Ozone depletion and chlorine activation in the Arctic winter 1999/2000 observed in Ny‐Ålesund

Abstract

We present vortex‐averaged calculations of ozone loss rates between late December 1999 and mid‐March 2000 derived from data collected by the Radiometer for Atmospheric Measurements (RAM). The ground‐based microwave radiometer RAM is operated at the Arctic station of the Network for the Detection of Stratospheric Change (NDSC) at Ny‐Ålesund, Spitsbergen (79°N, 12°E). Simultaneous observations of stratospheric ozone and chlorine monoxide (ClO) profiles were performed by the RAM during winter and spring 1999/2000. Ozone was monitored continuously and ClO was observed between late February and early April. Maximum ozone loss rates of 35 ppb/d were obtained in mid‐February and in the beginning of March. The ozone loss accumulated to 41% in a layer with a thickness of approximately 10 km centered at the 475 K isentropic level. Ozone loss estimates are compared to results obtained by other groups and to model calculations showing good agreement when all results are adjusted to the same vertical resolution. Simultaneously, we have observed record ClO mixing ratios in the lower stratosphere with a peak mixing ratio of 1.25 ppb on 1 March, corresponding to the strong chemical ozone loss at the same time. The ClO observations are compared to model calculations indicating that the SLIMCAT model underestimates the amount of chlorine activation at the end of the winter in Ny‐Ålesund, in contrast to the good agreement between modeled and observed ozone loss.

Atmospheric integrated water vapour measured by IR and MW techniques at the Peterhof site (Saint Petersburg, Russia)

“…This was the reason that neither the IWV retrieval scheme nor its accuracy were optimized. Pałm et al (2010) used the microwave radiometer RAM, which measured the 142 GHz emission of O 3 and operated at the AWIPEV base in Ny-Ålesund (Klein et al 2002). MW and FTIR measurements of IWV were in a good qualitative agreement, but the quantitative analysis of comparison was not presented.…”

The ground-based MW radiometer OZORAM on Spitsbergen – description and status of stratospheric and mesospheric O<sub>3</sub>-measurements

“…It has been committed to operation in 1994 (Sinnhuber et al, 1998) and has been modified for measurements of mesospheric emissions in 2006-2008 (for a history of the instrument see Table 1). (Sinnhuber et al, 1998;Klein et al, , 2002 Klein (1993) and have been omitted for clarity. The dashed line encloses the front end with the quasi optical system and the first mixing stage.…”

Integrated water vapor above Ny Ålesund, Spitsbergen: a multi-sensor intercomparison

“…Klein et al, 2002). While the main purpose of this instrument is monitoring stratospheric and mesospheric O 3 , IWV can be derived as a by-product (Wohltmann, 2002).…”

“…Regular FTIR measurements in solar and lunar absorption (Notholt et al, 1995) have been conducted since 1993. The RAM started operational measurements in 1996 (Klein et al, 2002). The GPS IWV data set starts in October 2000 (Heise et al, 2009).…”