• Ainsworth, E. A., , and A. Rogers, 2007: The response of photosynthesis and stomatal conductance to rising [CO2]: Mechanisms and environmental interactions. Plant Cell Environ., 30, 258270, doi:10.1111/j.1365-3040.2007.01641.x.

    • Search Google Scholar
    • Export Citation
  • Allen, M. R., , and W. J. Ingram, 2002: Constraints on future changes in climate and the hydrologic cycle. Nature, 419, 224232, doi:10.1038/nature01092.

    • Search Google Scholar
    • Export Citation
  • Allen, R. G., , L. S. Pereira, , D. Raes, , and M. Smith, 1998: Crop evapotranspiration-guidelines for computing crop water requirements. Food and Agriculture Organization of the United Nations Irrigation and Drainage Paper 56, 326 pp.

  • Anchukaitis, K. J., , M. N. Evans, , A. Kaplan, , E. A. Vaganov, , H. D. Grissino-Mayer, , M. K. Hughes, , and M. A. Cane, 2006: Forward modeling of regional-scale tree-ring patterns in the southeastern United States and the recent influence of summer drought. Geophys. Res. Lett., 33, L04705, doi:10.1029/2005GL025050.

    • Search Google Scholar
    • Export Citation
  • Anchukaitis, K. J., , B. M. Buckley, , E. R. Cook, , B. I. Cook, , R. D. D'Arrigo, , and C. M. Ammann, 2010: Influence of volcanic eruptions on the climate of the Asian monsoon region. Geophys. Res. Lett., 37, L22703, doi:10.1029/2010GL044843.

    • Search Google Scholar
    • Export Citation
  • Ault, T. R., , J. E. Cole, , J. T. Overpeck, , G. T. Pederson, , S. St. George, , B. Otto-Bliesner, , C. A. Woodhouse, , and C. Deser, 2013a: The continuum of hydroclimate variability in western North America during the last millennium. J. Climate, 26, 58635878, doi:10.1175/JCLI-D-11-00732.1.

    • Search Google Scholar
    • Export Citation
  • Ault, T. R., , C. Deser, , M. Newman, , and J. Emile-Geay, 2013b: Characterizing decadal to centennial variability in the equatorial Pacific during the last millennium. Geophys. Res. Lett., 40, 34503456, doi:10.1002/grl.50647.

    • Search Google Scholar
    • Export Citation
  • Ault, T. R., , J. E. Cole, , J. T. Overpeck, , G. T. Pederson, , and D. M. Meko, 2014: Assessing the risk of persistent drought using climate model simulations and paleoclimate data. J. Climate, 27, 7529–7549, doi:10.1175/JCLI-D-12-00282.1.

    • Search Google Scholar
    • Export Citation
  • Betts, A. K., , J. H. Ball, , A. C. M. Beljaars, , M. J. Miller, , and P. A. Viterbo, 1996: The land surface-atmosphere interaction: A review based on observational and global modeling perspectives. J. Geophys. Res., 101, 72097225, doi:10.1029/95JD02135.

    • Search Google Scholar
    • Export Citation
  • Burke, E. J., 2011: Understanding the sensitivity of different drought metrics to the drivers of drought under increased atmospheric CO2. J. Hydrometeor., 12, 13781394, doi:10.1175/2011JHM1386.1.

    • Search Google Scholar
    • Export Citation
  • Burke, E. J., , and S. J. Brown, 2008: Evaluating uncertainties in the projection of future drought. J. Hydrometeor., 9, 292299, doi:10.1175/2007JHM929.1.

    • Search Google Scholar
    • Export Citation
  • Burke, E. J., , S. J. Brown, , and N. Christidis, 2006: Modeling the recent evolution of global drought and projections for the twenty-first century with the Hadley Centre climate model. J. Hydrometeor., 7, 11131125, doi:10.1175/JHM544.1.

    • Search Google Scholar
    • Export Citation
  • Coats, S., , J. E. Smerdon, , B. I. Cook, , and R. Seager, 2013a: Stationarity of the tropical Pacific teleconnection to North America in CMIP5/PMIP3 model simulations. Geophys. Res. Lett.,40, 4927–4932, doi:10.1002/grl.50938.

  • Coats, S., , J. E. Smerdon, , R. Seager, , B. I. Cook, , and J. F. González-Rouco, 2013b: Megadroughts in southwestern North America in ECHO-G millennial simulations and their comparison to proxy drought reconstructions. J. Climate, 26, 76357649, doi:10.1175/JCLI-D-12-00603.1.

    • Search Google Scholar
    • Export Citation
  • Coats, S., , B. I. Cook, , J. E. Smerdon, , and R. Seager, 2015a: North American pancontinental droughts in model simulations of the last millennium. J. Climate, doi:10.1175/JCLI-D-14-00634.1, in press.

    • Search Google Scholar
    • Export Citation
  • Coats, S., , J. E. Smerdon, , B. I. Cook, , and R. Seager, 2015b: Are simulated megadroughts in the North American southwest forced? J. Climate, 28, 124–142, doi:10.1175/JCLI-D-14-00071.1.

    • Search Google Scholar
    • Export Citation
  • Cook, B. I., , J. E. Smerdon, , R. Seager, , and S. Coats, 2014a: Global warming and 21st century drying. Climate Dyn., 43, 2607–2627, doi:10.1007/s00382-014-2075-y.

    • Search Google Scholar
    • Export Citation
  • Cook, B. I., , J. E. Smerdon, , R. Seager, , and E. R. Cook, 2014b: Pan-continental droughts in North America over the last millennium. J. Climate, 27, 383397, doi:10.1175/JCLI-D-13-00100.1.

    • Search Google Scholar
    • Export Citation
  • Cook, E. R., , R. Seager, , M. A. Cane, , and D. W. Stahle, 2007: North American drought: Reconstructions, causes and consequences. Earth-Sci. Rev., 81, 93134, doi:10.1016/j.earscirev.2006.12.002.

    • Search Google Scholar
    • Export Citation
  • Cook, E. R., , R. Seager, , R. R. Heim Jr., , R. S. Vose, , C. Herweijer, , and C. Woodhouse, 2010: Megadroughts in North America: Placing IPCC projections of hydroclimatic change in a long-term palaeoclimate context. J. Quat. Sci., 25, 4861, doi:10.1002/jqs.1303.

    • Search Google Scholar
    • Export Citation
  • Dai, A., 2011a: Characteristics and trends in various forms of the Palmer drought severity index during 1900-2008. J. Geophys. Res., 116, D12115, doi:10.1029/2010JD015541.

    • Search Google Scholar
    • Export Citation
  • Dai, A., 2011b: Drought under global warming: a review. Wiley Interdiscip. Rev.: Climate Change, 2, 4565, doi:10.1002/wcc.81.

  • Dai, A., 2013: Increasing drought under global warming in observations and models. Nat. Climate Change, 3, 5258, doi:10.1038/nclimate1633.

    • Search Google Scholar
    • Export Citation
  • De Kauwe, M. G., and et al. , 2013: Forest water use and water use efficiency at elevated CO2: A model-data intercomparison at two contrasting temperate forest FACE sites. Global Change Biol., 19, 17591779, doi:10.1111/gcb.12164.

    • Search Google Scholar
    • Export Citation
  • Ding, Y., , M. J. Hayes, , and M. Widhalm, 2011: Measuring economic impacts of drought: A review and discussion. Disaster Prev. Manage., 20, 434446, doi:10.1108/09653561111161752.

    • Search Google Scholar
    • Export Citation
  • Domec, J. C., , S. Palmroth, , E. Ward, , C. A. Maier, , M. Therezien, , and R. Oren, 2009: Acclimation of leaf hydraulic conductance and stomatal conductance of Pinus taeda (loblolly pine) to long-term growth in elevated CO2 (free-air CO2 enrichment) and N-fertilization. Plant Cell Environ., 32, 15001512, doi:10.1111/j.1365-3040.2009.02014.x.

    • Search Google Scholar
    • Export Citation
  • Evans, M. N., , B. K. Reichert, , A. Kaplan, , K. J. Anchukaitis, , E. A. Vaganov, , M. K. Hughes, , and M. A. Cane, 2006: A forward modeling approach to paleoclimatic interpretation of tree-ring data. J. Geophys. Res., 111, G03008, doi:10.1029/2006JG000166.

    • Search Google Scholar
    • Export Citation
  • Fernández-Donado, L., and et al. , 2013: Large-scale temperature response to external forcing in simulations and reconstructions of the last millennium. Climate Past, 9, 393421, doi:10.5194/cp-9-393-2013.

    • Search Google Scholar
    • Export Citation
  • Gerten, D., , R. Betts, , and P. Döll, 2014: Cross-chapter box on the active role of vegetation in altering water flows under climate change. Climate Change 2014: Impacts, Adaptation, and Vulnerability, C. B. Field et al., Eds., Cambridge University Press, 157–161.

    • Search Google Scholar
    • Export Citation
  • Goosse, H., , E. Crespin, , A. de Montety, , M. E. Mann, , H. Renssen, , and A. Timmermann, 2010: Reconstructing surface temperature changes over the past 600 years using climate model simulations with data assimilation. J. Geophys. Res., 115, D09108, doi:10.1029/2009JD012737.

    • Search Google Scholar
    • Export Citation
  • Goosse, H., , E. Crespin, , S. Dubinkina, , M.-F. Loutre, , M. E. Mann, , H. Renssen, , Y. Sallaz-Damaz, , and D. T. Shindell, 2012: The role of forcing and internal dynamics in explaining the “Medieval Climate Anomaly.” Climate Dyn., 39, 28472866, doi:10.1007/s00382-012-1297-0.

    • Search Google Scholar
    • Export Citation
  • Guttman, N. B., 1998: Comparing the Palmer drought index and the standardized precipitation index. J. Amer. Water Res. Assoc., 34, 113121, doi:10.1111/j.1752-1688.1998.tb05964.x.

    • Search Google Scholar
    • Export Citation
  • Harris, I., , P. D. Jones, , T. J. Osborn, , and D. H. Lister, 2014: Updated high-resolution grids of monthly climatic observations—The CRU TS3.10 dataset. Int. J. Climatol., 34, 623642, doi:10.1002/joc.3711.

    • Search Google Scholar
    • Export Citation
  • Headey, D., 2011: Rethinking the global food crisis: The role of trade shocks. Food Policy, 36, 136146, doi:10.1016/j.foodpol.2010.10.003.

    • Search Google Scholar
    • Export Citation
  • Hernandez, E., , and V. Uddameri, 2014: Standardized precipitation evaporation index (SPEI)-based drought assessment in semi-arid south Texas. Env. Earth Sci., 71, 24912501, doi:10.1007/s12665-013-2897-7.

    • Search Google Scholar
    • Export Citation
  • Hind, A., , and A. Moberg, 2013: Past millennial solar forcing magnitude. A statistical hemispheric-scale climate model versus proxy data comparison. Climate Dyn., 41, 25272537, doi:10.1007/s00382-012-1526-6.

    • Search Google Scholar
    • Export Citation
  • Hind, A., , A. Moberg, , and R. Sundberg, 2012: Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium—Part 2: A pseudo-proxy study addressing the amplitude of solar forcing. Climate Past, 8, 13551365, doi:10.5194/cp-8-1355-2012.

    • Search Google Scholar
    • Export Citation
  • Hoerling, M., , J. K. Eischeid, , X. W. Quan, , H. F. Diaz, , R. S. Webb, , R. M. Dole, , and D. R. Easterling, 2012: Is a transition to semipermanent drought conditions imminent in the U.S. Great Plains? J. Climate, 25, 83808386, doi:10.1175/JCLI-D-12-00449.1.

    • Search Google Scholar
    • Export Citation
  • Hoerling, M., and et al. , 2013: Anatomy of an extreme event. J. Climate, 26, 28112832, doi:10.1175/JCLI-D-12-00270.1.

  • Hoerling, M., , J. Eischeid, , A. Kumar, , R. Leung, , A. Mariotti, , K. Mo, , S. Schubert, , and R. Seager, 2014: Causes and predictability of the 2012 Great Plains drought. Bull. Amer. Meteor. Soc., 95, 269–282, doi:10.1175/BAMS-D-13-00055.1.

    • Search Google Scholar
    • Export Citation
  • Hussain, M. Z., , A. VanLoocke, , M. H. Siebers, , U. M. Ruiz-Vera, , R. J. Cody Markelz, , A. D. B. Leakey, , D. R. Ort, , and C. J. Bernacchi, 2013: Future carbon dioxide concentration decreases canopy evapotranspiration and soil water depletion by field-grown maize. Global Change Biol., 19, 15721584, doi:10.1111/gcb.12155.

    • Search Google Scholar
    • Export Citation
  • Inauen, N., , C. Körner, , and E. Hiltbrunner, 2013: Hydrological consequences of declining land use and elevated CO2 in alpine grassland. J. Ecol., 101, 8696, doi:10.1111/1365-2745.12029.

    • Search Google Scholar
    • Export Citation
  • Jones, P. D., and et al. , 2009: High-resolution palaeoclimatology of the last millennium: A review of current status and future prospects. Holocene, 19, 349, doi:10.1177/0959683608098952.

    • Search Google Scholar
    • Export Citation
  • Lehner, F., , C. C. Raible, , and T. F. Stocker, 2012: Testing the robustness of a precipitation proxy-based North Atlantic Oscillation reconstruction. Quat. Sci. Rev., 45, 8594, doi:10.1016/j.quascirev.2012.04.025.

    • Search Google Scholar
    • Export Citation
  • Li, X., , S. R. Waddington, , J. Dixon, , A. K. Joshi, , and M. C. Vicente, 2011: The relative importance of drought and other water-related constraints for major food crops in South Asian farming systems. Food Security, 3, 1933, doi:10.1007/s12571-011-0111-x.

    • Search Google Scholar
    • Export Citation
  • Lobell, D. B., , W. Schlenker, , and J. Costa-Roberts, 2011: Climate Trends and global crop production since 1980. Science, 333, 616620, doi:10.1126/science.1204531.

    • Search Google Scholar
    • Export Citation
  • Mann, M. E., and et al. , 2009: Global signatures and dynamical origins of the Little Ice Age and Medieval Climate Anomaly. Science, 326, 12561260, doi:10.1126/science.1177303.

    • Search Google Scholar
    • Export Citation
  • Masson-Delmotte, V., and et al. , 2014: Information from paleoclimate archives. Climate Change 2013: The Physical Science Basis, T. F. Stocker et al., Eds., Cambridge University Press, 383–464.

  • Naudts, K., , J. Berge, , I. Janssens, , I. Nijs, , and R. Ceulemans, 2013: Combined effects of warming and elevated CO2 on the impact of drought in grassland species. Plant Soil, 369 (1–2), 497507, doi:10.1007/s11104-013-1595-2.

    • Search Google Scholar
    • Export Citation
  • Neukom, R., , J. Luterbacher, , R. Villalba, , M. Küttel, , D. Frank, , P. D. Jones, , M. Grosjean, , J. Esper, , L. Lopez, , and H. Wanner, 2010: Multi-centennial summer and winter precipitation variability in southern South America. Geophys. Res. Lett., 37, L14708, doi:10.1029/2010GL043680.

    • Search Google Scholar
    • Export Citation
  • Neukom, R., and et al. , 2011: Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries. Climate Dyn., 37 (1–2), 3551, doi:10.1007/s00382-010-0793-3.

    • Search Google Scholar
    • Export Citation
  • PAGES 2k Consortium, 2013: Continental-scale temperature variability over the last two millennia. Nat. Geosci.,6, 339–346, doi:10.1038/ngeo1797.

  • Palmer, W. C., 1965: Meteorological drought. U.S. Weather Bureau Research Paper 45, 58 pp.

  • Peng, S., and et al. , 2011: Recent change of vegetation growth trend in China, Environ. Res. Lett.,6, 044027, doi:10.1088/1748-9326/6/4/044027.

  • Penman, H. L., 1948: Natural evaporation from open water, bare soil and grass. Proc. Roy. Soc. London, 193, 120145, doi:10.1098/rspa.1948.0037.

    • Search Google Scholar
    • Export Citation
  • Phipps, S. J., and et al. , 2013: Paleoclimate data–model comparison and the role of climate forcings over the past 1500 years. J. Climate, 26, 69156936, doi:10.1175/JCLI-D-12-00108.1.

    • Search Google Scholar
    • Export Citation
  • Scheff, J., , and D. M. W. Frierson, 2014: Scaling potential evapotranspiration with greenhouse warming. J. Climate, 27, 15391558, doi:10.1175/JCLI-D-13-00233.1.

    • Search Google Scholar
    • Export Citation
  • Schmidt, G. A., 2010: Enhancing the relevance of palaeoclimate model/data comparisons for assessments of future climate change. J. Quat. Sci.,25, 79–87, doi:10.1002/jqs.1314.

  • Schmidt, G. A., and et al. , 2014: Using palaeo-climate comparisons to constrain future projections in CMIP5. Climate Past, 10, 221250, doi:10.5194/cp-10-221-2014.

    • Search Google Scholar
    • Export Citation
  • Seager, R., , R. Burgman, , Y. Kushnir, , A. Clement, , E. Cook, , N. Naik, , and J. Miller, 2008: Tropical Pacific forcing of North American medieval megadroughts: Testing the concept with an atmosphere model forced by coral-reconstructed SSTs. J. Climate, 21, 61756190, doi:10.1175/2008JCLI2170.1.

    • Search Google Scholar
    • Export Citation
  • Seager, R., , M. Ting, , C. Li, , N. Naik, , B. Cook, , J. Nakamura, , and H. Liu, 2013: Projections of declining surface-water availability for the southwestern United States. Nat. Climate Change, 3, 482486, doi:10.1038/nclimate1787.

    • Search Google Scholar
    • Export Citation
  • Sellers, P. J., and et al. , 1997: Modeling the exchanges of energy, water, and carbon between continents and the atmosphere. Science, 275, 502509, doi:10.1126/science.275.5299.502.

    • Search Google Scholar
    • Export Citation
  • Seneviratne, S. I., 2012: Climate science: Historical drought trends revisited. Nature,491, 338–339, doi:10.1038/491338a.

  • Sheffield, J., , E. F. Wood, , and M. L. Roderick, 2012: Little change in global drought over the past 60 years. Nature, 491, 435438, doi:10.1038/nature11575.

    • Search Google Scholar
    • Export Citation
  • Smerdon, J. E., 2012: Climate models as a test bed for climate reconstruction methods: pseudoproxy experiments. Wiley Interdiscip. Rev.: Climate Change, 3, 6377, doi:10.1002/wcc.149.

    • Search Google Scholar
    • Export Citation
  • Stocker, R., , P. W. Leadley, , and C. Körner, 1997: Carbon and water fluxes in a calcareous grassland under elevated CO2. Funct. Ecol., 11, 222230, doi:10.1046/j.1365-2435.1997.00071.x.

    • Search Google Scholar
    • Export Citation
  • Sundberg, R., , A. Moberg, , and A. Hind, 2012: Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium—Part 1: Theory. Climate Past, 8, 13391353, doi:10.5194/cp-8-1339-2012.

    • Search Google Scholar
    • Export Citation
  • Taylor, K. E., , R. J. Stouffer, , and G. A. Meehl, 2012: An overview of CMIP5 and the experiment design. Bull. Amer. Meteor. Soc., 93, 485498, doi:10.1175/BAMS-D-11-00094.1.

    • Search Google Scholar
    • Export Citation
  • Thornthwaite, C., 1948: An approach toward a rational classification of climate. Geogr. Rev., 38, 5594, doi:10.2307/210739.

  • Tierney, J. E., , J. E. Smerdon, , K. J. Anchukaitis, , and R. Seager, 2013: Multidecadal variability in East African hydroclimate controlled by the Indian Ocean. Nature, 493, 389392, doi:10.1038/nature11785.

    • Search Google Scholar
    • Export Citation
  • Tingley, M. P., , P. F. Craigmile, , M. Haran, , B. Li, , E. Mannshardt, , and B. Rajaratnam, 2012: Piecing together the past: Statistical insights into paleoclimatic reconstructions. Quat. Sci. Rev., 35, 122, doi:10.1016/j.quascirev.2012.01.012.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., , A. Dai, , G. van der Schrier, , P. D. Jones, , J. Barichivich, , K. R. Briffa, , and J. Sheffield, 2014: Global warming and changes in drought. Nat. Climate Change, 4, 1722, doi:10.1038/nclimate2067.

    • Search Google Scholar
    • Export Citation
  • Trouet, V., , J. Esper, , N. E. Graham, , A. Baker, , D. C. Frank, , and J. D. Scourse, 2009: Persistent positive North Atlantic Oscillation mode dominated the Medieval Climate Anomaly. Science, 324, 7880, doi:10.1126/science.1166349.

    • Search Google Scholar
    • Export Citation
  • van der Schrier, G., , P. D. Jones, , and K. R. Briffa, 2011: The sensitivity of the PDSI to the Thornthwaite and Penman-Monteith parameterizations for potential evapotranspiration. J. Geophys. Res., 116, D03106, doi:10.1029/2010JD015001.

    • Search Google Scholar
    • Export Citation
  • van der Schrier, G., , J. Barichivich, , K. R. Briffa, , and P. D. Jones, 2013: A scPDSI-based global data set of dry and wet spells for 1901–2009. J. Geophys. Res. Atmos.,118, 4025–4048, doi:10.1002/jgrd.50355.

    • Search Google Scholar
    • Export Citation
  • Vicente-Serrano, S. M., , S. Beguera, , and J. I. López-Moreno, 2010a: A multiscalar drought index sensitive to global warming: The standardized precipitation evapotranspiration index. J. Climate, 23, 16961718, doi:10.1175/2009JCLI2909.1.

    • Search Google Scholar
    • Export Citation
  • Vicente-Serrano, S. M., , S. Beguera, , J. I. López-Moreno, , M. Angulo, , and A. El Kenawy, 2010b: A new global 0.5° gridded dataset (1901–2006) of a multiscalar drought index: Comparison with current drought index datasets based on the Palmer drought severity index. J. Hydrometeor., 11, 10331043, doi:10.1175/2010JHM1224.1.

    • Search Google Scholar
    • Export Citation
  • Wahl, E. R., , and J. E. Smerdon, 2012: Comparative performance of paleoclimatic field and index reconstructions derived from climate proxies and noise-only predictors. Geophys. Res. Lett., 39, L06703, doi:10.1029/2012GL051086.

    • Search Google Scholar
    • Export Citation
  • Wells, N., , S. Goddard, , and M. J. Hayes, 2004: A self-calibrating Palmer drought severity index. J. Climate, 17, 23352351, doi:10.1175/1520-0442(2004)017<2335:ASPDSI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Willmott, C. J., , C. M. Rowe, , and Y. Mintz, 1985: Climatology of the terrestrial seasonal water cycle. J. Climatol.,5, 589–606.

  • Xu, C. Y., , and V. P. Singh, 2002: Cross comparison of empirical equations for calculating potential evapotranspiration with data from Switzerland. Water Res. Manage., 16, 197219, doi:10.1023/A:1020282515975.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 67 67 21
PDF Downloads 45 45 11

Bridging Past and Future Climate across Paleoclimatic Reconstructions, Observations, and Models: A Hydroclimate Case Study

View More View Less
  • 1 Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
  • | 2 NASA Goddard Institute for Space Studies, New York, and Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
  • | 3 Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
© Get Permissions
Restricted access

Abstract

Potential biases in tree-ring reconstructed Palmer drought severity index (PDSI) are evaluated using Thornthwaite (TH), Penman–Monteith (PM), and self-calibrating Penman–Monteith (SC) PDSI in three diverse regions of the United States and tree-ring chronologies from the North American drought atlas (NADA). Minimal differences are found between the three PDSI reconstructions and all compare favorably to independently reconstructed Thornthwaite-based PDSI from the NADA. Reconstructions are bridged with model-derived PDSI_TH and PDSI_PM, which both closely track modeled soil moisture (near surface and full column) during the twentieth century. Differences between modeled moisture-balance metrics only emerge in twenty-first-century projections. These differences confirm the tendency of PDSI_TH to overestimate drying when temperatures exceed the range of the normalization interval; the more physical accounting of PDSI_PM compares well with modeled soil moisture in the projection interval. Remaining regional differences in the secular behavior of projected soil moisture and PDSI_PM are interpreted in terms of underlying physical processes and temporal sampling. Results demonstrate the continued utility of PDSI as a metric of surface moisture balance while additionally providing two recommendations for future work: 1) PDSI_PM (or similar moisture-balance metrics) compare well to modeled soil moisture and are an appropriate means of representing soil-moisture balance in model simulations and 2) although PDSI_PM is more physically appropriate than PDSI_TH, the latter metric does not bias tree-ring reconstructions of past hydroclimate variability and, as such, reconstructions targeting PDSI_TH can be used with confidence in data–model comparisons. These recommendations and the collective results of this study thus provide a framework for comparing hydroclimate variability within paleoclimatic, observational, and modeled data.

Denotes Open Access content.

Lamont-Doherty Earth Observatory Publication Number 7873.

Corresponding author address: Jason E. Smerdon, Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, P.O. Box 1000, Palisades, NY 10964. E-mail: jsmerdon@ldeo.columbia.edu

Abstract

Potential biases in tree-ring reconstructed Palmer drought severity index (PDSI) are evaluated using Thornthwaite (TH), Penman–Monteith (PM), and self-calibrating Penman–Monteith (SC) PDSI in three diverse regions of the United States and tree-ring chronologies from the North American drought atlas (NADA). Minimal differences are found between the three PDSI reconstructions and all compare favorably to independently reconstructed Thornthwaite-based PDSI from the NADA. Reconstructions are bridged with model-derived PDSI_TH and PDSI_PM, which both closely track modeled soil moisture (near surface and full column) during the twentieth century. Differences between modeled moisture-balance metrics only emerge in twenty-first-century projections. These differences confirm the tendency of PDSI_TH to overestimate drying when temperatures exceed the range of the normalization interval; the more physical accounting of PDSI_PM compares well with modeled soil moisture in the projection interval. Remaining regional differences in the secular behavior of projected soil moisture and PDSI_PM are interpreted in terms of underlying physical processes and temporal sampling. Results demonstrate the continued utility of PDSI as a metric of surface moisture balance while additionally providing two recommendations for future work: 1) PDSI_PM (or similar moisture-balance metrics) compare well to modeled soil moisture and are an appropriate means of representing soil-moisture balance in model simulations and 2) although PDSI_PM is more physically appropriate than PDSI_TH, the latter metric does not bias tree-ring reconstructions of past hydroclimate variability and, as such, reconstructions targeting PDSI_TH can be used with confidence in data–model comparisons. These recommendations and the collective results of this study thus provide a framework for comparing hydroclimate variability within paleoclimatic, observational, and modeled data.

Denotes Open Access content.

Lamont-Doherty Earth Observatory Publication Number 7873.

Corresponding author address: Jason E. Smerdon, Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, P.O. Box 1000, Palisades, NY 10964. E-mail: jsmerdon@ldeo.columbia.edu
Save