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The ocean-atmosphere system: primary responses to orbital forcings

The ocean-atmosphere system: primary responses to orbital forcings. Orbital forcings. GLACIAL. INTERGLACIAL. temperature humidity CO 2 winds. ATMOSPHERE. OCEAN. volume temperature CO 2 currents. The oceanic d 18 O record: 80-90% RSL response; 10-20% temperature response?.

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The ocean-atmosphere system: primary responses to orbital forcings

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  1. The ocean-atmosphere system:primary responses to orbital forcings Orbital forcings GLACIAL INTERGLACIAL temperature humidity CO2 winds ATMOSPHERE OCEAN volume temperature CO2 currents

  2. The oceanic d18O record:80-90% RSL response;10-20% temperatureresponse?

  3. SST changesfrom LGM to present in coastal waters of N. California(~100 km offshore?)

  4. Radiolarian assemblages in core 1019 (989 m water depth) YD T1 green line = GISP2 d18O record; black line=radiolarian record

  5. Primary productivity and zones of coastal upwelling image: terra.nasa.gov

  6. Pelagic diatom assemblages of the N. Pacific(e.g. Okhotsk Sea cluster = one of three subarctic water masses, shown in black) RC10-216 V20-119 V21-172 580 V20-107 579 from: Sancetta & Silvestri (1986) Paleoceanography 1, 163-180.

  7. “Okhotskcluster” through time

  8. RSL -temperature - salinity interactions in the Red Sea from: Rohling et al. (1998) Nature, 394, 162-165. Low RSL = hypersaline Red Sea = no planktonic forams

  9. A Heinrich layer (H-1) in a deep-sea core pelagic ooze H - layer (ooze-filled burrows?) ooze

  10. Iceberg-rafted detritus (IRD) in H1

  11. Heinrich events in the North Atlantic Ocean

  12. Oceanographic effects of drifting icebergs drift cold fresh water nutrient-deficient >200 m nutrient-rich detritus

  13. Heinrich (5-10 ka) events and Bond cycles (~1.5 ka)in VM23-81

  14. N. Atlantic currents:iceberg-drift routes

  15. The N. Atlantic ‘gate’ and the ‘binge-purge’ cycle of the Laurentide ice sheet cold Ocean ‘polar front’ warm

  16. Dansgaard-Oeschger cycles and Heinrich events

  17. Thermohaline circulation

  18. Binge and purge: is there a Heinrich record in Antarctica? antiphasing?

  19. SST C(org)% Inferred Late Glacial and Holocene SST(Aegean Sea) YD H1 from: Geraga et al., (2000), Palaeo3, 156, 1-17

  20. Sapropel stratum in a core from the eastern Mediterranean(“sapro” = putrid - refers to high Corg content); “pel” = mud

  21. S1 S3 S4 S5 S6 S7 Episodes of sapropel formation in the last 200 000 years in the eastern Mediterranean 30°N from: Kallel et al., (2000), Palaeo3, 157, 45-58

  22. Laminated sapropel deposits from: Kemp et al., (1999), Nature, 398, 57-61

  23. Sapropels:annually laminated diatom mats from: Kemp et al., (1999), Nature, 398, 57-61

  24. Sapropel formation hypothesis after Kemp et al., (1999), Nature, 398, 57-61. (see Sancetta (1999), Nature 398, 27-29 for discussion) • Greater freshwater runoff to eastern Mediterranean (heavy rainfall in Nile headwaters and in Med. Basin); leads to: • Enhanced stratification of surface waters, produces ‘nutricline’ across surface halocline; leads to: • Massive bloom of diatoms adapted to stratified waters (chieflyRhizosolenia spp. and Hemiaulus hauckii). • Winter mixing of water column causes mass sinking of diatom mats. • Mixing brings nutrients to surface, promoting conventional near- surface winter blooms of mixed diatoms.

  25. Freshwater sources in the Mediterranean base map from: Kallel et al., (2000), Palaeo3, 157, 45-58

  26. Sapropels and climate of the Nile basin Eastern Mediterranean sedimentary record* “sapropelic” S1a S1b 11 10 9 8 7 6 5 4 3 2 1 0 ka BP arid wet arid Eastern Saharan sedimentary and archaeological record** * Geraga et al., (2000), Palaeo3, 156, 1-17 ** Malville et al., (1998), Nature 392, 488-491

  27. Location of core74 KL in the Arabian Sea

  28. 74 KL: d18O, dust deposition and CaCo3 production Dust minimum7850 8850

  29. Sahara dust storm over adjacent Atlantic Ocean image: terra.nasa.gov

  30. Dust accumulation and palaeoproductivity (core Meteor 12392: on continental rise offshore of Spanish Sahara)

  31. Japan Sea dust record Dust source: Mongolia/N. China

  32. Iron fertilization experiment:polar Southern Ocean (I) days from: Boyd et al., (2000), Nature 407, 695-702.

  33. Iron fertilization experiment:polar Southern Ocean (II)

  34. Mechanisms of CO2 drawdown

  35. CO2 drawdown (Vostok)

  36. Iron fertilization experiment:polar Southern Ocean (III)

  37. DMS makes clouds “brighter than white” from: Charlson et al., (1987) Nature 326, 655-661

  38. Points to consider Ocean/atmosphere temperature - CO2 - sea icefeedbacks. Continental climates and oceanic responses:dust exports and palaeoproductivity;monsoonal rains and sapropels;glacial surging and THC switching. Palaeoproductivity patterns: consider effects of currents, RSL and marine food chains.

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