Ranu Lamongan, East Java, Indonesia 800 Year Drought Index Crausbay, S.D.; Russell, J.M.; Schnurrenberger, D.W. Crausbay, S.D. Russell, J.M. Schnurrenberger, D.W. earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (magnesium,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,Value of 0.5 = semi-quantitative value denoting calcite presence however low abundance or presence in thin laminae precluded measurement of mol% MgCO3. Value of 12 = semi-quantitative value denoting aragonite presence based on empirical results from Müller et al. 1972; when aragonite and calcite were both present the value of 12 representing aragonite was used. Other values are measurements of mol% MgCO3; see Crausbay et al. 2006 for complete discussion.) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Ranu Lamongan>LATITUDE -7.9833>LONGITUDE 113.3833) Lithostratigraphic analyses of a sub-annually laminated core from Ranu Lamongan, a maar lake on the island of Java, document considerable changes in the lake's chemistry and water balance over the past ca. 800 calendar years. Composition of the dark (clastics) and light (diatoms and/or calcium carbonate minerals) couplets suggests that these laminations form in response to seasonal changes in rainfall and water-column overturn in the lake. Calcium carbonate is not continuous in the core, and when it occurs it varies, sometimes abruptly, in carbonate phase and elemental composition (low Mg-calcite Mg-calcite, and aragonite). A significant correlation between Mg/Ca changes and d18O variations in authigenic calcium carbonate suggest the basin is highly sensitive to hydrologic variation. Lithologic data suggest calcium carbonate precipitates and thus records hydrologic conditions during the dry season - a season in which rainfall anomalies are highly correlated with the phase of ENSO. Our carbonate-based record of Mg/Ca shows variability in evaporative concentration on a quasi-seasonal frequency for the past ca. 800 years. Our record shows two multi-decadal periods of drought - ca. 1275-1325 and ca. 1450-1650 CE - the latter of which was especially strong and/or prolonged. Our record also shows a possible change in drought frequency at around 1650 CE, in which periods of calcium carbonate precipitation and Mg/Ca change shifted from multi-decadal to interannual variability. Given the strong correlations between modern-day drought in East Java and ENSO variability, our drought record may indicate a regime shift in the behavior of the ENSO system about 350 years ago. Finally, comparisons between our record and others suggest that variation in ENSO on centennial and sub-centennial scales is not strongly associated with changes in the global mean climate state. STUDY NOTES: Drought Index for the past millennium from sub-annually laminated lake sediment in lowland East Java, Indonesia. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Crausbay, S.D. Investigator : Russell, J.M. Investigator : Schnurrenberger, D.W. 2017-07-10 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/22409 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/indonesia/lamongan2006di.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/indonesia/lamongan2006di.txt English https://www.ncdc.noaa.gov/paleo/study/22409 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/indonesia/lamongan2006di.txt Crausbay, Shelly D.; Russell, James M.; Schnurrenberger, Douglas W.2006A ca. 800-year lithologic record of drought from sub-annually laminated lake sediment, East JavaJournal of Paleolimnology353641-65910.1007/s10933-005-4440-7http://dx.doi.org/10.1007/s10933-005-4440-7 START YEAR: 870 14C yr BP * END YEAR: 60 14C yr BP 113.3833 -7.9833 113.3833 -7.9833