- About CDIAC
Modern Records of Atmospheric Aerosols and Related Parameters
This page provides an introduction and links to records of atmospheric aerosols, emphasizing large data bases including satellite data and surface stations. Cloud and cloud droplet data are not emphasized, although occasional links to files containing data are included in the files accessible from the material below. Links include access to data from the United States Department of Energy (DOE) Atmospheric Radiation Measurements (ARM) program, The National Aeronautics and Space Administration (NASA) program, the National Oceanic and Atmospheric Administration (NOAA) Aerosols Group (AERO), the French National Space Agency (CNES), and other groups that have archived more spatially and temporally limited data. The World Data Center for Aerosols (WDC) provides data for stations around the world.
The most comprehensive data are those from satellites, but ground-based measurements are necessary to support the satellite measurements and to more fully investigate influences on concentrations of the various aerosol types. Much ground-based aerosol data are collected in the course of campaigns, typically a year or more in duration, and often initiated for other related purposes such as the study of cloud formation. Complimentary aerosol studies add value to such studies as well as supporting satellite aerosol measurements and investigations of local or regional influences on aerosol concentrations. Records of dust in ice cores over the last 800,000 years are presented on a separate page.
Introduction to Aerosols
As is clear from the width of the error bars in Figure TS6 of the Technical Summary of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2013), the lack of precision in characterizing the radiative effects of aerosols is somewhat of a limiting factor to our understanding of climate change. This is because aerosol effects on climate are numerous and complicated. There are several kinds of aerosols, each with their own properties; they can intercept incoming solar radiation and scatter it back to space (e.g., sulfates and nitrates), absorb it to provide heat some distance above the ground while denying that same heat to the earth's surface (e.g., black carbon), or some combination of scattering and absorption. Aerosols can contribute to increasing or decreasing the reflective property, or albedo, of the underlying surface.
The term albedo, or whiteness (cf. albino, albumen), comes from the Latin albus, and refers to the fraction of incident visible light that is reflected from a surface. If light in all wavelengths is reflected equally, the surface will appear white. The albedo of the earth as a planet is about 30%. This means that about 30% of the incoming solar radiation is reflected back to space, thereby reducing the earth's temperature.
Aerosols can increase albedo by providing cloud condensation nuclei, or solid points of contact with water vapor, so as to encourage the growth of small droplets of liquid water that form clouds which reflect or otherwise scatter incoming solar radiation. Aerosols can decrease albedo by landing on snow surfaces, absorbing light, and converting it to heat. This is especially effective if the aerosol is black carbon.
The myriad of aerosol types is a major problem in determining their radiative effects; there are other complications which will be introduced in the supplementary material found via the links below. For now we will note that the properties of aerosols affecting their radiative influence include sun angle and wavelength of the radiation. Thus, parameters are often given as annual averages over all sun angles, and/or for more than one wavelength of incoming solar radiation.
Another brief introduction to aerosols can be found here.
- Atmospheric Radiation Measurements (ARM) Program, U.S. Department of Energy
- French National Space Agency (CNES)
- National Aeronautics and Space Administration (NASA)
- National Oceanic and Atmospheric Administration (NOAA)
- The World Data Center for Aerosols (WDCA)
- Carbon Dioxide Information Analysis Center (CDIAC)
Period of Record
- ARM: 1990 forward
- CNES: 1972 – current: Stations with the earliest start dates frequently have short records.
- NASA: Primarily 1989 forward
- NOAA: 1974 – current at the South Pole, shorter records at other locations
- WDC: 1974 (South Pole Station) - recent
- CDIAC: A record of H.H. Lamb's Dust Veil Index extends back to the eruption of Santorin. Lamb placed that event at 1470 B.C.E. but modern evidence suggests it may have occurred before 1500 B.C.E.
The space agencies (CNES and NASA) provide primarily satellite data covering all or large portions of the earth (space-based data). Ground-based and vertical-profile measurements from aircraft (Earth-based data) frequently provide supporting/verification data for the satellite missions. Links to maps or lists of Earth-based measurement sites are given below.
- ARM: Map
- NASA: Provides satellite data for all or large portions of the earth. Click here for a map of the Earth-based AERONET sites where observations are made to provide support and verification for the satellite measurements.
- NOAA: Site descriptions. Data plots and data files may also be found from this page.
- WDCA: Maps of various networks and scroll down, or go here and search under "stations by network" (2nd search category in the column on the left). Not all of these stations are active; not all the active stations have aerosol data.
- CDIAC: The names, locations (latitudes and longitudes) and dates of specific volcanoes are given in the data and in the data documentation.
- NASA: A sequence of monthly values of Aerosol Optical Depth (AOD) can be found here. You may fast-forward this sequence to better visualize annual movements of dust patterns. For an artistic (smoothed digital) portrait of dust (red) sea salt (blue) smoke (green) and sulfate aerosol (white) produced by a GEOS-5 simulation at a 10-kilometer resolution, go here.
- NOAA: Recent Aerosol Optical Depth. It says monthly mean but is sometimes for other periods (read the fine print).
- Some graphics for sites in New Hampshire, USA,. Station Locations and data files may also be found from this page.
- ARM: Data discovery page. A more direct link to aerosol data is located here.
- CNES: Register and obtain data. Scroll down to the program of interest (e.g., PARASOL), or go directly to:
- NASA: For those who know which data set they want, go here. NASA offers several levels of data access. The most general of these is located here. Go to "atmosphere" and then to aerosols to get a list of aerosol parameters. Data for some spatially and/or temporally limited projects and/or missions are located here.
- NOAA General introduction. Direct access to data. Station Locations and data plots are also accessible from this page.
- WDCA: If you know what you are looking for go here and click "OK" at the bottom of the page. Three-letter station codes are found here.
- CDIAC: Dust veil index. Year, latitude and longitude of the volcanic eruption are given in the first 3 columns. Data documentation is found here.
A wide variety of instruments is used to measure the numerous types of atmospheric aerosols and their associated parameters. To account for the properties of aerosols that vary with wavelength, these instruments frequently measure at more than one wavelength of light, e.g., red, green, blue, from which the "Angstrom coefficient characterizing the radiative properties of aerosols can be calculated. Some links to instrument descriptions are given below. For a general overview, go here and click any of the instruments listed.
- ARM: The Atmospheric Radiation Measurements program has two web pages that provide links to similar information about the instruments, but in different formats. These links are instrument contacts and instruments.
- NOAA: The National Oceanic and Atmospheric Administration (NOAA) provides brief descriptions of the instruments and links to the reference manual and procedures at the bottom of this page.
- NASA: Instruments that Measure Aerosol. In addition to the above information, you can link to some descriptive material on certain types of instruments:
- Aethalometer, 7 wavelength aethalometer: measures absorption as the attenuation (at a specific wavelength) of light through a quartz filter as the filter loads over time from the air passing through.
- Condensation particle counter: condenses a liquid on particles to grow them to a size that is easily counted and measured by optical scattering. The condensing liquid is typically an alcohol (e.g., butanol) or water.
- Differential Mobility Particle Sizers sort by mobility of electrically charged particles.
- Multi-Angle Absorption Photometer: also listed under "PSAP and MAAP" in the first link given in this (Methods) section.
- Nephelometer measures the total scattering and hemispheric backscattering of aerosol.
- Optical Particle Counters: A beam of monochromatic light scans a controlled volume and the instrument electronically counts the number of pulses produced by the scattered light. In some instruments the shadows cast by absorbing particles are also counted. The strength of the pulses of reflected/scattered light provides information about particle sizes and shapes. Information from lengthwise and depthwise scanning helps to deconvolve the information about particle sizes and shapes.
Satellite records go back to around 1980; since that time increasing trends in atmospheric optical depth (i.e., increases in opacity) are observed over areas including and downwind of developing nations, notably China and India. Changing patterns of wind transport of desert dust are likely responsible for increases over the Arabian Sea and decreases over the Atlantic Ocean just west of the Sahara Desert. Decreases in optical depth (i.e., increases in transparency) have occurred in Eastern North America and Europe; weaker decreases have occurred over Central-and-South America. Global trends are small and their sign is difficult to determine due to platform-to-platform differences in such things as calibration algorithms and retrieval accuracy (Zhao et al, 2008; Zhang et al. 2010; Hsu et al. 2012). Fires, volcanic eruptions, and dust storms frequently make it difficult to distinguish natural from anthropogenic effects (Streets et al. 2009).
- Haywood, J.M. and K.P. Shine, 1995. The effect of anthropogenic sulfate and soot aerosol on the clear sky planetary radiation budget. Geophys. Res. Lett. 22(5): 603-606.
- Hsu, N.C. et al. 2012. Global and regional trends of aerosol optical depth over land and ocean using SeaWiFS measurements from 1997 to 2010. Atmos. Chem. Phys. 12, 8465–8501, doi:10.5194/acpd-12-8465-2012.
- IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T. F., D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
- Ogren J. 1998. Measurements of the climate-forcing properties of atmospheric aerosols. Slide presentation at the Center for Atmospheric Sciences, University of Mexico, Mexico City, (Jan.23).
- Streets, D.G., et al. 2009. Anthropogenic and natural contributions to regional trends in aerosol optical depth, 1980–2006. J. Geophys. Res.: Atmospheres 114, D 10, DOI: 10.1029/2008JD011624.
- Zhang, J. and J.S. Reid. 2010. A decadal regional and global trend analysis of the aerosol optical depth using a data-assimilation grade over-water MODIS and Level 2 MISR aerosol products. Atmos. Chem. Phys. 10, 10949-10963. doi:10.5194/acp-10-10949-2010.
- Zhao T.X.P, et al. 2008. Study of long-term trend in aerosol optical thickness observed from operational AVHRR satellite instrument, J. Geophys. Res., 113, D7, doi:10.1029/2007JD009061.
Citing This Material
Please be sure to cite the primary data source (ARM, NASA, etc.), specific project, or program, and provide a link to the data set and the date the file was accessed.
Data are from the National Oceanic and Atmospheric Administration (NOAA), Global Monitoring Division (GMD), Aerosols Group. ftp://ftp.cmdl.noaa.gov/aerosol/brw/archive/ accessed 10/20/2013.
Data are from the AERONET (Aerosol Robotic Network Program) available from the Goddard Space Flight Center, http://aeronet.gsfc.nasa.gov/ National Aeronautics and Space Administration (NASA) Accessed 10/20/2013.
Data are from the ARM (Atmospheric Radiation Measurements) Program Archive maintained by Oak Ridge National Laboratory. http://www.archive.arm.gov/armlogin/login.jsp, accessed 10/20/2013.
If accessing the data from this site: please also cite: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy. For the Dust Veil Index, specifically, the link is http://cdiac.ess-dive.lbl.gov/ndps/ndp013.html
If citing material from this page only, cite as: Modern Records of Atmospheric Nitrous Oxide (N2O) and a 2000-year Ice-core Record from Law Dome Ice Cores in Antarctica, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy. http://cdiac.ess-dive.lbl.gov/modern_aerosols.html