Abstract
Abstract. A new annually resolved sedimentary record of Southern Hemisphere mid-latitude hydroclimate was recovered from Lake Ohau, South Island, New Zealand, in March 2016. The Lake Ohau Climate History (LOCH) project acquired cores from two sites (LOCH-1 and -2) that preserve sequences of laminated mud that accumulated since the lake formed ∼ 17 000 years ago. Cores were recovered using a purpose-built barge and drilling system designed to recover soft sediment from thick sedimentary sequences in lake systems up to 150 m deep. This system can be transported in two to three 40 ft long shipping containers and is suitable for use in a range of geographic locations. A comprehensive suite of data has been collected from the sedimentary sequence using state-of-the-art analytical equipment and techniques. These new observations of past environmental variability augment the historical instrumental record and are currently being integrated with regional climate and hydrological modelling studies to explore causes of variability in extreme/flood events over the past several millennia.
Highlights
The Lake Ohau Climate History (LOCH) project is an international initiative involving scientists, engineers, drilling professionals, and students from New Zealand, Italy, Republic of Korea, United States of America, and Australia
Inter-annual climate variability around New Zealand and the south-western Pacific is primarily driven by the position and intensity of Southern Hemisphere westerly winds (SWW) which are sensitive to changes in the Southern Annular Mode (SAM) (Ummenhofer and England, 2007; Ummenhofer et al, 2009; Wang and Cai, 2013), the influence of El Niño– Southern Oscillation (ENSO) (Ummenhofer and England, 2007; Wang and Cai, 2013) and the Interdecadal Pacific Oscillation (IPO) (Folland et al, 2002; Salinger et al, 2001)
These climate phenomena have a considerable influence on New Zealand rainfall, which is clearly illustrated by a reduction in South Island summer precipitation of up to 40 % over the past 30 years in response to a trend towards a high positive phase of SAM (Ummenhofer et al, 2009)
Summary
The Lake Ohau Climate History (LOCH) project is an international initiative involving scientists, engineers, drilling professionals, and students from New Zealand, Italy, Republic of Korea, United States of America, and Australia. Between 12 February and 5 March 2016 our drilling operations team completed a field expedition that recovered core from an 80 m thick sedimentary sequence of laminated mud that lies beneath the floor of Lake Ohau, South Island, New Zealand (Fig. 1). This sequence accumulated after glacial ice retreated from the lake basin approximately 17 900 years ago (Putnam et al, 2013). Four holes at two sites (LOCH-1 and LOCH-2, Fig. 1) were drilled during this operation and a total of 229 m of sediment was recovered This new sedimentary record offers a high-resolution (annual to decadal) climate record for the Southern Hemisphere. This progress report provides an overview of the scientific objectives of the LOCH project, summarizes drilling operations, highlights the new lake drilling capability that was developed and utilized for the project, and provides an update on the status of scientific work
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
