How Well Do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare?

Journal Article · Wed Feb 01 04:00:00 EST 2006 · Journal of Geophysical Research - Atmospheres

DOI:https://doi.org/10.1029/2005JD005837· OSTI ID:877542

Schmid, Beat; Ferrare, Richard; Flynn, Connor M; Elleman, Robert; Covert, David; Strawa, A; Welton, E J; Turner, David D; Jonsson, Haf; Redemann, Jens; Eilers, J; Ricci, K; Hallar, A G; Clayton, M B; Michalsky, Joseph J; Smirnov, A; Holben, B N; Barnard, James C

The recent U.S. Department of Energy Atmospheric Radiation Measurements (ARM) Aerosol Intensive Observation Period (AIOP, May 2003) yielded one of the best measurement sets obtained to-date to assess our ability to measure the vertical profile of ambient aerosol extinction. During one month, a heavily instrumented aircraft with well characterized aerosol sampling ability carrying well proven and new aerosol instrumentation, devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from 6 different instruments: airborne Sun photometer, airborne nephelometer/absorption photometer, airborne cavity ring-down system, ground-based Raman lidar and two ground-based elastic backscatter lidars. We find the in situ measurements to be biased low (2 - 4 Mm 1 equivalent to 12-17% in the visible, or 45% in the near-infrared) when compared to airborne sunphotometer extinction. On the other hand, we find that with respect to AATS-14, the lidar ?ep(?) are biased high. Bias differences are 0.004 Km-1 (13%) and 0.007 Km-1 (24%) for the two elastic back-scatter lidars (MPLARM and MPLNET, ? = 523 nm) and 0.029 Km-1 (54%) for the Raman lidar (? = 355 nm). An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP and we expect better agreement from the recently restored system. Looking at the collective results from six field campaigns conducted since 1996, airborne in situ measurements of extinction tend to be biased slightly low (17% at visible wavelengths) when compared to airborne sunphotometer extinction. On the other hand, extinction derived from lidars tend to have no or positive biases. We conclude that the error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state-of-the art instrumentation is 15-20% at visible wavelengths and potentially larger in the UV near-infrared.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 877542
• Report Number(s): PNNL-SA-44010; 830403000
• Journal Information: Journal of Geophysical Research - Atmospheres, Journal Name: Journal of Geophysical Research - Atmospheres Journal Issue: D5 Vol. 111; ISSN 0747-7309
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AEROSOLS
AIRCRAFT
COMPARATIVE EVALUATIONS
MEASURING METHODS
Mid-Atlantic Coast
OPTICAL RADAR
PHOTOMETERS
REMOTE SENSING
SAMPLING
SENSITIVITY
TROPOSPHERE
airborne sun photometer
columnar water-vapor
ground-based measurements
optical-depth spetra
particulate black carbon
radiation measurement program
remote-sensing measurements
single-scattering albedo
southern great-plains