1. Tropical ocean climate during the LIA and MWP: Mud drift sediments in the East China Sea and more regional data synthesis
Min-Te Chen*
*National Taiwan Ocean University
Corroborators: Masanobu Yamamoto, Shengfa Liu, Xuefa Shi,
Yusuke Yokoyama, Xiaopei Lin, Hong Yan, and ---
4th Asia 2K Kyoto

2. 2K climate in the WP LIA: cold / dry (terrestrial)
MWP: warm / humid (terrestrial)
Asia Monsoons weak in LIA & strong in MWP (only one cave record, Wanxiang shows it, Zhang et al., 2008)
Why WP marginal seas? It fills out the data gap of the Eastern China, and is important to know how it affect the settlements adjacent to the seas, fisheries, aquatic activities, etc.

3. 2K climate in the WP
Marine sediments provide multi-proxy records of SST and salinity (precipitation), productivity, etc..
However, the sediments maybe more age uncertain, relying on 14C dating, and often bioturbated so give dampened results ;
Stable high sed rate cores (coast & mud drifts) now show large changes of LIA and MWP climate but complicated by local hydrology --

4. Coastal & Mud Drift Sediments in the WP
Extensive Shelves
Heavy Precipitation
High Sedimentation Rates

5. Study Area & Samples from ECS shelves: heavy precipitation and huge sediment flux output from Yangtze, Min, Choshui Rivers
• MZ01 (120°50.94'E, 26°32.82'N), a gravity core taken from a mud drift area near Fujian coast (core length 2.96 m; water depth 64.7 m.
• Monsoon precipitation in the drainage areas.
• Strong winter monsoon driven CCC transports annually exported sediments from the Yangtze and Yellow Rivers into ECS shelves.
• SSTs are determined by the monsoon wind (Ekman transport), the CCC and Kuroshio front, and water stratification (barrier effect)!.
• Age model by 13 AMS 14C dating (benthics) indicates an averaged sed. rate ~ 36 cm/kyr. (Multi-decadal resolution!?)

6. Uk’37 SST
- Brassell et al., (1986): established relationship between alkenone unsaturation & upper ocean temperature
- Prahl and Weakham (1987): Uk’37 index = [37:2] / ( [37:2] + [37:3] )
- Alkenone-producing alage: Emiliania huxleyi and Gephyrocapsa oceanica
- Advection Transport & Species Variarion: First appearance datum of E. huxleyri - 256ka
- Calibration Equations: Uk’37 index = a*SST(oC) + b
- Regional Equation (South China Sea): Uk’37 index = 0.031*SST(oC) (Pelejero & Grimalt., 1997)
- Global Equation: Uk’37 index = 0.033*SST(oC) (Muller et al., 1998)

7. TEX86 SST: but reflect subsurface temperature
Crenarchaeota
TEX86=
Range : 0~1 1
terrestrial
marine
TEX86=0.015×SST＋0.028
(Schouten et al., 2002)
(Hopmans et al., 2004)

8. MZ01 2K SST errors linearly related to age errors!
SSTerror = Σ [(SST-SSTEEMD)2]1/2 x Ageerror / Σ (Ageerror/n)
Errors in average --
SST ±1°C
Age ±100 yrs

9. WP 2K data to be submitted!
2K criteria:
- At least one numerical age per 500-year interval
- At least one analysis every 200 years
- Must span 500 years during the past 2k
MD972146
• MZ01 (this study) - sediments
• ODP 1202 (Wu et al., 2012)
• MD (Lin, Chen et al., 2013; 2014) - sediments
• Leizhou & Xisha (Hong et al., 2015) – Porites lutea, Tridacna gigas

10. (Yang et al., 2002)
MWP
LIA
1°C
100 yrs

11. MWP
LIA
(Wu et al., 2012)
1°C
100 yrs

12. (Yan et al., 2015)
MWP
LIA
1°C
100 yrs

13. (Lin, Chen et al., 2013; 2014)
MWP
LIA
1°C
100 yrs

14. (Oppo et al., 2009)
MWP
LIA
1°C
100 yrs

15. WP 2K SST patterns Here we contribute a new WP SST 2K data set.
While focusing on the LIA and MWP: mud drift core near East China show SST changes with more warming in early LIA and cooling in the early MWP (which may result from fresh water barrier layer effects)
WP open oceans (SCS and WPWP, low resolution!) show cooling in the LIA and warming in MWP (but the magnitudes are determined by the nature of paleoclimatic archives, oceanic setting!

16. More contribution to the future 2K studies --
Keeping going to form a new marine sediment proxy data base of western Pacific marginal seas --
More contribution to the future 2K studies -- ★
WEPAD (Western Pacific Drilling):
• 3rd working group meeting – May 18-19, 2015, Jeju, Korea (You are welcomed!)

17. Sea surface salinity (SSS) pattern suggest the possibly more important barrier layer effects during strong winter monsoon seasons (data provided by Xiaopei Lin, OUC)
January
July

18. Hydrography and Water Stratification: Barrier Layer effect ->increased fresh lens prevent mixing and cause surface warming!
West
East
China
Sea level
China Coastal Current
Taiwan Warm Current
MZ-1