Background
What Does Dirtmap Contain?
Current DIRTMAP Activities
Contact Information
Contributors to the DIRTMAP database
Acknowledged Support
Publications Using DIRTMAP
17 March 2002 Asian Dust Storm, SEAWIFS
Background
Mineral dust aerosols play an important role in the global climate system, by mediating physical and biogeochemical exchanges among the atmosphere, land and ocean, on both modern and Quaternary timescales. Records of dust accumulation from ice cores, marine sediments and loess deposits clearly demonstrate that glacial periods were dustier than interglacial periods throughout the Quaternary. The high concentrations of atmospheric dust during glacial periods make this time period an excellent test of our ability to model the processes that determine fluxes, concentrations, and feedbacks of dust in the atmosphere (see e.g. the MAGIC Project).Global validation datasets are crucial for quantifying changes in the magnitude and extent of dust deposition during past climate periods. The Dust Indicators and Records from Terrestrial and MArine Palaeoenvironments (DIRTMAP) Database was established in 1998 as part of the Mineral Aerosols on Glacial-Interglacial Cycles (MAGIC) project but has since expanded to serve the broader the earth science and modelling communities.
Figure 1: Map of sites currently contained within the DIRTMAP database
What Does Dirtmap Contain?
The DIRTMAP Database contains records of dust accumulation rates, grain size, and mineralogical properties, and mineralogical and isotopic provenance tracer data from ice cores, marine sediment cores and sediment traps, and terrestrial sites (loess, lakes). Different elements of these data can be used to document changes in the dust cycle, to provide important additional information (e.g. regional mineralogy, grain size distributions) for modelling the dust cycle, and to evaluate simulations of the palaeo dust cycle. The DIRTMAP database targets data from 0 to 150,000 years B.P., and also contains sediment age models and accumulation rates, bulk densities, chronological data (e.g. radiocarbon dates, luminescence dates, stratigraphic correlations, etc) and additional documentation that is required for interpretation.
Data sets that are publicly available:
- DIRTMAP Dataset Version 1. (Mahowald et al., 1999)
- Mid-Continental USA Gridded Maps of Loess Thickness (Kohfeld and Harrison, 2001) DIRTMAP Dataset Version 2. (Kohfeld and Harrison, 2001; Tegen et al., 2002)
Current DIRTMAP Activities
1. DIRTMAP Special Issue - The Loess Record (Editors: Ed Derbyshire
and Sandy P. Harrison):
One development from the Mineral Aerosols in Quaternary Climate
Cycles Workshop (8-11 October 2000, Jena, Germany) was the submission
of nine papers for a special issue volume in Quaternary Science Reviews
(QSR 22). The papers focus on key loess regions around the world and
address questions of how dust accumulation rates have changed during
the Quaternary. The key regions and paper contributions include:
- Alaska (D. R. Muhs, T.A. Ager, E.A. Bettis, III, J. McGeehin, J.M. Been, J.E. Begét, M.J. Pavich, T.W. Stafford, Jr., and D. Pinney)
- Australia (P. Hesse and G. McTainsh)
-
- Europe (M. Frechen)
- New Zealand (D. Eden and A. Hammond)
- Siberia (J. Chlachula)
- South America (M. Zarate)
- USA midcontinent (E. A. Bettis, III, D. R. Muhs, H. Roberts, A. Wintle)
Review of Global Modeling of the Dust Cycle (I. Tegen)
2. Characterization of aeolian material in marine sediments (Helen A. Pfuhl and Karen E. Kohfeld):
DIRTMAP is still incomplete in its coverage of the world oceans both at modern and Last Glacial Maximum times. Our aim is to increase the spatial coverage of dust accumulation rate measurements for both these time-intervals. At the same time we will generate data on carbonate, total organic carbon, biogenic opal accumulation, and sediment particle size. A special focus of our work is to improve age control on existing measurements in DIRTMAP, as well as establishing continuous records of dust accumulation for the last 22 kyrs around the Australian continent.
3. Validation of modern climate modelling experiments (Ina Tegen
and Grant McTainsh):
Modern model simulations of the dust cycle aim to predict
global dust emissions, transport and deposition, but must be validated
and constrained using in-situ observational data and/or remotely-sensed
aerosol products. Because of limited knowledge of global dust characteristics
and their temporal and spatial changes, it is crucial to combine the
different available datasets to obtain sufficient information for constraining
the dust models. For example, to retrieve quantitative information about
atmospheric dust loadings from satellite radiances, a priori assumptions
need to be made about dust particle characteristics.
Several datasets are currently available providing quantitative information on atmospheric dust concentrations, dust storm frequency (see Figure below) deposition fluxes, and aerosol products. Given the spatial and temporal complexity of dust processes, these measurements are often too sparse (particularly in the southern hemisphere) and sometimes difficult to interpret. The MPI-BGC has sponsored a workshop (2-5 May 2002) to plan how to extend the DIRTMAP project by compiling a modern dust database. The workshop addressed questions of where major gaps exist in the types and distributions of data available for modern dust model evaluation, and how we can incorporate the available observational dust data into a global database for model validation.
Example of one form of modern data that could be used for validation of dust emissions. Dust storm frequencies (days/yr) estimated using daily measurements from 2225 meteorological stations from the International Station Meteorological Climate Summary (ISMCS) data set. A dust storm occurs when visibility is less than 1 km, and resulting from dust. (Tegen et al., 2004).
Contact Information
DIRTMAP is intended be a public-access database. Participants will have access to the data during the developmental phase. Scientists interested in contributing to this effort or in obtaining more information can contact Karen Kohfeld, the DIRTMAP Database Coordinator, at the address below.
DIRTMAP Coordinator:
Karen E. Kohfeld
DIRTMAP Scientific Advisory Committee
Edward Derbyshire, London, UK
Sandy P. Harrison, Bristol, UK
Paul Hesse, Sydney, Australia
Daniel Robert Muhs, USGS, Denver, CO, USA
Ann Grace Wintle, U. Wales, Aberystwyth, UK
Liping Zhou, Beijing, China
Contributors to the DIRTMAP database
R. F. Anderson, Lamont-Doherty Earth Observatory, Palisades, NY, USA
E. Arthur Bettis, III, University of Iowa, Iowa City, IA, USA
Alan James Busacca, Washington State Univ., USA
Fahu Chen, National Laboratory of Western China's Environmental Systems,
Lanzhou, China
Jiri Chlachula, Laboratory for Palaeoecology, University Zlin, Czech
Republic
Peter B. deMenocal, Columbia Univ., USA
Edward Derbyshire, London, UK
Zhongli Ding
Dennis N. Eden, Ashhurst, Palmerston North, New Zealand
Nicolas Federoff
Andrew P. Hammond, Griffith University, Brisbane, Queensland, Australia
Margareta Hansson, Univ. Stockholm, Sweden
Paul Hesse, Sydney, Australia
Grant McTainsh, Griffith Univ., Australia
Daniel Robert Muhs, USGS, Denver, CO, USA
Helen Marie Roberts, Univ. of Wales, UK
Jimin Sun, Beijing, China
Caroline Tye
Marcelo Arìstides Zàrate, CONICET/Ianigla-Cricyt, Mendoza,
Argentina
Weijian Zhou, Xian, China
Rixiang Zhu, Chinese Academy of Sciences, Beijing, China
Acknowledged Support
The DIRTMAP initiative was named a highest priority item for the IGBP/GAIM Paleo Trace Gas and Mineral Aerosol Challenge (TRACES), and is endorsed by International Geological Correlation Programme (IGCP) #413. It has been recognized as an important formal activity of the INQUA Loess Commission, over the next two inter-Congress periods (1999-2007).
Publications using DIRTMAP
Harrison, S.P., Kohfeld, K.E., Roelandt, C., Claquin, T. (2001). The role of dust in climate changes today, at the last glacial maximum and in the future. Earth Science Reviews 54: 43-80.
Mahowald, N., Kohfeld, K.E., Hansson, M., Balkanski, Y., Harrison, S.P., Prentice, I.C., Schulz, M. and Rodhe, H. (1999) Dust sources and deposition in the last glacial maximum and current climate: A comparison of model results with paleodata from ice cores and marine sediments. Journal of Geophysical Research - Atmospheres, 104(D13): 15,895-15,916
Kohfeld, K.E., Harrison, S.P. (2000) How well can we simulate past climates? Evaluating the models using global palaeoenvironmental datasets. Quaternary Science Reviews 19: 321-346
Kohfeld, K.E., Harrison, S.P. (2001). DIRTMAP: The geological record of dust. Earth Science Reviews 54: 81-114.
Kohfeld, K.E., Harrison, S.P. (2003) Glacial-interglacial changes in dust deposition on the Chinese Loess Plateau, Quaternary Science Reviews, 21:1859-1878
Reader, M.C., I. Fung, and N. MacFarlane (2000) Mineral aerosols: a comparison of the last glacial maximum and preindustrial Holocene, Canadian Journal of Earth Science, 37: 751-767.
Sun, J.M., K.E. Kohfeld and S.P. Harrison (2000): Records of aeolian dust deposition on the Chinese Loess Plateau during the Late Quaternary. Technical Reports - Max-Planck-Institute für Biogeochemie 1, pp 318.
Tegen, I., S.P. Harrison, K.E. Kohfeld, I.C. Prentice, M. Coe and M. Heimann (2002). The impact of vegetation and preferential source areas on global dust aerosol: Results from a model study. Journal of Geophysical Research, 107: AAC 14-1-AAC14-27
Claquin, T., Roelandt, C., Kohfeld, K.E., Harrison, S.P., Prentice, I.C., Balkanski, Y., Bergametti, G., Hansson, M., Mahowald, N., Rodhe, H. Schulz, M., 2003. Radiative forcing of climate by ice-age atmospheric dust. Climate Dynamics 20: 193-202. (DOI 10.1007/s00382-002-0269-1, 2002)
Werner, M., Tegen, I., Harrison, S.P., Kohfeld, K.E., Prentice, I.C., Balkanski, Y., Rodhe, H. and Roelandt, C., 2003. Seasonal and interannual variability of the mineral dust cycle under present and glacial climate conditions. Geophysical Research Letter 108, No. D24, 47744, (DOI 10.1029/2002JD002365,2002).
Tegen, I., Werner, M., Harrison, S.P. and Kohfeld, K.E., 2004. Relative importance of climate and land use in determining present and future global soil dust emission. Geophysical Research Letter 31, L05105. (DOI: 10.1029/2003GLO19216).