Technical Note: Intercomparison of ILAS-II version 2 and 1.4 trace species with MIPAS-B measurements

The Improved Limb Atmospheric Spectrometer (ILAS)-II sensor aboard the Japanese ADEOS-II satellite was launched into its sun-synchronous orbit on 14 December 2002 and performed solar occultation measurements of trace species, aerosols, temperature, and pressure in the polar stratosphere until 25 October 2003. Vertical trace gas profiles obtained with the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) provide one of the sparse data sets for validating ILAS-II version 2 and 1.4 data. The MIPAS-B limb emission spectra were collected on 20 March 2003 over Kiruna (Sweden, 68° N) at virtually the same location that has been sounded by ILAS-II about 5.5 h prior to the sampling of MIPAS-B. The intercomparison of the new ILAS-II version 2 (Northern Hemispheric sunrise) data to MIPAS-B vertical trace gas profiles shows a good to excellent agreement within the combined error limits for the species O<sub>3</sub>, N<sub>2</sub>O, CH<sub>4</sub>, H<sub>2</sub>O (above 21 km), HNO<sub>3</sub>, ClONO<sub>2</sub>, and CFC-11 (CCl<sub>3</sub>F) in the compared altitude range between 16 and 31 km such that these data appear to be very useful for scientific analysis. With regard to the previous version 1.4 ILAS-II data, significant improvements in the consistency with MIPAS-B are obvious especially for the species CH<sub>4</sub> and H<sub>2</sub>O, but also for O<sub>3</sub>, HNO<sub>3</sub>, ClONO<sub>2</sub>, NO<sub>2</sub>, and N<sub>2</sub>O<sub>5</sub>. However, comparing gases like NO<sub>2</sub>, N<sub>2</sub>O<sub>5</sub>, and CFC-12 (CCl<sub>2</sub>F<sub>2</sub>) exhibits only poor agreement with MIPAS-B such that these species cannot be assumed to be validated at the present time

Collapse in the nonlocal nonlinear Schr\"odinger equation

We discuss spatial dynamics and collapse scenarios of localized waves governed by the nonlinear Schr\"{o}dinger equation with nonlocal nonlinearity. Firstly, we prove that for arbitrary nonsingular attractive nonlocal nonlinear interaction in arbitrary dimension collapse does not occur. Then we study in detail the effect of singular nonlocal kernels in arbitrary dimension using both, Lyapunoff's method and virial identities. We find that for for a one-dimensional case, i.e. for $n=1$, collapse cannot happen for nonlocal nonlinearity. On the other hand, for spatial dimension $n\geq2$ and singular kernel $\sim 1/r^\alpha$, no collapse takes place if $\alpha<2$, whereas collapse is possible if $\alpha\ge2$. Self-similar solutions allow us to find an expression for the critical distance (or time) at which collapse should occur in the particular case of $\sim 1/r^2$ kernels. Moreover, different evolution scenarios for the three dimensional physically relevant case of Bose Einstein condensate are studied numerically for both, the ground state and a higher order toroidal state with and without an additional local repulsive nonlinear interaction. In particular, we show that presence of an additional local repulsive term can prevent collapse in those cases

HCl and ClO in activated Arctic air; first retrieved vertical profiles from TELIS submillimetre limb spectra

The first profile retrieval results of the Terahertz and submillimeter Limb Sounder (TELIS) balloon instrument are presented. The spectra are recorded during a 13-h balloon flight on 24 January 2010 from Kiruna, Sweden. The TELIS instrument was mounted on the MIPAS-B2 gondola and shared this platform with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the mini- Differential Optical Absorption Spectroscopy (mini-DOAS) instruments. The flight took place within the Arctic vortex at an altitude of ≈34 km in chlorine activated air, and both active (ClO) and inactive chlorine (HCl) were measured over an altitude range of respectively ≈16–32 km and ≈10– 32 km. In this altitude range, the increase of ClO concentration levels during sunrise has been recorded with a temporal resolution of one minute. During the daytime equilibrium, a maximum ClO level of 2.1±0.3 ppbv has been observed at an altitude of 23.5 km. This equilibrium profile is validated against the ClO profile by the satellite instrument Microwave Limb Sounder (MLS) aboard EOS Aura. HCl profiles have been determined from two different isotopes – H35Cl and H37Cl – and are also validated againstMLS. The precision of all profiles is well below 0.01 ppbv and the overall accuracy is therefore governed by systematic effects. The total uncertainty of these effects is estimated to be maximal 0.3 ppbv for ClO around its peak value at 23.5 km during the daytime equilibrium, and for HCl it ranges from 0.05 to 0.4 ppbv, depending on altitude. In both cases the main uncertainty stems from a largely unknown non-linear response in the detector

Validation and data characteristics of methane and nitrous oxide profiles observed by MIPAS and processed with Version 4.61 algorithm

The ENVISAT validation programme for the atmospheric instruments MIPAS, SCIAMACHY and GOMOS is based on a number of balloon-borne, aircraft, satellite and ground-based correlative measurements. In particular the activities of validation scientists were coordinated by ESA within the ENVISAT Stratospheric Aircraft and Balloon Campaign or ESABC. As part of a series of similar papers on other species [this issue] and in parallel to the contribution of the individual validation teams, the present paper provides a synthesis of comparisons performed between MIPAS CH4 and N2O profiles produced by the current ESA operational software (Instrument Processing Facility version 4.61 or IPF v4.61, full resolution MIPAS data covering the period 9 July 2002 to 26 March 2004) and correlative measurements obtained from balloon and aircraft experiments as well as from satellite sensors or from ground-based instruments. In the middle stratosphere, no significant bias is observed between MIPAS and correlative measurements, and MIPAS is providing a very consistent and global picture of the distribution of CH4 and N2O in this region. In average, the MIPAS CH4 values show a small positive bias in the lower stratosphere of about 5%. A similar situation is observed for N2O with a positive bias of 4%. In the lower stratosphere/upper troposphere (UT/LS) the individual used MIPAS data version 4.61 still exhibits some unphysical oscillations in individual CH4 and N2O profiles caused by the processing algorithm (with almost no regularization). Taking these problems into account, the MIPAS CH4 and N2O profiles are behaving as expected from the internal error estimation of IPF v4.61 and the estimated errors of the correlative measurements

Diurnal variations of reactive chlorine and nitrogen oxides observed by MIPAS-B inside the January 2010 Arctic vortex

The winter 2009/2010 was characterized by a strong Arctic vortex with extremely cold mid-winter temperatures in the lower stratosphere associated with an intense activation of reactive chlorine compounds (ClOx) from reservoir species. Stratospheric limb emission spectra were recorded during a flight of the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 24 January 2010 inside the Arctic vortex. Several fast limb sequences of spectra (in time steps of about 10 min) were measured from nighttime photochemical equilibrium to local noon allowing the retrieval of chlorine- and nitrogen-containing species which change rapidly their concentration around the terminator between night and day. Mixing ratios of species like ClO, NO2, and N2O5 show significant changes around sunrise, which are temporally delayed due to polar stratospheric clouds reducing the direct radiative flux from the sun. ClO variations were derived for the first time from MIPAS-B spectra. Daytime ClO values of up to 1.6 ppbv are visible in a broad chlorine activated layer below 26 km correlated with low values (below 0.1 ppbv) of the chlorine reservoir species ClONO2. Observations are compared and discussed with calculations performed with the 3-dimensional Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). Mixing ratios of the species ClO, NO2, and N2O5 are well reproduced by the model during night and noon. However, the onset of ClO production and NO2 loss around the terminator in the model is not consistent with the measurements. The MIPAS-B observations along with Tropospheric Ultraviolet-Visible (TUV) radiation model calculations suggest that polar stratospheric clouds lead to a delayed start followed by a faster increase of the photodissoziation of ClOOCl and NO2 near the morning terminator since stratospheric clouds alter the direct and the diffuse flux of solar radiation. These effects are not considered in the EMAC model simulations which assume a cloudless atmosphere

First remote sensing measurements of ClOOCl along with ClO and ClONO₂ in activated and deactivated Arctic vortex conditions using new ClOOCl IR absorption cross sections

Active chlorine species play a dominant role in the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Recently, the correct understanding of the ClO dimer cycle was challenged by the release of new laboratory absorption cross sections (Pope et al., 2007) yielding significant model underestimates of observed ClO and ozone loss (von Hobe et al., 2007). Under this aspect, nocturnal Arctic stratospheric limb emission measurements carried out by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 11 January 2001 and 20/21 March 2003 have been reanalyzed with regard to the chlorine reservoir species ClONO2 and the active species, ClO and ClOOCl (Cl2O2). New laboratory measurements of IR absorption cross sections of ClOOCl for various temperatures and pressures allowed for the first time the retrieval of ClOOCl mixing ratios from remote sensing measurements. High values of active chlorine (ClOx) of roughly 2.3 ppbv at 20 km were observed by MIPAS-B in the cold mid-winter Arctic vortex on 11 January 2001. While nighttime ClOOCl shows enhanced values of nearly 1.1 ppbv at 20 km, ClONO2 mixing ratios are less than 0.1 ppbv at this altitude. In contrast, high ClONO2 mixing ratios of nearly 2.4 ppbv at 20 km have been observed in the late winter Arctic vortex on 20 March 2003. No significant ClOx amounts are detectable on this date since most of the active chlorine has already recovered to its main reservoir species ClONO2. The observed values of ClOx and ClONO2 are in line with the established polar chlorine chemistry. The thermal equilibrium constants between the dimer formation and its dissociation, as derived from the balloon measurements, are on the lower side of reported data and in good agreement with values recommended by von Hobe et al. (2007). Calculations with the ECHAM/MESSy Atmospheric Chemistry model (EMAC) using established kinetics show similar chlorine activation and deactivation, compared to the measurements in January 2001 and March 2003, respectively