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NASA NTRS1994

Improvements to TOVS retrievals over sea ice and applications to estimating Arctic energy fluxes

Modeling studies suggest that polar regions play a major role in modulating the Earth's climate and that they may be more sensitive than lower latitudes to climate change. Until recently, however, data from meteorological stations poleward of 70 degs have been sparse, and consequently, our understanding of air-sea-ice interaction processes is relatively poor. Satellite-borne sensors now offer a promising opportunity to observe polar regions and ultimately to improve parameterizations of energy transfer processes in climate models. This study focuses on the application of the TIROS-N operational vertical sounder (TOVS) to sea-ice-covered regions in the nonmelt season. TOVS radiances are processed with the improved initialization inversion ('3I') algorithm, providng estimates of layer-average temperature and moisture, cloud conditions, and surface characteristics at a horizontal resolution of approximately 100 km x 100 km. Although TOVS has flown continuously on polar-orbiting satellites since 1978, its potential has not been realized in high latitudes because the quality of retrievals is often significantly lower over sea ice and snow than over the surfaces. The recent availability of three Arctic data sets has provided an opportunity to validate TOVS retrievals: the first from the Coordinated Eastern Arctic Experiment (CEAREX) in winter 1988/1989, the second from the LeadEx field program in spring 1992, and the third from Russian drifting ice stations. Comparisons with these data reveal deficiencies in TOVS retrievals over sea ice during the cold season; e.g., ice surface temperature is often 5 to 15 K too warm, microwave emissivity is approximately 15% too low at large view angles, clear/cloudy scenes are sometimes misidentified, and low-level inversions are often not captured. In this study, methods to reduce these errors are investigated. Improvements to the ice surface temperature retrieval have reduced rms errors from approximately 7 K to 3 K; correction of microwaves (50 GHz) brightness temperatures for view angle dependence now allows the surface type (open water versus sea ice) to be determined; modifications to the clear/cloud tests have improved cloud detection over sea ice, especially where it is inhomogeneous; and improved surface temperature estimates have resulted in more successful diagnoses of low-level stratification. Applications of improved retrievals to studies of the Arctic energy budget are encouraging. Preliminary calculations of air-ice stress vectors, 10-m wind speed, and horizontal advection of heat and moisture are presented.

Francis, Jennifer A.↗

NASA NTRS2010

Interannual Variability of Ozone in the Winter Lower Stratosphere and the Relationship to Lamina and Irreversible Transport

We use the high-resolution dynamic limb sounder (HIRDLS) high-vertical resolution ozone profiles in the northern hemisphere lower stratosphere to examine the meridional transport out of the tropics. We focus on February 2005.2007 when there are differences in the dynamical background in the lower stratosphere due to the states of the quasibiennial oscillation and polar vortex. HIRDLS data reveal a large number of low ozone laminae that have the characteristics of tropical air at midlatitudes. More laminae are observed in February in 2006 than in 2005 or 2007. Because laminae can form, move out of the tropics, and return to the tropics without mixing into the midlatitude ozone field, the number of laminae is not directly related to the net transport. We use equivalent latitude coordinates to discriminate between reversible and irreversible laminar transport. The equivalent latitude analysis shows greater irreversible transport between the tropics and lower midlatitudes in both 2005 and 2007 compared to 2006 despite the higher number of laminae observed in 2006. Our conclusion that there was more irreversible transport of tropical air into the lower midlatitudes in 2005 and 2007 is supported by equivalent length analysis of mixing using microwave limb sounder N2O measurements. This study shows that reversibility must be considered in order to infer the importance of lamination to net transport.

Olsen, Mark A.↗

NASA NTRS1981

Passive optical and infrared meteorology

Applications of passive visible and infrared techniques to the study of meteorological parameters are presented. For the remote sensing of temperature and humidity profiles, infrared sounder improvements have proceeded with the narrow band-pass channels approach, and the partially scanned interferogram approach. Current and planned infrared and microwave sea-surface temperature sounders have an expected accuracy of approximately 2 K, and this can be improved by using three super window channels from the 3.7 micron window region, with narrow band passes away from principal water vapor absorption lines. Cloud data remote sensing is currently performed from satellites, and these visible and infrared images have been used to track weather patterns. In addition, a passive infrared correlation-spectroscopy technique has been proposed for wind measurements. Finally, these techniques have also been applied to monitor such parameters as the Solar Constant, aerosols, and minor gas constituents.

Chahine, M. T.↗

NASA NTRSDate not supplied

International Satellite Cloud Climatology Project (ISCCP) Stage D2 Monthly Cloud Product - Revised Algorithm in Hierarchical Data Format (ISCCP_D2)

Since 1983 an international group of institutions has collected and analyzed satellite radiance measurements from up to five geostationary and two polar orbiting satellites to infer the global distribution of cloud properties and their diurnal, seasonal and interannual variations. The primary focus of the first phase of the project (1983-1995) was the elucidation of the role of clouds in the radiation budget (top of the atmosphere and surface). In the second phase of the project (1995 onwards) the analysis also concerns improving understanding of clouds in the global hydrological cycle. [Location=TROPOSPHERE] [Temporal_Coverage: Start_Date=1983-07-01; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=280 Km; Longitude_Resolution=280 Km; Temporal_Resolution=Monthly].

CLOUD TOP PRESSURE↗

NASA NTRS2008

1D-VAR Retrieval Using Superchannels

Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.

Liu, Xu↗

NASA NTRS2006

Atmospheric Infrared Sounder (AIRS) Project Status

This viewgraph presentation reviews the status of the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU). These instruments are on board the EOS Aqua Spacecraft that was launched May 4, 2002. The instruments are working normally. The objectives of the mission were to improve weather forecasting, assist in climate studies, and provide information as to the composition of Earth's atmosphere. The Aqua spacecraft is operating normally, the the primary life-limiting resource is fuel for maneuvers. The presentation also contains charts indicating who are using the data. There is information on the type of data available, and the propsal process. Also there is a few views of some of the planned instruments that were made possible in part due to the success of AIRS.

science team↗

NASA NTRS2015

Retrieved Products from Simulated Hyperspectral Observations of a Hurricane

This research uses GCM derived products, with 1 km spatial resolution and sampled every 10 minutes, over a moving area following the track of a simulated severe Atlantic storm. Model products were aggregated over sounder footprints corresponding to 13 km in LEO, 2 km in LEO, and 5 km in GEO sampled every 72 minutes. We simulated radiances for instruments with AIRS-like spectral coverage, spectral resolution, and channel noise, using these aggregated products as the truth, and analyzed them using a slightly modified version of the operational AIRS Version-6 retrieval algorithm. Accuracy of retrievals obtained using simulated AIRS radiances with a 13 km footprint was similar to that obtained using real AIRS data. Spatial coverage and accuracy of retrievals are shown for all three sounding scenarios. The research demonstrates the potential significance of flying Advanced AIRS-like instruments on future LEO and GEO missions.

AIRS↗

NASA NTRS2003

AIRS Level 2 Status

The Atmospheric Infrared Sounder (AIRS) is a facility instrument onboard EOS Aqua. Major level 2 products are highlighted including temperature profile; water vapor profile; surface skin temperature and other surface parameters; and, cloud friction and top cloud pressure. Level 2 files and data availability are discussed.

AIRS↗

NASA NTRS2012

Improving the Automatic Inversion of Digital Alouette/ISIS Ionogram Reflection Traces into Topside Electron Density Profiles

The topside sounders of the International Satellites for Ionospheric Studies (ISIS) program were designed as analog systems. The resulting ionograms were displayed on 35 mm film for analysis by visual inspection. Each of these satellites, launched between 1962 and 1971, produced data for 10 to 20 years. A number of the original telemetry tapes from this large data set have been converted directly into digital records. Software, known as the Topside Ionogram Scalar With True-Height (TOPIST) algorithm, has been produced and used for the automatic inversion of the ionogram reflection traces on more than 100,000 ISIS-2 digital topside ionograms into topside vertical electron density profiles Ne(h). Here we present some topside ionospheric solar cycle variations deduced from the TOPIST database to illustrate the scientific benefit of improving and expanding the topside ionospheric Ne(h) database. The profile improvements will be based on improvements in the TOPIST software motivated by direct comparisons between TOPIST profiles and profiles produced by manual scaling in the early days of the ISIS program. The database expansion will be based on new software designed to overcome limitations in the original digital topside ionogram database caused by difficulties encountered during the analog-to-digital conversion process in the detection of the ionogram frame sync pulse and/or the frequency markers. This improved and expanded TOPIST topside Ne(h) database will greatly enhance investigations into both short- and long-term ionospheric changes, e.g., the observed topside ionospheric responses to magnetic storms, induced by interplanetary magnetic clouds, and solar cycle variations, respectively.

Benson, Robert F.↗

NASA NTRS2019

Implementing Polar Projections with OGC Services for the Enhancement of AIRS NRT Visualization in LANCE

The Atmospheric Infrared Sounder (AIRS) NRT product is one important element in the Land, Atmosphere Near real-time Capability for EOS (LANCE). The LANCE processing of AIRS NRT products and the image generation are performed at the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). The Open Geospatial Consortium (OGC) services are being utilized to access AIRS NRT images. The ongoing AIRS NRT imagery enhancement work includes adding a new set of the images in polar projections. Polar projections are commonly used for mapping Antarctica and Arctic regions. We have implemented more precise south polar (EPSG:3031) projection and north polar (EPSG:3413) projection making our OGC service instances more useful and interoperable. Thus, AIRS NRT data can be easily accessed and integrated with other applications. It greatly increases the impact of our data on researches in polar regions.In this presentation, we will introduce the optimized processing workflow for OGC services from data access with spatial-temporal index to data visualization with different SLD, and demonstrate how to use open source software to provide more precise map images in polar projections.

Zhao, Peisheng↗

NASA NTRSDate not supplied

Synergy of Satellite Radiation, Precipitation, and Other Meteorological Variable Observations for Global Mean Sea Surface Turbulent Heat Flux Estimation

Sea surface turbulent heat flux is one of the key components in global freshwater and energy balances and plays an important role in atmospheric dynamics, thermodynamics and general circulation. This turbulent heat flux is dominantly decided by sea surface latent heat release with some contribution from sensible heat exchange. The flux and its anomaly could significantly affect ocean heat storage and ocean circulation. They are part of and have great impacts on climate variability. Though the turbulent heat flux is extremely important for the climate and weather systems, only very limited ship and buoy observations of the flux are available over open oceans. There are no global, operational, direct measurements of this crucial meteorological variable. Global estimates are, basically, indirectly calculated from bulk turbulent flux parameterization with a combination of satellite column water vapor, sea surface water temperature, and wind speed observations. Critical parameters such as sea surface air temperature and humidity are estimated from empirical relations of theses variables with the water vapor and sea surface water temperature, respectively. Lacking accurate knowledge on surface air temperature and humidity, uncertainties in the parameterization and potential changes in the non-linear turbulent processes with long-term climate variations could cause large errors in estimated long-term turbulent fluxes from the indirect method as shown in current global sea surface turbulent flux datasets. This study uses synergized data of satellite global radiation, precipitation, and other meteorological variable observations to estimate sea surface turbulent heat fluxes. The radiation observations are made by the satellite Clouds and the Earth’s Radiant Energy System (CERES) sensors, while the global precipitation data is from NASA’s satellite Global Precipitation Climatology Project (GPCP). Other data includes satellite sea surface water temperature and wind speed observations. These datasets are obtained from a wide range of space sensors from passive to active instruments and from visible and near infrared to thermal infrared and microwave spectral sounders. One significant feature of these datasets is that they have multi-decades long climate records. Top-of-atmosphere (TOA) radiation and its anomaly represents the net heat energy input to the climate system, and the oceanic precipitation and ocean-land moisture transport can be used to quantify sea surface latent heat release. Based on the synergized datasets and the principle of global water and energy balances, global mean turbulent heat fluxes are estimated. The turbulent heat anomalies for the first two decades of the 21st century are, then, obtained mainly from global CERES radiation and GPCP precipitation anomalies, along with CERES derived ocean-land heat transports. Analysis indicates that the uncertainties in the estimated turbulent flux anomalies may be reduced considerably. The results suggest a strong needs in synchronized and synergized observations of atmospheric radiation, precipitation, and oceanic meteorological variables for long-term climate studies.

Bing Lin↗

NASA NTRS2018

GES DISC Long-Term Data Analysis Services Using AIRS and CMS Methane Data as an Example

NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) archives and distributes rich collections of data on atmospheric greenhouse gases from multiple satellite missions and model results. Among those greenhouse gases, atmospheric methane is a powerful greenhouse gas contributing ~0.5 (W/m^2) to total radiative forcing, and its concentration has increased by about 150% since 1750. Observations or estimates of methane emissions typically have sparse spatial and temporal coverage. The lack of comprehensive spatial and temporal coverage of methane source and sink observations has made analyzing atmospheric methane trends challenging. In this study the GES DISC aims to provide the community with the resources to better understand changes in atmospheric methane concentrations and the underlying causes. We will utilize methane datasets from Atmospheric Infrared Sounder (AIRS) retrieved methane concentration and three Carbon Monitoring System (CMS) methane emission datasets (in regions of North America, Canada, and Mexico) to compare AIRS methane growth with corresponding CMS regional methane emissions. Comparisons of AIRS methane growth rates and CMS methane emissions suggests wetland emissions may impact methane growth rate trends over North America. As the record for CMS methane data is extended, both datasets can be used in conjunction to better understand impacts on atmospheric methane trends. GES DISCs new anomaly tool can also be used on select datasets to further quantify trends in atmospheric greenhouse gases.

long-term data analysis↗

NASA NTRS1981

Airborne laser ranging system for monitoring regional crustal deformation

Alternate approaches for making the atmospheric correction without benefit of a ground-based meteorological network are discussed. These include (1) a two-color channel that determines the atmospheric correction by measuring the time delay induced by dispersion between pulses at two optical frequencies; (2) single-color range measurements supported by an onboard temperature sounder, pressure altimeter readings, and surface measurements by a few existing meteorological facilities; and (3) inclusion of the quadratic polynomial coefficients as variables to be solved for along with target coordinates in the reduction of the single-color range data. It is anticipated that the initial Airborne Laser Ranging System (ALRS) experiments will be carried out in Southern California in a region bounded by Santa Barbara on the norht and the Mexican border on the south. The target area will be bounded by the Pacific Ocean to the west and will extend eastward for approximately 400 km. The unique ability of the ALRS to provide a geodetic 'snapshot' of such a large area will make it a valuable geophysical tool.

Degnan, J. J.↗

NASA NTRS1985

Production of global sea surface temperature fields for the Jet Propulsion Laboratory workshop comparisons

Sea surface temperature (SST) is measured from space by the advanced very high resolution radiometer (AVHRR), scanning multichannel microwave radiometer (SMMR), high resolution infrared sounder (HIRS) and VISSR atmospheric sounder (VAS). Typical accuracies have been reported from 0.5 C regionally to 2.0 C on a global basis. To evaluate the accuracy of the satellite-derived sea surface temperatures, a series of three workshops was organized to provide uniform data reduction and analysis. The analytical techniques used to intercompare satellite and in situ measurements are described in detail. Selected results showed the overall average rms errors were in the range 0.5-1.0 C.

Hilland, J. E.↗

NASA NTRS1996

A New Method of Deriving Time-Averaged Tropospheric Column Ozone over the Tropics Using Total Ozone Mapping Spectrometer (TOMS) Radiances: Intercomparison and Analysis Using TRACE A Data

Error analysis of archived total 03 from total ozone mapping spectrometer (TOMS) (version 6) presented. Daily total 03 maps for the tropics, from the period October 6-21, 1992, are derived from TOMS radiances following correction for these errors. These daily maps, averaged together, show a wavelike feature, which is observed in all latitude bands, underlying sharp peaks which occur at different longitudes depending on the latitude. The wave pattern is used to derive both time-averaged stratospheric and tropospheric 03 fields. The nature of the wave pattern (stratospheric or tropospheric) cannot be determined with certainty due to missing data (no Pacific sondes, no lower stratospheric Stratospheric Aerosol and Gas Experiment (SAGE) ozone for 18 months after the Mt. Pinatubo eruption) and significant uncertainties in the corroborative satellite record in the lower stratosphere (solar backscattered ultraviolet (SBUV), microwave limb sounder (MLS)). However, the time- averaged tropospheric ozone field, based on the assumption that the wave feature is stratospheric, agrees within 10% with ultraviolet differential absorption laser Transport and Atmospheric Chemistry near the Equator-Atlantic) (TRACE A) 03 measurements from the DC-8 and with ozonesonde measurements over Brazzaville, Congo, Ascension Island, and Natal, Brazil, for the period October 6-21, 1992. The derived background (nonpolluted) Indian Ocean tropospheric ozone amount, 26 Dobson units (DU), agrees with the cleanest African ozonesonde profiles for September-October 1992. The assumption of a totally tropospheric wave (flat stratosphere) gives 38 DU above the western Indian Ocean and 15-40% disagreements with the sondes. Tropospheric column 03 is high from South America to Africa, owing to interaction of dynamics with biomass burning emissions. Comparison with fire distributions from advanced very high resolution radiometer (AVHHR) during October 1992 suggests that tropospheric 03 produced from biomass burning in South America and Africa dominates the 03 budget in the tropical southern hemisphere during the study period.

Kim, J. H.↗

NASA NTRS2008

Global Daily Atmospheric State Profiles from the Atmospheric Infrared Sounder

The Atmospheric Infrared Sounder (AIRS) is a hyperspectral infrared instrument on the EOS Aqua Spacecraft, launched on May 4, 2002. AIRS has 2378 infrared channels ranging from 3.7 (micro)m to 15.4 (micro)m and a 13.5 km footprint. AIRS, in conjunction with the Advanced Microwave Sounding Unit (AMSU), produces temperature profiles with 1K/km accuracy on a global scale, as well as water vapor profiles, clouds, dust and trace gas amounts for CO2, CO, SO2, O3 and CH4.[1] AIRS data are used for weather forecasting and studies of global climate change. The AIRS is a 'facility' instrument developed by NASA as an experimental demonstration of advanced technology for remote sensing and the benefits of high resolution infrared spectra to science investigations.

sounder↗

NASA NTRS2009

Regional Data Assimilation of AIRS Profiles and Radiances at the SPoRT Center

This slide presentation reviews the Short Term Prediction Research and Transition (SPoRT) Center's mission to improve short-term weather prediction at the regional and local scale. It includes information on the cold bias in Weather Research and Forcasting (WRF), troposphere recordings from the Atmospheric Infrared Sounder (AIRS), and vertical resolution of analysis grid.

Zavodsky, Brad↗

NASA NTRS2001

Data Comparison: Satellite and Falling Sphere Temperatures

Small meteorological rocketsondes providing temperature data have beam used for comparison with, and validation of measurements from satellite-borne instruments. A significant number of rocket-borne falling spheres were launched in conjunction with the Upper Atmosphere Research Satellite (UARS) for validation of the Halogen Occultation Experiment (HALOE), High Resolution Doppler Interferometer (HRDI), and the Microwave Limb Sounder (MLS) instruments. Upper stratosphere and mesosphere temperatures measured with these instruments on UARS are compared with inflatable spheres launched from Wallops Island (1992-1999), Brazil (1994), Hawaii (1992), Norway (1992), and Sweden (1993 and 1996). Time and space differences varied between the satellite measurement and the rocketsonde launch, for example HALOE overpasses occurred within 5 days and in some cases there were spatial differences of up to 30 degrees longitude. Validation measurements of the HRDI instrument occurred at Wallops Island when it passed within 20 minutes and 330 kilometers of the launch site. Because of discontinuity in the falling sphere drag coefficients when fall speed neared MACH 1 falling sphere temperatures near 70 kilometers attitude are biased toward lower temperatures. Availability of improved software and a new atmospheric model have helped to reduce this bias. The validated remote instrument measurements permit a new perspective of atmospheric structure to be formed, not always possible with the limited number of falling sphere measurements. Features of the remote measurement temperature profiles and their possible use to extend the climatological data base at the rocketsonde sites will be discussed.

Schmidlin, Francis J.↗