Much of my paleoclimate research seeks to learn what drives global climate change over the last 20,000 years. This time frame includes the Last Glacial Maximum (LGM), the deglaciation and Holocene. To reconstruct processes on timescales ranging from decades to millennia requires high-resolution data. For this purpose, I make use of sediment cores raised from locations with fast deposition rates. I find these sediment records in lakes or marine deposits in shallow water.
My work on this time scale includes my dissertation studies of the California Current, work on the oxygen minimum zone off Baja California, the Healy-Oden Trans Arctic Expedition (HOTRAX), and a number of other NSF-funded research expeditions.
Publications:
1500-year cycle dominated Holocene dynamics of Yellow River delta, L Yi, S Chen, JD Ortiz, G Chen, J Peng, F Liu, Y Chen, C Deng, The Holocene.
The surface expression of radiocarbon anomalies near Baja California during deglaciation, CM Lindsay, SJ Lehman, TM Marchitto, and JD Ortiz, Earth and Planetary Science Letters, 422 67–74.
Reconstruction of late Quaternary paleohydrologic conditions in
southeastern British Columbia using visible derivative spectroscopy of Cleland Lake sediment, LN Mihindukulasooriya, JD Ortiz, DP Pompeani, BA Steinman and MB Abbott, Quaternary Research.
Application of quotient normalization technique to minimize errors in diffuse spectral reflectance data collected under various conditions, EC Nwaodua and JD Ortiz, The Journal of Sedimentary Research, 84, 729-742.
Diffuse spectral reflectance of surficial sediments indicates sedimentary environments on the shelves of the Bering Sea and western Arctic, EC Nwaodua, JD Ortiz and EM Griffith, Marine Geology, 355, 218–233.
Ocean-atmosphere forcing of hydroclimate in the Pacific Northwest on centennial timescales, BA Steinman, MB Abbott, ME Mann, JD Ortiz, B Finney and DP Pompeani, Geophysical Research Letters.
Paleoenvironments during Younger Dryas-Early Holocene retreat of the Greenland Ice Sheet from outer Disko Trough, central west Greenland, AE Jennings, ME Walton, C O’Cofaigh, A Kilfeather, JT Andrews, JD Ortiz, A deVernal and JA Dowdeswell, J. Quaternary Science.
Mid–Late Holocene coastal environmental changes in southeastern Sri Lanka: New evidence for sea level variations in southern Bay of Bengal, PN Ranasinghe, JD Ortiz, AL Moore, B McAdoo, N Wells, CHER Siriwardana and DTDS Wijesundara, Quaternary International.
Mid- to late-Holocene Indian winter monsoon variability from a terrestrial record in eastern and southeastern coastal environments of Sri Lanka, PN Ranasinghage, JD Ortiz, AJ Smith, EM Griffith, CHER Siriwardana, SN De Silva, and DTDS Wijesundara, The Holocene.
1,500 year cycle in the Arctic Oscillation identified in Holocene Arctic sea-ice drift, DA Darby, JD Ortiz, CE Grosch and SP Lund, Nature Geoscience, 5, 897–900.
Paleolimnological conditions inferred from fossil diatom assemblages and derivative spectral properties of sediments in thermokarst ponds of subarctic Quebec, Canada, Boreas, F Bouchard, R Pienitz, JD Ortiz, P Francus and I Laurion, Early View.
The Late Quaternary flow through the Bering Strait has been forced by the Southern Ocean Winds, JD Ortiz, D Nof, L Polyak, G St. Onge, A Lise-Pronovost, S Naidu, D Darby and S Brachfeld, Journal of Physical Oceanography, 42(11), 2014-2029.
The arrested Agulhas retroflection, D Nof, V Zharkov, JD Ortiz, N Paldor and E Chassignet, Journal of Marine Research, 69, (Stern Vol. Special Issue), 659-691.
Application of Visible/near Infrared derivative spectroscopy to Arctic paleoceanography, JD Ortiz, IOP Conference Series: Earth and Environmental Science, 14.
Drought variability in the Pacific Northwest from a 6,000-yr lake sediment record, DB Nelson, MB Abbott, B Steinman, PJ Polissar, ND Stansell, JD Ortiz, MF Rosenmeier, BP Finney and J Riedel, Proceedings of the National Academy of Sciences.
Dynamical response of the tropical Pacific Ocean to solar forcing during the early Holocene, TM Marchitto, R Muscheler, JD Ortiz, J Carriquiry and A van Geen, Science, 330, 1378-1381.
Centennial variations in Sea surface temperature and productivity over the last 14ka from core PC14 off Baja California, X Lei, D Ling, Z Mei-Xum, R-P Zhang, A van Geen and JD Ortiz, [In Chinese with English Abstract], Oceanologica et Limnologia Sinica, 40, 385-392.
Provenance of Holocene sediment on the Chukchi-Alaskan margin based on combined diffuse spectral reflectance and quantitative x-ray diffraction analysis, JD Ortiz, L Polyak, JM Grebmeier, DA Darby, DD Eberl, S Naidu and D Nof, Global and Planetary Change, (68), 73-84.
The role of currents and sea ice in both slowly deposited central Arctic and rapidly deposited Chukchi-Alaskan margin sediments, DA Darby, JD Ortiz, J.D., L Polyak, S Lund, M Jakobsson and RA Woodgate, Global and Planetary Change, (68), 58-72.
Detrital and diagenetic magnetic signatures of sediment supply and water column stratification in Holocene sedimentary records from the eastern Chukchi Sea, S Brachfeld, F Barletta, G St-Onge, DA Darby and JD Ortiz, Global and Planetary Change, (68), 100-114.
Toward a non-linear grayscale calibration method for legacy photographic collections, JD Ortiz and S O’Connell, In P. Francus, J. Thurow, (eds.) Developments in Paleocenvironmental Research Series: Image Analysis, Sediments and Paleoenvironmental Reconstruction, 125-137.
Rapid Vegetational and Sediment Change from Rano Aroi Crater, Easter Island, D Peteet, W Beck, JD Ortiz, S O’Connell, D Kurdyla, and D Mann, In Easter Island, Scientific Exploration into the World’s Environmental Problems in Microcosm, J. Loret and J.T. Tanacredi, Eds., Kluwer, Academic/Plenum Publishers, NY, 79-89.
Anthropogenic CO2 invasion into the northeast Pacific based on concurrent δ13CDIC and nutrient profiles from the California Current, JD Ortiz, AC Mix, PA Wheeler and RM Key, Global Biogeochemical Cycles, 14, 917-929.
Coherent high- and low-latitude Climate Variability during the Holocene Warm Period, P deMenocal, JD Ortiz, T Guilderson and M Sarnthein, Science, 288, 2198-2202.
Abrupt onset and terminations of the African Humid Period: Rapid climate responses to gradual insolation forcing, P deMenocal, JD Ortiz, T Guilderson, J Adkins, M Sarnthein, L Baker and M Yarusinsky, Quaternary Science Reviews, 19, 347-361.
Non-invasive sediment monitoring methods: Current and future tools for high-resolution climate studies, JD Ortiz and FR Rack, in Reconstructing Ocean History: A window into the future, Kluwer, New York, 343-380.
Comparison of Imbrie-Kipp transfer function and Modern Analog Temperature estimates using sediment trap and coretop foraminiferal faunas, JD Ortiz and AC Mix, Paleoceanography, 12, 175-190.
The California Current of the Last Glacial Maximum at 42oN: Reconstruction based on multiple proxies, JD Ortiz, AC Mix, S Hostetler and M Kashgarian, Paleoceanography, 12, 191-206.
Deep-dwelling planktonic foraminifera of the Northeast Pacific reveal environmental control of oxygen and carbon isotopic disequilibria, JD Ortiz, AC Mix, W Rugh, JM Watkins and RW Collier, Geochimica et Cosmochimica Acta, 60, 4509-4523.
Environmental control of living symbiotic and asymbiotic foraminifera of the California Current, JD Ortiz, AC Mix and RW Collier, Paleoceanography, 10, 987-1009.
The spatial distribution and seasonal succession of planktonic Foraminifera in the California Current System off Oregon, September 1987-September 1988, JD Ortiz and AC Mix, in Upwelling Systems: Evolution since the early Miocene, Geological Society Special Publication No. 64, CP Summerhays, W Prell and KC Emeis (Eds.), London.