{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,18]],"date-time":"2026-03-18T01:36:59Z","timestamp":1773797819077,"version":"3.50.1"},"reference-count":34,"publisher":"Copernicus GmbH","issue":"10","license":[{"start":{"date-parts":[[2010,10,12]],"date-time":"2010-10-12T00:00:00Z","timestamp":1286841600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Hydrol. Earth Syst. Sci."],"abstract":"<jats:p>Abstract. Space-time variability of hydrological drought and wetness over Iran is investigated using the National Centers for Environmental Prediction\/National Center for Atmospheric Research (NCEP\/NCAR) reanalysis and the Global Precipitation Climatology Centre (GPCC) dataset for the common period 1948\u20132007. The aim is to complement previous studies on the detection of long-term trends in drought\/wetness time series and on the applicability of reanalysis data for drought monitoring in Iran. Climate conditions of the area are assessed through the Standardized Precipitation Index (SPI) on 24-month time scale, while Principal Component Analysis (PCA) and Varimax rotation are used for investigating drought\/wetness variability, and drought regionalization, respectively. Singular Spectrum Analysis (SSA) is applied to the time series of interest to extract the leading nonlinear components and compare them with linear fittings.  Differences in drought and wetness area coverage resulting from the two datasets are discussed also in relation to the change occurred in recent years. NCEP\/NCAR and GPCC are in good agreement in identifying four sub-regions as principal spatial modes of drought variability. However, the climate variability in each area is not univocally represented by the two datasets: a good agreement is found for south-eastern and north-western regions, while noticeable discrepancies occur for central and Caspian sea regions. A comparison with NCEP Reanalysis II for the period 1979\u20132007, seems to exclude that the discrepancies are merely due to the introduction of satellite data into the reanalysis assimilation scheme.<\/jats:p>","DOI":"10.5194\/hess-14-1919-2010","type":"journal-article","created":{"date-parts":[[2010,10,15]],"date-time":"2010-10-15T02:28:11Z","timestamp":1287109691000},"page":"1919-1930","source":"Crossref","is-referenced-by-count":31,"title":["Space-time variability of hydrological drought and wetness in Iran using NCEP\/NCAR and GPCC datasets"],"prefix":"10.5194","volume":"14","author":[{"given":"T.","family":"Raziei","sequence":"first","affiliation":[]},{"given":"I.","family":"Bordi","sequence":"additional","affiliation":[]},{"given":"L. S.","family":"Pereira","sequence":"additional","affiliation":[]},{"given":"A.","family":"Sutera","sequence":"additional","affiliation":[]}],"member":"3145","published-online":{"date-parts":[[2010,10,12]]},"reference":[{"key":"ref1","unstructured":"Beck, C., Grieser, J., and Rudolf, B.: A new monthly precipitation climatology for the global land areas for the period 1951 to 2000. DWD, Klimastatusbericht KSB 2004, ISSN 1437\u20137691, ISSN 1616\u20135063 (internet), ISBN 3-88148-402-7, 181\u2013190, 2005."},{"key":"ref2","unstructured":"Bordi I., Frigio, S., Parenti, P., Speranza, A., and Sutera, A.: The analysis of the Standardized Precipitation Index in the Mediterranean area: large-scale patterns, Annali di Geofisica, 44, 965\u2013978, 2001."},{"key":"ref3","doi-asserted-by":"crossref","unstructured":"Bordi, I., Dell'Aquila, A., Speranza, A., and Sutera, A.: Formula for a baroclinic adjustment theory of climate, Tellus, 54A, 260\u2013272, 2002.","DOI":"10.1034\/j.1600-0870.2002.00296.x"},{"key":"ref4","doi-asserted-by":"crossref","unstructured":"Bordi, I. and Sutera, A.: Drought variability and its climatic implications, Global and Planet Change, 40, 115\u2013127, 2004.","DOI":"10.1016\/S0921-8181(03)00102-4"},{"key":"ref5","doi-asserted-by":"crossref","unstructured":"Bordi, I., Dell'Aquila, A., Speranza, A., and Sutera, A.: On the mid-latitude tropopause height and the orographic-baroclinic adjustment theory, Tellus, 56A, 278\u2013286, 2004.","DOI":"10.1111\/j.1600-0870.2004.00065.x"},{"key":"ref6","doi-asserted-by":"crossref","unstructured":"Bordi, I., Fraedrich, K., Petitta, M., and Sutera, A.: Large-scale assessment of drought variability based on NCEP\/NCAR and ERA-40 re-analyses. Water Resour. Manage, 20, 899\u2013915, 2006.","DOI":"10.1007\/s11269-005-9013-z"},{"key":"ref7","doi-asserted-by":"crossref","unstructured":"Bordi, I., Fraedrich, K., and Sutera, A.: Observed drought and wetness trends in Europe: an update. Hydrol. Earth Syst. Sci., 13, 1519\u20131530, 2009.","DOI":"10.5194\/hess-13-1519-2009"},{"key":"ref8","doi-asserted-by":"crossref","unstructured":"Fraedrich, K.: Estimating the dimensions of weather and climate attractors, J. Atmos. Sci., 43, 419\u2013432, 1986.","DOI":"10.1175\/1520-0469(1986)043<0419:ETDOWA>2.0.CO;2"},{"key":"ref9","doi-asserted-by":"crossref","unstructured":"Ghil, M., Allen, M. R., and Dettinger, M. D.: Advanced spectral methods for climatic time series, Rev. Geophys., 40, 1.1\u20131.41, 2002.","DOI":"10.1029\/2000RG000092"},{"key":"ref10","doi-asserted-by":"crossref","unstructured":"Hayes, M. J., Wilhelmi, O. V., and Knutson, C. L.: Reducing drought risk: bridging theory and practice, Nat. Hazard Rev., 5, 106\u2013113, 2004.","DOI":"10.1061\/(ASCE)1527-6988(2004)5:2(106)"},{"key":"ref11","doi-asserted-by":"crossref","unstructured":"Janowiak, J. E., Gruber, A., Kondragunta, C. R., Livezey, R. E., and Huffman, G. J.: A comparison of the NCEP-NCAR reanalysis precipitation and the GPCP rain gauge-satellite combined dataset with observational error considerations, J. Climate, 11, 2960\u20132979, 1998.","DOI":"10.1175\/1520-0442(1998)011<2960:ACOTNN>2.0.CO;2"},{"key":"ref12","doi-asserted-by":"crossref","unstructured":"Kalnay, E., Kanamitsu M., Kistler R., Collins W., Deaven D., Gandin L., Iredell M., Saha S., White G., Woollen J., Zhu Y., Leetmaa A., Reynolds R., Chelliah M., Ebisuzaki W., Higgins W., Janowiak J., Mo K.C., Ropelewski C., Wang J., Jenne R., and Joseph D.: The NCEP\/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437\u2013471, 1996.","DOI":"10.1175\/1520-0477(1996)077<0437:TNYRP>2.0.CO;2"},{"key":"ref13","doi-asserted-by":"crossref","unstructured":"Kanamitsu, M., Ebisuzaki, W., Woollen, J., Yang, S.-K., Hnilo, J. J., Fiorino, M., and Potter, G. L.: NCEP-DOE AMIP-II Reanalysis (R-2), Bull. Amer. Meteor. Soc., 83, 1631\u20131643, 2002.","DOI":"10.1175\/BAMS-83-11-1631(2002)083<1631:NAR>2.3.CO;2"},{"key":"ref14","doi-asserted-by":"crossref","unstructured":"Keyantash, J. and Dracup, J. A.: The quantification of drought: an evaluation of drought indices, Bull. Amer. Meteor. Soc., 83, 1167\u20131180, 2002.","DOI":"10.1175\/1520-0477-83.8.1167"},{"key":"ref15","doi-asserted-by":"crossref","unstructured":"Kistler, R., Kalnay, E., Collins, W., Saha, S., White, G., Woollen, J., Chelliah, M., Ebisuzaki, W., Kanamitsu, M., Kousky, V., van den Dool, H., Jenne, R., and Fiorino, M.: The NCEP-NCAR 50-year reanalysis: monthly means CD-ROM and documentation, Bull. Amer. Meteor. Soc., 82, 247\u2013267, 2001.","DOI":"10.1175\/1520-0477(2001)082<0247:TNNYRM>2.3.CO;2"},{"key":"ref16","unstructured":"Knutson, C., Hayes, M., and Phillips, T.: How to Reduce Drought Risk. A guide prepared by the Preparedness and Mitigation Working Group of the Western Drought Coordination Council. National Drought Mitigation Center, Lincoln, Nebraska, available online at: http:\/\/drought.unl.edu\/plan\/handbook\/risk.pdf, 1998."},{"key":"ref17","doi-asserted-by":"crossref","unstructured":"Koutsoyiannis, D.: Climate change, the Hurst phenomenon, and hydrological statistics, Hydrol. Sci. J., 48(1), 3\u201324, 2003.","DOI":"10.1623\/hysj.48.1.3.43481"},{"key":"ref18","doi-asserted-by":"crossref","unstructured":"Lloyd-Hughes, B. and Saunders, M. A.: A drought climatology for Europe. Int. J. Climatol., 22, 1571\u20131592, 2002.","DOI":"10.1002\/joc.846"},{"key":"ref19","unstructured":"McKee, T. B., Doesken, N. J., and Kleist J.: The relationship of drought frequency and duration to time scales, in Proc. of the 8th Conference on Applied Climatology, 17\u201322 January, Anaheim, CA, American Meteorological Society, Boston, MA, USA, 179\u2013184, 1993."},{"key":"ref20","doi-asserted-by":"crossref","unstructured":"North, G. R., Bell, T. L., and Cahalan, R. F.: Sampling errors in the estimation of empirical orthogonal functions. Mon. Wea. Rev., 110, 699\u2013706, 1982.","DOI":"10.1175\/1520-0493(1982)110<0699:SEITEO>2.0.CO;2"},{"key":"ref21","unstructured":"Pereira, L. S., Cordery, I., and Iacovides, I.: Coping with water scarcity, Addressing the challenges, Springer, Dordrecht, The Netherlands, 2009."},{"key":"ref22","doi-asserted-by":"crossref","unstructured":"Raziei, T., Saghafian, B., Paulo, A. A., Pereira, L. S., and Bordi, I.: Spatial and temporal variability of drought in western Iran, Water Resour. Manage., 23, 439\u2013455, 2009.","DOI":"10.1007\/s11269-008-9282-4"},{"key":"ref23","doi-asserted-by":"crossref","unstructured":"Raziei, T., Bordi, I., and Pereira, L. S.: An application of GPCC and NCEP\/NCAR datasets for drought variability analysis in Iran. Special Issue: Water Resources Conservancy and Risk Reduction, Water Resour. Manage., https:\/\/doi.org\/10.1007\/s11269-010-9657-1, 2010.","DOI":"10.1007\/s11269-010-9657-1"},{"key":"ref24","unstructured":"Rencher, A. C.: Multivariate statistical inference and applications, John Wiley &amp; Sons Inc., 559 pp., 1998."},{"key":"ref25","doi-asserted-by":"crossref","unstructured":"Rossi, G.: Requisites for a drought watch system, in G. Rossi et al. (Eds) Tools for drought mitigation in Mediterranean regions, Kluwer Academic Publishers, Dordrecht, 147\u2013157, 2003.","DOI":"10.1007\/978-94-010-0129-8_9"},{"key":"ref26","unstructured":"Schneider, U., Fuchs, T., Meyer-Christoffer, A., and Rudolf, B.: Global Precipitation Analysis Products of the GPCC. Global Precipitation Climatology Centre (GPCC), DWD, Internet Publication, available online at: http:\/\/www.dwd.de, 1\u201312, 2008."},{"key":"ref27","doi-asserted-by":"crossref","unstructured":"Trenberth, K. E. and Guillemot, C. J.: Evaluation of the atmospheric moisture and hydrological cycle in the NCEP\/NCAR reanalyses, Clim. Dynam., 14, 213\u2013231, 1998.","DOI":"10.1007\/s003820050219"},{"key":"ref28","doi-asserted-by":"crossref","unstructured":"Tsakiris, G. and Vangelis, H.: Towards a drought watch system based on spatial SPI. Water Resour. Manag., 18, 1\u201312, 2004.","DOI":"10.1023\/B:WARM.0000015410.47014.a4"},{"key":"ref29","doi-asserted-by":"crossref","unstructured":"Vautard, R. and Ghil, M.: Singular spectrum analysis in nonlinear dynamics, with applications to paleoclimatic time series, Physica D, 35, 395\u2013424, 1989.","DOI":"10.1016\/0167-2789(89)90077-8"},{"key":"ref30","doi-asserted-by":"crossref","unstructured":"Vicente-Serrano, S. M.: Spatial and temporal analysis of droughts in the Iberian Peninsula (1910\u20132000), Hydrolog. Sci. J., 51, 83\u201397, 2006.","DOI":"10.1623\/hysj.51.1.83"},{"key":"ref31","doi-asserted-by":"crossref","unstructured":"Vicente-Serrano, S. M.: Differences in spatial patterns of drought on different time scales: an analysis of the Iberian Peninsula, Water Resour. Manage., 20, 37\u201360, 2006.","DOI":"10.1007\/s11269-006-2974-8"},{"key":"ref32","doi-asserted-by":"crossref","unstructured":"Wilhite, D. A., Hayes, M. J., Knutson, C., and Smith, K. H.: Planning for Drought: Moving from Crisis to Risk Management, J. Am. Water Resour. Assoc., 36, 697\u2013710, 2000.","DOI":"10.1111\/j.1752-1688.2000.tb04299.x"},{"key":"ref33","unstructured":"Wilhite, D. A.: Drought as a natural hazard: Concepts and definitions, Drought: A global assessment, Vol. 1, edited by: Wilhite, D. A., Routledge, New York, USA, 1\u201318, 2000."},{"key":"ref34","unstructured":"Yevjevich, V., Hall, W. A., and Salas, J. D.: Drought research needs, in: Proc. of the Conference on Drought Research Needs, December 12\u201315, 1977, Colorado State University, Fort Collins, Colorado, Water Resources Publication, Fort Collins, Colorado, USA, 276 pp., 1978."}],"container-title":["Hydrology and Earth System Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/hess.copernicus.org\/articles\/14\/1919\/2010\/hess-14-1919-2010.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,2,15]],"date-time":"2025-02-15T17:21:52Z","timestamp":1739640112000},"score":1,"resource":{"primary":{"URL":"https:\/\/hess.copernicus.org\/articles\/14\/1919\/2010\/"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2010,10,12]]},"references-count":34,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2010]]}},"URL":"https:\/\/doi.org\/10.5194\/hess-14-1919-2010","relation":{"has-preprint":[{"id-type":"doi","id":"10.5194\/hessd-7-3249-2010","asserted-by":"subject"},{"id-type":"doi","id":"10.5194\/hessd-7-3249-2010","asserted-by":"object"}]},"ISSN":["1607-7938"],"issn-type":[{"value":"1607-7938","type":"electronic"}],"subject":[],"published":{"date-parts":[[2010,10,12]]}}}