Reconstruction of Lamb weather type series back to the eighteenth century

The Lamb weather type series is a subjective catalogue of daily atmospheric patterns and flow directions over the British Isles, covering the period 1861–1996. Based on synoptic maps, meteorologists have empirically classified surface pressure patterns over this area, which is a key area for the progression of Atlantic storm tracks towards Europe. We apply this classification to a set of daily pressure series from a few stations from western Europe, in order to reconstruct and to extend this daily weather type series back to 1781. We describe a statistical framework which provides, for each day, the weather types consistent enough with the observed pressure pattern, and their respective probability. Overall, this technique can correctly reconstruct almost 75% of the Lamb daily types, when simplified to the seven main weather types. The weather type series are described and compared to the original series for the winter season only. Since the low frequency variability of synoptic conditions is directly related to the North Atlantic Oscillation (NAO), we derive from the weather type series an NAO index for winter. An interesting feature is a larger multidecadal variability during the nineteenth century than during the twentieth century

Data Descriptor: A global multiproxy database for temperature reconstructions of the Common Era

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.(TABLE)Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013').This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product.This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike

Physical Environments in Hong Kong Connected to Slow and Abnormal Growth in Porites Corals

Theme: Asia Pacific Science in the 21st Century: Meeting the Challenges of Global Chang

A multicoral calibration method to approximate a universal equation relating Sr/Ca and growth rate to sea surface temperature

Combining strontium-to-calcium ratios (Sr/Ca) with mean annual growth rates in Bermuda Diploria labyrinthiformis (brain corals) is shown to improve sea surface temperature (SST) calibrations relative to instrumental data. Growth-corrected Sr/Ca-SST calibrations based on single-coral colonies over the same calibration interval, however, are found to be poorly suited for application to data from different coral colonies. This raises concerns about the accuracy of SST reconstructions from fossil coral measurements that involve extrapolation beyond the range of values seen during the calibration period. Here we pursue a novel approach to this problem by incorporating data from multiple coral colonies into a single growth-corrected Sr/Ca-SST calibration equation, effectively expanding the range of modern values constraining the model. The use of a multiple-colony calibration model for reconstructing SST yields greater precision and accuracy relative to instrumental data than single-colony models, providing greater confidence for applications to fossil coral samples. Copyright 2007 by the American Geophysical Union.link_to_subscribed_fulltex

Limited North Atlantic shallow water ventilation over the past 200 years

Panel - ScienceThe 10th International Conference on Paleoceanography, University of California, San Diego, CA., 29 August-3 September 2010

Two centuries of limited variability in subtropical North Atlantic thermocline ventilation

Ventilation and mixing of oceanic gyres is important to ocean-atmosphere heat and gas transfer, and to mid-latitude nutrient supply. The rates of mode water formation are believed to impact climate and carbon exchange between the surface and mid-depth water over decadal periods. Here, a record of 14 C/ 12 C (1780-1940), which is a proxy for vertical ocean mixing, from an annually banded coral from Bermuda, shows limited inter-annual variability and a substantial Suess Effect (the decrease in 14 C/12 C since 1900). The Sargasso Sea mixing rates between the surface and thermocline varied minimally over the past two centuries, despite changes to mean-hemispheric climate, including the Little Ice Age and variability in the North Atlantic Oscillation. This result indicates that regional formation rates of sub-tropical mode water are stable over decades, and that anthropogenic carbon absorbed by the ocean does not return to the surface at a variable rate. © 2012 Macmillan Publishers Limited. All rights reserved.link_to_subscribed_fulltex

Experiential learning in a common core curriculum: student expectations, evaluations, and the way forward

Universities are becoming increasingly conscious of how learning activities align with the attributes they desire in their graduates. Experiential learning is viewed by many institutions as an essential activity for students to gain attributes such as problem solving skills, observation skills, advocacy, and critical thinking. An experiential learning activity, in the form of an environmental fieldtrip, was examined in the context of a university's new common core curriculum. Student expectations were compared to evaluation of the fieldtrip itself, and guidelines for future trip outings are made in consideration of both published works and our own experiences. The ability of departments and faculties to engage students in beneficial and enjoyable learning will be of utmost importance in attracting student enrollment. This is particularly pressing in universities that are transitioning into less differentiated first year intakes.link_to_OA_fulltex

Temporal distributions of anthropogenic Al, Zn and Pb in Hong Kong Porites coral during the last two centuries

A 182-year long record of trace metal concentrations of aluminum, zinc and lead was reconstructed from a massive Porites coral skeleton from southeastern Hong Kong to evaluate the impacts of anthropogenic activity on the marine environment. Zn/Ca and Pb/Ca ratios fluctuate synchronously from the early 19th century to the present, indicating that the marine environment has been anthropogenically influenced since industrialization. Additionally, land reclamation, mining, and ship building activities are recorded by elevated Al/Ca ratios from 1900 to 1950. The coral record indicates that high levels of Zn, Pb and Al occur coincidentally with local wars, and may have contributed to partial colony mortality. Pb/Ca does not correlate well with hemispheric proxy records after 1950, indicating that coastal corals may be recording local rather than hemispheric contamination. Pb/Ca levels in Hong Kong, Guangdong and Hainan corals imply a continuous supply of Pb-based contamination to southern China not reflected in hemispheric signals. © 2011 Elsevier Ltd.link_to_subscribed_fulltex