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

  • Aaron Wang J-W; Sardeshmukh PD. (May 2021). Inconsistent Global Kinetic Energy Spectra in Reanalyses and Models. Journal of the Atmospheric Sciences. 10.1175/jas-d-20-0294.1
  • Slivinski LC; Compo GP; Sardeshmukh PD; Whitaker JS; McColl C; Allan RJ; Brohan P; Yin X; Smith CA; Spencer LJ. (Feb 2021). An Evaluation of the Performance of the Twentieth Century Reanalysis Version 3. Journal of Climate , 34(4), 1417-1438. 10.1175/JCLI-D-20-0505.1
  • Shin S-I; Sardeshmukh PD; Newman M; Penland C; Alexander MA. (Jan 2021). Impact of Annual Cycle on ENSO Variability and Predietability. Journal of Climate , 34(1), 171-193. 10.1175/JCLI-D-20-0291.1
  • Robertson FR; Roberts JB; Bosilovich MG; Bentamy A; Clayson CA; Fennig K; Schroeder M; Tomita H; Compo GP; Gutenstein M. (Oct 2020). Uncertainties in Ocean Latent Heat Flux Variations over Recent Decades in Satellite-Based Estimates and Reduced Observation Reanalyses. Journal of Climate , 33(19), 8415-8437. 10.1175/JCLI-D-19-0954.1
  • Berner J; Christensen HM; Sardeshmukh PD. (Feb 2020). Does ENSO Regularity Increase in a Warming Climate?. Journal of Climate , 33(4), 1247-1259. 10.1175/JCLI-D-19-0545.1
  • Capotondi, A; Sardeshmukh, PD; Di Lorenzo, E; Subramanian, AC; Miller, AJ. (29-Jul 2019). Predictability of US West Coast Ocean Temperatures is not solely due to ENSO. SCIENTIFIC REPORTS, 9. 10.1038/s41598-019-47400-4
  • Slivinski, L., Gilbert P. Compo, Jeffrey S. Whitaker, Prashant D. Sardeshmukh, Benjamin S. Giese, Chesley McColl, Rob Allan, Xungang Yin, Russell Vose, Holly Titchner, John Kennedy, Lawrence J. Spencer, Linden Ashcroft, Stefan Br�nnimann, Manola Brunet, Dario Camuffo, Richard Cornes, Thomas A. Cram, Richard Crouthamel, Fernando Dom�nguez-Castro, J. Eric Freeman, Jo�lle Gergis, Ed Hawkins, Philip D. Jones, Sylvie Jourdain, Alexey Kaplan, Hisayuki Kubota, Frank Le Blancq, Tsz-Cheung Lee, Andrew Lorrey, J�rg Luterbacher, Maurizio Maugeri, Cary J. Mock, G.W. Kent Moore, Rajmund Przybylak, Christa Pudmenzky, Chris Reason, Victoria C. Slonosky, Cathy Smith, Birger Tinz, Blair Trewin, Maria Ant�nia Valente, Xiaolan L. Wang, Clive Wilkinson, Kevin Wood, Przemys#322aw Wyszy#324ski. (2019). Towards a more reliable historical reanalysis: Improvements for version 3 of the Twentieth Century Reanalysis system. Quarterly Journal of the Royal Meteorological Society.
  • Wang, JWA; Sardeshmukh, PD; Compo, GP; Whitaker, JS; Slivinski, LC; McColl, CM; Pegion, PJ. (APR 2019). Sensitivities of the NCEP Global Forecast System. MONTHLY WEATHER REVIEW, 147(4), 1237-1256. 10.1175/MWR-D-18-0239.1
  • Slivinski, LC; Compo, GP; Whitaker, JS; Sardeshmukh, PD; Giese, BS; McColl, C; Allan, R; Yin, XG; Vose, R; Titchner, H; Kennedy, J; Spencer, LJ; Ashcroft, L; Bronnimann, S; Brunet, M; Camuffo, D; Cornes, R; Cram, TA; Crouthamel, R; Dominguez-Castro, F; Freeman, JE; Gergis, J; Hawkins, E; Jones, PD; Jourdain, S; Kaplan, A; Kubota, H; Le Blancq, F; Lee, TC; Lorrey, A; Luterbacher, J; Maugeri, M; Mock, CJ; Moore, GWK; Przybylak, R; Pudmenzky, C; Reason, C; Slonosky, VC; Smith, CA; Tinz, B; Trewin, B; Valente, MA; Wang, XL; Wilkinson, C; Wood, K; Wyszynski, P. (OCT 2019). Towards a more reliable historical reanalysis: Improvements for version 3 of the Twentieth Century Reanalysis system. QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, 145(724), 2876-2908. 10.1002/qj.3598
  • Slivinski, LC; Compo, GP; Whitaker, JS; Sardeshmukh, PD; Wang, JWA; Friedman, K; McColl, C. (JUL 2019). What Is the Impact of Additional Tropical Observations on a Modern Data Assimilation System?. MONTHLY WEATHER REVIEW, 147(7), 2433-2449. 10.1175/MWR-D-18-0120.1
  • Berner, J, PD Sardeshmukh and HM Christensen. (OCT 2018). On the Dynamical Mechanisms Governing El Nino-Southern Oscillation Irregularity. JOURNAL OF CLIMATE, 31(20), 8401-8419. 10.1175/JCLI-D-18-0243.1
  • Capotondi, A, PD Sardeshmukh and L Ricciardulli. (OCT 2018). The Nature of the Stochastic Wind Forcing of ENSO. JOURNAL OF CLIMATE, 31(19), 8081-8099. 10.1175/JCLI-D-17-0842.1
  • 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. (MAY 2018). ADVANCING SCIENCE AND SERVICES DURING THE 2015/16 EL NINO The NOAA El Nino Rapid Response Field Campaign. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 99(5), 975-1002. 10.1175/BAMS-D-16-0219.1
  • Newman, M and PD Sardeshmukh. (28-Aug 2017). Are we near the predictability limit of tropical Indo-Pacific sea surface temperatures?. GEOPHYSICAL RESEARCH LETTERS, 44(16), 8520-8529. 10.1002/2017GL074088
  • Capotondi, A and PD Sardeshmukh. (28-Aug 2017). Is El Nino really changing?. GEOPHYSICAL RESEARCH LETTERS, 44(16), 8548-8556. 10.1002/2017GL074515
  • Giese, BS, HF Seidel, GP Compo and PD Sardeshmukh. (SEP 2016). An ensemble of ocean reanalyses for 1815-2013 with sparse observational input. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 121(9), 6891-6910. 10.1002/2016JC012079
  • Bronnimann, S, AM Fischer, E Rozanov, P Poli, GP Compo and PD Sardeshmukh. (DEC 2015). Southward shift of the northern tropical belt from 1945 to 1980. NATURE GEOSCIENCE, 8(12), 969-U110. 10.1038/NGEO2568
  • Sardeshmukh, PD and C Penland. (MAR 2015). Understanding the distinctively skewed and heavy tailed character of atmospheric and oceanic probability distributions. CHAOS, 25(3). 10.1063/1.4914169
  • Muller, WA, D Matei, M Bersch, JH Jungclaus, H Haak, K Lohmann, GP Compo, PD Sardeshmukh and J Marotzke. (APR 2015). A twentieth-century reanalysis forced ocean model to reconstruct the North Atlantic climate variation during the 1920s. CLIMATE DYNAMICS, 44(8-Jul), 1935-1955. 10.1007/s00382-014-2267-5
  • Sardeshmukh, PD, GP Compo and C Penland. (DEC 2015). Need for Caution in Interpreting Extreme Weather Statistics. JOURNAL OF CLIMATE, 28(23), 9166-9187. 10.1175/JCLI-D-15-0020.1
  • Stucki, P, S Bronnimann, O Martius, C Welker, R Rickli, S Dierer, DN Bresch, GP Compo and PD Sardeshmukh. (AUG 2015). Dynamical Downscaling and Loss Modeling for the Reconstruction of Historical Weather Extremes and Their Impacts: A Severe Foehn Storm in 1925. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 96(8). 10.1175/BAMS-D-14-00041.1
  • Capotondi, A and PD Sardeshmukh. (28-Nov 2015). Optimal precursors of different types of ENSO events. GEOPHYSICAL RESEARCH LETTERS, 42(22), 9952-9960. 10.1002/2015GL066171
  • Sandeep, S, F Stordal, PD Sardeshmukh and GP Compo. (JUL 2014). Pacific Walker Circulation variability in coupled and uncoupled climate models. CLIMATE DYNAMICS, 43(2-Jan), 103-117. 10.1007/s00382-014-2135-3
  • Compo, GP, PD Sardeshmukh, JS Whitaker, P Brohan, PD Jones and C McColl. (28-Jun 2013). Independent confirmation of global land warming without the use of station temperatures. GEOPHYSICAL RESEARCH LETTERS, 40(12), 3170-3174. 10.1002/grl.50425
  • Wang, XLL, Y Feng, GP Compo, VR Swail, FW Zwiers, RJ Allan and PD Sardeshmukh. (JUN 2013). Trends and low frequency variability of extra-tropical cyclone activity in the ensemble of twentieth century reanalysis. CLIMATE DYNAMICS, 40(12-Nov), 2775-2800. 10.1007/s00382-012-1450-9
  • Newman, M, GN Kiladis, KM Weickmann, FM Ralph and PD Sardeshmukh. (1-Nov 2012). Relative Contributions of Synoptic and Low-Frequency Eddies to Time-Mean Atmospheric Moisture Transport, Including the Role of Atmospheric Rivers. JOURNAL OF CLIMATE, 25(21), 7341-7361. 10.1175/JCLI-D-11-00665.1
  • Penland, C and PD Sardeshmukh. (JUN 2012). Alternative interpretations of power-law distributions found in nature. CHAOS, 22(2). 10.1063/1.4706504
  • Bronnimann, S, O Martius, H von Waldow, C Welker, J Luterbacher, GP Compo, PD Sardeshmukh and T Usbeck. (FEB 2012). Extreme winds at northern mid-latitudes since 1871. METEOROLOGISCHE ZEITSCHRIFT, 21(1), 13-27. 10.1127/0941-2948/2012/0337
  • Wang, XLL, H Wan, FW Zwiers, VR Swail, GP Compo, RJ Allan, RS Vose, S Jourdain and XG Yin. (DEC 2011). Trends and low-frequency variability of storminess over western Europe, 1878-2007. CLIMATE DYNAMICS, 37(12-Nov), 2355-2371. 10.1007/s00382-011-1107-0
  • Shin, SI, PD Sardeshmukh and SW Yeh. (18-Nov 2011). Sensitivity of the northeast Asian summer monsoon to tropical sea surface temperatures. GEOPHYSICAL RESEARCH LETTERS, 38. 10.1029/2011GL049391
  • Pegion, K and PD Sardeshmukh. (NOV 2011). Prospects for Improving Subseasonal Predictions. MONTHLY WEATHER REVIEW, 139(11), 3648-3666. 10.1175/MWR-D-11-00004.1
  • Shin, SI and PD Sardeshmukh. (APR 2011). Critical influence of the pattern of Tropical Ocean warming on remote climate trends. CLIMATE DYNAMICS, 36(8-Jul), 1577-1591. 10.1007/s00382-009-0732-3
  • 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. (JAN 2011). The Twentieth Century Reanalysis Project. QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, 137(654), 1-28. 10.1002/qj.776
  • Shin, SI, PD Sardeshmukh and K Pegion. (4-Nov 2010). Realism of local and remote feedbacks on tropical sea surface temperatures in climate models. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 115. 10.1029/2010JD013927
  • Shin, SI, PD Sardeshmukh and RS Webb. (JUL 2010). Optimal Tropical Sea Surface Temperature Forcing of North American Drought. JOURNAL OF CLIMATE, 23(14), 3907-3917. 10.1175/2010JCLI3360.1
  • Compo, GP and PD Sardeshmukh. (15-Apr 2010). Removing ENSO-Related Variations from the Climate Record. JOURNAL OF CLIMATE, 23(8), 1957-1978. 10.1175/2009JCLI2735.1
  • Giese, BS, GP Compo, NC Slowey, PD Sardeshmukh, JA Carton, S Ray and JS Whitaker. (FEB 2010). THE 1918/19 EL NINO. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 91(2), 177-183. 10.1175/2009BAMS2903.1
  • Sura, P and PD Sardeshmukh. (SEP 2009). A global view of air-sea thermal coupling and related non-Gaussian SST variability. ATMOSPHERIC RESEARCH, 94(1), 140-149. 10.1016/j.atmosres.2008.08.008
  • Newman, M, PD Sardeshmukh and C Penland. (JUN 2009). How Important Is Air-Sea Coupling in ENSO and MJO Evolution?. JOURNAL OF CLIMATE, 22(11), 2958-2977. 10.1175/2008JCLI2659.1
  • Compo, GP and PD Sardeshmukh. (FEB 2009). Oceanic influences on recent continental warming. CLIMATE DYNAMICS, 32(3-Feb), 333-342. 10.1007/s00382-008-0448-9
  • Sardeshmukh, PD and P Sura. (1-Mar 2009). Reconciling Non-Gaussian Climate Statistics with Linear Dynamics. JOURNAL OF CLIMATE, 22(5), 1193-1207. 10.1175/2008JCLI2358.1
  • Newman, M and PD Sardeshmukh. (SEP 2008). Tropical and stratospheric influences on extratropical short-term climate variability. JOURNAL OF CLIMATE, 21(17), 4326-4347. 10.1175/2008JCLI2118.1
  • Sura, P and PD Sardeshmukh. (MAR 2008). A Global view of non-Gaussian SST variability. JOURNAL OF PHYSICAL OCEANOGRAPHY, 38(3), 639-647. 10.1175/2007JPO3761.1
  • Sardeshmukh, PD and P Sura. (DEC 2007). Multiscale impacts of variable heating in climate. JOURNAL OF CLIMATE, 20(23), 5677-5695. 10.1175/2007JCLI1411.1
  • Compo, GP, JS Whitaker and PD Sardeshmukh. (FEB 2006). Feasibility of a 100-year reanalysis using only surface pressure data. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 87(2), 175-+. 10.1175/BAMS-87-2-175
  • Shin, SI, PD Sardeshmukh, RS Webb, RJ Oglesby and JJ Barsugli. (15-Jun 2006). Understanding the mid-Holocene climate. JOURNAL OF CLIMATE, 19(12), 2801-2817. 10.1175/JCLI3733.1
  • Barsugli, JJ, SI Shin and PD Sardeshmukh. (OCT 2006). Sensitivity of global warming to the pattern of tropical ocean warming. CLIMATE DYNAMICS, 27(5), 483-492. 10.1007/s00382-006-0143-7
  • Barsugli, J, SI Shin and PD Sardeshmukh. (APR 2005). Tropical climate regimes and global climate sensitivity in a simple setting. JOURNAL OF THE ATMOSPHERIC SCIENCES, 62(4), 1226-1240. 10.1175/JAS3404.1
  • Sura, P, M Newman, C Penland and P Sardeshmukh. (MAY 2005). Multiplicative noise and non-gaussianity: A paradigm for atmospheric regimes?. JOURNAL OF THE ATMOSPHERIC SCIENCES, 62(5), 1391-1409. 10.1175/JAS3408.1
  • Bergman, JW and PD Sardeshmukh. (MAR 2004). Dynamic stabilization of atmospheric single column models. JOURNAL OF CLIMATE, 17(5), 1004-1021. 10.1175/1520-0442(2004)017<1004:DSOASC>2.0.CO;2
  • Compo, GP and PD Sardeshmukh. (OCT 2004). Storm track predictability on seasonal and decadal scales. JOURNAL OF CLIMATE, 17(19), 3701-3720. 10.1175/1520-0442(2004)017<3701:STPOSA>2.0.CO;2
  • Bergman, JW and PD Sardeshmukh. (NOV 2003). Usefulness of single column model diagnosis through short-term predictions. JOURNAL OF CLIMATE, 16(22), 3803-3819. 10.1175/1520-0442(2003)016<3803:UOSCMD>2.0.CO;2
  • Sardeshmukh, PD, C Penland and M Newman. (AUG 2003). Drifts induced by multiplicative red noise with application to climate. EUROPHYSICS LETTERS, 63(4), 498-504. 10.1209/epl/i2003-00550-y
  • Newman, M, PD Sardeshmukh, CR Winkler and JS Whitaker. (AUG 2003). A study of subseasonal predictability. MONTHLY WEATHER REVIEW, 131(8), 1715-1732. 10.1175//2558.1
  • Ricciardulli, L and PD Sardeshmukh. (OCT 2002). Local time- and space scales of organized tropical deep convection. JOURNAL OF CLIMATE, 15(19), 2775-2790. 10.1175/1520-0442(2002)015<2775:LTASSO>2.0.CO;2
  • Barsugli, JJ and PD Sardeshmukh. (DEC 2002). Global atmospheric sensitivity to tropical SST anomalies throughout the Indo-Pacific basin. JOURNAL OF CLIMATE, 15(23), 3427-3442. 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. JOURNAL OF CLIMATE, 14(16), 3356-3374. 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. JOURNAL OF CLIMATE, 14(24), 4474-4494. 10.1175/1520-0442(2001)014<4474:ALMOWL>2.0.CO;2
  • Newman, M, PD Sardeshmukh and JW Bergman. (JAN 2000). An assessment of the NCEP, NASA, and ECMWF reanalyses over the tropical west Pacific warm pool. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 81(1), 41-48. 10.1175/1520-0477(2000)081<0041:AAOTNN>2.3.CO;2
  • Huang, HP and PD Sardeshmukh. (15-Sep 2000). Another look at the annual and semiannual cycles of atmospheric angular momentum. JOURNAL OF CLIMATE, 13(18), 3221-3238. 10.1175/1520-0442(2000)013<3221:ALATAA>2.0.CO;2
  • Smith, CA and PD Sardeshmukh. (15-Nov 2000). The effect of ENSO on the intraseasonal variance of surface temperatures in winter. INTERNATIONAL JOURNAL OF CLIMATOLOGY, 20(13), 1543-1557. 10.1002/1097-0088(20001115)20:13<1543::AID-JOC579>3.0.CO;2-A
  • Sardeshmukh, PD, GP Compo and C Penland. (2000). Changes of probability associated with El Nino. JOURNAL OF CLIMATE, 13(24), 4268-4286. 10.1175/1520-0442(2000)013<4268:COPAWE>2.0.CO;2
  • Hall, NMJ and PD Sardeshmukh. (1-Jan 1998). Is the time-mean northern hemisphere flow baroclinically unstable?. JOURNAL OF THE ATMOSPHERIC SCIENCES, 55(1), 41-56. 10.1175/1520-0469(1998)055<0041:ITTMNH>2.0.CO;2
  • Whitaker, JS and PD Sardeshmukh. (15-Jan 1998). A linear theory of extratropical synoptic eddy statistics. JOURNAL OF THE ATMOSPHERIC SCIENCES, 55(2), 237-258. 10.1175/1520-0469(1998)055<0237:ALTOES>2.0.CO;2
  • Newman, M and PD Sardeshmukh. (15-Apr 1998). The impact of the annual cycle on the North Pacific North American response to remote low-frequency forcing. JOURNAL OF THE ATMOSPHERIC SCIENCES, 55(8), 1336-1353. 10.1175/1520-0469(1998)055<1336:TIOTAC>2.0.CO;2