Visible-near infrared (VIS-NIR) and thermal infrared (TIR) methods have long been used for ice cloud property retrievals based on satellite observations. Both retrieval methods are sensitive to the assumed ice particle models, which can significantly impact the accuracy of the retrieved microphysical and radiative properties of ice clouds. The Two-Habit model (THM) is considered a suitable ice particle model for passive remote sensing of global ice clouds, as confirmed by spectral consistency in cloud optical thickness (COT), which refers to agreement between VIS-NIR and TIR COT retrievals. However, the ratio of COTs retrieved from these two methods using the THM varies with scattering angle, indicating the potential influence of atmospheric and cloud properties on the spectral consistency of the inferred COT. The present study investigates potential factors affecting the angular dependence of the COT ratio based on observations made by the Advanced Baseline Imager (ABI) sensors on seventeenth Geostationary Operational Environmental Satellite (GOES-17). For optically thin clouds (COT<1) illuminated at a solar zenith angle (SZA)<20 degrees, the heterogeneous particle combination of mixed-phase clouds is the dominant factor that produces an angular-dependent negative bias in COT spectral consistency. At greater SZAs, cloud three-dimensional radiative effects are presumed to be a dominant factor. Negative biases in the cloud top temperature and sea surface temperature contribute to negative biases in the COT ratio. This study suggests that the angular dependence of the COT ratio could help identify mixed-phase clouds and estimate their impact on the spectral consistency in retrieving ice cloud COT.

Next generation LEO/GEO atmospheric sounding instruments should be capable of providing near-continuous high spatial resolution atmospheric temperature and humidity soundings on both global and regional scales. Global measurements are important for producing extended range forecasts of synoptic scale weather patterns and providing the boundary conditions for regional mesoscale models designed to provide warnings of localized intense storms. Experimental forecast system results indicate that the temperature and moisture measurements should be with high-spatial (2 to 8-km) and temporal (30 to 120 min) resolution to resolve the thermodynamic (i.e., atmospheric stability) and dynamic (i.e., horizontal, and vertical motions) processes responsible for global environmental conditions and localized severe weather. This paper provides a synopsis of expected improvements in global Numerical Weather Prediction (NWP) weather forecasts initialized using vertical atmospheric profiles retrieved from a combination of currently operational polar and geostationary satellite data, which simulate the sounding capabilities of next generation satellite sounding systems.

The Edition 2 (Ed2) cloud property retrieval algorithm system was upgraded and applied to the MODerate-resolution Imaging Spectroradiometer (MODIS) data for the Clouds and the Earth's Radiant Energy System (CERES) Edition 4 (Ed4) products. New calibrations for solar channels and the use of the 1.24-μm channel for cloud optical depth (COD) over snow improve the daytime consistency between Terra and Aqua MODIS retrievals. Use of additional spectral channels and revised logic enhanced the cloud-top phase retrieval accuracy. A new ice crystal reflectance model and a CO2-channel algorithm retrieved higher ice clouds, while a new regional lapse rate technique produced more accurate water cloud heights than in Ed2. Ice cloud base heights are more accurate due to a new cloud thickness parameterization. Overall, CODs increased, especially over the polar (PO) regions. The mean particle sizes increased slightly for water clouds, but more so for ice clouds in the PO areas. New experimental parameters introduced in Ed4 are limited in utility, but will be revised for the next CERES edition. As part of the Ed4 retrieval evaluation, the average properties are compared with those from other algorithms and the differences between individual reference data and matched Ed4 retrievals are explored. Part II of this article provides a comprehensive, objective evaluation of selected parameters. More accurate interpretation of the CERES radiation measurements has resulted from the use of the Ed4 cloud properties.

Assessments of the Clouds and the Earth's Radiant Energy System Edition 4 (Ed4) cloud retrievals are critical for climate studies. Ed4 cloud parameters are evaluated using instruments in the A-Train Constellation. Cloud-Aerosol LiDAR with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) retrievals are compared with Ed4 retrievals from the Aqua Moderate-Resolution Imaging Spectroradiometer (MODIS) as a function of the CALIOP horizontal averaging (HA) scale. Regardless of the HA scale, MODIS daytime (nighttime) water cloud fraction (CF) is greater (less) than that from CALIOP. MODIS ice CF is less than CALIOP overall, with the largest differences in polar regions. Ed4 and CALIOP retrieve the same cloud phase in 70%-98% of simultaneous observations depending on the time of day, surface conditions, HA scales, and type of cloud vertical structure. Mean cloud top height (CTH) differences for single-layer water clouds over snow-/ice-free surfaces are less than 100 m. Base altitude positive biases of 170-460 m may be impacted by CPR detection limitations. Average MODIS ice CTHs are underestimated by 70 m for some deep convective clouds and up to ~2.2 km for thin cirrus. Ice cloud base altitudes are typically underestimated (overestimated) during daytime (nighttime). MODIS and CALIOP cirrus optical depths over oceans are within 46% and 5% for daytime and nighttime observations, respectively. Ice water path differences depend on the CALIOP retrieval version and warrant further investigation. Except for daytime cirrus optical depth, Ed4 cloud property retrievals are at least as accurate as other long-term operational cloud property retrieval systems.

To reduce societal impacts from severe weather, the USA should expeditiously implement a Hyperspectral Imaging Infrared Sounder (HIIS) in Geostationary (GEO) orbit. Observations from a GEO HIIS would contain unique information that is crucial for giving the populace more time to react to ensuing severe weather, a key lifesaving capability for a Weather Ready Nation. The GEO HIIS will provide frequent hyperspectral infrared radiance observations for understanding storm scale atmospheric processes and improving weather hazard predictions. These observations will provide the unique ability to detect rapid changes in atmospheric stability and the moisture flux convergence that serves both as a triggering mechanism for initial storm development and a fuel source for continued storm growth.

Today's state-of-the-art infrared hyperspectral sounders in Low Earth Orbit have demonstrated very high performance in several basic, but very critical, performance characteristics. Because of this, and the high information content of the infrared hyperspectral radiance spectra, the data has proven valuable for a range of applications including 1) radiance data assimilation for medium range numerical weather forecasting, 2) atmospheric soundings for various meteorological applications, 3) trace gases studies, 4) reference inter-calibration, and 5) climate process studies and radiance trending. This paper will discuss the desirable characteristics of the next generation of the US infrared hyperspectral sounder, envisioned to continue the hyperspectral data record after the JPSS series ends in the late 2030s, in order to maintain very high value and return on investment, and even improve the quality of the available data over the current generation.

The Clouds and Earth's Radiant Energy System (CERES) has been monitoring clouds and radiation since 2000 using algorithms developed before 2002 for CERES Edition 2 (Ed2) products. To improve cloud amount accuracy, CERES Edition 4 (Ed4) applies revised algorithms and input data to Terra and Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) radiances. The Ed4 cloud mask uses 5-7 additional channels, new models for clear-sky ocean and snow/ice-surface radiances, and revised Terra MODIS calibrations. Mean Ed4 daytime and nighttime cloud amounts exceed their Ed2 counterparts by 0.035 and 0.068. Excellent consistency between average Aqua and Terra cloud fraction is found over nonpolar regions. Differences over polar regions are likely due to unresolved calibration discrepancies. Relative to Ed2, Ed4 cloud amounts agree better with those from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). CALIPSO comparisons indicate that Ed4 cloud amounts are more than or as accurate as other available cloud mask systems. The Ed4 mask correctly identifies cloudy or clear areas 90%-96% of the time during daytime over nonpolar areas depending on the CALIPSO-MODIS averaging criteria. At night, the range is 88%-95%. Accuracy decreases over land. The polar day and night accuracy ranges are 90%-91% and 80%-81%, respectively. The mean Ed4 cloud fractions slightly exceed the average for seven other imager cloud masks. Remaining biases and uncertainties are mainly attributed to errors in Ed4 predicted clear-sky radiances. The resulting cloud fractions should help CERES produce a more accurate radiation budget and serve as part of a cloud property climate data record.

Previous research has revealed inconsistencies between the Collection 5 (C5) calibrations of certain channels common to the Terra and Aqua MODerate-resolution Imaging Spectroradiometers (MODIS). To achieve consistency between the Terra and Aqua MODIS radiances used in the Clouds and the Earth's Radiant Energy System (CERES) Edition 4 (Ed4) cloud property retrieval system, adjustments were developed and applied to the Terra C5 calibrations for channels 1-5, 7, 20, and 26. These calibration corrections were developed independently of those used for MODIS Collection 6 (C6) data, which became available after the CERES Ed4 processing had commenced. The comparisons demonstrate that the corrections applied to the Terra C5 data for CERES Edition 4 generally resulted in Terra-Aqua radiance consistency that is as good as or better than that of the C6 datasets. The C5 adjustments resulted in more consistent Aqua and Terra cloud property retrievals than seen in the previous CERES edition. Other calibration artifacts were found in one of the corrected channels and in some of the uncorrected thermal channels after Ed4 began. Where corrections were neither developed nor applied, some artifacts are likely to have been introduced into the Ed4 cloud property record. For example, the degradation in the Aqua MODIS 0.65-μm channel in both the C5 and C6 datasets affects trends in cloud optical depth retrievals. Thus, despite the much-improved consistency achieved for the Terra and Aqua datasets in Ed4, the CERES Ed4 cloud property datasets should be used cautiously for cloud trend studies because of those remaining calibration artifacts.

Since launch of the Suomi NPP (SNPP) satellite in late 2011, two airborne field campaigns have been conducted with a primary focus on SNPP instrument and data product calibration / validation: 1) mid-latitude flights based out of Palmdale, CA during May 2013 (SNPP-1), and 2) flights over Greenland during March 2015 while based out of Keflavik, Iceland (SNPP-2). In addition to under-flying SNPP, aircraft flight profiles were defined to also obtain coincident observations with the NASA A-train (i.e. AQUA), MetOP-A, and MetOP-B advanced sounder satellites (i.e. AIRS, IASI, and CrIS), along with radiosonde and ground truth sites. The NASA LaRC National Airborne Sounder Testbed-Interferometer (NAST-I) was one of the key payload sensors aboard the ER-2 aircraft during these campaigns. This presentation summarizes the SNPP field campaigns and shows sample inter-comparisons results involving NAST-I and other measurement assets.

This paper describes an analysis of the potential of using an airborne Fourier transform spectrometer (FTS) or radiometer to detect wake vortices. The goal was to determine the requirements for an infrared (IR) FTS to effectively detect wake vortices. Initially, a theoretical analysis of wake vortex detection by thermal radiation was realized in a series of simulations. The first stage used the Terminal Area Simulation System (TASS) dynamic model to simulate wake vortex temperature, moisture, and velocity fields. The second stage used these fields as input to the line-by-line radiative transfer model (LBLRTM) to simulate responses from both an imaging IR hyperspectral FTS and an IR imaging radiometer. These numerical simulations generated FTS and radiometer imagery that was compared with the original temperature data. This research supported an effort, using ground-based imaging FTS instruments, to make measurements of wake vortices of various landing aircraft. Results from two different field campaigns have been previously reported. Instrument specifications for wake vortex thermal detection are recommended for an imaging radiometer sensitive within the following two narrow spectral bands: 670-750 cm-1and 2200-2350 cm-1. The instrument must have at the very minimum a noise equivalent differential temperature-1.

This paper summarizes work investigating the zenith angular dependence of residual cloud and/or aerosol contamination on “clear-sky” infrared observations, which include cloud-cleared radiances and cloud-masked data, along with the implication for achieving agreement with forward calculations over the scanning range of the sensor.

Given the prevalence of technology in the workplace, an understanding of employees' attitudes towards technology is essential. Such attitudes have been linked to such important issues as the successful implementation of new technologies in the workplace, employee intent to use technology, and the actual usage of technology by employees. As a result of the rapidly aging workforce, and because age has been linked to computer use and comfort, it is important to examine the relationship that may exist between age and attitudes towards technology. This study examines age as a moderator of 612 employees' attitudes towards technology in relation to work motivation (intrinsic and extrinsic) and overall job satisfaction. Further, given the technological socialisation of the Generation X (Gen X) versus the Baby Boomers, our sample comprised these two demographics. Hierarchical moderated multiple regression indicates age moderates the relationship between attitude towards technology and intrinsic motivation, extrinsic motivation, and to a lesser extent, overall job satisfaction. In each instance, older employees exhibit the strongest relationships with the outcome variables when possessing a high attitude towards technology. In contrast, older employees exhibit the weakest relationships when possessing a low attitude towards technology. These results are supportive of the moderating effect of age on attitude towards technology. Lastly, implications and directions for future research are discussed.

Cloud properties were retrieved by applying the Clouds and Earth's Radiant Energy System (CERES) project Edition-2 algorithms to 3.5 years of Tropical Rainfall Measuring Mission Visible and Infrared Scanner data and 5.5 and 8 years of MODerate Resolution Imaging Spectroradiometer (MODIS) data from Aqua and Terra, respectively. The cloud products are consistent quantitatively from all three imagers; the greatest discrepancies occur over ice-covered surfaces. The retrieved cloud cover (~59%) is divided equally between liquid and ice clouds. Global mean cloud effective heights, optical depth, effective particle sizes, and water paths are 2.5 km, 9.9, 12.9 μm , and 80 g·m-2, respectively, for liquid clouds and 8.3 km, 12.7, 52.2 μm, and 230 g·m-2for ice clouds. Cloud droplet effective radius is greater over ocean than land and has a pronounced seasonal cycle over southern oceans. Comparisons with independent measurements from surface sites, the Ice Cloud and Land Elevation Satellite, and the Aqua Advanced Microwave Scanning Radiometer-Earth Observing System are used to evaluate the results. The mean CERES and MODIS Atmosphere Science Team cloud properties have many similarities but exhibit large discrepancies in certain parameters due to differences in the algorithms and the number of unretrieved cloud pixels. Problem areas in the CERES algorithms are identified and discussed.

The National Aeronautics and Space Administration's Clouds and the Earth's Radiant Energy System (CERES) Project was designed to improve our understanding of the relationship between clouds and solar and longwave radiation. This is achieved using satellite broad-band instruments to map the top-of-atmosphere radiation fields with coincident data from satellite narrow-band imagers employed to retrieve the properties of clouds associated with those fields. This paper documents the CERES Edition-2 cloud property retrieval system used to analyze data from the Tropical Rainfall Measuring Mission Visible and Infrared Scanner and by the MODerate-resolution Imaging Spectrometer instruments on board the Terra and Aqua satellites covering the period 1998 through 2007. Two daytime retrieval methods are explained: the Visible Infrared Shortwave-infrared Split-window Technique for snow-free surfaces and the Shortwave-infrared Infrared Near-infrared Technique for snow or ice-covered surfaces. The Shortwave-infrared Infrared Split-window Technique is used for all surfaces at night. These methods, along with the ancillary data and empirical parameterizations of cloud thickness, are used to derive cloud boundaries, phase, optical depth, effective particle size, and condensed/frozen water path at both pixel and CERES footprint levels. Additional information is presented, detailing the potential effects of satellite calibration differences, highlighting methods to compensate for spectral differences and correct for atmospheric absorption and emissivity, and discussing known errors in the code. Because a consistent set of algorithms, auxiliary input, and calibrations across platforms are used, instrument and algorithm-induced changes in the data record are minimized. This facilitates the use of the CERES data products for studying climate-scale trends.

Ultraspectral resolution infrared (IR) radiances obtained from nadir observations provide information about the atmosphere, surface, aerosols, and clouds. Surface spectral emissivity (SSE) and surface skin temperature from current and future operational satellites can and will reveal critical information about the Earth's ecosystem and land-surface-type properties, which might be utilized as a means of long-term monitoring of the Earth's environment and global climate change. In this study, fast radiative transfer models applied to the atmosphere under all weather conditions are used for atmospheric profile and surface or cloud parameter retrieval from ultraspectral and/or hyperspectral spaceborne IR soundings. An inversion scheme, dealing with cloudy as well as cloud-free radiances observed with ultraspectral IR sounders, has been developed to simultaneously retrieve atmospheric thermodynamic and surface or cloud microphysical parameters. This inversion scheme has been applied to the Infrared Atmospheric Sounding Interferometer (IASI). Rapidly produced SSE is initially evaluated through quality control checks on the retrievals of other impacted surface and atmospheric parameters. Initial validation of retrieved emissivity spectra is conducted with Namib and Kalahari desert laboratory measurements. Seasonal products of global land SSE and surface skin temperature retrieved with IASI are presented to demonstrate seasonal variation of SSE.

As a part of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) and the NPOESS Preparatory Project (NPP), the instruments Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) make up the Cross-track Infrared and Microwave Sounder Suite (CrIMSS). CrIMSS will primarily provide global temperature, moisture, and pressure profiles and calibrated radiances [1]. In preparation for the NPOESS/NPP launch, porting and testing of the CrIMSS Environmental Data Record (EDR) algorithms need to be performed.

In this paper, a methodology to retrieve cloud water content profiles from operational satellite data is described. Initial results, comparisons with CloudSat and Calipso active sensor data, and potential applications are presented. This new product could provide an improved depiction of the vertical distribution of cloud water at the high spatial and temporal resolution needed for short term weather analyses and forecasts.

The geosynchronous-imaging Fourier transform spectrometer (GIFTS) engineering demonstration unit (EDU) is an imaging infrared spectrometer designed for atmospheric soundings. It measures the infrared spectrum in two spectral bands (14.6 to 8.8 mum, 6.0 to 4.4 mum) using two 128times128 detector arrays with a spectral resolution of 0.57 cm-1with a scan duration of ~11 seconds. From a geosynchronous orbit, the instrument will have the capability of taking successive measurements of such data to scan desired regions of the globe, from which atmospheric status, cloud parameters, wind field profiles, and other derived products can be retrieved. The GIFTS EDU provides a flexible and accurate testbed for the new challenges of the emerging hyperspectral era. The EDU ground-based measurement experiment, held in Logan, Utah during September 2006, demonstrated its extensive capabilities and potential for geosynchronous and other applications (e.g., earth observing environmental measurements). This paper addresses the experiment objectives and overall performance of the sensor system with a focus on the GIFTS EDU imaging capability and proof of the GIFTS measurement concept.

The National Polar-orbiting Operational Environmental Satellite System (NPOESS) is expected to become the central element of the long-term global observing system. While the critical design and fabrication for many sensor suites have been completed, some aspects of the instrument configuration of NPOESS's primary infrared sensor, the Cross-track Infrared Sounder (CrIS), can still be optimized. This paper considers the relationship between various specifications for the sensor spatial resolution (sampling area size) and the anticipated performance of global temperature and water vapor profile sounding, these being among the highest priority measurements NPOESS will provide. Although the trade-off between signal to noise ratio, dwell time, sampling area (SA), and other instrumental issues such as weight, power and volume are complicated and need to be carefully considered, a finer SA will theoretically enable improved sounding through scattered clouds. Preliminary analysis of high-spectral infrared measurements from Atmospheric InfRared Sounder (AIRS) (which has a 13.5 km nadir SA) on NASA's polar-orbiting EOS-Aqua satellite shows that the percentage of its SA being cloud free is less than 20%. In addition, we demonstrate using sounding and imaging data from NPOESS' surrogate, AIRS and MODIS, how improved SA can achieve not only the improved sounding performance for meeting threshold and objective requirements, but also reduce processing demands, simplify data assimilation and utilization, and enhance delineation of mesoscale moisture gradients.

A long-term surface-based measurement program has been established at an oceanic site to validate new products being derived globally as part of NASA's Earth Observing System for global change studies. This unique site, located at the Chesapeake Lighthouse in the Atlantic Ocean is completely surrounded by water offering a uniform background with well-known physical properties ideal for validating space-based retrievals of climatologically important parameters such as radiative fluxes and aerosol properties. A description of the site and synergy among current and future measurement programs established at the Chesapeake Lighthouse along with radiation and aerosol data from the first three years of measurements are presented.

The methodology for retrieval of atmospheric temperature and composition profiles, and surface thermal properties from observed radiance spectra is reported. These retrieval parameters are determined using a three-stage approach that combines three algorithms: (1) statistical physical-eigenvector-regression, (2) simultaneous non-linear matrix inversion, and (3) trace species profile enhancement. NAST-I aboard a high altitude aircraft has been successfully collecting data during many field campaigns. NAST-I provides relatively high spectral resolution (0.25 cm/sup -1/) measurements in the spectral region of 645-2700 cm/sup -1/ with moderate spatial resolution (a linear resolution equal to 13% of the aircraft altitude at nadir) and cross track scanning (producing a swath width on the Earth's surface of approximately twice the aircraft altitude). Retrieval results from several NAST-I field campaigns are presented in conjunction with co-incident ground and in situ measurements for validation. These results demonstrate the ability of the NAST interferometer to reveal fine-scale horizontal features with relatively high vertical resolution.

The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU), and the Humidity Sounder for Brazil (HSB) form an integrated cross-track scanning temperature and humidity sounding system on the Aqua satellite of the Earth Observing System (EOS). AIRS is an infrared spectrometer/radiometer that covers the 3.7-15.4-/spl mu/m spectral range with 2378 spectral channels. AMSU is a 15-channel microwave radiometer operating between 23 and 89 GHz. HSB is a four-channel microwave radiometer that makes measurements between 150 and 190 GHz. In addition to supporting the National Aeronautics and Space Administration's interest in process study and climate research, AIRS is the first hyperspectral infrared radiometer designed to support the operational requirements for medium-range weather forecasting of the National Ocean and Atmospheric Administration's National Centers for Environmental Prediction (NCEP) and other numerical weather forecasting centers. AIRS, together with the AMSU and HSB microwave radiometers, will achieve global retrieval accuracy of better than 1 K in the lower troposphere under clear and partly cloudy conditions. This paper presents an overview of the science objectives, AIRS/AMSU/HSB data products, retrieval algorithms, and the ground-data processing concepts. The EOS Aqua was launched on May 4, 2002 from Vandenberg AFB, CA, into a 705-km-high, sun-synchronous orbit. Based on the excellent radiometric and spectral performance demonstrated by AIRS during prelaunch testing, which has by now been verified during on-orbit testing, we expect the assimilation of AIRS data into the numerical weather forecast to result in significant forecast range and reliability improvements.

The Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit/Humidity Sounder for Brazil (AIRS/AMSU/HSB) instrument suite onboard Aqua observes infrared and microwave radiances twice daily over most of the planet. AIRS offers unprecedented radiometric accuracy and signal to noise throughout the thermal infrared. Observations from the combined suite of AIRS, AMSU, and HSB are processed into retrievals of atmospheric parameters such as temperature, water vapor, and trace gases under all but the cloudiest conditions. A more limited retrieval set based on the microwave radiances is obtained under heavy cloud cover. Before measurements and retrievals from AIRS/AMSU/HSB instruments can be fully utilized they must be compared with the best possible in situ and other ancillary "truth" observations. Validation is the process of estimating the measurement and retrieval uncertainties through comparison with a set of correlative data of known uncertainties. The ultimate goal of the validation effort is retrieved product uncertainties constrained to those of radiosondes: tropospheric rms uncertainties of 1.0 degC over a 1-km layer for temperature, and 10% over 2-km layers for water vapor. This paper describes the data sources and approaches to be used for validation of the AIRS/AMSU/HSB instrument suite, including validation of the forward models necessary for calculating observed radiances, validation of the observed radiances themselves, and validation of products retrieved from the observed radiances. Constraint of the AIRS product uncertainties to within the claimed specification of 1 K/1 km over well-instrumented regions is feasible within 12 months of launch, but global validation of all AIRS/AMSU/HSB products may require considerably more time due to the novelty and complexity of this dataset and the sparsity of some types of correlative observations.

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) combines advanced technologies to observe surface thermal properties and atmospheric weather and chemistry variables in four dimensions. Large area format Focal Plane detector Arrays (LFPAs) provide near instantaneous large area coverage with high horizontal resolution. A Fourier Transform Spectrometer (FTS) enables atmospheric radiance spectra to be observed simultaneously for all LFPA detector elements thereby providing high vertical resolution temperature and moisture sounding information. The fourth dimension, time, is provided by the geosynchronous satellite platform, which enables near continuous imaging of the atmosphere's three-dimensional structure. The key advances that GIFTS achieves beyond current geosynchronous capabilities are: (1) the water-vapor winds will be altitude-resolved throughout the troposphere, (2) surface temperature and atmospheric soundings will be achieved with high spatial and temporal resolution, and (3) the transport of tropospheric pollutant gases (i.e. CO and O/sub 3/) will be observed. GIFTS will be launched in 2005 as NASA's third New Millennium Program (NMP) Earth Observing (EO-3) satellite mission, and will serve as the prototype of sounding systems to fly on future operational geosynchronous satellites. After a one-year validation period in view of North America, the GIFTS will be repositioned to become the Navy's Indian Ocean METOC Imager (IOMI). We describe the GIFTS technology and provide examples of the GIFTS remote sensing capabilities using aircraft interferometer data. The GIFTS is an important step in implementing the NASA Earth Science Enterprise vision of a sensor web for future Earth observations.

Remote sensing of surface properties and estimation of clear-sky and surface albedo generally assume that the albedo depends only on the solar zenith angle. The effects of dew, frost, and precipitation as well as evaporation and wind can lead to some systematic diurnal variability resulting in an asymmetric diurnal cycle of albedo. This paper examines the symmetry of both surface-observed and top-of-the-atmosphere (TOA) albedos derived from satellite data. Broadband surface albedos were measured at the Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains Central Facility near Lamont, Oklahoma and several extended facilities. GOES satellite radiance data are converted to broadband albedo using bidirectional reflectance functions and an empirical narrowband-to-broadband relationship. The surface and top-of-atmosphere albedos vary in a consistent fashion during both the morning and afternoon. The initial results indicate that surface moisture, probably in the form of dew, has a significant effect and can change the albedo by 10% at a given solar zenith angle between the morning and afternoon. Wind speed is well correlated with the diurnal albedo asymmetry. Light winds and small dew point depressions are associated with the greatest morning/afternoon albedo differences. Aerosols tend to moderate those differences. Changes in the surface properties from dew may alter the bidirectional reflectance characteristics of the scene, affecting the interpretation of remote sensing data. Errors in the diurnally averaged albedos derived from Sun-synchronous satellite measurements that arise from albedo asymmetry are generally less than 3%. Further examination of surface albedo asymmetry is needed to assess its influence on satellite measurements and the surface energy budget over a range of land surface types.