A33A-0116 1340h
Tools and Data Services from the GSFC Earth Sciences DAAC for Aura Science Data Users
In these times of rapidly increasing amounts of archived data, tools and data services that manipulate data and uncover nuggets of information that potentially lead to scientific discovery are becoming more and more essential. While science research is becoming more specialized, the vast amounts of archived data are becoming more and more difficult to exploit. Thus, better tools and services are needed to quickly distinguish relevant signatures in the data and extract this information for further study. The Goddard Space Flight Center (GSFC) Earth Sciences (GES) Distributed Active Archive Center (DAAC) has made great strides in facilitating science and applications research by, in consultation with its users, developing innovative tools and data services. That is, as data users become more sophisticated in their research and more savvy with information extraction methodologies, the GES DAAC has been responsive to this evolution. This presentation addresses the tools and data services available and under study at the GES DAAC, applied to the Earth sciences atmospheric data. Now, with the data from NASA's latest Atmospheric Chemistry mission, Aura, being readied for public release, GES DAAC tools, proven successful for past atmospheric science missions such as MODIS, AIRS, TRMM, TOMS, and UARS, provide an excellent basis for similar tools updated for the data from the Aura instruments. GES DAAC resident Aura data sets are from the Microwave Limb Sounder (MLS), Ozone Monitoring Instrument (OMI), and High Resolution Dynamics Limb Sounder (HIRDLS). Data obtained by these instruments afford researchers the opportunity to acquire accurate and continuous atmospheric chemistry measurements. Tools and services, such as data access, subsetting, visualization and analysis, customized for Aura data, will facilitate the use and increase the usefulness of the new data. The Aura data, together with other heritage data at the GES DAAC, can potentially provide a long time series of data. GES DAAC tools will be discussed, as well as the GES DAAC Near Archive Data Mining (NADM) environment, the GIOVANNI on-line analysis tool, and rich data search and order services. The GES DAAC always strives to better understand the data access, usage, and manipulation needs of the audience, so that it can continue to be on the leading edge for user-focused data services. Any user feedback would be greatly appreciated. Additional information can be found at: http://daac.gsfc.nasa.gov/upperatm/aura/.
http://daac.gsfc.nasa.gov/upperatm/aura/
A33A-0117 1340h
Aura Atmospheric Data Products and Their Availability From NASA Goddard Earth Sciences DAAC
NASA's EOS-Aura spacecraft was launched successfully on July 15, 2004. The four instruments onboard the spacecraft are the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), the Tropospheric Emission Spectrometer(TES), and the High Resolution Dynamics Limb Sounder (HIRDLS). The Aura instruments are designed to gather earth sciences measurements across the ultraviolet, visible, infrared, thermal and microwave regions of the electromagnetic spectrum. Aura will provide over 70 distinct standard atmospheric data products for use in ozone layer and surface UV-B monitoring, air quality forecast, and atmospheric chemistry and climate change studies (http://eos-aura.gsfc.nasa.gov/). These products include earth-atmosphere radiances and solar spectral irradiances; total column, tropospheric, and profiles of ozone and other trace-gases, surface UV-B flux; clouds and aerosol characteristics; and temperature, geopotential height, and water vapor profiles. The MLS, OMI, and HIRDLS data products will be archived at the NASA Goddard Earth Sciences (GES) Distributed Active Archive Center (DAAC), while data from TES will be archived at NASA Langley Research Center DAAC. Some of the standard products which have gone through quick preliminary checks are already archived at the GES DAAC(http://daac.gsfc.nasa.gov/) and are available to the Aura science team and Aura data validation team members for data validation; and to the application and visualization software developers, for testing their application modules. Once data are corrected for obvious calibration problems and partially validated using in-situ observations, they would be made available to the broader user community. This presentation will provide details of the whole suite of Aura atmospheric data products, and the time line of the availability of the rest of the preliminary products and of the partially validated provisional products. Software and tools available for data access, visualization, and data mining will also be discussed. Details of the data access and data mining tools will be provided in another presentation (see J. Johnson et al. at this AGU meeting).
http://daac.gsfc.nasa.gov
A33A-0118 1340h
NASA Langley Atmospheric Sciences Data Center: The Source for TES Data
The NASA Langley Atmospheric Sciences Data Center (ASDC) is the archive and distribution center for data from the Tropospheric Emissions Spectrometer (TES) instrument. TES was launched into a sun-synchronous orbit aboard Aura, the third of NASA's Earth Observing System spacecraft, on July 15, 2004. The primary objective of TES is to make global, three-dimensional measurements of ozone and other chemical species involved in its formation and destruction. TES standard Level 2 data products will include global-scale vertical profile measurements of ozone, water vapor, carbon monoxide, methane, nitric oxide, nitrogen dioxide and nitric acid for 16 orbits every other day. Additional products include atmospheric temperature profiles, surface skin temperatures, and land surface emissivity. These data are planned for public release at the ASDC in late Summer, 2005. The TES instrument is a high-resolution imaging infrared Fourier-transform spectrometer that operates in both nadir and limb-sounding modes. In addition, special events can be monitored with the ability of TES to point at a specific location for a few minutes on any given orbit. This capability can be used for targets such as gas-emitting volcanoes, to support the study of volcanic emissions for hazard mitigation, indications of the chemical state of the magma, and eruption prediction. The ASDC provides data access, services and tools for over 35 projects in the discipline areas of Earth's radiation budget, clouds, aerosols and tropospheric chemistry. Additional information is available from our web site, http://eosweb.larc.nasa.gov
http://eosweb.larc.nasa.gov
A33A-0119 1340h
First retrievals of tropospheric ozone from the AURA TES experiment
We will show the initial retrievals of global tropospheric ozone together with available validations, intercomparisons and models.
http://tes.jpl.nasa.gov
A33A-0120 1340h
TES Measurement of CO
The Tropospheric Emission Spectrometer (TES) on-board Aura satellite makes measurements of atmospheric spectral radiance covering 4.7 band of CO in both nadir and limb modes. The quality of the radiance in this spectral region obtained from TES depends on the interfrometer alignment and some other factors. In this paper we will present the preliminary assessment on the CO spectra, the initial results of CO retrievals and characteristics, and limited comparisons with other observations.
A33A-0121 1340h
Radiometric and Frequency Calibration of TES Infrared Spectra
TES is an infrared Fourier transform spectrometer on board the Aura spacecraft. The first on-orbit interferograms were acquired August 20, 2004. We present the methods for producing calibrated radiance spectra and show initial results for atmospheric nadir and limb spectra. We will also show comparisons of TES nadir spectra to Aqua-AIRS spectra, where the AIRS data are taken on the same orbit path about 12 minutes before TES data are taken.
http://tes.jpl.nasa.gov/
A33A-0122 1340h
Initial measurements of column ozone by the Tropospheric Emission Spectrometer (TES)
We show early measurements of total ozone column measured by TES on the NASA Aura spacecraft and compare results to TOMS observations and model results. The TES total ozone column is calculated from retrieved TES profiles, with the column error calculated from the retrieved error covariance. We also highlight TES measurements of the tropospheric ozone column for different atmospheric conditions.
A33A-0123 1340h
First Comparison of TES Tropospheric Ozone Retrievals with Results from a Global 3-D CTM
The Tropospheric Emission Spectrometer (TES) onboard the Aura satellite will provide the first global profile measurements of tropospheric ozone and its photochemical precursors. We use the GEOS-CHEM global 3-D chemistry transport model to interpret the TES observations of tropospheric ozone. TES profile retrievals and computed tropospheric ozone columns from the global survey and special transect viewing modes during August-October 2004 are compared with model results for the same time period. The averaging kernels and a priori profile used in the retrievals are applied to the model simulated ozone profiles to allow direct comparison between the observations and model. We examine the consistency of the spatial and temporal variability of tropospheric ozone observed by TES with the model, focusing on the large-scale features such as the ozone maximum over the south Atlantic during September-October.
A33A-0124 1340h
Preliminary Validation of TES Nadir Retrievals for Tropospheric Ozone Using Ozonesonde Data from Ascension Island.
TES is one of four instruments on board the Aura spacecraft, launched on July 16, 2004. TES is an infrared Fourier transform spectrometer with a pointing system that allows staring at individual ground locations in the nadir view. The first spectra from TES were obtained in late August, and a special observation period in late September will focus on the south central Atlantic. Ozone mixing ratios in the upper troposphere are usually high at this time, because of transport of ozone formed from biomass burning in Africa. Ozonesondes will be launched several times a week from Ascension Island (8°S) during Aura overpasses in September, specifically for early validation studies of the TES nadir product. We will present the results of this validation, and discuss the capabilities of TES based on this work.
A33A-0125 1340h
Tropospheric Ozone Retrievals for TES Validations at the ARM sites
A fundamental objective of the Tropospheric Emission Spectrometer (TES) deployed on the AURA platform, is the production of global maps of tropospheric ozone. The retrieval of troposphere information is dependent on the fact that the line shapes in the stratosphere and troposphere are different: Doppler in the stratosphere and Lorentz in the troposphere. As a consequence, the radiometric information describing the distribution of ozone in the troposphere is located in the parts of the spectrum lying between the strong ozone lines. The retrieval of the tropospheric information from space-borne sensors is also highly susceptible to systematic errors due to the nature of the relevant inverse problem. Errors in the forward model, in the characterization of the instrument function, in the photometry of the measurement and in the background fields (e.g., temperature, water vapor and surface properties) can give rise to unacceptable errors in the retrieval. Therefore, the validation of the TES tropospheric ozone retrievals on a continuous basis is very desirable. Presented is an approach to continuously retrieve tropospheric ozone column amounts at the three DoE Atmospheric Radiation Measurement Climate Research Facility (ACRF) sites utilizing spectral downwelling radiation measurements from the Atmospheric Emittance Radiometric Interferometer (AERI). The ACRF sites instrumented with an AERI interferometer are: North Slope of Alaska (NSA), Southern Great Plains (SGP), and Tropical Western Pacific (TWP) on the island of Nauru. For these ground-based measurements, the radiation from the tropospheric ozone is not impeded by the stratospheric component. The retrieval is robust under conditions of clear sky and is also expected to be useful for validating TES retrievals under conditions of thin clouds, e.g. thin cirrus. Cloud statistics show that for TES overpasses the skies are either clear or have a thin cloud cover about 50% of the time, except for the TWP site. During normal TES global survey mode there will be 4 to 30 opportunities within each 16-day cycle for an AURA overpass of an ACRF site. In addition there are special TES observation surveys that approximately double the ARCF viewing. Following closely the maximum likelihood least squares retrieval method implemented by TES, preliminary tropospheric ozone column retrieval results are presented showing that two pieces of information: tropospheric ozone column amounts and improve profile information in the upper troposphere/lower stratosphere can be retrieved on a continuous basis at the SGP ACRF site. Future ozonesondes launches at the ACRF sites will also be used to simultaneously validate both the TES and AERI ozone retrievals.
A33A-0126 1340h
TES Ozone Retrievals, Error Covariances, and Vertical Resolution.
Initial ozone retrievals from the Tropospheric Emission Spectrometer are shown for selected regions representative of the northern mid-latitudes, southern mid-latitudes, and tropics. Estimated error covariances and vertical resolutions are reported for these regions. These estimated error covariances are compared to error estimates from the radiance residuals for the ensemble of retrievals reported in each region. Errors reported for ozone are seperated into contributions from temperuture and water, clouds, measurement noise, and spectroscopy.
A33A-0127 1340h
Usage of TES Data for Assimilation, Inverse Modeling and Intercomparison
The TES retrieval algorithm estimates an atmospheric profile by simultaneously minimizing the difference between observed and model spectral radiances subject to the constraint that the solution is consistent with an a priori mean and covariance. Consequently, the retrieved profile includes contributions from observations with random and systematic errors and from the prior. These contributions must be properly characterized in order to use TES retrievals in data assimilation, inverse modeling, averaging, and intercomparison with other measurements. All TES retrievals include measurement and systematic error covariances along with averaging kernel and a priori vector. We illustrate how to use these TES data with a couple of examples such as regional averaging, comparisons with sondes, and chemical transport models.
A33A-0128 1340h
Line Parameters for the TES Forward Model: Assessment of Their Validity from Preliminary TES Nadir Observations
The basis for the line parameters in the TES forward model is the HITRAN 2000 database with relevant updates available at the HITRAN website [Rothman et al., 2003]. Particularly significant among these updates has been the improvement of the water valor line parameters, e.g. Toth, 2000. A select and limited set of tested modifications have been implemented for TES. These or similar modifications are included in the beta version of HITRAN 2004. No changes in the TES forward model were possible after 1 July 2004 for reasons of forward model stability. This precluded the incorporation of the HITRAN 2004 release [Rothman et al., 2005],which will require a period for proper assessment. Since the retrieval of tropospheric ozone is a key objective of TES, it is of critical importance that the ozone line parameters be as accurate and internally self consistent as possible, especially with respect to line widths for tropospheric retrievals. The ozone line parameters selected for TES are those developed for MIPAS [Wagner et al., 2002]. Selected enhancements for CO and CH4 have been provided by L.R. Brown [Rothman et al., 2005]. The HNO3 line parameters in the current version of the TES database will be replaced by improved parameters before HNO3 profiles retrieved from TES limb spectra are released. Assessment of the line parameters has been accomplished by analyzing validation cases from HIS (High-resolution Interferometer Sounder; U. of Wisc.), AERI (Atmospheric Emitted Radiance Interferometer, U. of Wisc.) and AIRS (Atmospheric InfraRed Sounder, NASA) atmospheric observations. Results from these validations and preliminary comparisons with TES spectral radiances will be presented. Issues with the CO2 line parameters will be discussed. The TES line parameter files are publicly available at http://rtweb.aer.com/ Clough SA, Shephard MW, Mlawer EJ, Delamere JS, Iacono MJ, Cady-Pereira K, Boukabara S, Brown PD. Atmospheric radiative transfer modeling: a summary of the AER codes, J. Quant. Spectrosc. and Radiat Transfer, In Press, Corrected Proof, Available online 28 July 2004. Rothman, L.S., et al., The HITRAN 2004 Molecular Spectroscopic Database, Accepted, J. Quant. Spectrosc. Radiat .Transfer, 2005. Rothman, L.S., et al., The HITRAN Molecular Spectroscopic Database: Edition of 2000 Including Updates through 2001. J. Quant. Spectrosc. Radiat. Transfer, 82: 5-44, 2003. Toth, R.A., Air- and N-2-Broadening parameters of water vapor: 604 to 2271 cm(-1), J. Mol. Spectrosc., 201 (2): 218-243, 2000. Wagner G, Birk M, Schreier F, Flaud JM. Spectroscopic database for ozone in the fundamental spectral regions. J. Geophys. Res., 107, D22, 4626 doi: 10:1029/2001JD000818, 2002.
A33A-0129 1340h
Quality Assurance of TES Data for Initial Observations
TES is one of four instruments on board the Aura spacecraft, launched on July 16, 2004. TES is an infrared Fourier transform spectrometer with a pointing system that allows staring at individual ground locations in the nadir view. The first spectra from TES were obtained in late August, and a special observation period in September will focus on the south central Atlantic. Data quality of these observations is analyzed with respect to several parameters determined from level 2 processing. Data quality parameters include retrieval success, residuals, chi-square (residuals normalized to NESR), number of degrees of freedom of data and number of degrees of freedom of noise. We will present and discuss initial data quality information from these observations.
A33A-0130 1340h
Implementation of Cloud Retrievals for Tropospheric Emission Spectrometer (TES) Atmospheric Retrievals
We have implemented an algorithm for the Tropospheric Emission Spectrometer (TES) that retrieves the altitude and optical depth of a frequency-dependent single-layer cloud. TES retrievals with this implementation using a simulated dataset succeed for targets containing a wide range of optical depths and cloud altitudes. TES retrievals with actual instrument data have markedly higher success rates with this approach. Additionally, this cloud retrieval approach makes possible the retrieval and error characterization of atmospheric parameters like temperature, water, and ozone, in the presence of clouds.
A33A-0131 1340h
OMI-EOS Research Programme at the Finnish Meteorological Institute: UV, Validation, Very Fast Delivery and Ozone Profiles from Occultation Instruments
For the OMI-EOS instrument on EOS-Aura, Finnish industry, led by the Finnish Meteorological Institute (FMI), has provided the Electronics Unit as well as the Detector Modules. In the operational phase of the mission, FMI will conduct its research on OMI data in close collaboration with KNMI, NASA and other members of the International OMI Science Team. The specific contributions from Finland are the UV product, with heritage from the TOMS UV product, the Direct Broadcast receiving and processing to Very Fast Delivery products in Sodankyl\"{a} (68 degrees North, 25 degrees East) as well as combining the OMI data with GOMOS data from ENVISAT, OSIRIS from Odin spacecraft, and active participation in the OMI validation programme. The FMI science team has participated in the improvement of the TOMS UV product at high latitudes in collaboration with NASA/GSFC. The most important contribution is a new surface albedo climatology to be used in generating the OMI UV product. In addition, input sanity check and quality flagging routines have been implemented in the UV algorithm. In addition to providing an improved algorithm for UV processing, FMI will also process and archive the global UV product during the Aura mission. The Arctic Research Centre of FMI has launched ozone-sounding balloons since 1988, and developed research infrastructure for supporting validation campaigns. Earlier campaigns have included ozone soundings, water vapour soundings, aerosol soundings and column ozone measurements from Brewer and SAOZ spectrometers. These facilities will be used in Aura validation, with special emphasis on validating the FMI-generated OMI UV product with ground data and comparisons with TOMS UV product. The FMI Team is also active in two profiling instruments: GOMOS and OSIRIS. After the launch of OMI we have a unique opportunity to combine OMI total column data with the profile information obtained from those missions. Assimilation methods are being developed to join those data for research use. In this presentation we discuss the elements and readiness of the FMI programme.
A33A-0132 1340h
Evaluation of OMI Pre-launch Radiometric Calibration Using In-flight Data
The Ozone Monitoring Instrument (OMI) launched aboard the EOS Aura satellite on 15 July 2004 is intended as the successor to the Total Ozone Mapping Spectrometer (TOMS) operated by NASA over the past 25 years. OMI uses hyperspectral sensors, has improved horizontal resolution, and an expanded wavelength range (270-500 nm). Thus its capabilities extend well beyond those of TOMS. In addition to the traditional TOMS products (column ozone, surface reflectance, aerosol index, UV surface flux), OMI will generate multiple additional products (ozone profile and tropospheric column; trace gases important to ozone chemistry and air quality; cloud fraction and height) using for some the spectroscopic structure of the backscattered Earth radiances. Calibration requirements for spectroscopy differ significantly from those for TOMS-like products, yet all must be met in order to achieve the expected data product quality. We use both traditional engineering (``hard'') and science data-based (``soft'') calibration techniques to assess OMI's initial on-orbit performance and evaluate the accuracy of its pre-launch calibration. Several techniques have been developed over the years to assess the calibration accuracy of backscatter ultraviolet sensors. Among these are comparisons with solar irradiance reference spectra and radiances measured over Antarctica and Greenland. Retrieved reflectances over the open ocean and cloud tops, and radiance residuals from column ozone retrievals also provide verification of radiometric calibrations. We present initial results of these verifications, which we use to evaluate the accuracy of the radiometric calibration provided at launch. We also assess the impact of observed calibration errors on the various OMI products, realizing that these errors will decrease as the OMI calibration is refined.
A33A-0133 1340h
An Initial Application of Internal Validation and Soft Calibration Techniques To Preliminary OMI Total Ozone Data
Internal validation and soft calibration techniques were previously developed and successfully used to help assess and correct the absolute and long-term calibrations of TOMS and SBUV instruments. Improvements in the new Version 8 total ozone retrieval algorithm allowed these techniques to be further refined and expanded. A key objective of the OMI instrument is to extend the long-term global ozone record previously provided by TOMS. OMI is a significantly more complex instrument and it is important to test the applicability of these internal calibration and validation techniques to this hyperspectral instrument. Here we report on the application of some of these techniques to initial OMI data at selected wavelengths corresponding to the TOMS discrete wavelengths. Application of the techniques to "First Light" OMI data revealed absolute calibration errors that are consistent with expected errors in the preliminary prelaunch calibration. These results suggest that the internal calibration/validation techniques can indeed be successfully applied to OMI. Thus, these results were used to develop calibration corrections that were then used to reprocess the first OMI data and produce near real-time images of the 2004 Antarctic Ozone Hole.
A33A-0134 1340h
The Antarctic Ozone Hole: Initial Results Fom Aura/OMI Compared with TOMS
A series of TOMS instruments (on Nimbus 7, Meteor 3, and Earth Probe) has been monitoring the annual development of the Antarctic ozone hole since the 1980s. The ozone mapping instrument on Aura, OMI, is expected to take over this record of observation from the aging Earth Probe TOMS instrument. The area of the ozone hole can be taken as a sensitive indicator of the magnitude of ozone destruction each year. The timing of initial formation of the ozone hole and its duration are sensitive to the atmospheric dynamics of the southern polar regions. The entire TOMS data record (1978 - 2004) has recently been reprocessed with the new version 8 algorithm, which includes a revised calibration. The effect has been to slightly increase ozone hole area over earlier estimates, but only by 2-4%. OMI (Ozone Monitoring Instrument) on Aura is a hyperspectral imaging instrument that operates in a pushbroom mode to measure solar backscattered radiation in the ultraviolet and visible. OMI has higher spatial resolution than TOMS - 14 x 24 km versus 38 km x 38 km for TOMS. OMI has now begun mapping total column ozone on a global basis in a measurement similar to TOMS. The ozone hole measurements for 2004 are compared with those from Earth Probe TOMS.
A33A-0135 1340h
First OMI In-Flight Performance and Calibration Results
The OMI instrument was launched on board of the EOS AURA satellite on 15 July 2004 and the first in-flight measurement results look very promising. This presentation discusses the first results of the performance and calibration evaluation. Besides Earth measurements, the OMI instrument also regularly performs dark, internal LED and white light source, and solar measurements. These measurements are used to assess the in-flight performance and calibration, and their time stability. The in-flight measurements enable investigations on detector and electronics, radiometric calibration, stray light, wavelength calibration, geolocation calibration. First results are presented and discussed. The interface to the 0-1 data processing is also discussed.
A33A-0136 1340h
First Global Maps of Stratospheric and Tropospheric NO$_{2}$ from OMI
The Ozone Monitoring Instrument (OMI) was launched successfully in July 2004, as one of four instruments on the EOS Aura satellite. OMI is an imaging spectrometer with a small pixel size (13km x 24km to 13km x 128km). The instrument's swath width and sun-synchronous orbit gives full global, high-resolution coverage every 24 hours. OMI-measured radiances are used to retrieve column densities of critical trace gases, including formaldehyde, BrO, SO$_{2}$ and NO$_{2}$. In addition, OMI measures aerosol optical properties and cloud fraction and height. We present the first results from the OMI operational NO$_{2}$ algorithm and demonstrate its ability to retrieve the tropospheric and stratospheric components of NO$_{2}$. The DOAS method is used to determine slant column densities, and initial air mass factors are used to give initial estimates of the vertical column densities. Vertical column densities from up to 15 consecutive orbits are collected, and a spatial filtering technique is applied to extract the synoptic-scale features characteristic of the stratospheric field. We take smaller-scale features to be evidence of tropospheric excess NO$_{2}$, and apply an air mass factor appropriate to polluted conditions, to obtain an improved retrieval of the NO$_{2}$ total vertical column density. We describe the assumptions underlying the algorithm in detail, and show global maps of NO$_{2}$ vertical column densities, based on the first operational data from OMI.
A33A-0137 1340h
First Look at the SO$_2$ Index Calculated from OMI Observations
We have applied the TOMS total ozone algorithm to the UV spectral radiance measurements from the Ozone Monitoring Instrument (OMI) onboard the recently launched EOS Aura spacecraft. In the UV2 channel (306-370 nm) OMI makes daily global hyper-spectral (spectral resolution of 0.45 nm, and spectral sampling of 0.15 nm/pixel) radiance measurements with a nadir resolution of 13 km x 24 km. Residuals in the UV2 spectral region are calculated as the difference between the measured and the computed theoretical radiances that account for the effects of ozone, Ring, and surface reflectivity. Analysis of these residuals is very useful in detecting instrument artifacts and calibration errors as well as unusual atmospheric conditions. Sulfur dioxide (SO$_2$) has a strong absorption in the wavelength range 306-340 nm. Residuals in this wavelength range show distinctive features if a significant amount of SO$_2$ is present in the atmosphere, such as in the case of volcanic clouds or air pollution. However, SO$_2$ is absent over most of the Earth and residuals are sensitive diagnostics of instrument performance. For this study, we will show maps of SO$_2$ index, defined as the residual differences at a pair of wavelengths, like 311.85 nm and 313.2 nm, which have large differential sensitivity to the SO$_2$ absorption.
A33A-0138 1340h
Spatial Stray Light for the Ozone Monitoring Instrument (OMI) Onboard Aura
OMI is a Dutch-Finnish imaging spectrograph onboard NASA's Aura mission, launched on 15 July of this year. Its wavelength range is from 270 nm to 500 nm. The imaging property of the CCD detectors is used to obtain simultaneous spectra over a 2600 km swath perpendicular to the satellite's path. These measurements will provide daily global coverage of a number of atmospheric gases, continuing and extending the measurements of such missions as UARS, ERS-1, ERS-2, Envisat, and the TOMS flights. Preflight measurements indicate that the spatial stray light fraction (i.e. light scattered in the cross-path direction, outside the line-spread-function) is in the range of 2-5%, depending on wavelength and incident light direction, and will need correction in order to meet the scientific goals of the instrument. The work reported here will present detailed characterization of the stray light and an algorithm for correcting for spatial stray light. Examples and estimates of the accuracy of the correction will be given.
A33A-0139 1340h
An Initial Comparison of Ozone Monitoring Instrument (OMI) Total Ozone with EP/TOMS, SBUV/2, and Ground Stations
The Ozone Monitoring Instrument (OMI) onboard the Aura spacecraft is measuring total column ozone at high spatial resolution. Initial measurements from OMI with a preliminary calibration are used to derive TOMS-like total ozone using only 4 wavelengths (312nm, 318nm, 331nm, 360nm) from OMI's UV2 channel. These OMI total ozone measurements are compared to ozone values from Earth-Probe TOMS (EP/TOMS), SBUV/2, and an ensemble of ground stations. The Aura spacecraft has an equator crossing time of approximately 1:50 pm and a field of view (FOV) of 13km x 24km square while EP/TOMS has a larger FOV ranging from 40 to 100km depending on the scan position and an equator crossing time of approximately 10:50 am. NOAA-16 SBUV/2 has an equator crossing time of approximately 2:00 p.m which is much closer to that of OMI but the field of view is 190 km square. Differences are analyzed as a function of latitude, solar zenith angle, total ozone, aerosol index, and reflectivity.
A33A-0140 1340h
Assimilation of Aura Ozone Data
This paper will present initial results from assimilating ozone data from Aura instruments into an existing ozone assimilation system at NASA's Global Modeling and Assimilation Office (GMAO). The assimilation includes total column ozone data together with stratospheric ozone profiles. These various data types are combined with a model forecast. The model includes parameterized chemistry modules for tropospheric and stratospheric ozone, including a simple "cold tracer" parameterization for heterogeneous processes that lead to ozone depletion. Resolved and sub-grid-scale transport are determined in the general circulation model (GCM) that is constrained by the GMAO's meteorological analyses. The assimilation system is being modified to include ozone data from EOS Aura instruments, either in place of or alongside other data. In the complete Aura configuration we plan to use all available OMI, MLS, HIRDLS, and possibly TES data. In reaching this system, intermediate steps will be taken, introducing one Aura ozone dataset at a time. The first step is likely to be using OMI in place of SBUV total ozone columns. The assimilated ozone fields will provide estimates of the global ozone distribution, including the lower stratosphere and the troposphere regions, where accurate estimates have been hard to obtain from data preceding EOS Aura. During the assimilation process, differences between ozone observations and the GCM forecasts are computed; these will be monitored to evaluate error characteristics of Aura ozone data. Assimilated Aura ozone data can be used in the GCM's radiation computations as an initial guess for the ozone distribution in the assimilation of infrared nadir radiance data from NASA's AIRS (Advanced Infrared Sounder) instrument. Both of these applications can have an impact on the skill of numerical weather forecasts, which will be investigated.
http://gmao.gsfc.nasa.gov/research/ozone/
A33A-0141 1340h
First daily global measurements of middle-atmosphere HCN
The MLS instrument on Aura has made the first daily global measurements of the mixing ratio Hydrogen Cyanide. The signal from this molecule is not large but permits the retrieval of a daily zonal mean between 10 and 0.1mb and a weekly zonal mean over a somewhat greater vertical range. We describe the nature of the measurements and the technique employed in the retrieval process. The first three months of data are presented and compared with previous measurements of HCN.
A33A-0142 1340h
Mesospheric CO Measured by Aura MLS
Carbon monoxide (CO) is a excellent tracer of dynamical processes in the mesosphere, especially in the winter polar region. EOS Aura's Microwave Limb Sounder (MLS) measurements of mesospheric / upper stratospheric CO are the first from satellite in over a decade. Preliminary results from the first 3 months of operation are presented and compared with previous ground-based and satellite-based measurements.
A33A-0143 1340h
First Results of Aura MLS Cloud Measurements: Data Analysis and Comparison With Other Satellite Measurements and Meteorological Data
We will present preliminary results of Aura MLS cloud radiance and cloud ice water content measurements, including a global morphology of cloud occurrence frequency derived from the first three months of Aura in orbit. Initial data from MLS during August 2004 is well correlated with GMAO OLR field in the tropics, and with cloud features in AIRS radiances. Data from the first three months of MLS observations will be compared to other satellite and meteorological data sets (e.g. AIRS, GMAO). Updated results and interpretations will be presented at the meeting.
A33A-0144 1340h
Initial Results of Gravity Wave Observations from Aura MLS
Microwave radiances can be used to measure the atmospheric temperature perturbations induced by gravity waves (GWs). Initial results from Aura MLS (Microwave Limb Sounder) show that the 118-GHz radiances have good sensitivity to GW-scale perturbations in the stratosphere and lower mesosphere. The zonal mean morphology of GW variance observed by Aura MLS is consistent with those previously reported with UARS (Upper Atmosphere Research Satellite) MLS. Different from UARS MLS, Aura MLS scans in the forward direction within the orbital plane. Because the satellite is on a polar orbit, Aura MLS is mainly sensitive to wave components propagating in the meridional direction, and quantitative estimates of southward/northward propagating waves can be obtained from separate ascending and descending measurements. In this paper we will also study MLS visibility function for temperature perturbations at various vertical and horizontal scales.
A33A-0145 1340h
Polarized Radiative Transfer Simulations of EOS-MLS Radiances in Cloudy Cases, and Their Comparison With Initial Data
We present a series of 3D polarized radiative transfer simulations made with recently developed Reversed Monte Carlo, and Discrete Ordinate Iterative radiative transfer algorithms, which are part of the ARTS-1.1.x software package. The software allows the study of the effect of horizontally aligned non-spherical ice crystals on EOS-MLS radiances. Simulation results will be presented, indicating features we should see from EOS-MLS radiances for various cloud scenarios. These will be compared with the initial data from the EOS-MLS instrument, and consequences for the retrieval of cloud information will be discussed.
A33A-0146 1340h
A First View of Temperature Fields form the Microwave Limb Sounder on Aura
A second-generation Microwave Limb Sounder (MLS) was launched in July of 2004 as a part of the Earth Observing System (EOS) Aura satellite. This instrument provides temperature fields co-located with atmospheric composition measurements from the upper troposphere through the mesosphere. In this poster we give an overview of the MLS temperature measurements from the first months of EOS Aura Observations. Of particular interest is the 3-dimensional evolution of temperatures in the Antarctic polar vortex during the late winter and spring final warming, including the evolution of temperatures in the lower stratosphere associated with polar processing, and planetary wave evolution during vortex breakup.
http://mls.jpl.nasa.gov
A33A-0147 1340h
A preliminary comparison of Aura MLS upper tropospheric humidity measurements with AIRS.
MLS on the Aura spacecraft was launched 15 July 2004 and began science operations on 12 August 2004. The Aura satellite flies 15 minutes behind the Aqua satellite which contains the AIRS instrument. The close proximity of these measurements provides a continuous stream of near coincident upper tropospheric humidity profile measurements for validation and comparison. We will show some preliminary results from these comparisons for the first three months of Aura MLS humidity data.
A33A-0148 1340h
Forward Modeling of HIRDLS Channel Radiances for Operational Retrievals
We describe the radiative transfer modeling developed for the High Resolution Dynamics Limb Sounder (HIRDLS) instrument aboard the NASA EOS-Aura satellite. HIRDLS is a 21-channel radiometer operating in the spectral region between 6 and 18 microns. Situated in a high-inclination orbit which provides global sampling, HIRDLS is designed to rapidly measure limb emission at tangent heights from the troposphere into the mesosphere. Science products will include profiles of temperature and chemical constituents, as well as aerosol estimates, the location of polar stratospheric clouds, and geopotential height gradients. A forward model must accurately and quickly estimate transmittances and channel radiances for use in the operational retrievals. The forward model must take into account the presence of many target and interfering gases, a wide range of atmospheric and radiative states, and requirements on the accuracy and precision of the retrieved science data. We describe techniques developed to address these issues. These collectively define the HIRDLS forward model hierarchy, which provides an effective solution to the requirement for fast and accurate radiative transfer modeling for operational use.
A33A-0149 1340h
Retrieval of Atmospheric Profiles of Temperature and Trace Species from the High Resolution Dynamics Limb Sounder (HIRDLS)
Retrieval algorithms for the High Resolution Dynamics Limb Sounder (HIRDLS) will be presented. HIRDLS is a 21-channel infrared limb sounder with a vertical resolution of 1-km and a twice per day global coverage achieved with a horizontal sampling of 5 by 5 degrees in latitude and longitude and an altitude coverage from the upper troposphere to the mesosphere. Detailed simulations of the HIRDLS measurement and retrieval process will be compared to the on-orbit performance and the quality of the Level-2 data products for a selection of the measured species (Temperature, O3, H2O, CH4, N2O, NO2, N2O5, HNO3, ClONO2, CFC11, CFC12, aerosols and cloud top height) will be shown.
http://www.eos.ucar.edu/hirdls/
A33A-0150 1340h
The High Resolution Dynamics Limb Sounder (HIRDLS) Validation Status
HIRDLS is an infrared limb-scanning radiometer, which was launched on the Aura spacecraft 15 July 2004. HIRDLS is designed to sound the upper troposphere, stratosphere, and mesosphere to determine temperature; the concentrations of O3, H2O, CH4, N2O, NO2, HNO3, N2O5, ClONO2, CFC11, CFC12, and aerosols; and the locations of polar stratospheric clouds and cloud tops. The HIRDLS instrument was designed to obtain global distributions of constituents with horizontal and vertical resolution superior to that previously measured. The vertical resolution is approximately 1.2 km. The horizontal resolution is tunable depending on science and validation needs. Typical scan modes have a 5 x 5 degrees global coverage over a 12-hour period. This presentation will give an overview of the validation status of each HIRDLS data product with correlative data from ground based, sondes, aircraft, and other satellite instruments. Specific comparisons between HIRDLS and the Houston October/November 2004 Aura Validation Experiment (AVE) will be shown. In addition, cross comparisons between HIRDLS and the other Aura instruments (i.e., MLS, TES, and OMI), along with available occultation and other limb viewing instruments will be shown.