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Data from ground-based ozone (O3) vertical profiling platforms operated during the FRAPPE/DISCOVER-AQ campaigns in summer 2014 were used to characterize key processes responsible for establishing O3 profile development in the boundary layer in the Northern Colorado Front Range. Morning mixing from the upper boundary layer and lower free troposphere into the lower boundary layer was the key process establishing the mid-morning boundary layer O3 mixing ratio. Photochemical O3 production throughout the boundary layer builds on the mid-morning profile. From late morning to mid-afternoon the continuing O3 increase was nearly uniform through the depth of the profile measured by the tethersonde (~400 m). Ozonesondes flown on a near daily schedule over a four week period with multiple profiles on a number of days captured the full 1500 to 2000 m vertical extent of O3 enhancements in the mixed boundary layer confirming O3 production throughout the entire boundary layer. Continuous O3 measurements from the Boulder Atmospheric Observatory (BAO) tall tower at 6 m and 300 m showed hourly O3 at the 6 m level ≥75 ppb on 15% of the days. The diurnal variation on these days followed a pattern similar to that seen in the tethersonde profiles. The association of high O3 days at the BAO tower with transport from sectors with intense oil and natural gas production toward the northeast suggests emissions from this industry were an important source of O3 precursors and are crucial in producing peak O3 events in the NCFR. Higher elevation locations to the west of the NCFR plains regularly experience higher O3 values than those in the lower elevation NCFR locations. Exposure of populations in these areas is not captured by the current regulatory network, and likely underestimated in population O3 exposure assessments.

Tropospheric ozone profiles have been retrieved from the new ground-based National Aeronautics and Space Administration (NASA) Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) in Greenbelt, MD (38.99° N, 76.84° W, 57 m a.s.l.), from 400 m to 12 km a.g.l. Current atmospheric satellite instruments cannot peer through the optically thick stratospheric ozone layer to remotely sense boundary layer tropospheric ozone. In order to monitor this lower ozone more effectively, the Tropospheric Ozone Lidar Network (TOLNet) has been developed, which currently consists of five stations across the US. The GSFC TROPOZ DIAL is based on the DIAL technique, which currently detects two wavelengths, 289 and 299 nm, with multiple receivers. The transmitted wavelengths are generated by focusing the output of a quadrupled Nd:YAG laser beam (266 nm) into a pair of Raman cells, filled with high-pressure hydrogen and deuterium, using helium as buffer gas. With the knowledge of the ozone absorption coefficient at these two wavelengths, the range-resolved number density can be derived. An interesting atmospheric case study involving the stratospheric–tropospheric exchange (STE) of ozone is shown, to emphasize the regional importance of this instrument as well as to assess the validation and calibration of data. There was a low amount of aerosol aloft, and an iterative aerosol correction has been performed on the retrieved data, which resulted in less than a 3 ppb correction to the final ozone concentration. The retrieval yields an uncertainty of 16–19% from 0 to 1.5 km, 10–18% from 1.5 to 3 km, and 11–25% from 3 to 12 km according to the relevant aerosol concentration aloft. There are currently surface ozone measurements hourly and ozonesonde launches occasionally, but this system will be the first to make routine tropospheric ozone profile measurements in the Baltimore–Washington, D.C. area.

MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK) and CSIC, Instituto de Astrofísica de Andalucía (IAA) and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infra-red (FTIR) spectrometers. For MIPAS temperatures (version V4O_T_204), no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203) is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause), but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202) has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution. No further significant biases have been detected. Cross-comparison to co-located observations of other satellite instruments (Aura/MLS, ACE-FTS, AIRS) is provided as well.

The main purpose of the NASA Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) is to measure the vertical distribution of tropospheric ozone for science investigations. Because of the important health and climate impacts of tropospheric ozone, it is imperative to quantify background photochemical and aloft ozone concentrations, especially during air quality episodes. To better characterize tropospheric ozone, the Tropospheric Ozone Lidar Network (TOLNet) has recently been developed, which currently consists of five different ozone DIAL instruments, including the TROPOZ. This paper addresses the necessary procedures to validate the TROPOZ retrieval algorithm and develops a primary standard for retrieval consistency and optimization within TOLNet. This paper is focused on ensuring the TROPOZ and future TOLNet algorithms are properly quantifying ozone concentrations and the following paper will focus on defining a systematic uncertainty analysis standard for all TOLNet instruments. Although this paper is used to optimize the TROPOZ retrieval, the methodology presented may be extended and applied to most other DIAL instruments, even if the atmospheric product of interest is not tropospheric ozone (e.g. temperature or water vapor). The analysis begins by computing synthetic lidar returns from actual TROPOZ lidar return signals in combination with a known ozone profile. From these synthetic signals, it is possible to explicitly determine retrieval algorithm biases from the known profile, thereby identifying any areas that may need refinement for a new operational version of the TROPOZ retrieval algorithm. A new vertical resolution scheme is presented, which was upgraded from a constant vertical resolution to a variable vertical resolution, in order to yield a statistical uncertainty of

The new CHEM2D-Ozone Photochemistry Parameterization (CHEM2D-OPP) for high-altitude numerical weather prediction (NWP) systems and climate models specifies the net ozone photochemical tendency and its sensitivity to changes in ozone mixing ratio, temperature and overhead ozone column based on calculations from the CHEM2D interactive middle atmospheric photochemical transport model. We evaluate CHEM2D-OPP performance using both short-term (6-day) and long-term (1-year) stratospheric ozone simulations with the prototype high-altitude NOGAPS-ALPHA forecast model. An inter-comparison of NOGAPS-ALPHA 6-day ozone hindcasts for 7 February 2005 with ozone photochemistry parameterizations currently used in operational NWP systems shows that CHEM2D-OPP yields the best overall agreement with both individual Aura Microwave Limb Sounder ozone profile measurements and independent hemispheric (10°–90° N) ozone analysis fields. A 1-year free-running NOGAPS-ALPHA simulation using CHEM2D-OPP produces a realistic seasonal cycle in zonal mean ozone throughout the stratosphere. We find that the combination of a model cold temperature bias at high latitudes in winter and a warm bias in the CHEM2D-OPP temperature climatology can degrade the performance of the linearized ozone photochemistry parameterization over seasonal time scales despite the fact that the parameterized temperature dependence is weak in these regions.

Two-dimensional radiance maps from Channel 9 (~60–90 hPa) of the Advanced Microwave Sounding Unit (AMSU-A), acquired over southern Scandinavia on 14 January 2003, show plane-wave-like oscillations with a wavelength λh of ~400–500 km and peak brightness temperature amplitudes of up to 0.9 K. The wave-like pattern is observed in AMSU-A radiances from 8 overpasses of this region by 4 different satellites, revealing a growth in the disturbance amplitude from 00:00 UTC to 12:00 UTC and a change in its horizontal structure between 12:00 UTC and 20:00 UTC. Forecast and hindcast runs for 14 January 2003 using high-resolution global and regional numerical weather prediction (NWP) models generate a lower stratospheric mountain wave over southern Scandinavia with peak 90 hPa temperature amplitudes of ~5–7 K at 12:00 UTC and a similar horizontal wavelength, packet width, phase structure and time evolution to the disturbance observed in AMSU-A radiances. The wave's vertical wavelength is ~12 km. These NWP fields are validated against radiosonde wind and temperature profiles and airborne lidar profiles of temperature and aerosol backscatter ratios acquired from the NASA DC-8 during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). Both the amplitude and phase of the stratospheric mountain wave in the various NWP fields agree well with localized perturbation features in these suborbital measurements. In particular, we show that this wave formed the type II polar stratospheric clouds measured by the DC-8 lidar. To compare directly with the AMSU-A data, we convert these validated NWP temperature fields into swath-scanned brightness temperatures using three-dimensional Channel 9 weighting functions and the actual AMSU-A scan patterns from each of the 8 overpasses of this region. These NWP-based brightness temperatures contain two-dimensional oscillations due to this resolved stratospheric mountain wave that have an amplitude, wavelength, horizontal structure and time evolution that closely match those observed in the AMSU-A data. These comparisons not only verify gravity wave detection and horizontal imaging capabilities for AMSU-A Channel 9, but provide an absolute validation of the anticipated radiance signals for a given three-dimensional gravity wave, based on the modeling of Eckermann and Wu (2006).

This paper presents three-dimensional prognostic O3 simulations with parameterized gas-phase photochemistry from the new NOGAPS-ALPHA middle atmosphere forecast model. We compare 5-day NOGAPS-ALPHA hindcasts of stratospheric O3 with satellite and DC-8 aircraft measurements for two cases during the SOLVE II campaign: (1) the cold, isolated vortex during 11-16 January 2003; and (2) the rapidly developing stratospheric warming of 17-22 January 2003. In the first case we test three different photochemistry parameterizations. NOGAPS-ALPHA O3 simulations using the NRL-CHEM2D parameterization give the best agreement with SAGE III and POAM III profile measurements. 5-day NOGAPS-ALPHA hindcasts of polar O3 initialized with the NASA GEOS4 analyses produce better agreement with observations than do the operational ECMWF O3 forecasts of case 1. For case 2, both NOGAPS-ALPHA and ECMWF 114-h forecasts of the split vortex structure in lower stratospheric O3 on 21 January 2003 show comparable skill. Updated ECMWF O3 forecasts of this event at hour 42 display marked improvement from the 114-h forecast; corresponding updated 42-hour NOGAPS-ALPHA prognostic O3 fields initialized with the GEOS4 analyses do not improve significantly. When NOGAPS-ALPHA prognostic O3 is initialized with the higher resolution ECMWF O3 analyses, the NOGAPS-ALPHA 42-hour lower stratospheric O3 fields closely match the operational 42-hour ECMWF O3 forecast of the 21 January event. We find that stratospheric O3 forecasts at high latitudes in winter can depend on both model initial conditions and the treatment of photochemistry over periods of 1-5 days. Overall, these results show that the new O3 initialization, photochemistry parameterization, and spectral transport in the NOGAPS-ALPHA NWP model can provide reliable short-range stratospheric O3 forecasts during Arctic winter.

Tropospheric ozone profiles have been retrieved from the new ground based National Aeronautics and Space Administration (NASA) Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) in Greenbelt, MD (38.99° N, 76.84° W, 57 m a.s.l.) from 400 m to 12 km a.g.l. Current atmospheric satellite instruments cannot peer through the optically thick stratospheric ozone layer to remotely sense boundary layer tropospheric ozone. In order to monitor this lower ozone more effectively, the Tropospheric Ozone Lidar Network (TOLNet) has been developed, which currently consists of five stations across the US. The GSFC TROPOZ DIAL is based on the Differential Absorption Lidar (DIAL) technique, which currently detects two wavelengths, 289 and 299 nm. Ozone is absorbed more strongly at 289 nm than at 299 nm. The DIAL technique exploits this difference between the returned backscatter signals to obtain the ozone number density as a function of altitude. The transmitted wavelengths are generated by focusing the output of a quadrupled Nd:YAG laser beam (266 nm) into a pair of Raman cells, filled with high pressure hydrogen and deuterium. Stimulated Raman Scattering (SRS) within the focus generates a significant fraction of the pump energy at the first Stokes shift. With the knowledge of the ozone absorption coefficient at these two wavelengths, the range resolved number density can be derived. An interesting atmospheric case study involving the Stratospheric–Tropospheric Exchange (STE) of ozone is shown to emphasize the regional importance of this instrument as well as assessing the validation and calibration of data. The retrieval yields an uncertainty of 16–19% from 0–1.5 km, 10–18% from 1.5–3 km, and 11–25% from 3 km to 12 km. There are currently surface ozone measurements hourly and ozonesonde launches occasionally, but this system will be the first to make routine tropospheric ozone profile measurements in the Baltimore–Washington DC area.

Results from a measurement campaign performed at Table Mountain Facility/Jet Propulsion Laboratory/ California Institute of Technology (34.388N, 117.688W, 2280 m ASL) are presented. Between 19 February and 18 March 1997 more than 400 h worth of lidar data were acquired and four backscatter sondes were launched. About 50% of the observations show the presence of cirrus clouds at altitudes close to and below the tropopause. Of these clouds 80% are characterized as subvisual with optical depths below 0.03 at a wavelength of 532 nm. Simple geometrical considerations lead to cloud spatial scales of 0.31 km vertically and 7.5 km horizontally, respectively. Deviations from color ratio values derived on the basis of geometrical optics are interpreted as small particle signatures. Comparing backscatter ratio profiles observed concurrently by three aerosol lidars, mean deviations of about 10% are found.

A ground-based millimeter wave radiometer for the Network for the Detection of Stratospheric Change (NDSC) was installed at Lauder, New Zealand (45°S, 169.7°E) in November 1992. It has been monitoring the middle atmospheric ozone with nearly continuous operation since then. Owing to special complications in the observing conditions at this southern midlatitude site, three refinements to the data analysis and calibration techniques were proposed: (1) the use of a radiative model of local tropospheric climate adopted to the low surface elevation of the observing site, (2) the correction of observing angle measurements due to the settling of the foundation of the site, and (3) the improved method of radiometric temperature determination of calibration sources. All data from 1992 to 1998 were reprocessed with these modifications implemented. The retrieved ozone profiles are compared to sonde, two lidars, and satellite (Halogen Occultation Experiment (HALOE), Stratospheric Aerosol and Gas Experiment (SAGE II)) overpass measurements. The agreement is very good, with mean differences from 56 to 1 mbar of generally 2–3% for the comparisons with sonde, HALOE, and SAGE II, and generally

The Ny-Alesund Ozone Monitoring Intercomparison (NAOMI) took place at Ny-Alesund,Spitsbergen (78.92 degrees N, 11.95 degrees E), from January 20 to February 10, 1998.This paper focuses on comparing stratospheric ozone profiles measured by the Alfred WegenerInstitute differential absorption lidar (AWI DIAL), in routine Network for Detection ofStratospheric Change (NDSC) operation at Ny-Alesund, the mobile Goddard Space Flight CenterDIAL (GSFC DIAL), the University of Bremen microwave radiometer (mu Wave), andelectrochemical concentration cell (ECC) ozonesondes, flown routinely by AWI. Below 30 km thetwo DIALs and the ECC sondes give virtually the same results, with instrumental precision(repeatability) better than +/-5% and no detectable bias. When their coarser altitude resolution isnot accounted for, the mu Wave data show 15% low bias at 16 km and 15% high bias at 23 km,Considerably better agreement, better than +/-5% around 20 km and above 30 km, is found whenthe altitude resolution of the other data is degraded to match that of the mu Wave. During NAOMIthe mu Wave data show high bias of up to 10% in a mixing ratio plateau around 25 km. Such biashas not been seen in routine intercomparisons between mu Wave and ECC sonde data atNy-Alesund. It is likely caused by an a priori profile 40% higher than the true profile duringNAOMI, Above 30 km the mu Wave data show the best precision (repeatability), about +/-3 to+/-5%. Precision of the GSFC DIAL data decreases from better than +/-5% at 30 km to about+/-10% at 40 km, and the precision for the AWI DIAL data decreases from better than +/-5% at30 km to +/-30% at 40 km. From 34 to 38 km the AWI profile is 12% lower than the GSFCprofile. AWI DIAL measurements that are low at 35 km often end below 40 km of show highvalues at 40 or 45 km, This behavior seems related to the way in which the AWI processingalgorithm changes altitude resolution for data with poor signal-to-noise ratio.

Temperature profiles were acquired on the Tropical Ozone Transport Experiment (TOTE) and Vortex Ozone Transport Experiment (VOTE) flights by the Goddard Airborne Raman Lidar. The objective was to compare the temperature product from this new instrument with those generated by the Jet Propulsion Laboratory's Microwave Temperature Profiler and Goddard Space Flight Center's ground-based Stratospheric Ozone Lidar. Simultaneous measurements were made between the Airborne Raman Lidar and O3 lidar on three dates; average temperatures differences varied from ∼0.5 K-5 K over the 16–24 km altitude region. Comparisons between the Microwave Temperature Profiler and Airborne Raman Lidar for all flights (17) during TOTE/VOTE were performed over the same altitude region. The average temperature difference, Airborne Raman Lidar minus Microwave Temperature Profiler, was +2.3 K. In comparing temperatures between the Airborne Raman Lidar and Goddard's Data Assimilation Model, the ARL showed small scale structures not evident in those of the model for altitudes between ∼16 and 43 km.

Following a blind intercomparison of ozone profiling instruments in the Network for the Detection of Stratospheric Change at Lauder, New Zealand, revisions to the analyses were made resulting in a new data set. This paper compares the revised results from two differential absorption lidars (RIVM and GSFC), a microwave radiometer (Millitech/LaRC), and electrochemical concentration cell (ECC) balloon sondes (NIWA). In general, the results are substantially improved compared to the earlier blind intercomparison. The level of agreement was similar both for single profiles and for the campaign average profile and was approximately 5% for the lidars and the sondes over the altitude range from 15 to 42 km (32 km for sondes). The revised microwave data show a bias of 5–10% high in the region from 22 to 42 km. Starting at 42 km, the lidar errors increase significantly, and comparisons of the microwave results were not possible above this altitude.

The Halogen Occultation Experiment (HALOE) onboard UARS measures profiles of limb path solar attenuation in eight infrared bands. These measurements are used to infer profiles of temperature, gas mixing ratios of seven species, and aerosol extinction at five wavelengths. The objective of this paper is to validate profiles of temperature retrieved from atmospheric transmission measurements in the 2.80-μm CO2 band. Temperatures are retrieved for levels above where aerosol affects the signals (35 km) to altitudes where the signal-to-noise decreases to unity (∽85 km). At altitudes from 45 to 35 km the profile undergoes a gradual transition from retrieved to National Meteorological Center (NMC) temperatures and below 35 km the profile is strictly from the NMC. This validation covers the uncertainty analysis, internal validations, and comparisons with independent measurements. Monte Carlo calculations using all known random and systematic errors determine typical measurement uncertainties of 5 K for altitudes below 80 km. Comparisons of coincident HALOE sunrise and sunset measurements are an indicator of the upper limit of measurement uncertainty. The sunrise-sunset comparisons have random and systematic differences which are less than 10 K for altitudes below 80 km. Comparisons of HALOE to lidar and rocket measurements typically have random differences of ∽5 K for altitudes below 65 km. The mean differences for the correlative comparisons indicate that HALOE temperatures have a cold bias (2 to 5 K) in the upper stratosphere and stratopause.

Ozone measurements made by the Cryogenic Limb Array Etalon Spectrometer (CLAES) aboard the NASA Upper Atmosphere Research Satellite (UARS) are compared to nearly coincident correlative measurements taken in 1992 and 1993 and to mean ozone distributions observed by other satellite instruments during past missions. This paper describes the CLAES measurement characteristics, uncertainties, predicted, and observed precisions and compares the observations with independent measurements both qualitatively and statistically. Satellite- and ground-based remote sensing as well as balloon-borne in situ measurements are represented in the correlative data set. The CLAES data are shown to be within ±20% of all correlative measurements between 0.5 and 30 mbar. Differences at lower altitudes may be related to effects of the Pinatubo aerosol on certain of the correlative measurements and the CLAES retrieval. Comparisons with historical data from the LIMS, SAGE II, and SBUV instruments indicate good agreement with the spatial and seasonal ozone distributions seen by CLAES.

The accuracy and precision of the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) atmospheric temperature and tangent-point pressure measurements are described. Temperatures and tangent- point pressure (atmospheric pressure at the tangent height of the field of view boresight) are retrieved from a 15-channel 63-GHz radiometer measuring O2 microwave emissions from the stratosphere and mesosphere. The Version 3 data (first public release) contains scientifically useful temperatures from 22 to 0.46 hPa. Accuracy estimates are based on instrument performance, spectroscopic uncertainty and retrieval numerics, and range from 2.1 K at 22 hPa to 4.8 K at 0.46 hPa for temperature and from 200 m (equivalent log pressure) at 10 hPa to 300 m at 0.1 hPa. Temperature accuracy is limited mainly by uncertainty in instrument characterization, and tangent-point pressure accuracy is limited mainly by the accuracy of spectroscopic parameters. Precisions are around 1 K and 100 m. Comparisons are presented among temperatures from MLS, the National Meteorological Center (NMC) stratospheric analysis and lidar stations at Table Mountain, California, Observatory of Haute Provence (OHP), France, and Goddard Spaceflight Center, Maryland. MLS temperatures tend to be 1-2 K lower than NMC and lidar, but MLS is often 5 - 10 K lower than NMC in the winter at high latitudes, especially within the northern hemisphere vortex. Winter MLS and OHP (44 deg N) lidar temperatures generally agree and tend to be lower than NMC. Problems with Version 3 MLS temperatures and tangent-point pressures are identified, but the high precision of MLS radiances will allow improvements with better algorithms planned for the future.

Simultaneous profiles of aerosol backscatter ratio were measured over Lauder, New Zealand (45 deg S, 170 deg E) on the night of November 24, 1992. Instrumentation comprised two complementary lidar systems and a backscattersonde, to give measurements at wavelengths 351, 490, 532, and 940 nm. The data from the lidars and the backscattersonde were self-consistent, enabling the wavelength dependence of aerosol backscatter to be determined as a function of altitude. This wavelength-dependence is a useful parameter in radiative transfer calculations. In the stratosphere, the average wavelength exponent between 351 and 940 nm was -1.23 +/- 0.1, which was in good agreement with values derived from measured physical properties of aerosols.

A method for remotely measuring ambient pressure and temperature at altitudes on the order of 40 km is presented. The technique is that of backscattered fluorescence from the OH radical measured from a balloon platform. Pressure is deduced from the ratio of (1, 1) fluorescence to (0, 0) fluorescence, while the temperature measurement is based on rotational level population changes with changes in temperature.

Thirteen clear nights in October 2005 allowed successful intercomparison of the lidar operated since 1987 by the German Weather Service (DWD) at Hohenpeißenberg (47.8° N, 11.0° E) with the Network for the Detection of Atmospheric Composition Change (NDACC) travelling standard lidar operated by NASA's Goddard Space Flight Center. Both lidars provide ozone profiles in the stratosphere, and temperature profiles in the strato- and mesosphere. Additional ozone profiles came from on-site Brewer/Mast ozonesondes, additional temperature profiles from Vaisala RS92 radiosondes launched at Munich (65 km north-east), and from operational analyses by the US National Centers for Environmental Prediction (NCEP). The intercomparison confirmed a low bias for ozone from the DWD lidar in the 33 to 43 km region, by up to 10%. This bias is caused by the DWD ozone algorithm, and is consistent with previous comparisons of the DWD lidar with SAGE, GOMOS and other instruments. During HOPE, precision (repeatability) for ozone data from both lidars was better than 5% between 20 and 40 km altitude, dropping to 10% near 45 km, and to 50% near 50 km. These results are consistent with previous NDACC intercomparisons, and confirm the reliability of the NASA NDACC travelling standard lidar. Temperature from the DWD lidar showed a 1 to 2 K cold bias from 30 to 65 km against the NASA lidar, and a 2 to 4 K cold bias against radiosondes and NCEP. This is also consistent with previous intercomparisons. Temperature precision (repeatability) for the DWD lidar was better than 2 K from 30 to 50 km, decreasing to 10 K near 70 km. For the NASA lidar, precision is expected to be better than 1 K over the 30 to 70 km range. However, due to the much lower temperature precision of the DWD lidar, this could not be checked during HOPE. It was noted that the current DWD algorithm over-estimates temperature uncertainty, which should be reduced by a factor of 2.2 (e.g. from 22 K to 10 K near 70 km). The HOPE intercomparison did uncover a 290 m range error (upward shift) of the DWD lidar data. When this shift is removed, the bias of the ozone algorithm is corrected, and a better background estimation is used, ozone profiles from the DWD lidar agree very well with both the NASA lidar and SAGE. Systematic differences are then smaller than 3% between 20 and 44 km, and smaller than 5% between 17 and 47 km. These differences are close to zero, and are not (statistically) significant. The cold temperature bias against the NASA lidar also disappears when the DWD temperature processing is corrected for the 290 m range error, and more appropriate values for the Earth's gravity acceleration are used. Compared to the radiosondes or NCEP analyses, however, both lidars show 1 to 2 K lower temperatures over the entire 15 to 35 km range. Temperature and ozone variations are tracked well by both lidars, by ozone- and radiosondes, and by NCEP analyses. Correlations exceed 0.8 to 0.9 at most stratospheric levels. They decrease at levels above 40 km, especially for ozone or NCEP temperature. The ozone and temperature bias of the DWD lidar does not appear to have changed over time. Records of ozone and temperature from the DWD lidar should be consistent over the years. Nevertheless, the HOPE intercomparison was instrumental in uncovering and repairing several long-standing errors. HOPE also confirmed the reliability of the NASA lidar as a travelling standard. Now the entire DWD lidar data record needs to be reprocessed with the improved and revised algorithms.

A model is presented that permits the simulation of the optical properties of cirrus clouds as measured with depolarization Raman lidars. It comprises a one-dimensional cirrus model with explicit microphysics and an optical module that transforms the microphysical model output to cloud and particle optical properties. The optical model takes into account scattering by randomly oriented or horizontally aligned planar and columnar monocrystals and polycrystals. Key cloud properties such as the fraction of plate-like particles and the number of basic crystals per polycrystal are parameterized in terms of the ambient temperature, the nucleation temperature, or the mass of the particles. The optical-microphysical model is used to simulate the lidar measurement of a synoptically forced cirrostratus in a first case study. It turns out that a cirrus cloud consisting of only monocrystals in random orientation is too simple a model scenario to explain the observations. However, good agreement between simulation and observation is reached when the formation of polycrystals or the horizontal alignment of monocrystals is permitted. Moreover, the model results show that plate fraction and morphological complexity are best parameterized in terms of particle mass, or ambient temperature which indicates that the ambient conditions affect cirrus optical properties more than those during particle formation. Furthermore, the modeled profiles of particle shape and size are in excellent agreement with in situ and laboratory studies, i.e., (partly oriented) polycrystalline particles with mainly planar basic crystals in the cloud bottom layer, and monocrystals above, with the fraction of columns increasing and the shape and size of the particles changing from large thin plates and long columns to small, more isometric crystals from cloud center to top. The findings of this case study corroborate the microphysical interpretation of cirrus measurements with lidar as suggested previously.

[1] The Earth Observing System (EOS) Microwave Limb Sounder (MLS) aboard the Aura satellite has provided essentially daily global measurements of ozone (O3) profiles from the upper troposphere to the upper mesosphere since August of 2004. This paper focuses on validation of the MLS stratospheric standard ozone product and its uncertainties, as obtained from the 240 GHz radiometer measurements, with a few results concerning mesospheric ozone. We compare average differences and scatter from matched MLS version 2.2 profiles and coincident ozone profiles from other satellite instruments, as well as from aircraft lidar measurements taken during Aura Validation Experiment (AVE) campaigns. Ozone comparisons are also made between MLS and balloon-borne remote and in situ sensors. We provide a detailed characterization of random and systematic uncertainties for MLS ozone. We typically find better agreement in the comparisons using MLS version 2.2 ozone than the version 1.5 data. The agreement and the MLS uncertainty estimates in the stratosphere are often of the order of 5%, with values closer to 10% (and occasionally 20%) at the lowest stratospheric altitudes, where small positive MLS biases can be found. There is very good agreement in the latitudinal distributions obtained from MLS and from coincident profiles from other satellite instruments, as well as from aircraft lidar data along the MLS track.

An intrusion of vortex edge air into the interior of the Arctic polar vortex was observed on the 31 January 2005 flight of the NASA DC-8 aircraft. This intrusion was identified as anomalously high values of ozone by Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTAL) and Differential Absorption Lidar (DIAL). Our analysis shows that this intrusion formed when a blocking feature near Iceland collapsed, allowing edge air to sweep into the vortex interior. Analysis of Aura Microwave Limb Sounder (MLS) observations made along the DC-8 flight track also shows the intrusion in both ozone and HNO3. Polar stratospheric clouds (PSCs) were observed by the DIAL lidar on the DC-8. The spatial variability of the PSCs can be explained using MLS HNO3 and H2O observations and meteorological analysis temperatures. We also estimate vortex denitrification using the relationship between N2O and HNO3. Reverse domain fill back trajectory calculations are used to focus on the features in the MLS data. The trajectory results improve the agreement between lidar measured ozone and MLS ozone and also improve the agreement between the HNO3 measurements and PSC locations. The back trajectory calculations allow us to compute the local denitrification rate and reduction of HCl within the filament. We estimate a denitrification rate of about 10% per day after exposure to below–PSC formation temperature.

Extensive ozone measurements were made during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). We compare high-latitude line-of-sight (LOS) slant column ozone measurements from the NASA DC-8 to ozone simulated by forward integration of measurement-derived ozone fields constructed both with and without the assumption of horizontal homogeneity. The average bias and rms error of the simulations assuming homogeneity are relatively small (−6 and 10%, respectively) in comparison to the LOS measurements. The comparison improves significantly (−2% bias; 8% rms error) using forward integrations of three-dimensional proxy ozone fields reconstructed from potential vorticity-O3 correlations. The comparisons provide additional verification of the proxy fields and quantify the influence of large-scale ozone inhomogeneity. The spatial inhomogeneity of the atmosphere is a source of error in the retrieval of trace gas vertical profiles and column abundance from LOS measurements, as well as a complicating factor in intercomparisons that include LOS measurements at large solar zenith angles.

The OHP Temperature and Ozone Intercomparison Campaign (OTOIC) took place at the Observatoire de Haute Provence, France, from 1–18 July 1997. The NASA Goddard Space Flight Center (GSFC) mobile lidar system was deployed at the Observatoire de Haute Provence (OHP) during a blind intercomparison as a part of the continuous validation process within the Network for the Detection of Stratospheric Change. The GSFC measurements were compared to two lidars permanently deployed at OHP and operated by the Centre National de la Recherche Scientifique (CNRS), one measuring ozone and the other measuring temperature.

Ozone measurements from ozonesondes, AROTAL, DIAL, and POAM III instruments during the SOLVE-2/VINTERSOL period are composited in a time-varying, flow-following quasi-conservative (PV-θ) coordinate space; the resulting composites from each instrument are mapped onto the other instruments' locations and times. The mapped data are then used to intercompare data from the different instruments. Overall, the four ozone data sets are found to be in good agreement. AROTAL shows somewhat lower values below 16 km, and DIAL has a positive bias at the upper limits of its altitude range. These intercomparisons are consistent with those obtained from more conventional near-coincident profiles, where available. Although the PV-θ mapping technique entails larger uncertainties of individual profile differences compared to direct near-coincident comparisons, the ability to include much larger numbers of comparisons can make this technique advantageous.

Ozone observations made by the Airborne Raman Ozone, Temperature, and Aerosol Lidar(AROTEL) and Differential Absorption Lidar (DIAL) on board the NASA DC-8 aircraft, the NOAAin situ instrument on board the NASA ER-2 aircraft, and Third European Stratospheric Experimenton Ozone 2000 (THESEO 2000) ozonesondes are analyzed by applying a quasi-conservativecoordinate mapping technique. Measurements from the late winter/early spring SAGE III OzoneLoss and Validation Experiment (SOLVE) period (January through March 2000) are incorporatedinto a time-varying composite field in a potential vorticity-potential temperature coordinate space;ozone loss rates are calculated both with and without diabatic effects. The average loss rate frommid-January to mid-March near the 450 K isentropic surface in the polar vortex is found to beapproximately 0.03 ppmv/d.

A significant issue in the use of the mismatch negativity evoked potential (MMN) concerns its low signal-to-noise ratio (SNR). One can improve the noise level by increasing the number of samples included in the averaged response. However, improvement achieved in this way assumes that the signal, the MMN, remains stable for extended test times, an assumption which has not been tested. If the MMN is not stable, or exhibits habituation over the test session, then SNR would be adversely affected. MMN response magnitude was measured in 5-min intervals over the course of a test session in response to various speech syllable contrasts. Significant long-term habituation of MMN was observed for all three subject populations tested: young adults, school-age children, and guinea pigs. The time course of the habituation and the stimulus conditions under which it occurs have important implications for research and clinical applications of the MMN. Recording procedures that minimize habituation effects may be used to advantage to improve the signal-to-noise ratio of the MMN.

This review paper describes an "acoustic-phonetic" experimental approach aimed at understanding normal and abnormal speech perception processes from both a behavioral and an electrophysiologic perspective. First, we consider the relevant acoustic characteristics of speech and identify a set of acoustic-phonetic classes that represent the parameters most important for making an acoustic signal sound like speech. Second, we review what is known about the neurophysiologic representation of acoustic-phonetic speech parameters in animal and human subjects. Third, we describe how an acoustic-phonetic approach has been useful in understanding the biologic basis of some auditory learning problems in children and in characterizing the behavioral and neurophysiologic changes resulting from speech-sound training. Finally, we discuss these findings and how they may expand the diagnostic and rehabilitative repertoire of practicing audiologists.

An intercomparison of ozone-profiling instruments, two differential absorption lidars, a microwave radiometer, electrochemical concentration sondes, and the SAGE II satellite instrument is presented. The ground-based instruments were located at the Network for the Detection of Stratospheric Change (NDSC) primary station at Lauder, New Zealand. The campaign, which took place between April 15 and 29, 1995, strictly followed the NDSC guidelines for a blind intercomparison. Agreement between the measurements was within 15% for single profiles and within 10% for the campaign average, in the region from 20 to 40 km altitude. Outside of this region the differences were greater but can generally be ascribed to the limits of a particular instrument.

The cognitive P300 evoked potential was elicited by speech stimuli in successful cochlear implant recipients, and the resulting P300 morphology was remarkably similar to that of normal-hearing individuals. The P300 was elicited by the synthesized speech pair/da/and/di/ presented using an oddball paradigm to nine "good" Nucleus cochlear implant users and nine age-matched normal-hearing subjects (34-81 yr old). There were no significant differences in P300 amplitude and latency between the two groups. Moreover, the N1 and P2 potentials occurred at similar latencies in the two groups, although the N1 amplitude was significantly smaller in the cochlear implant users. The P300 was absent in one "poor" cochlear implant user. The results suggest that the P300 may serve as a useful tool for evaluating the cognitive aspects of auditory processing in cochlear implant recipients, and that it may aid in assessing the success of cochlear implantation.

International audience; A series of coordinated atmospheric ozone profile measurements was made during October and November 1988. The instruments making observations and their locations were as follows. The Jet Propulsion Laboratory (JPL) and Goddard Space Flight Center differential absorption lidar systems were located at the JPL-Table Mountain Facility 34.4°N, 117.7°W. The electrochemical concentration cell balloon sondes and the rocket ozonesondes were both launched from Point Mugu Naval Air Station at 34.2°N, 119.2°W. Stratospheric Aerosol and Gas Experiment (SAGE II) satellite measurements were at various latitudes and longitudes but only measurements made within 1000 km of both of the above sites were considered for this intercomparison study. It was found that at least for the time of year of the study, SAGE II measurements agreed only when they were made much closer than 1000 km (

Between October 15 and November 8, 1988, the GSFC mobile stratospheric ozone lidar was operated at Table Mountain Observatory to intercompare with the permanent JPL ozone lidar. These lidars both use the technique of differential absorption to measure ozone. XeCl excimer lasers are used to generate the on-line 307.9 nm light absorbed by ozone. However, the GSFC lidar generates the off-line 354.7 nm light using a Nd/YAG laser operating at 16.5 Hz, while the JPL lidar uses stimulated Raman scattering in hydrogen to generate off-line 353 nm light. Backscattered on and off-line are detected by the lidars using telescopes. The ratio of the absorbed on-line signal to the scattered off-line signal is proportional to the number density of ozone in the atmosphere.

The NASA/Goddard Space Flight Center Stratospheric Ozone Lidar Trailer Experiment (STROZ LITE) participated in the stratospheric ozone measurement intercomparison campaigns in October-November 1988 and July-August 1989 at Table Mountain Observatory near Wrightwood, CA. As part of these campaigns ozone profiles between 20 and 35 obtained by the lidar were compared to profiles measured by Wallops Flight Facility electrochemical cell (ECC) sondes in Fall 1988 and Wallops and NOAA ECC sondes in Summer 1989.

In July, 1989, the Goddard Space Flight Center mobile stratospheric lidar was deployed at JPL's Table Mountain Facility in the San Gabriel Mountains east of Los Angeles (34.4N, 117.7W). The purpose was a major intercomparison of ozone sensors in order to validate the lidar technique as a reliable, accurate and precise instrument for the measurement of stratospheric ozone. The GSFC lidar data have also been used to extract a temperature profile between 30 and 65 km. The temperature retrieval utilizes the ozone profile reference wavelength (355 nm) which is essentially no absorption due to ozone. Because the retrieval is sensitive to aerosols, no attempt is made to extract temperature below 30 km.