Ozone measurements during the Airborne Polar Experiment : Aircraft instrument validation, isentropic trends, and hemispheric fields prior to the 1997 Arctic ozone depletion

The first deployment of the ECOC electro chemical ozone cell (ECOC) instrument onboard the high-altitude research aircraft, the Geophysica M-55, took place from Rovaniemi, northern Finland, between December 23, 1996, and January 14, 1997. The ECOC data were compared against contemporaneous data from a network of balloon-borne ozone sondes. The comparison was carried out in potential vorticity-potential temperature (PV, Θ) coordinates, using meteorological analyses from the European Centre for Medium-Range Forecasts. The comparison showed that ozone mixing ratios measured by ECOC are lower than those measured by ozonesonde by a small but statistically significant bias of (−5.7 ± 2.8)% at the cruising altitudes of the aircraft, 15 to 19 km. After establishing and removing the average bias, ECOC and ozonesonde data were analyzed together to follow the development of ozone distributions in the early winter Arctic stratosphere. The analysis showed no evidence of chemical ozone depletion at the cruising altitudes of the aircraft, that is, between 435 and 490 K. The absence of chemical depletion is in agreement with polar statospheric cloud (PSC) observations, which showed no PSCs at aircraft cruising altitudes, although from January 5 onwards, PSCs were observed above cruising altitudes. Results from a three-dimensional chemical transport model reproduce the basic features of the reconstructed ozone fields. However, the model does not capture the observed ozone increase during the campaign, due to weak modeled ozone vertical gradients, and indicates small ozone depletion of about 3% inside the vortex at 480 K by mid January.

[1]  Mark R. Schoeberl,et al.  Reconstruction of O3 and N2O fields from ER‐2, DC‐8, and balloon observations , 1990 .

[2]  M. Loewenstein,et al.  Ozone Loss Inside the Northern Polar Vortex During the 1991-1992 Winter , 1993, Science.

[3]  Richard Swinbank,et al.  A Stratosphere-Troposphere Data Assimilation System , 1994 .

[4]  P. Crutzen,et al.  HALOE observations of the vertical structure of chemical ozone depletion in the Arctic Vortex during winter and early spring 1996–1997 , 1997 .

[5]  Adrian F. Tuck,et al.  Synoptic and chemical evolution of the Antarctic vortex in late winter and early spring, 1987 , 1989 .

[6]  Mark R. Schoeberl,et al.  The structure of the polar vortex , 1992 .

[7]  T. Palmer,et al.  Breaking planetary waves in the stratosphere , 1983, Nature.

[8]  Mark R. Schoeberl,et al.  Reconstruction of the constituent distribution and trends in the Antarctic polar vortex from ER‐2 flight observations , 1989 .

[9]  C. T. McElroy,et al.  Ozone, column ClO, and PSC measurements made at the NDSC Eureka Observatory (80°N, 86°W) during the spring of 1997 , 1997 .

[10]  Hiroshi Kanzawa,et al.  Ozone depletion in and below the Arctic Vortex for 1997 , 1998 .

[11]  Mark R. Schoeberl,et al.  Intrusions into the lower stratospheric Arctic vortex during the winter of 1991–1992 , 1994 .

[12]  M. Chipperfield,et al.  Relative influences of atmospheric chemistry and transport on Arctic ozone trends , 1999, Nature.

[13]  L. Froidevaux,et al.  MLS observations of Arctic ozone loss in 1996–97 , 1997 .

[14]  M. Juckes,et al.  A high-resolution one-layer model of breaking planetary waves in the stratosphere , 1987, Nature.

[15]  Franck Lefèvre,et al.  The 1997 Arctic Ozone depletion quantified from three‐dimensional model simulations , 1998 .

[16]  James F. Gleason,et al.  Anomalously low ozone over the Arctic , 1997 .

[17]  A. W. Brewer.  Evidence for a world circulation provided by the measurements of helium and water vapour distribution in the stratosphere , 1949 .

[18]  M. Rummukainen,et al.  Dynamical diagnostics of the edges of the polar vortices , 1994 .

[19]  Warwick A. Norton,et al.  Breaking Rossby Waves in a Model Stratosphere Diagnosed by a Vortex-Following Coordinate System and a Technique for Advecting Material Contours , 1994 .

[20]  U. Bonafè,et al.  A Chemiluminescent Analyzer for Stratospheric Measurements of the Ozone Concentration (FOZAN) , 1999 .

[21]  M. Chipperfield,et al.  Ozone depletion at the edge of the Arctic polar vortex 1996/1997 , 1999 .

[22]  L. Polvani,et al.  Rossby-wave breaking, microbreaking, filamentation, and secondary vortex formation-The dynamics of a perturbed vortex , 1992 .

[23]  Martyn P. Chipperfield,et al.  Multiannual simulations with a three‐dimensional chemical transport model , 1999 .

[24]  Robert A. Barnes,et al.  Electrochemical concentration cell ozonesonde performance evaluation during STOIC 1989 , 1995 .

[25]  M. Rummukainen,et al.  Observational evidence for chemical ozone depletion over the Arctic in winter 1991–92 , 1995, Nature.

[26]  Costas A. Varotsos,et al.  Match observations in the Arctic winter 1996/97: High stratospheric ozone loss rates correlate with low temperatures deep inside the polar vortex , 2000 .

[27]  L. Lait.  An Alternative Form for Potential Vorticity , 1994 .

[28]  Stanley C. Solomon,et al.  Stratospheric ozone depletion: A review of concepts and history , 1999 .

[29]  David R. Hanson,et al.  Laboratory studies of the nitric acid trihydrate: Implications for the south polar stratosphere , 1988 .

[30]  S. Balestri,et al.  APE-POLECAT - rationale, road map and summary of measurements , 1999 .

[31]  James M. Russell,et al.  Analysis of UARS data in the southern polar vortex in September 1992 using a chemical transport model , 1996 .

[32]  A. MacKenzie,et al.  The M-55 Geophysica as a Platform for the Airborne Polar Experiment , 1999 .

[33]  B. Connor,et al.  An assessment of ECC ozonesondes operated using 1% and 0.5% KI cathode solutions at Lauder, New Zealand , 1998 .