The use of SMILES data to study ozone loss in the Arctic winter 2009/2010 and comparison with Odin/SMR data using assimilation techniques

摘要

The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board theInternational Space Station observed ozone in the stratosphere with high precisionfrom October 2009 to April 2010.Although SMILES measurements only cover latitudes from 38° S to 65° N,the combination of data assimilation methods and an isentropic advection model allowsus to quantify the ozone depletion in the 2009/2010 Arctic polar winter by making use ofthe instability of the polar vortex in the northern hemisphere.Ozone data from both SMILES and Odin/SMR (Sub-Millimetre Radiometer) for the winterwere assimilated into the Dynamical Isentropic Assimilation Model for OdiN Data (DIAMOND).DIAMOND is an off-line wind-driven transport model on isentropic surfaces.Wind data from the operational analyses of the European Centre for Medium- RangeWeather Forecasts (ECMWF) were used to drive the model.In this study, particular attention is paid to the cross isentropic transport of thetracer in order to accurately assess the ozone loss.The assimilated SMILES ozone fields agree well with the limitation of noise inducedvariability within the SMR fields despite the limited latitude coverage of the SMILESobservations.Ozone depletion has been derived by comparing the ozone field acquired by sequentialassimilation with a passively transported ozone field initialized on 1 December 2009.Significant ozone loss was found in different periods and altitudes from using bothSMILES and SMR data:The initial depletion occurred at the end of January below 550 K with an accumulatedloss of 0.6–1.0 ppmv (approximately 20%) by 1 April.The ensuing loss started from the end of February between 575 K and 650 K.Our estimation shows that 0.8–1.3 ppmv (20–25 %) of O has beenremoved at the 600 K isentropic level by 1 April in volume mixing ratio (VMR).