1813.
- Saji, N.H., Goswami, B.N., Vinayachandran, P.N. and Yamagata, T. (1999) A dipole mode in the tropical Indian Ocean. Nature, 401, 360–363.
- Shinoda, T., Hendon, H.H. and Alexander, M.A. (2004) Surface and subsurface dipole variability in the Indian Ocean and its relation with ENSO. Deep Sea Research Part I: Oceanographic Research Papers, 51, 619–635.
- Shukla, J. (1975) Effect of Arabian Sea surface temperature anomaly on Indian summer monsoon: a numerical experiment with the GFDL model. Journal of the Atmospheric Sciences, 32, 503–511.
- Sikka, D.R. (1980) Some aspects of the large-scale fluctuations of summer monsoon rainfall over India in relation to fluctuations in the planetary and regional scale circulation parameters. Proceedings of the Indian Academy of Sciences - Earth Planetary Science, 89, 179–195.
- Sikka, D.R. and Gadgil, S. (1980) On the maximum cloud zone and the ITCZ over Indian longitudes during the southwest monsoon. Monthly Weather Review, 108, 1840–1853.
- Smith, T.M. and Reynolds, R.W. (2003) Extended reconstruction of global sea surface temperatures based on COADS data (1854–1997). Journal of Climate, 16, 1495–1510.
- S. Solomon, D. Qin, M. Manning, M. Marquis, K. Averyt, M.M.B. Tignor, H.L. Miller and Z. Chen (Eds.) (2007) Climate Change 2007: The Physical Science Basis. Cambridge: Cambridge University Press. pp. 996.
- Stephens, G.L., Vane, D.G., Boain, R.J., Mace, G.G., Sassen, K., Wang, Z., Illingworth, A.J., O’Connor, E.J., Rossow, W.B., Durden, S.L., Miller, S.D., Austin, R.T., Benedetti, A. and Mitrescu, C. (2002) The Cloudsat mission and A-train: a new dimension of space based observations of clouds and precipitation. Bulletin of the American Meteorological Society, 83, 1771–1790.
- Sundqvist, H., Berge, E. and Kristjansson, J.E. (1989) Condensation and cloud studies with mesoscale numerical weather prediction model. Monthly Weather Review, 117, 1641–1757.
- Thompson, A., Stefanova, L. and Krishnamurti, T.N. (2008) Baroclinic splitting of jets. Meteorology and Atmospheric Physics, 100, 257–274.
- Wallace, J.M., Smith, C. and Bretherton, C.S. (1992) Singular value decomposition of wintertime sea surface temperature and 500-mb height anomalies. Journal of Climate, 5, 561–576.
- Wang, B., Ding, Q., Fu, X., Kang, I.-S., Jin, K., Shukla, J. and Doblas-Reyes, F. (2005a) Fundamental challenge in simulation and prediction of summer monsoon rainfall. Geophysical Research Letters, 32, L15711. https://doi.org/10.1029/2005GL022734.
- Wang, B. and Fan, Z. (1999) Choice of South Asian summer monsoon indices. Bulletin of the American Meteorological Society, 80, 629–638.
- Wang, B., Xiang, B., Li, J., Webster, P.J., Rajeevan, M.N., Liu, J. and Ha, K.J. (2015) Rethinking Indian monsoon rainfall prediction in the context of recent global warming. Nature Communications, 6, 7154. https://doi.org/10.1038/ncomms8154.
- Wang, W.S., Saha, H.L., Pan, S., Nadiga, S. and White, G. (2005b) Simulation of ENSO in the new NCEP coupled forecast system model. Monthly Weather Review, 133, 1574–1593.
- Wang, Y.F. and Lupo, A.R. (2009) An extratropical air–sea interaction over the North Pacific in association with a preceding El Niño episode in early summer. Monthly Weather Review, 137, 3771–3785. https://doi.org/10.1175/2009MWR2949.1.
- Webster, P.J., Magana, V.O., Palmer, T.N., Shukla, J., Tomas, R.A., Yanai, M. and Yasunari, T. (1998) Monsoons: processes, predictability and the prospectus for prediction. Journal of Geophysical Research, 103, 14451–14510.
- Webster, P.J. and Yang, S. (1992) Monsoon and ENSO: selectively interactive systems. Quarterly Journal of the Royal Meteorological Society, 118, 877–926.
- Wilks, D.S. (2011) Statistical Methods in the Atmospheric Sciences, 3rd edition. Oxford; Waltham, MA: Academic Press.
- Wu, R.G. and Kirtman, B.P. (2007) Regimes of seasonal air–sea interaction and implications for performance of forced simulations. Climate Dynamics, 29, 393–410.
- Wu, X., Moorthi, K.S., Okomoto, K. and Pan, H.L. (2005) Sea ice impacts on GFS forecasts at high latitudes. In: Eighth Conference on Polar Meteorology and Oceanography. San Diego, CA: American Meteorological Society.
- Yoo, H., Li, Z., Yu-Tai, H., Lord, S., Weng, F. and Barker, H.W. (2013) Diagnosis and testing of low-level cloud parameterizations for the NCEP/ GFS model using satellite and ground-based measurements. Climate Dynamics, 41, 1595–1613. https://doi.org/10.1007/s00382-013-1884-8.
- Zhao, Q.Y. and Carr, F.H. (1997) A prognostic cloud scheme for operational NWP models. Monthly Weather Review, 125, 1931–1953.
- Zhou, Y.-P., Tao, W.-K., Hou, A.-Y., Olson, W.S., Shie, C.-L., Lau, K.M., Chou, M.D., Lin, X. and Grecu, M. (2007) Use of high-resolution satellite observations to evaluate cloud and precipitation statistics from cloud-resolving model simulations. Part I: south China Sea monsoon experiment. Journal of the Atmospheric Sciences, 64, 4309–4329.