Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Prashant Sardeshmukh

Research Interests

I am a climate dynamicist with broad interests in the diagnosis, modeling, prediction, and potential predictability of large-scale weather and climate variations around the globe on time scales of days to centuries. Our team is engaged in documenting and understanding the regional aspects of ongoing climate changes, especially changes in the statistics of extreme weather, and determining to what extent they are anthropogenic or consistent with natural climate variability. We are also interested in documenting and understanding the actual and potential skill of weather and climate predictions, which is inherently limited due to the chaotic nature of the system, and how current prediction systems need to be improved to achieve the potential skill.

Current Research

Sensitivities of the global weather forecasting system used at the National Centers of Environmental Prediction (NCEP)

The large improvement in weather prediction skill over the past several decades has been described as a “quiet revolution” resulting from many small steps rather than a few dramatic leaps. One has now apparently entered a stage of diminishing returns in skill improvement, with no clear guidance as to improving which aspects of current forecast systems will yield the greatest benefit. Broadly speaking, forecast systems have three basic elements: 1) the input observations, 2) the data assimilation (DA) method used to merge those observations with model-generated guess fields to create the forecast initial conditions, and 3) the forecast model itself. As forecast systems continue to evolve, it will remain important to assess their relative sensitivities to these three elements to help set priorities in system development. In a recently published study (Wang et al, Monthly Weather Review, 2019) we investigated these sensitivities of the current Global Forecast System (GFS) of the National Centers for Environmental Prediction (NCEP). Four parallel sets of 7-day ensemble forecasts were generated for 100 forecast cases in mid-January to mid-March 2016. The sets differed in their 1) inclusion or exclusion of additional observations collected over the eastern Pacific during NOAA’s El Niño Rapid Response (ENRR) field campaign, 2) use of a “Hybrid 4D-EnVar” versus a “pure EnKF” DA method to prepare the initial conditions, and 3) inclusion or exclusion of “stochastic parameterizations” of chaotic physical processes in the forecast model. In general, the forecast errors were found to be only slightly sensitive to the additional observations, more sensitive to the DA method, and most sensitive to the inclusion of stochastic parameterizations in the model, which reduced errors globally in almost all the variables considered. The reduction in the precipitation forecast errors were particularly striking.



Root-Mean Square (R.M.S) errors of Day-7 precipitation forecasts over 100 forecast cases in January-March 2016 (upper left), and how they were impacted by including the ENRR field campaign observations (lower left), using a “Hybrid 4D-EnVar” versus a pure “EnKF” data assimilation method (upper right), and by including “stochastic parameterizations” of chaotic physical processes in the forecast model (lower right panel). Blue shading in the three “impact” panels indicates a decrease, and red shading an increase, in the R.M.S. forecast error. For each forecast case an ensemble of 80 forecasts was generated, and the forecast error was defined as the error of the ensemble-mean forecast. (From Wang, Sardeshmukh, Compo, Whitaker, Slivinski, McColl, and Pegion, 2019; Monthly Weather Review)

View Publications

  • Wang, JWA; Sardeshmukh, PD; Compo, GP; Whitaker, JS; Slivinski, LC; McColl, CM; Pegion, PJ (2019), Sensitivities of the NCEP Global Forecast System. Version: 1 MONTHLY WEATHER REVIEW 147 (4) 1237-1256, issn: 0027-0644, doi: 10.1175/MWR-D-18-0239.1
  • Dole, RM, JR Spackman, iman, W Otto, O Persson, XW Quan, I RangwalaM Newman, GP Compo, CA Smith, LM Hartten, JJ Barsugli, RS Webb, MP Hoerling, R Cifelli, K Wolter, CD Barnet, M Gehne, R Gelaro, GN Kiladis, S Abbott, E Akish, J Albers, JM Brown, CJ Cox, L Darby, G de Boer, B DeLuisi, J Dias, J Dunion, J Eischeid, C Fairall, A Gambacorta, BK Gorton, A Hoell, J Intrieri, D Jackson, PE Johnston, R Lataitis, KM Mahoney, K McCaffrey, HA McColl, MJ Mueller, D Murrrray, PJ Ne, AJ Ray, D Reynolds, ER Dellaripa, K Rosenlof, N Sakaeda, PD Sardeshmukh, LC Slivinski, L Smith, A Solomon, D Swales, S Tulich, A White, G Wick, MG Winterkorn, DE Wolfe and R Zamora (2018), ADVANCING SCIENCE AND SERVICES DURING THE 2015/16 EL NINO The NOAA El Nino Rapid Response Field Campaign. Bull. Amer. Meteorol. Soc. Version: 1 99 (5) 975-1002, issn: 0003-0007, ids: GH8CF, doi: 10.1175/BAMS-D-16-0219.1
  • Capotondi, A, PD Sardeshmukh and L Ricciardulli (2018), The Nature of the Stochastic Wind Forcing of ENSO. J. Clim. Version: 1 31 (19) 8081-8099, issn: 0894-8755, ids: GR7CP, doi: 10.1175/JCLI-D-17-0842.1
  • Berner, J, PD Sardeshmukh and HM Christensen (2018), On the Dynamical Mechanisms Governing El Nino-Southern Oscillation Irregularity. J. Clim. Version: 1 31 (20) 8401-8419, issn: 0894-8755, ids: GT1IQ, doi: 10.1175/JCLI-D-18-0243.1
  • Capotondi, A and PD Sardeshmukh (2017), Is El Nino really changing?. Geophys. Res. Lett. Version: 1 44 (16) 8548-8556, issn: 0094-8276, ids: FG8DR, doi: 10.1002/2017GL074515
  • Newman, M and PD Sardeshmukh (2017), Are we near the predictability limit of tropical Indo-Pacific sea surface temperatures?. Geophys. Res. Lett. Version: 1 44 (16) 8520-8529, issn: 0094-8276, ids: FG8DR, doi: 10.1002/2017GL074088
  • Giese, BS, HF Seidel, GP Compo and PD Sardeshmukh (2016), An ensemble of ocean reanalyses for 1815-2013 with sparse observational input. J. Geophys. Res.-Oceans Version: 1 121 (9) 6891-6910, issn: 2169-9275, ids: EA8TZ, doi: 10.1002/2016JC012079
  • Capotondi, A and PD Sardeshmukh (2015), Optimal precursors of different types of ENSO events. Geophys. Res. Lett. Version: 1 42 (22) 9952-9960, issn: 0094-8276, ids: DB2MO, doi: 10.1002/2015GL066171
  • Bronnimann, S, AM Fischer, E Rozanov, P Poli, GP Compo and PD Sardeshmukh (2015), Southward shift of the northern tropical belt from 1945 to 1980. Nat. Geosci. Version: 1 8 (12) 969-U110, issn: 1752-0894, ids: CZ6GW, doi: 10.1038/NGEO2568
  • Muller, WA, D Matei, M Bersch, JH Jungclaus, H Haak, K Lohmann, GP Compo, PD Sardeshmukh and J Marotzke (2015), A twentieth-century reanalysis forced ocean model to reconstruct the North Atlantic climate variation during the 1920s. Clim. Dyn. Version: 1 44 (8-Jul) 1935-1955, issn: 0930-7575, ids: CD9YS, doi: 10.1007/s00382-014-2267-5
  • Stucki, P, S Bronnimann, O Martius, C Welker, R Rickli, S Dierer, DN Bresch, GP Compo and PD Sardeshmukh (2015), Dynamical Downscaling and Loss Modeling for the Reconstruction of Historical Weather Extremes and Their Impacts: A Severe Foehn Storm in 1925. Bull. Amer. Meteorol. Soc. Version: 1 96 (8) , issn: 0003-0007, ids: CR5FG, doi: 10.1175/BAMS-D-14-00041.1
  • Sardeshmukh, PD, GP Compo and C Penland (2015), Need for Caution in Interpreting Extreme Weather Statistics. J. Clim. Version: 1 28 (23) 9166-9187, issn: 0894-8755, ids: CX7DC, doi: 10.1175/JCLI-D-15-0020.1
  • Sardeshmukh, PD and C Penland (2015), Understanding the distinctively skewed and heavy tailed character of atmospheric and oceanic probability distributions. Chaos Version: 1 25 (3) , Art. No. 36410, issn: 1054-1500, ids: CF1OB, doi: 10.1063/1.4914169, PubMed ID: 25833448
  • Sandeep, S, F Stordal, PD Sardeshmukh and GP Compo (2014), Pacific Walker Circulation variability in coupled and uncoupled climate models. Clim. Dyn. Version: 1 43 (2-Jan) 103-117, issn: 0930-7575, ids: AK3PS, doi: 10.1007/s00382-014-2135-3
  • Wang, XLL, Y Feng, GP Compo, VR Swail, FW Zwiers, RJ Allan and PD Sardeshmukh (2013), Trends and low frequency variability of extra-tropical cyclone activity in the ensemble of twentieth century reanalysis. Clim. Dyn. Version: 1 40 (12-Nov) 2775-2800, issn: 0930-7575, ids: 149ZU, doi: 10.1007/s00382-012-1450-9
  • Compo, GP, PD Sardeshmukh, JS Whitaker, P Brohan, PD Jones and C McColl (2013), Independent confirmation of global land warming without the use of station temperatures. Geophys. Res. Lett. Version: 1 40 (12) 3170-3174, issn: 0094-8276, ids: 185FJ, doi: 10.1002/grl.50425
  • Newman, M, GN Kiladis, KM Weickmann, FM Ralph and PD Sardeshmukh (2012), Relative Contributions of Synoptic and Low-Frequency Eddies to Time-Mean Atmospheric Moisture Transport, Including the Role of Atmospheric Rivers. J. Clim. Version: 1 25 (21) 7341-7361, issn: 0894-8755, ids: 036BZ, doi: 10.1175/JCLI-D-11-00665.1
  • Penland, C and PD Sardeshmukh (2012), Alternative interpretations of power-law distributions found in nature. Chaos Version: 1 22 (2) , Art. No. 23119, issn: 1054-1500, ids: 966JM, doi: 10.1063/1.4706504, PubMed ID: 22757526
  • Bronnimann, S, O Martius, H von Waldow, C Welker, J Luterbacher, GP Compo, PD Sardeshmukh and T Usbeck (2012), Extreme winds at northern mid-latitudes since 1871. Meteorol. Z. Version: 1 21 (1) 13-27, issn: 0941-2948, ids: 906XQ, doi: 10.1127/0941-2948/2012/0337
  • Compo, GP, JS Whitaker, PD Sardeshmukh, N Matsui, RJ Allan, X Yin, BE Gleason, RS Vose, G Rutledge, P Bessemoulin, S Bronnimann, M Brunet, RI Crouthamel, AN Grant, PY Groisman, PD Jones, MC Kruk, AC Kruger, GJ Marshall, M Maugeri, HY Mok, O Nordli, TF Ross, RM Trigo, XL Wang, SD Woodruff and SJ Worley (2011), The Twentieth Century Reanalysis Project. Q. J. R. Meteorol. Soc. Version: 1 137 (654) 1-28, issn: 0035-9009, ids: 724QX, doi: 10.1002/qj.776
  • Shin, SI and PD Sardeshmukh (2011), Critical influence of the pattern of Tropical Ocean warming on remote climate trends. Clim. Dyn. Version: 1 36 (8-Jul) 1577-1591, issn: 0930-7575, ids: 744PA, doi: 10.1007/s00382-009-0732-3
  • Pegion, K and PD Sardeshmukh (2011), Prospects for Improving Subseasonal Predictions. Mon. Weather Rev. Version: 1 139 (11) 3648-3666, issn: 0027-0644, ids: 840XP, doi: 10.1175/MWR-D-11-00004.1
  • Shin, SI, PD Sardeshmukh and SW Yeh (2011), Sensitivity of the northeast Asian summer monsoon to tropical sea surface temperatures. Geophys. Res. Lett. Version: 1 38 , Art. No. L22702, issn: 0094-8276, ids: 851HH, doi: 10.1029/2011GL049391
  • Wang, XLL, H Wan, FW Zwiers, VR Swail, GP Compo, RJ Allan, RS Vose, S Jourdain and XG Yin (2011), Trends and low-frequency variability of storminess over western Europe, 1878-2007. Clim. Dyn. Version: 1 37 (12-Nov) 2355-2371, issn: 0930-7575, ids: 852GU, doi: 10.1007/s00382-011-1107-0
  • Compo, GP and PD Sardeshmukh (2010), Removing ENSO-Related Variations from the Climate Record. J. Clim. Version: 1 23 (8) 1957-1978, issn: 0894-8755, ids: 594LE, doi: 10.1175/2009JCLI2735.1
  • Giese, BS, GP Compo, NC Slowey, PD Sardeshmukh, JA Carton, S Ray and JS Whitaker (2010), THE 1918/19 EL NINO. Bull. Amer. Meteorol. Soc. Version: 1 91 (2) 177-183, issn: 0003-0007, ids: 572XH, doi: 10.1175/2009BAMS2903.1
  • Shin, SI, PD Sardeshmukh and K Pegion (2010), Realism of local and remote feedbacks on tropical sea surface temperatures in climate models. J. Geophys. Res.-Atmos. Version: 1 115 , Art. No. D21110, issn: 2169-897X, ids: 676UT, doi: 10.1029/2010JD013927
  • Shin, SI, PD Sardeshmukh and RS Webb (2010), Optimal Tropical Sea Surface Temperature Forcing of North American Drought. J. Clim. Version: 1 23 (14) 3907-3917, issn: 0894-8755, ids: 643FK, doi: 10.1175/2010JCLI3360.1
  • Sardeshmukh, PD and P Sura (2009), Reconciling Non-Gaussian Climate Statistics with Linear Dynamics. J. Clim. Version: 1 22 (5) 1193-1207, issn: 0894-8755, ids: 426AZ, doi: 10.1175/2008JCLI2358.1
  • Newman, M, PD Sardeshmukh and C Penland (2009), How Important Is Air-Sea Coupling in ENSO and MJO Evolution?. J. Clim. Version: 1 22 (11) 2958-2977, issn: 0894-8755, ids: 467SR, doi: 10.1175/2008JCLI2659.1
  • Compo, GP and PD Sardeshmukh (2009), Oceanic influences on recent continental warming. Clim. Dyn. Version: 1 32 (3-Feb) 333-342, issn: 0930-7575, ids: 389IO, doi: 10.1007/s00382-008-0448-9
  • Sura, P and PD Sardeshmukh (2009), A global view of air-sea thermal coupling and related non-Gaussian SST variability. Atmos. Res. Version: 1 Special Session on Ocean-Atmosphere Coupling held at the 24th IUGG 94 (1) 140-149, Perugia, ITALY, JUL 02-12, 2007, issn: 0169-8095, ids: 496HR, doi: 10.1016/j.atmosres.2008.08.008
  • Newman, M and PD Sardeshmukh (2008), Tropical and stratospheric influences on extratropical short-term climate variability. J. Clim. Version: 1 21 (17) 4326-4347, issn: 0894-8755, ids: 345JC, doi: 10.1175/2008JCLI2118.1
  • Sura, P and PD Sardeshmukh (2008), A Global view of non-Gaussian SST variability. J. Phys. Oceanogr. Version: 1 38 (3) 639-647, issn: 0022-3670, ids: 276EQ, doi: 10.1175/2007JPO3761.1
  • Sardeshmukh, PD and P Sura (2007), Multiscale impacts of variable heating in climate. J. Clim. Version: 1 20 (23) 5677-5695, issn: 0894-8755, ids: 239RG, doi: 10.1175/2007JCLI1411.1
  • Barsugli, JJ, SI Shin and PD Sardeshmukh (2006), Sensitivity of global warming to the pattern of tropical ocean warming. Clim. Dyn. Version: 1 27 (5) 483-492, issn: 0930-7575, ids: 076KM, doi: 10.1007/s00382-006-0143-7
  • Shin, SI, PD Sardeshmukh, RS Webb, RJ Oglesby and JJ Barsugli (2006), Understanding the mid-Holocene climate. J. Clim. Version: 1 19 (12) 2801-2817, issn: 0894-8755, ids: 057ZT, doi: 10.1175/JCLI3733.1
  • Compo, GP, JS Whitaker and PD Sardeshmukh (2006), Feasibility of a 100-year reanalysis using only surface pressure data. Bull. Amer. Meteorol. Soc. Version: 1 87 (2) 175-+, issn: 0003-0007, ids: 021CW, doi: 10.1175/BAMS-87-2-175
  • Sura, P, M Newman, C Penland and P Sardeshmukh (2005), Multiplicative noise and non-gaussianity: A paradigm for atmospheric regimes?. J. Atmos. Sci. Version: 1 62 (5) 1391-1409, issn: 0022-4928, ids: 929IB, doi: 10.1175/JAS3408.1
  • Barsugli, J, SI Shin and PD Sardeshmukh (2005), Tropical climate regimes and global climate sensitivity in a simple setting. J. Atmos. Sci. Version: 1 62 (4) 1226-1240, issn: 0022-4928, ids: 918EL, doi: 10.1175/JAS3404.1
  • Compo, GP and PD Sardeshmukh (2004), Storm track predictability on seasonal and decadal scales. J. Clim. Version: 1 17 (19) 3701-3720, issn: 0894-8755, ids: 860RZ, doi: 10.1175/1520-0442(2004)017<3701:STPOSA>2.0.CO;2
  • Bergman, JW and PD Sardeshmukh (2004), Dynamic stabilization of atmospheric single column models. J. Clim. Version: 1 17 (5) 1004-1021, issn: 0894-8755, ids: 801RX, doi: 10.1175/1520-0442(2004)017<1004:DSOASC>2.0.CO;2
  • Newman, M, PD Sardeshmukh, CR Winkler and JS Whitaker (2003), A study of subseasonal predictability. Mon. Weather Rev. Version: 1 131 (8) 1715-1732, issn: 0027-0644, ids: 704NY, doi: 10.1175//2558.1
  • Sardeshmukh, PD, C Penland and M Newman (2003), Drifts induced by multiplicative red noise with application to climate. Europhys. Lett. Version: 1 63 (4) 498-504, issn: 0295-5075, ids: 709GU, doi: 10.1209/epl/i2003-00550-y
  • Bergman, JW and PD Sardeshmukh (2003), Usefulness of single column model diagnosis through short-term predictions. J. Clim. Version: 1 16 (22) 3803-3819, issn: 0894-8755, ids: 742MT, doi: 10.1175/1520-0442(2003)016<3803:UOSCMD>2.0.CO;2
  • Ricciardulli, L and PD Sardeshmukh (2002), Local time- and space scales of organized tropical deep convection. J. Clim. Version: 1 15 (19) 2775-2790, issn: 0894-8755, ids: 593RQ, doi: 10.1175/1520-0442(2002)015<2775:LTASSO>2.0.CO;2
  • Barsugli, JJ and PD Sardeshmukh (2002), Global atmospheric sensitivity to tropical SST anomalies throughout the Indo-Pacific basin. J. Clim. Version: 1 15 (23) 3427-3442, issn: 0894-8755, ids: 615WH, doi: 10.1175/1520-0442(2002)015<3427:GASTTS>2.0.CO;2
  • Compo, GP, PD Sardeshmukh and C Penland (2001), Changes of subseasonal variability associated with El Nino. J. Clim. Version: 1 14 (16) 3356-3374, issn: 0894-8755, ids: 464WF, doi: 10.1175/1520-0442(2001)014<3356:COSVAW>2.0.CO;2
  • Winkler, CR, M Newman and PD Sardeshmukh (2001), A linear model of wintertime low-frequency variability. Part I: Formulation and forecast skill. J. Clim. Version: 1 14 (24) 4474-4494, issn: 0894-8755, ids: 504XE, doi: 10.1175/1520-0442(2001)014<4474:ALMOWL>2.0.CO;2
  • Sardeshmukh, PD, GP Compo and C Penland (2000), Changes of probability associated with El Nino. J. Clim. Version: 1 13 (24) 4268-4286, issn: 0894-8755, ids: 385EF, doi: 10.1175/1520-0442(2000)013<4268:COPAWE>2.0.CO;2
  • Newman, M, PD Sardeshmukh and JW Bergman (2000), An assessment of the NCEP, NASA, and ECMWF reanalyses over the tropical west Pacific warm pool. Bull. Amer. Meteorol. Soc. Version: 1 81 (1) 41-48, issn: 0003-0007, ids: 270GT, doi: 10.1175/1520-0477(2000)081<0041:AAOTNN>2.3.CO;2
  • Huang, HP and PD Sardeshmukh (2000), Another look at the annual and semiannual cycles of atmospheric angular momentum. J. Clim. Version: 1 13 (18) 3221-3238, issn: 0894-8755, ids: 364MN, doi: 10.1175/1520-0442(2000)013<3221:ALATAA>2.0.CO;2
  • Smith, CA and PD Sardeshmukh (2000), The effect of ENSO on the intraseasonal variance of surface temperatures in winter. Int. J. Climatol. Version: 1 20 (13) 1543-1557, issn: 0899-8418, ids: 376EP, doi: 10.1002/1097-0088(20001115)20:13<1543::AID-JOC579>3.0.CO;2-A
  • Hall, NMJ and PD Sardeshmukh (1998), Is the time-mean northern hemisphere flow baroclinically unstable?. J. Atmos. Sci. Version: 1 55 (1) 41-56, issn: 0022-4928, ids: YQ943, doi: 10.1175/1520-0469(1998)055<0041:ITTMNH>2.0.CO;2
  • Newman, M and PD Sardeshmukh (1998), The impact of the annual cycle on the North Pacific North American response to remote low-frequency forcing. J. Atmos. Sci. Version: 1 55 (8) 1336-1353, issn: 0022-4928, ids: ZJ701, doi: 10.1175/1520-0469(1998)055<1336:TIOTAC>2.0.CO;2
  • Whitaker, JS and PD Sardeshmukh (1998), A linear theory of extratropical synoptic eddy statistics. J. Atmos. Sci. Version: 1 55 (2) 237-258, issn: 0022-4928, ids: YT205, doi: 10.1175/1520-0469(1998)055<0237:ALTOES>2.0.CO;2
  • KLINKER, E and PD SARDESHMUKH (1992), THE DIAGNOSIS OF MECHANICAL DISSIPATION IN THE ATMOSPHERE FROM LARGE-SCALE BALANCE REQUIREMENTS. J. Atmos. Sci. Version: 1 49 (7) 608-627, issn: 0022-4928, ids: HQ272, doi: 10.1175/1520-0469(1992)049<0608:TDOMDI>2.0.CO;2