Maintenance of a rural precipitation chemistry center at Whiteface Mountain

For the Past 11 years, Whiteface Mountain (WFM) has been successfully collecting data according to the MAP3S (Multistate Power Production Pollution Study) protocols. These protocols include field sampling, laboratory procedures, sample handling and shipment, and supporting measurements at the summit or lodge including meteorological and air quality parameters. All blind tests and audits have been successfully passed. Since the beginning of the MAP3S program it was recognized that, because of its remoteness, WFM needed some additional support to process the samples and to obtain site specific supporting data. The primary purpose of this funding was to insure the technical support to maintain the availability of WFM so that the necessary high quality research monitoring could continue. In addition, during the past year, we were able to: (1) perform all operations required by the National Trends Network (NTN) precipitation monitoring network: (2) begin the comparison of MAP3S data with similar data taken at WFM; (3) begin a series of ion chromatography measurements on MAP3S duplicate samples (when sufficient volume was available) to study the effect of time delays between sample collection and chemical analysis: (4) provide wet deposition data to the EPA Mountain Cloud Chemistry Program (MCCP); (5) assess the precipitation data quality of the ENSR measurements collocated with MAP3S. Selected results are presents. 6 refs., 1 fig

Lagrangian approach for stratospheric aerosol and gas experiment (SAGE) II profile intercomparisons

Trajectory calculations are employed to identify Stratospheric Aerosol and Gas Experiment (SAGE) II flights sampling the same air mass as is observed by a groundbased aerosol lidar at Garmisch-Partenkirchen, Germany (47.5°N, 11.1°E, 735 m above sea level), during the periods of January-April 1993 and January-December 1998. Intercomparisons between lidar-observed and SAGE II-derived backscatters at 532 nm are conducted. Percentage differences between trajectory-tracked SAGE II profiles and ground-based lidar observations with respect to aerosol lidar are generally within 20 - 40 %, though localized discrepancies > 50 % are found for some cases. In addition, aerosol extinction, aerosol to molecular extinction ratio, and ozone mixing ratio profiles obtained from the SAGE II flights overpassing the vicinity of Garmisch-Partenkirchen during the January-April 1993 period are compared with profiles obtained from corresponding trajectory-tracked SAGE II flights. Percentage discrepancies between SAGE II ozone profiles are generally within 10 - 20 % above the Junge layer. Data comparisons for aerosol profiles show mixed results. While some cases agree within the error bars, there are several cases where percentage discrepancies exceed 50 %

Intercomparison of stratospheric ozone profiles obtained by stratospheric aerosol and gas experiment II, halogen occulation experiment, and ozone sondes in 1994-1995

Stratospheric ozone mixing ratio profiles measured by satellite-borne Stratospheric Aerosol and Gas Experiment (SAGE 11 data version 5.93) and Halogen Occultation Experiment (HALOE data versions 17 and 18) are compared with each other and with balloon-borne ozonesonde profiles at Payerne, Lauder, and Macquarie Island stations during 1994-1995. The SAGE 11-HALOE ozone mixing ratio profiles are compared at 13-55 km altitudes, and the satellite-ozonesonde profiles are compared at 13-33 km altitudes. It is found that HALOE data version 18 ozone values are systematically larger than HALOE data version 17, particularly in the lower stratosphere. HALOE data version 18 ozone profiles are about 2 per cent, 5-8 per cent, and 10-20 per cent larger than the corresponding HALOE data version 17 at 40-55, 25-40, and 15-25 km altitudes, respectively. The new version of HALOE ozone agrees better with SAGE 11 and Payerne ozonesonde profiles than HALOE data version 17 does. In general, the agreements bet ween satellite-borne sensors and ozonesondes are all within their stated level of uncertainties. Intercomparison results between SAGE 11-Payerne ozonesonde and SAGE II-Lauder ozonesonde are compared with earlier comparative studies between SAGE II Payerne ozonesonde and SAGE II-Lauder ozonesonde by Veiga et al. (1995). Better agreement is achieved at Payerne station, but no improvement is discernible at Lauder ozonesonde station. At altitudes above 20 km the intercomparisons between SAGE II and HALOE data version 18 and between SAGE 11 and ozonesondes seem to indicate that aerosol has no statistically significant impact on SAGE 11 ozone retrieval during the period of 1994-1995

Retrieving aerosol optical properties from moments of the particle size distributrion

The randomized minimization search technique (RMST) is a powerful tool for retrieving aerosol size distribution from a set of aerosol extinction measurements. This technique is now extended to retrieve aerosol optical properties from a known moment sequence. The new usage of the RMST is demonstrated by using particle size distributions obtained from fits to in situ measurements conducted in the troposphere and stratosphere. Good agreements (with differences less than 5 per cent) between some aerosol optical properties calculated from the moments and those calculated directly from the particle size distributions are obtained. Our results illustrate that the RMST can be applied to parameterize particle optical properties from the lower-order moments of an aerosol size distribution