Anna Gannet Hallar

Director, Storm Peak Laboratory
Assistant Research Professor
Division of Atmospheric Sciences

My research interest is studying anthropogenic effects on climate using innovative in situ measurement techniques for atmospheric constituents. During my graduate studies at the University of Colorado, I worked with a near-infrared tunable diode laser hygrometer used for the airborne measurement of total water (i.e. vapor plus particulate water). This instrument, a closed-path tunable diode laser hygrometer (CLH), was attached to a subisokinetic inlet for increased sensitivity to very thin cirrus layers. Using the data of CLH, I studied the radiative effect and microphysical properties of tropopause cirrus. As a National Research Council Associateship post-doctoral position at NASA Ames Research Center, I study the wavelength dependence of aerosol optical properties and the vertical distribution of aerosols using an optical technique referred to as "Cavity Ring Down" (CRD) spectroscopy.  Now at Storm Peak Laboratory, I will continue studies of cloud and aerosol interactions.

RESEARCH AREAS:

• Cloud Microphysics; In Situ Trace Gas Measurements; Aerosol Optical Properties

SELECTED PUBLICATIONS:

Strawa, A.W., T.W. Kirchstetter, A.G. Hallar, G.A. Ban-Weiss, J.P. McLaughlin, R.A. Harley, and M.M. Lunden, 2010:

Optical and physical properties of primary on-road vehicle particle emissions and their implications for climate change. J. Aerosol Sci., 41, 36-50.

de Wekker,S.F.J., A. Ameen, G. Song, B.B. Stephens, A.G. Hallar, and I.B. McCubbin, 2009:

A preliminary investigation of boundary layer effects on daytime atmospheric CO2 concentrations at a mountaintop location in the Rocky Mountains. Acta Geophysica, published on-line, doi:10.2478/s11600-009-0033-6.

Wiedinmyer, C., R.M. Bowers, N. Fierer, E. Horanyi, M. Hannigan, A.G. Hallar, I. McCubbin, K. Baustian, 2009:

The contribution of biological particles to observed particulate organic carbon at a remote high altitude site. Atmos. Environ., 43, 4278–4282.

Faïn, X., Obrist, D., Hallar, A. G., McCubbin, I., and Rahn, T., 2009:

High levels of reactive gaseous mercury observed at a high elevation research laboratory in the Rocky Mountains, Atmos. Chem. Phys. Discuss., 9, 15641-156719.

Bowers, R.M., C.L. Lauber, C. Wiedinmyer,  M. Hamady, A.G. Hallar, R. Fall, R. Knight, and N. Fierer, 2009:

Characterization of Airborne Microbial Communities at a High-Elevation Site and their Potential to Act as Atmospheric Ice Nuclei, Applied and Environmental Microbiology, Aug. 2009, p. 1–2 Vol. 75, No. 15, doi:10.1128/AEM.00447-09.

Obrist D., A.G. Hallar, I. McCubbin, B.B. Stephens, and T. Rahn, 2008:

Measurements of atmospheric mercury at Storm Peak Laboratory in the Rocky Mountains: Evidence for long-range transport from Asia, boundary layer contributions, and plant mercury uptake. Atmos. Environ., doi:10.1016/j.atmosenv.2008.06.051.

Davis, S., A.G. Hallar, L. M. Avallone, T. Campos, B. Engblom, 2006:

Measurement of total water with a tunable diode laser hygrometer: Inlet analysis calibration procedure, and ice water content determination.J. Atmos. and Oceanic Technol., 24(3), 463-475.

Hallar, A.G., A.W. Strawa, B. Schmid, E. Andrews, J. Ogren, P. Sheridan, R. Ferrare, D. Covert, R. Elleman, H. Jonsson, K. Bokarius, A. Luu, 2005:

ARM Aerosol Intensive Operating Period: Comparison of aerosol scattering during coordinated flights. J. Geophys. Res., doi: 2005JD006250RR.

Thornton, B.F., D.W. Toohey, L.M. Avallone, A. G. Hallar, H. Harder, M. Martinez, J. B. Simpas, W. H. Brune, M. Koike, Y. Kondo, N. Takegawa, B. E. Anderson, M. A. Avery 2005:

Variability of active chlorine in the lowermost Arctic stratosphere. J. Geophys. Res., 110, D22304, doi:10.1029/2004JD005580.

Strawa, A.W., R. Elleman, A.G. Hallar, D. Covert, K. Ricci, R. Provencal, T. Owano, H. Jonsson, B. Schmid, A. Luu, K. Bokarius, E. Andrews, 2005:

In-Situ Measurement of Aerosol Optical Properties Made During the DOE Aerosol IOP: 1. Comparison of Extinction and Scattering Coefficients. J. Geophys. Res., doi: 2005JD006056.

Schmid, B., R. Ferrare, C. Flynn, R. Elleman, D. Covert, A. Strawa, E. Welton, D. Turner, H. Jonsson, J. Redemann, J. Eilers, K. Ricci, A. G. Hallar, M. Clayton, J. Michalsky, A. Smirnov, B. Holben, J. Barnard, 2005:

How well can we measure the vertical profile of tropospheric aerosol extinction? J. Geophys. Res., doi: 2005JD005837.

Hallar, A.G., L.M. Avallone, R.L. Herman, B.E. Anderson, and A.J. Heymsfield, 2004:

Measurements of ice water content in tropopause region arctic cirrus during the SAGE III Ozone Loss and Validation Experiment (SOLVE). J. Geophys. Res., 109 (D17203) doi 10.1029/2003JD004348.

Kondo, Y., O.B. Toon, H. Irie, B. Gamblin, M. Koike, N. Takegawa, M.A. Tolbert, P.K. Hudson, A.A. Viggiano, L.M. Avallone, A.G. Hallar, B.E. Anderson, G.W. Sachse, D.E. Hunton, J.O. Balentine, and T.M. Miller, 2003:

Uptake of nitric acid on cirrus cloud particles in the upper troposphere and lowermost stratosphere. Geophys. Res. Lett., 30 (4), doi:10.1029/2002GL016539.