HR: 0800h
AN: GC11A-0126    [Abstracts]
TI: Multi-GCM Projections of Global Drought Conditions With Use of the Palmer Drought Indices
AU: * Dubrovsky, M
EM: dub@ufa.cas.cz
AF: Institute of Atmospheric Physics ASCR, Bocni II/1401, Prague, 14131, Czech Republic
AU: * Dubrovsky, M
EM: dub@ufa.cas.cz
AF: Institute for Agrosystems and Bioclimatology, Mendel University of Agriculture and Forestry, Zemedelska 1, Brno, 61300, Czech Republic
AU: Svoboda, M
EM: msvoboda@unlnotes.unl.edu
AF: National Drought Mitigation Center, School of Natural Resources, University of Nebraska- Lincoln, 819 Hardin Hall, 3310 Holdrege St., Lincoln, NE 68583, United States
AU: Trnka, M
EM: mirek_trnka@yahoo.com
AF: Institute of Atmospheric Physics ASCR, Bocni II/1401, Prague, 14131, Czech Republic
AU: Trnka, M
EM: mirek_trnka@yahoo.com
AF: Institute for Agrosystems and Bioclimatology, Mendel University of Agriculture and Forestry, Zemedelska 1, Brno, 61300, Czech Republic
AU: Hayes, M
EM: mjhayes@unlnotes.unl.edu
AF: National Drought Mitigation Center, School of Natural Resources, University of Nebraska- Lincoln, 819 Hardin Hall, 3310 Holdrege St., Lincoln, NE 68583, United States
AU: Wilhite, D
EM: dwilhite@unlnotes.unl.edu
AF: National Drought Mitigation Center, School of Natural Resources, University of Nebraska- Lincoln, 819 Hardin Hall, 3310 Holdrege St., Lincoln, NE 68583, United States
AU: Zalud, Z
EM: zalud@mendelu.cz
AF: Institute of Atmospheric Physics ASCR, Bocni II/1401, Prague, 14131, Czech Republic
AU: Zalud, Z
EM: zalud@mendelu.cz
AF: Institute for Agrosystems and Bioclimatology, Mendel University of Agriculture and Forestry, Zemedelska 1, Brno, 61300, Czech Republic
AB: We use two Palmer Drought Indices (the PDSI and Z-index) to assess the drought conditions in future climates as projected by seven Global Climate Models (GCMs). Both indices are based on precipitation and temperature data (this makes them more suitable for climate change impact studies compared to the Standardized Precipitation Index, which is based only on precipitation) and the available water content of the soil. In contrast to the PDSI, the Z-index does not account for any persistence within the climate; rather, it characterizes the immediate (for a given week or month) conditions. The indices are calculated by computer programs available from the National Drought Mitigation Center and the Computer Science and Engineering Department, both located at the University of Nebraska-Lincoln. To allow for the assessment of climate change impacts, we modified the original computer code: the indices (which we named "relative" drought indices) are now calibrated using the present climate weather series and then applied to the future climate weather series. The resultant time series thus displays the drought conditions in terms of the present climate. The relative drought indices are applied to gridded (whole globe) GCM-simulated surface monthly weather series (available from the IPCC database), and the available water content is based on soil- texture-based water holding capacity global data developed by Webb et al. (1993, Global Biogeochem. Cycles 7: 97–108). The indices are calibrated with 1991-2020 period (considered to be the present climate) and then applied to two future periods: 2031-2060 and 2060-2099. To quantify impacts of climate change on the drought conditions, we analyze shifts in the grid-specific means of the drought indices and in the frequency of months belonging to drought spells. The drought spell is defined here as continuous periods in which the index does not exceed -1, and falls below -3 for at least one month. Results obtained by single GCMs related to North America and Europe were already discussed earlier (http://www.ufa.cas.cz/dub/impacts/2006-longmont-drought.pdf). Here, the emphasis will be put on (1) assessing drought conditions on the whole globe, and (2) aggregating results from the set of seven GCMs. We will identify (i) regions where the drought conditions (when averaged over all 7 GCMs) will change most significantly, and (ii) regions where the between-GCMs concordance in projected drought change is the greatest thus indicating the highest reliability of the projection. For example, for North America and Europe, the projection of the PDSI for the end of the 21st century indicate the following regions with the highest potential risk of drought exaggeration (indicated by high decreases in PDSI combined with a high between-GCM concordance): the belt along the Canadian-U.S. border, central Mexico, the Mediterranean, and central Europe. Acknowledgements: The study is supported by the AMVIS-KONTAKT project (ME 844) and the National Agency for the Agricultural Research (project QG60051).
DE: 1626 Global climate models (3337, 4928)
DE: 1812 Drought
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting