A 780-year annually resolved record of Indian Ocean monsoon precipitation from a speleothem from south Oman

[1] Meteorological records of monsoon rainfall in the Indian Ocean are generally less than 100 years long. The relative brevity of these records makes it difficult to investigate monsoon variation on decadal and centennial timescales, to determine what factors influence the intensity of rainfall on these timescales, or to place possible changes in the twentieth century into a broader historical context. Development of a geologic proxy for rainfall that records annual variation in the monsoon over much longer time periods than are covered by instrumental records would be a significant step forward. We have developed an annually resolved record of monsoon rainfall variation for the past 780 years based on annual layer thickness and stable isotope analyses of a laminated stalagmite from southern Arabia. Our results show that monsoon variation over the past century is not outside of the range of the past 800 years. Decreasing monsoon rainfall over the past century is related to increasing sea surface temperature in the Indian Ocean. Spectral analyses of the record are dominated by cycles that are similar to those observed in records of solar activity on centurial timescales. Decadal to interannual cycles in the record appear to originate in the tropical Pacific Ocean. INDEX TERMS: 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 3354 Meteorology and Atmospheric Dynamics: Precipitation (1854); 1620 Global Change: Climate dynamics (3309); 1699 Global Change: General or miscellaneous; KEYWORDS: Monsoon, paleoclimate, rainfall, Indian Ocean, speleothem, oxygen isotopes

[1]  M. Stuiver,et al.  Sun, ocean, climate and atmospheric 14CO2 : an evaluation of causal and spectral relationships , 1993 .

[2]  Balaji Rajagopalan,et al.  Analyses of global sea surface temperature 1856–1991 , 1998 .

[3]  T. Palmer,et al.  Sahel rainfall and worldwide sea temperatures, 1901–85 , 1986, Nature.

[4]  G. Meehl,et al.  Coupled Land-Ocean-Atmosphere Processes and South Asian Monsoon Variability , 1994, Science.

[5]  McClanahan,et al.  Tropical pacific forcing of decadal SST variability in the western indian ocean over the past two centuries , 2000, Science.

[6]  W. Barnes,et al.  Testing Theoretically Predicted Stalagmite Growth Rate with Recent Annually Laminated Samples: Implications for Past Stalagmite Deposition , 1998 .

[7]  G. Meehl.  Influence of the land surface in the Asian summer monsoon , 1994 .

[8]  J. G Doyle,et al.  The sun in time , 1993 .

[9]  Gonzalez,et al.  Climate and vegetation history of the midcontinent from 75 to 25 ka: A speleothem record from crevice cave, missouri, USA , 1998, Science.

[10]  Russell S. Vose,et al.  The Global Historical Climatology Network: Long-term monthly temperature, precipitation, sea level pressure, and station pressure data , 1992 .

[11]  S. Solanki,et al.  The solar spectral irradiance since 1700 , 2000 .

[12]  P. Webster,et al.  Monsoons: Processes, predictability, and the prospects for prediction , 1998 .

[13]  Michael Schulz,et al.  Spectrum: spectral analysis of unevenly spaced paleoclimatic time series , 1997 .

[14]  M. Bar-Matthews,et al.  Late Quaternary Paleoclimate in the Eastern Mediterranean Region from Stable Isotope Analysis of Speleothems at Soreq Cave, Israel , 1997, Quaternary Research.

[15]  H. Schwarcz,et al.  Paleoclimate and vegetation of the Last Glacial Cycles in Jerusalem from a Speleothem Record , 2000 .

[16]  G. B. Pant,et al.  Construction of All-India Summer Monsoon Rainfall Series for the Period 1844–1991 , 1993 .

[17]  J. H. Parkinson.  New measurements of the solar diameter , 1983, Nature.

[18]  Richard G. Fairbanks,et al.  Interaction Between the ENSO and the Asian Monsoon in a Coral Record of Tropical Climate , 1997 .

[19]  J. Overpeck,et al.  Influence of mean climate change on climate variability from a 155-year tropical Pacific coral record , 2000, Nature.

[20]  S. Burns,et al.  Speleothem evidence from Oman for continental pluvial events during interglacial periods , 2001 .

[21]  S. Burns,et al.  Speleothem-based paleoclimate record from northern Oman , 1998 .

[22]  C. Hendy,et al.  The isotopic geochemistry of speleothems—I. The calculation of the effects of different modes of formation on the isotopic composition of speleothems and their applicability as palaeoclimatic indicators , 1971 .

[23]  Thompson,et al.  A high-resolution millennial record of the south asian monsoon from himalayan ice cores , 2000, Science.

[24]  A. Matter,et al.  Strong coherence between solar variability and the monsoon in Oman between 9 and 6 kyr ago , 2001, Nature.

[25]  D. Chambers,et al.  Anomalous warming in the Indian Ocean coincident with El Niño , 1999 .

[26]  P. Swart,et al.  Climate change in continental isotopic records , 1993 .

[27]  Andy Baker,et al.  Annual growth banding in a cave stalagmite , 1993, Nature.

[28]  Malcolm K. Hughes,et al.  Global-scale temperature patterns and climate forcing over the past six centuries , 1998, Nature.

[29]  C. Hendy,et al.  Palaeoclimatic Data from Speleothems , 1968, Nature.

[30]  R. Dickson,et al.  Eurasian Snow Cover versus Indian Monsoon Rainfall--An Extension of the Hahn-Shukla Results. , 1984 .