TY - JOUR
T1 - Analysis of the climate signal contained within δ18O and growth rate parameters in two Ethiopian stalagmites>
AU - Baker, Andy
AU - Asrat, Asfawossen
AU - Fairchild, Ian J.
AU - Leng, Melanie J.
AU - Wynn, Peter M.
AU - Bryant, Charlotte
AU - Genty, Dominique
AU - Umer, Mohammed
N1 - Funding Information:
Research was supported by a Philip Leverhulme Prize to A.B., a Royal Society International Exchange Grant to A.A. and A.B., NERC Grants (Radiocarbon 1096.1004; Standard NE/C511805/1; ICP 055299) to A.B. and I.J.F., and a START Grant to A.A. We thank Hailu Dibabe and Jo Baker for field support, Hilary Sloane for the isotope analyses, Paul Hands for thin sectioning, Henry Lamb for Fig. 1 , and Ming Tan and two anonymous referees for comments on the manuscript.
PY - 2007/6/15
Y1 - 2007/6/15
N2 - We combine surface and cave climate monitoring with multiple stalagmite parameters to help understand and calibrate the climate records contained within stalagmites from a region with strong rainfall seasonality. Two actively growing stalagmites from Ethiopia were analysed in order to investigate the climate signal contained within δ18O and growth rate parameters. The δ18O and growth rate of the two stalagmites give different responses to surface climate due to variations in the climate signal transfer. Both stalagmites (Merc-1 and Asfa-3) have a climate response that is seasonal; however this signal is subsequently smoothed by the mixing of event and storage water within the aquifer. Merc-1 responds more to high frequency ('event') climate, due to a greater ratio of event to storage water in this sample, whereas Asfa-3 responds more to low frequency ('storage') climate. In addition, different parameters respond to different seasons. For example, stalagmite Asfa-3, from greater depth from the surface and with a slow drip rate, has a growth rate that responds to the amount of summer rain. In contrast, Merc-1, closer to the surface and with a faster drip rate, exhibits no clear response to surface climate, probably due to a more complex climate signal transfer. δ18O response varies with stalagmite due to the interplay between rainfall forcing factors (amount, seasonality) and disequilibrium kinetics, with opposing correlations between seasonal rainfall and δ18O between the samples. Our results demonstrate that analysis of seasonal climate forcing, and transfer functions reflecting the mixing of event and storage water, may be the most appropriate approach to develop of transfer functions appropriate for high-resolution, stalagmite climate reconstruction.
AB - We combine surface and cave climate monitoring with multiple stalagmite parameters to help understand and calibrate the climate records contained within stalagmites from a region with strong rainfall seasonality. Two actively growing stalagmites from Ethiopia were analysed in order to investigate the climate signal contained within δ18O and growth rate parameters. The δ18O and growth rate of the two stalagmites give different responses to surface climate due to variations in the climate signal transfer. Both stalagmites (Merc-1 and Asfa-3) have a climate response that is seasonal; however this signal is subsequently smoothed by the mixing of event and storage water within the aquifer. Merc-1 responds more to high frequency ('event') climate, due to a greater ratio of event to storage water in this sample, whereas Asfa-3 responds more to low frequency ('storage') climate. In addition, different parameters respond to different seasons. For example, stalagmite Asfa-3, from greater depth from the surface and with a slow drip rate, has a growth rate that responds to the amount of summer rain. In contrast, Merc-1, closer to the surface and with a faster drip rate, exhibits no clear response to surface climate, probably due to a more complex climate signal transfer. δ18O response varies with stalagmite due to the interplay between rainfall forcing factors (amount, seasonality) and disequilibrium kinetics, with opposing correlations between seasonal rainfall and δ18O between the samples. Our results demonstrate that analysis of seasonal climate forcing, and transfer functions reflecting the mixing of event and storage water, may be the most appropriate approach to develop of transfer functions appropriate for high-resolution, stalagmite climate reconstruction.
UR - http://www.scopus.com/inward/record.url?scp=34249704631&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34249704631&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2007.03.029
DO - 10.1016/j.gca.2007.03.029
M3 - Article
AN - SCOPUS:34249704631
SN - 0016-7037
VL - 71
SP - 2975
EP - 2988
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 12
ER -
