Earth Observation Data Group

Abstract:

The Aerosol Direct Radiative Experiment (ADRIEX) took place over the Adriatic and Black Seas during August and September 2004 with the aim of characterizing anthropogenic aerosol in these regions in terms of its physical and optical properties and establishing its impact on radiative balance. Eight successful flights of the UK BAE-146 Facility for Atmospheric Airborne Measurements were completed together with surface-based lidar and AERONET measurements, in conjunction with satellite overpasses. This paper outlines the motivation for the campaign, the methodology and instruments used, describes the synoptic situation and provides an overview of the key results. ADRIEX successfully measured a range of aerosol conditions across the northern Adriatic, Po Valley and Black Sea. Generally two layers of aerosol were found in the vertical: in the flights over the Black Sea and the Po Valley these showed differences in chemical and microphysical properties, whilst over the Adriatic the layers were often more similar. Nitrate aerosol was found to be important in the Po Valley region. The use of new instruments to measure the aerosol chemistry and mixing state and to use this information in determining optical properties is demonstrated. These results are described in much more detail in the subsequent papers of this special issue. Copyright © 2007 Royal Meteorological Society.

Abstract:

MIPAS is a Fourier transform interferometer on Envisat, observing the infra-red thermal self emission of the atmosphere. We investigate the trend in the observed concentrations of CFC-11 (CCl3F) and CFC-12 (CCl 2F2) throughout the life of the instrument. From September 2002 to March 2004, the nominal 'high resolution' (0.025 cm -1) reprocessed L1B data is used. New work was performed to enable the use of the 'reduced resolution' (0.0625cm-1) data now being taken so the trend calculation could be extended to early 2006. CFCs are implicated in the catalytic destruction of ozone and the polar 'ozone holes'. They are controlled by the Montreal protocol, and this work provides some means of quantifying its effect. The long time series from a single satellite instrument is useful for tracking the evolution of the CFC stratospheric loading, and checking the accuracy of simulations. The profiles of these species were determined using 'MORSE', developed at Oxford. It uses optimal estimation. Resulting profiles were combined a posteriori and three-day means calculated on a monthly basis. These means were used to determine the trends in various zonal latitude bands and globally.

Abstract:

[1] The six longest records of stratospheric aerosol ( in situ measurements at Laramie, Wyoming, lidar records at: Garmisch-Partenkirchen, Germany; Hampton, Virginia; Mauna Loa, Hawaii; Sao Jose dos Campos, Brazil, and SAGE II measurements) were investigated for trend by ( 1) comparing measurements in the 3 volcanically quiescent periods since 1970 using standard analysis of variance techniques, and ( 2) analyzing residuals from a time/volcano dependent empirical model applied to entire data sets. A standard squared-error residual minimization technique was used to estimate optimum parameters for each measurement set, allowing for first order autocorrelation, which increases standard errors of trends but does not change magnitude. Analysis of variance over the 3 volcanically quiescent periods is controlled by the end points (pre-El Chichon and post-Pinatubo), and indicates either no change (Garmisch, Hampton, Sao Jose dos Campos, Laramie-0.15 mu m) or a slight, statistically insignificant, decrease ( Mauna Loa, Laramie-0.25 mu m), - 1 +/- 0.5% yr(-1). The empirical model was applied to the same records plus 1020 nm SAGE II data separated into 33 latitude/altitude bins. No trend in stratospheric aerosol was apparent for 31 of 33 SAGE II data sets, 3 of 4 lidar records, and in situ measurements at 0.15 mu m. For Hampton and Laramie-0.25 mu m, the results suggest a weak negative trend, - 2 +/- 0.5% yr(-1), while 2 SAGE II data sets ( 30 - 35 km, 30 degrees and 40 degrees N) suggest a positive trend of similar magnitude. Overall we conclude that no long-term change in background stratospheric aerosol has occurred over the period 1970 - 2004.