Citation:

PANGAEA.859426

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Abstract:

The deglacial transition from the last glacial maximum at ∼20 kiloyears before present (ka) to the Holocene (11.7 ka to Present) was interrupted by millennial-scale cold reversals, viz., Antarctic Cold Reversal (∼14.5–12.8 ka) and Greenland Younger Dryas (∼12.8–11.8 ka) which had different timings and extent of cooling in each hemisphere. The cause of this synchronously initiated, but different hemispheric cooling during these cold reversals (Antarctic Cold Reversal ∼3∘C and Younger Dryas ∼10∘C) is elusive because CO2, the fundamental forcing for deglaciation, and Atlantic meridional overturning circulation, the driver of antiphased bipolar climate response, both fail to explain this asymmetry. We use centennial-resolution records of the local surface water 𝛿18O of the Eastern Arabian Sea, which constitutes a proxy for the precipitation associated with the Indian Summer Monsoon, and other tropical precipitation records to deduce the role of tropical forcing in the polar cold reversals. We hypothesize a mechanism for tropical forcing, via the Indian Summer Monsoons, of the polar cold reversals by migration of the Inter-Tropical Convergence Zone and the associated cross-equatorial heat transport.

Related to:

SST time-series for Eastern Arabian Sea

Banakar, Virupaxa K; Baidya, Sweta; Piotrowski, Alexander M; Shankar, Doraiswami (2017): Indian summer monsoon forcing on the deglacial polar cold reversals. Journal of Earth System Science, 126(6), https://doi.org/10.1007/s12040-017-0864-5

Coverage:

Latitude: 15.491500 * Longitude: 72.727330

Date/Time Start: 2008-10-15T00:00:00 * Date/Time End: 2008-10-15T00:00:00

Minimum DEPTH, sediment/rock: 0.59 m * Maximum DEPTH, sediment/rock: 4.21 m

Event(s):

ABP32GC01R * Latitude: 15.491500 * Longitude: 72.727330 * Date/Time: 2008-10-15T00:00:00 * Elevation: -639.0 m * Recovery: 4.22 m * Location: Eastern Arabian Sea * Method/Device: Gravity corer (GC)

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	DEPTH, sediment/rock	Depth sed	m	Banakar, Virupaxa K		Geocode
2	AGE	Age	ka BP	Banakar, Virupaxa K		Geocode – radiocarbon measured at Arizona University's AMS Facility
3	Age, comment	Comm		Banakar, Virupaxa K
4	Globigerinoides sacculifer, δ18O	G. sacculifer δ18O	‰ PDB	Banakar, Virupaxa K		size fraction 250-355 µm, measured at Godwin Laboratory, University of Cambridge, UK
5	Globigerinoides sacculifer, Magnesium/Calcium ratio	G. sacculifer Mg/Ca	mmol/mol	Banakar, Virupaxa K		size fraction 250-355 µm, measured at National Institute of Oceanography's ICP-OES Laboratory
6	Sea surface temperature, annual mean	SST (1-12)	°C	Banakar, Virupaxa K	Calculated from Mg/Ca ratios (Dekens et al. 2002)
7	δ18O, water	δ18O H2O	‰ SMOW	Banakar, Virupaxa K	Calculated (Epstein et al., 1953)	calculated from residual d18O obtained from subtracting global ice-volume effect
8	Sea surface salinity	SSS		Banakar, Virupaxa K	Calculated	calculated from Dahl&Opp, 2006 Arabian Sea d18O-Salinity relationship

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

461 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Depth sed [m]	2 Age [ka BP]	3 Comm	4 G. sacculifer δ18O [‰ PDB]	5 G. sacculifer Mg/Ca [mmol/mol]	6 SST (1-12) [°C]	7 δ18O H2O [‰ SMOW]	8 SSS
0.59	4.53	14C age	-1.91	4.718	28.2	0.71	36.3
0.61	4.70		-1.94	4.668	28.0	0.63	36.2
0.65	5.05		-2.04	4.550	27.7	0.46	35.9
0.69	5.39		-1.94	4.454	27.6	0.58	36.1
0.73	5.73		-2.13	4.819	28.5	0.63	36.2
0.77	6.08		-2.23	4.543	27.7	0.39	35.8
0.81	6.42		-2.10	4.221	26.8	0.59	36.1
0.85	6.77		-2.15	4.477	27.4	0.38	35.8
0.89	7.11		-1.95	4.600	27.7	0.63	36.2
0.93	7.46		-1.75	4.410	27.3	0.72	36.3
0.97	7.80		-2.05	4.630	27.8	0.52	36.0
1.01	8.15		-1.93	4.465	28.6	0.78	36.5
1.05	8.49		-1.99	4.614	27.8	0.49	36.0
1.09	8.84		-1.80	4.719	28.1	0.69	36.3
1.13	9.18		-1.84	4.705	28.0	0.64	36.2
1.17	9.53		-1.97	4.901	28.5	0.65	36.2
1.21	9.87		-2.02	4.706	28.0	0.55	36.0
1.25	10.22	14C age	-1.51	5.127	29.0	1.26	37.3
1.29	10.27		-1.40	4.960	28.6	1.28	37.3
1.33	10.33		-1.66	5.115	29.0	1.09	37.0
1.37	10.38		-1.57	4.940	28.6	1.10	37.0
1.41	10.44		-1.87	4.889	28.5	0.77	36.4
1.45	10.50		-1.45	5.024	28.8	1.25	37.3
1.49	10.55		-1.53	4.997	28.7	1.15	37.1
1.53	10.61		-1.52	4.942	28.6	1.13	37.1
1.57	10.66		-1.45	5.079	28.9	1.26	37.3
1.61	10.72		-1.17	4.892	28.5	1.44	37.6
1.65	10.78		-1.47	5.004	28.7	1.19	37.2
1.69	10.83		-1.47	5.032	28.8	1.20	37.2
1.73	10.89		-1.30	5.157	29.0	1.42	37.6
1.77	10.94		-1.25	5.122	29.0	1.45	37.6
1.81	11.00		-1.26	4.934	28.6	1.35	37.5
1.85	11.06		-1.17	5.066	28.8	1.49	37.7
1.89	11.11		-0.86	5.081	28.9	1.80	38.2
1.93	11.17		-0.89	4.564	27.7	1.50	37.7
1.97	11.22		-0.89	4.373	27.2	1.39	37.5
2.01	11.28	14C age	-0.69	4.410	27.3	1.60	37.9
2.05	11.38		-0.55	4.297	27.0	1.66	38.0
2.09	11.48		-0.63	4.421	27.3	1.62	37.9
2.13	11.58		-0.51	4.355	27.2	1.69	38.1
2.17	11.67		-0.58	4.312	27.1	1.58	37.9
2.21	11.77		-0.78	4.013	26.3	1.19	37.2
2.25	11.87		-0.69	4.336	27.1	1.44	37.6
2.33	12.07		-0.67	4.233	26.8	1.36	37.5
2.37	12.17		-0.77	4.270	26.9	1.25	37.5
2.41	12.27		-0.54	4.411	27.3	1.53	37.3
2.45	12.36		-0.63	4.497	27.5	1.46	37.8
2.49	12.46		-0.55	4.137	26.6	1.31	37.6
2.53	12.56		-0.72	4.108	26.5	1.09	37.4
2.57	12.66	14C age	-0.78	4.045	26.3	0.96	37.0
2.61	12.76		-0.60	3.925	26.0	1.04	36.8
2.65	12.85		-0.70	3.949	26.1	0.93	36.9
2.69	12.95		-0.70	4.269	26.9	1.09	36.7
2.73	13.04		-0.96	4.434	27.4	0.90	37.0
2.77	13.14		-1.16	4.138	26.6	0.52	36.7
2.81	13.24		-0.83	4.060	26.4	0.79	36.0
2.85	13.33		-0.70	4.142	26.6	0.95	36.5
2.89	13.43		-0.82	4.084	26.5	0.78	36.8
2.93	13.53		-0.68	4.134	26.6	0.94	36.5
2.97	13.62		-0.93	4.183	26.7	0.71	36.7
3.01	13.72		-0.94	4.048	26.4	0.60	36.3
3.05	13.82		-1.03	4.335	27.1	0.66	36.1
3.09	13.91		-0.88	4.167	26.7	0.71	36.3
3.13	14.01		-0.80	4.452	27.4	0.93	36.3
3.17	14.10		-0.80	4.428	27.4	0.89	36.7
3.21	14.20		-0.79	4.489	27.5	0.91	36.7
3.25	14.30		-0.62	4.550	27.7	1.08	36.7
3.29	14.39		-0.91	4.419	27.3	0.70	37.0
3.33	14.49		-0.92	4.666	27.9	0.79	36.3
3.37	14.59		-0.80	4.482	27.5	0.79	36.5
3.41	14.68	14C age	-0.45	4.480	27.5	1.11	36.5
3.45	14.87		-0.24	4.275	27.0	1.16	37.0
3.49	15.05		-0.45	4.704	28.0	1.15	37.1
3.53	15.24		-0.29	4.437	27.4	1.17	37.1
3.57	15.42		-0.28	4.171	26.7	1.04	37.1
3.61	15.61		-0.30	4.405	27.3	1.16	36.9
3.65	15.80		-0.13	4.357	27.2	1.31	37.1
3.69	15.98		-0.17	4.210	26.8	1.20	37.4
3.73	16.17		-0.16	4.247	26.9	1.22	37.2
3.77	16.35		0.00	4.092	26.5	1.29	37.2
3.81	16.54		-0.09	3.992	26.2	1.13	37.3
3.85	16.72	14C age	-0.04	3.911	26.0	1.13	37.1
3.89	16.91		0.02	3.921	26.0	1.19	37.1
3.93	17.09		-0.04	3.754	25.5	1.04	37.2
3.97	17.28		0.16	3.881	25.9	1.35	36.9
4.01	17.46		0.15	3.922	26.0	1.39	37.5
4.05	17.65		0.21	3.742	25.5	1.37	37.5
4.09	17.84		0.04	3.853	25.8	1.30	37.5
4.13	18.02		0.19	3.838	25.8	1.46	37.4
4.17	18.21		0.02	3.883	25.9	1.26	37.6
4.21	18.39		0.33	3.763	25.5	1.45	37.3