Lancaster Environment Centre

Leader:

Prof. B A Maher, Lancaster Environment Centre, University of Lancaster, Farrer Avenue, Lancaster, LA1 4YQ, U.K., b.maher@lancaster.ac.uk; fax:(0044) 1524 510269 (S, terrestrial and marine dust records).

Co-Leaders:

Dr Diego Gaiero, Universidad Nacional de Córdoba, Argentina, dgaiero@efn.uncor.edu (ECS, dust provenance, isotope tracing).

Dr Natalie Mahowald, 2140 Snee Hall, Cornell University, Ithaca, NY 14850, USA, Mahowald@cornell.edu, Phone: 607-255-5166 (S, modeler).

Quick Links

Rationale
International participation (country, person, affiliation, role)
Main objectives
Specific goals
Methods/approach
Planned workshops/meetings
Anticipated results
Links to other INQUA or non-INQUA Projects
DIRTMAP 3 Recently Updated
Co-sponsorship/additonal funding

Rationale

The influence of dust on climate, through changes in the radiative properties of the atmosphere and/or the CO2 content of the oceans and atmosphere (through iron fertilisation of high nutrient, low chlorophyll, HNLC, regions of the world’s oceans), remains a poorly quantified and actively changing element of the Earth’s climate system. Dust-cycle models presently employ a relatively simple representation of dust properties; these simplifications may severely limit the realism of simulations of the impact of changes in dust loading on either or both radiative forcing and biogeochemical cycling. Further, whilst state-of-the-art models achieve reasonable estimates of dust deposition in the far-field (i.e. at ocean locations), they under-estimate - by an order of magnitude- levels of dust deposition over the continents, unless glacigenic dust production is explicitly and spatially represented. This ’DIRTMAP3’ working group aims to address these problems directly, through a series of explicitly interacting contributions from the modelling and palaeo-data communities (see Objectives list below).

International participation (country, person, affiliation, role)

Scientific members:

France, Yves Balkanski, LSCE/IPSL, Laboratoire CEA-CNRS-UVSQ, S (modeler)
USA, Jim Beget, University of Alaska, S (terrestrial palaeo-dust records)
USA, Art Bettis, University of Iowa, S (terrestrial palaeo-dust records)
UK, Joanna Bullard, Loughborough University, S (geomorphology, dust emissions)
Germany, Peter Croot, GEOMAR, ECS (dust and ocean biogeochemistry)
Italy, Barbara Delmonte, University of Milan, ECS (dust provenance, isotope tracing)
UK, Adam Durant, Bristol University, PD (modeler)
Switzerland, Hubertus Fischer, ECS (dust in ice cores)
USA, Santiago Gasso, NASA, ECS (remote sensing of dust)
Israel, Hezi Gildor, Weizmann Institute, S (modeler)
Australia, Paul Hesse, Macquarie University, S (terrestrial and marine palaeo-dust records)
Canada, Karen Kohfeld, Simon Fraser University, S (data synthesis)
Israel, Ilan Koren, Weizmann Institute, S (modeler, clouds)
New Zealand, Doug Mackie, University of Otago, ECS (dust and ocean biogeochemistry)
France, Jean-Robert Petit, LGGE-CNRS Université Joseph Fourier-Grenoble, S (ice cores)
USA, Joe Prospero, University of Miami, S (terrestrial and marine dust fluxes and records)
UK, Helen Roberts, University of Wales, Aberysytwyth, ECS (luminescence dating)
France, Dennis Rousseau, Laboratoire de météorologie dynamique, S (loess records)
Germany, Jan-Berend Stuut, University of Bremen, S (marine dust records)
China, Youbin Sun, Chinese Academy of Sciences, ECS (loess records)
Italy, Paul Vallelonga, University of Venice, PD (dust provenance, isotope tracing)
USA, Gisela Winckler, Lamont-Doherty Earth Observatory, S (marine palaeo-dust records. Sources)

Associate members:

Germany, Anna Wegner, AWI, PhD
USA, Jason Addison, Alaska, PhD
USA, Jeff Benowitz, Alaska, PhD
France, Maxime Debret, UJF-Grenoble, PhD
USA, Sebastian Engelstaedter, Cornell, PD

Note: PhD = PhD student, PD = postdoctoral researcher, ECS = Early Career Scientist, S = scientist

Main objectives

(1) Recent international evaluation of the current DIRTMAP database indicates that a considerable amount of new data (spatial, temporal) exists which need to be incorporated to improve our ability to evaluate dust-cycle models. DIRTMAP3 will be enhanced with: new data from e.g. South America, Eurasia and the Middle East, and from the Southern Hemisphere in the marine realm; with dust fluxes from time slices beyond the LGM and from higher resolution sediment sequences (e.g. at Dansgaard/Oeschger cycle resolution); with information regarding possible source, mineralogy (especially iron oxides, with regard both to radiative properties and bioavailability of iron), and clastic grain size.

(2) Protocols will be developed to enable quality-control evaluation of the DIRTMAP3 data, via addition of key metadata (e.g. site stratigraphy and quality control information including age control, in situ disturbance, aeolian vs non-aeolian contributions etc). This requires inputs from the original and new DIRTMAP contributors, solicited and compiled through our international network of palaeo-data researchers.

(3) There is a clear need for new field studies to gain information now required for development of improved dust-cycle models, and contribute to the new questions regarding radiative and biogechemical dust-climate interactions. The DIRTMAP3 working group will seek to frame a prioritization of future studies around key science questions and hypothesis- testing.

(4) Geomorphic studies indicate that the modelling approach to defining preferential dust-source areas is both simplistic and incomplete. DIRTMAP3 palaeo-data and modelling researchers will combine to identify how dust source variability could be parameterized in a modeling context, and identify key regions requiring significantly improved source area characterization.

(5) State-of-the-art dust-cycle models need to incorporate better characterization of dust properties (including size distribution, mineralogy – especially with regard to iron oxides, and particle shape). The DIRTMAP3 group, with its internationally-distributed regional experts, can make a large contribution to both collating present data and driving new data collection.

(6) Currently, no standards exist for ‘benchmarking’ of dust-cycle models. This requires definition of protocols for the datasets used, for comparison methods and for dealing with uncertainties both in the observations and in the models. The DIRTMAP3 group will work to establish such these required protocols on an international, and explicitly combined data/model basis.

(7) Many palaeo-questions require new types of dust-cycle model simulations, notably, transient simulations with fully-coupled climate-dust models, and also meso-scale modeling, for example, in order to simulate patterns of dust transport and deposition over the continents. Interactions between the DIRTMAP3 palaeo-researchers and the modellers will frame the new experiments and evaluate their outcomes.

Specific goals

Atmospheric dust fluxes to the oceans estimated by Duce et al. (1991)

(1) Provide the means for ‘benchmarking’ of dust cycle model simulations by producing an updated version of the DIRTMAP database (‘DIRTMAP3’), incorporating (a) records and age models newly available since ~ 2001, (b) longer records, and especially high-resolution records, that will target time windows also focused on by other international research programs (e.g. DO8/9, MIS5), (c) metadata to allow quality-control issues to be dealt with objectively, (d) information on mineralogy and isotopes relevant to provenancing, radiative forcing and iron bioavailability, and (e) enhanced characterisation of the aeolian component of existing records. This update will be coordinated with work (led by Karen Kohfeld) to expand the DIRTMAP database to incorporate information on marine productivity and improved sedimentation rate estimation techniques. It will also build upon a recently-developed dust model evaluation tool for current climate (e.g. Miller et al. 2006) to enable application of this and other evaluative models to palaeoclimate simulations.

(2) Lead international liaison between groups working on characterisation of the land surface, and assess the feasibility of producing a global map of source-area characteristics which could be used as a basis for devising a new model parameterisation of preferential dust sources.

(3) Address, through carefully designed experiments, the impact of changing dust loads on radiative forcing during the Late Quaternary and through careful evaluation of these experiments assess the level of confidence that can be placed in the predictions of the impact of future changes in dust loading.

(4) Address the major issue of iron bioavailability in dust, and iron fertilisation of high nutrient, low chlorophyll ocean regions, by direct interaction with other international groups, e.g. within SOLAS and iLEAPS, to ensure maximum data-transfer/sharing and synergies with these groups.

from Winckler et al., 2008, Science, 320, 93-96

Methods/approach

• Website-based data collation and research communication. In addition to this website, we will establish a wiki which will (a) facilitate communication between members of the working group, (b) allow members to exchange information, (c) allow data to be updated directly into the database, and (d) facilitate collaboration on joint products.
• Exchange visits by young scientists within the working group. We will encourage and facilitate younger scientists within the working group to make short (one to two week) visits to other members.
• Annual workshops, co-organised by young scientists (see details below), focused on specific issues. Each workshop will produce one joint-authored synthesis paper for publication in an INQUA-sponsored journal.
• Joint publications, initiated at the workshops and spearheaded by individual members of the working group

Planned workshops/meetings

• Workshop on dust-source characterization and modelling, Villefranche-sur-Mer, October 2008. Workshop organized by Adam Durant (Bristol)
• Workshop on terrestrial records of dust deposition, Xian, August 2009. Workshop organized by Sun Youbin (Xi’an)
• Workshop on evaluation of dust-cycle simulations, USA, 2010. Organised by Sebastian Engelstaedter (Cornell)
• Dust-cycle session at INQUA Congress, Bern 2011

Dome C ICE CORE, Gaspari et al. (2006), Geophysical Research Letters, 33, (L03704) 2006.

Anticipated results

• Synthesis of newly available data documenting changes in dust sources, fluxes and properties during the Late Quaternary
• Improved modelling tools to address questions about the dust cycle
• Better understanding of the role of dust in past climate changes
• Quantification of the magnitude of dust forcing, and resulting changes in climate, in the past and in the future

Links to other INQUA or non-INQUA Projects

Sand seas and dune fields of the world: a digital Quaternary atlas
Leader: Nicholas Lancaster, Desert Research Institute, United States
INQUA Project 0704.

DIRTMAP3 Database

Citation: to reference the DIRTMAP’3’ database, please use the following convention: " Maher, BA and Kohfeld, K., 2009, ‘DIRTMAP’ Version 3, LGM and late Holocene Aeolian Fluxes from Ice Cores, Marine Sediment Traps, Marine Sediments and Loess Deposits. http://www.lec.lancs.ac.uk/dirtmap3 "

Co-sponsorship/additonal funding

The QUEST (Quantifying Uncertainties in the Earth System) programme of the UK Natural Environmental Research Council supports a ’parent’ Working Group on Dust.

Support for Adam Durant (Bristol, working on the parameterisation of dust properties in dust-cycle models) has been obtained through the QUEST DESIRE (Dynamics of the Earth System and the Ice Core Record) project. A NERC consortium proposal designed to provide support for database work is currently under development under the direction of Barbara Maher. Additional funds are being sought in the USA (Natalie Mahowald) and France (Yves Balkanski). DIRTMAP3 working group members are encouraged to develop independent proposals to national funding sources, contributing to the research priorities and aims identified above.

Email: b.maher@lancaster.ac.uk
Tel: +44 (0)1524 510268
Fax: +44 (0)1524 510269
www: Staff Profile