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FASCODE for the Environment (FASE) is the latest in a long line of atmospheric transmittance and radiance models developed by the Battlespace Environment Division of the Air Force Research Laboratory (AFRL), formerly known as the Optical Physics Division of the Geophysics Directorate, USAF Phillips Laboratory, and before that, the Air Force Geophysics Laboratory (AFGL). FASE is a direct descendent of the line-by-line atmospheric transmittance/radiance model FASCOD3. It also incorporates recent developments from the similar model LBLRTM. This report presents the additions and improvements in FASE over previous models, including: (1) improvements and corrections to the geometry routines, (2) corrections to the NLTE routines, (3) corrections to the blackbody function when aerosols are included, (4) corrections and improvements to the Hartley-Huggins and the Hertzberg continua, (5) corrections to the calculations of absorption cross-sections and to the laser calculation, (6) addition of the Schumann-Runge Band and continuum, (7) inclusion of a solar spectrum module, (8) inclusion of a spectral limit check when line coupling is included, and (9) acceptance of the HITRAN96 line parameters.

Our approach provides a flexible, realistic, low-risk, integrated approach to precipitation and hydrological forecasting. This approach: (a) exploits the enhanced capability of the NEXRAD system to provide accurate high-resolution rainfall maps over the continental U.S.; (b) utilizes state-of-the-art precipitation and hydrological forecasting techniques; but, (c) overcomes the inherent limitations of these approaches by optimally merging the results of the different techniques to provide a robust solution. River forecasting has many uses and benefits. Floods affect civilian populations, Army Corps operations, mobility, forward army units, and others. River management optimizes the use of water for drinking, agriculture, hydroelectricity, navigation and environmental quality control.

The main objective of the proposed study was to investigate the complementary information provided by microwave and infrared sensors in order to enhance both the microwave retrieval and the current cloud analysis. This primary task investigated and assessed the impact of incorporating cloud horizontal and vertical spatial distribution information on the performance and accuracy of simultaneous physical retrievals of atmospheric profiles from microwave sensors. The second task explored additional attributes of the microwave measurements, particularly related to ice clouds, to investigate the possibility of identifying multi-layer clouds from simultaneous microwave, visible and infrared data, and to provide infrared emission properties needed for threshold-based cloud detection. We also applied the UR approach to DMSP data to provide the basis for screening out cases where the infrared/visible-derived low cloud properties were uncertain and to assess ability to characterize the vertical structure of multi-layer clouds. The third task investigated the feasibility of predicting infrared emission properties using the microwave data, and assessed if this information could be used to enhance low cloud and thin high cloud identification in totally overcast conditions, especially at night. This task included deriving empirical relationships between microwave and infrared surface emission based on dependent clear data sets, and performing exploratory cloud analyses using both the surface temperature data from the current surface temperature data base and the microwave derived surface emission properties. The last task addressed the application of the UR algorithm to land and to snow/ice backgrounds and assessed the algorithm's capability using new data collected over the Northern Hemisphere in the winter.

Our long-term goal is to use DMSP SSM/I satellite data to improve the depiction of marine atmospheric storms, which in turn would aid nowcasting in support of execution of operations at sea and forecasting of the evolution of these storms in support of planning. The anticipated results of our research are algorithms and prototype software to use SSM/I observations of integrated water vapor (IWV) and surface wind speed in data assimilation. These algorithms, based on the work of Hoffman and Grassotti (1996, referred to as HG96 below), are designed to match observable features in the SSM/I data to those in the short term forecast (or background) field used in the data assimilation system, shifting the background field to best match the available satellite data. The algorithms will be optimized for the Navy weather central regional prediction facility models but will be adaptable to other satellite data and other forecast models. In practical terms, the goal of this project is to translate the work of HG96 into an operational algorithm and to perform sufficient testing to demonstrate the utility of this algorithm by showing that it improves the forecasts of marine storms. To reach this goal we worked towards the following key technical objectives: case selection; impact study; algorithm development and tuning. Suitable cases for study were selected. For each selected case one or more impact experiments was conducted. These experiments showed the utility of applying the distortion correction within the operational data assimilation cycle, and provided quantitative measures of the improvements in forecast skill in the selected cases. The algorithm will be extended to allow for operational implementation. Tuning of the algorithm was refined., See also ADM002252.

This work describes the work done during the first year of a contract to analyze and model data from high altitude background measurements. The contract has 5 separate tasks: 1. MSX Data Analysis: 2.1 Trace Species in Modtran, 2.2 Radiance Inversion Techniques, 2.3 Mesospheric Radiance Model, 2.4 FAScode for the Environment (FASE). In Task 1, techniques for analyzing data from the Midcourse Space Experiment (MSX) are developed, including developing experiment plans, developing software for the automated analysis of data from visible and ultraviolet imagers, and developing techniques for correlating data from meteorological satellites with MSX data. In Task 2.2, a package for the general inversion for advanced retrieval of atmospheric species from high spectral resolution measurements is described. In Task 2.4, progress in the development of the line-by-line atmospheric transmittance/radiance program FASE (FAScode for the Environment) is described.

A three-year, multi-faceted effort to develop and apply state-of-the-art techniques for analysis of environmental satellite data is described. Principal accomplishments include development of satellite data analysis and image processing algorithms and software suitable for interpreting environmental satellite sensor measurements; adaptation and application of satellite-based cloud property retrieval algorithms for processing of large multiple-satellite data sets; development and application of improved cloud-phase and cloud optical property retrieval algorithms; investigation of techniques potentially applicable for retrieval of cloud spatial properties from very high resolution remotely sensed data; and data analysis in support of a contrail-formation experiment. Software development and data analysis were performed using the Air Force Interactive Meteorological System (AIMS) located at PL. AIMS is an integrated computer facility that includes multiple direct-broadcast satellite ground stations and associated data processing facilities; an extensive satellite and conventional data archive; a database access system; and a library of environmental-property retrieval algorithms. Several system enhancements were developed for AIMS including a new Geostationary satellite acquisition and analysis capability. All software and data-analysis products developed under this effort are available on AIMS.

This report describes the results of a 3 year project for development of a regional analysis system based on the method of optimal interpolation. The TAP project primary objective is to develop robust analysis procedures to support the tactical user. The function of TAP is to combine background (i.e. a priori) information with observations of diverse type, quality, and density to produce analyses of meteorological fields, which are either provided directly to the end user or used as input to other algorithms, such as mesoscale forecast models. The prototype system design and its implementation are described, along with the ancillary climatology and error statistics databases. The results of system tests are described in which real data collected over North America were used for the generation of customized analysis products, and for initialization of the MM5 mesoscale forecast model.

This interim scientific report describes a multi-faceted effort to support PL/GPD in the development and application of state-of-the-art analysis techniques for remotely sensed data. The resulting tools, techniques and data sets will support the improved analysis of archived data as well as current and future geophysical parameter acquisition and analysis. The principal accomplishments during the reporting period were: development of improved algorithms for retrieval of cirrus emissivity and estimation of cloud altitude; development of improved cloud-phase discrimination algorithms for analysis of GOES imager and AVHRR data; application of existing cloud detection and new cloud-phase and emissivity algorithms to a two-month data set collected from one GOES and two NOAA satellites over the eastern and central portions of the continental U.S. and western Atlantic; reduction and quality assurance processing of approximately one month of raw radiosonde data from five sites; and software tool and technique development for enhanced satellite image processing capabilities on the Air Force Interactive Meteorological System.

This report summarizes four years of the Phillips Laboratory and AER, Inc.'s efforts in the calibration of the DMSP SSM/T-2 millimeter wave moisture sounder. Thirteen underflights of the T-2 were made by the NASA ER-2 research aircraft which carried the MIR, an instrument similar to the T-2. Comparisons of the 183 GHz measurements over water FOVs displayed RMS differences of 0.9 to 1.6 K, roughly within the accuracy limits of the calibrating MIR instrument. The overall conclusion was that the T-2 suffered no significant bias in its calibration. An additional focus was to examine the T-2 sensitivity to the variability of the atmosphere: temperature and moisture profiles, surface temperature and emissivity, satellite viewing angle, clouds and precipitation. Also, with the failure of the 150 GHz channel on F-11 in June 1993, an additional challenge was to synthesize 150 GHz Tbs by a multiple regression method. This work highlighted the necessity of aircraft in the calibration of satellite sensors. In addition, the wealth of information collected during a calibration effort provided invaluable understanding of the sensor behavior and limitations, both essential to users of the satellite information.

Support of Environmental Requirements for Cloud Analysis and Archives (SERCAA) was a four-year, two-phase research and development program. Program goals were to produce a global multispectral, multisensor cloud analysis capability for retrieval of spatial, radiative, microphysical, and environmental cloud properties through analysis of sensor data from multiple operational environmental satellites. Program accomplishments during Phase 1 included development of three customized cloud-detection algorithms for analysis of NOAA/AVHRR, DMSP/OLS, and geostationary sensor data; a new algorithm for discrimination of vertical cloud layers within a 25 km grid cell; and an innovative analysis-integration algorithm for optimally combining the results of the source-specific cloud analysis modules. During Phase 2, retrieval capabilities were expanded to include cloud particle size, emissivity/transmissivity, optical depth, and altitude. Additional work toward characterization of cloud-free bidirectional reflectance provides a basis for enhanced analysis of visible-channel data in the cloud detection process. SERCAA algorithms have been selected for operational implementation at the Air Force Global Weather Central., Original contains color plates: All DTIC and NTIS reproductions will be in black and white.

This report describes the results of the second year of a 3-year project for development of a regional analysis system based on the method of optimal interpolation. The TAP project primary objective is to develop robust analysis procedures to support the tactical user. These analysis procedures provide stable meteorological products for end users. The function of TAP is to combine background (i.e. a priori) information with observations of diverse type, quality, and density to produce analyses of meteorological fields. The status of the system design and prototyping is reviewed. The error statistics databases generated during the first two years, and their implementation in TAP, are described. The results of real-data tests of the prototype system are discussed.

This report describes the results of the first year of a 3-year project for development of a theater-scale meteorological analysis system based on the method of optimal interpolation. The TAP project primary objective is to develop robust analysis procedures to Support the tactical user. These analysis procedures provide stable meteorological products for end users. The function of TAP is to combine background (i.e. a priori) information with observations of diverse type, quality, and density to produce analyses of meteorological fields. The status of the system design and prototyping is reviewed. Real data collected for system testing is described. The climatology and error statistics databases generated during the first year are described.

The TACNEPH program was a four year effort to develop a relocatable regional cloud analysis model for operational use in a transportable satellite ground station facility. Key features of the model are the ability to assimilate and analyze data from both military and civilian polar orbiting satellites in real time and to perform cloud analyses in the absence of any data source other than direct satellite sensor transmissions. In particular, data from the DMSP OLS, SSM/I, and SSM/T are used together with NOAA AVHRR multispectral imagery. In addition to direct broadcast satellite data, the only additional data requirements are for surface temperature climatology and geographic classification databases. Algorithms were developed to perform nephanalysis over the range of conditions expected to be encountered in a tactical environment (e.g., variable mix of sensor and supporting data and the absence of conventional observations). The TACNEPH program has the capability to operate in a 'gracefully degrading' mode wherein different algorithms are employed as various sources of data are lost. Cloud algorithms consist of a series of cloud tests, each sensitive to a different satellite sensor spectral signature. Since the model must be able to operate when no conventional data are available, clear scene characteristics are inferred from climatology and sensor data. A technique has been developed to predict clear-scene satellite brightness temperatures through dynamic adjustments to climatological surface temperatures derived from shelter measurements.

A satellite database management facility was developed to support implementation and real-data testing of new multisource, multi spectral satellite-based cloud analysis algorithms. Cloud algorithms were produced separately under Phase I of the Support of Environmental Requirements for Cloud Analysis and Archive (SERCAA) research and development project. The objective of the database project was to develop a unified capability to store, update, retrieve and catalog satellite and supporting data plus derived algorithm products. Data processing and storage requirements dictated a centralized database management facility capable of operating over a network of processing and mass storage systems. Based on these requirements, specifications were generated for a suitable database management facility. This was followed by development and implementation of software and hardware on the Air Force Interactive Meteorological System (AIMS) used by the Atmospheric Sciences Division at the Air Force Phillips Laboratory for SERCAA algorithm testing. Key features of the database management facility include simultaneous access to the database by multiple users, support for interactive and programmed queries, easy access to satellite and ancillary data from within application programs, network access to the database from multiple-vendor computers, and support for both on-line and removable data storage media.

This report describes the results of a 3O-month effort aimed at evaluating forecasts of temperature, winds, humidity, and clouds from the advanced physics global spectral model (APGSM) developed by the Phillips Laboratory, in comparison with the currently operational GSM and cloud forecast models at Global Weather Central (GWC). Forecasts out to four days were generated for four separate months of 1989. Results show improved forecasts of thicknesses in the extratropics from the APGSM, but wind forecasts with generally larger errors. Forecasts of humidity are improved at some levels, regions, and forecast lead times, degraded at others. Root mean square errors of total cloud cover forecasts based on APGSM output are lower than those of the currently operational 5-layer model only for those techniques with much too smooth cloudiness distributions. (MM)

This report documents the development and testing of nowcasting methods for satellite imagery. Techniques for identifying, tracking, and forecasting features of interest through contours of brightness temperature in geostationary IR imagery were evaluated in a study covering over 200 features from all four seasons. Results indicate that because contours frequently split, merge, or dissipate, contour based techniques are successful in only a minority of cases. The most skillful contour extrapolation technique is movable persistence, which simply extrapolates the position of the contour based on the past movement of its centroid position. Its verification scores are significantly better than persistence for forecasts from 1/2 to 3 hours in advance. As an alternative to the contour-based schemes, a cross-correlation technique for predicting short-term changes in pixel grayshade values (brightness temperatures) was developed and tested. Pixel-based verification of the cross-correlation forecasts show an improvement over persistence out to 2 1/ 2 hours (the longest time period studied for this technique). Contour forecasts derived from the cross-correlation are significantly more skillful than those of the best contour extrapolation technique (movable persistence) out to 1 hour, and no worse out to 2 1/2 hours.... Satellite imagery, Nowcasting, Cross- correlation, Image processing.

Results are presented from the second year of a three-year contract to explore the feasibility of local thunderstorm forecasting based on the assimilation of single-Doppler radar data. The method used can assimilate Doppler radial winds, derive a tangential component, infer temperature distributions from the wind, and assimilate the resultant information. The underlying analysis and assimilation methodology is explained in detail. This is then followed with a set of sensitivity experiments using simulated Doppler radar data generated from a numerical model forecast. A simple 2-D experiment is first presented which confirms the benefit of temperature assimilation to complement wind data assimilation. Second, a set of 3-D model experiments is presented to test the sensitivity of the model to observational data type and error characteristics. The results suggest that forecast accuracy is relatively insensitive to the observational error, though this result is in part due to the inherent smoothing built into the objective analysis and the assumption of no biases in the wind observations.... Numerical weather prediction, Mesoscale meteorology, Doppler radar data analysis, Thunderstorm forecasting.

This study describes the development of a vectorized, multiprocessing global spectral model (GSM) with enhanced physical parameterizations. The starting point was the Phillips Laboratory GSM, in its GL90 version, containing an enhanced suite of physical parameterizations. The latitude tasking scheme for multiprocessing the loop over latitude in the calculation of the spectral tendencies and adjusted model variables was implemented, using the general truncation version of the hydrodynamics code. Wavenumber calculations were vectorized over wavenumber and multiprocessed over vertical level. All gridpoint calculations were vectorized over longitude, and the physics packages were brought into closer compliance with plug-compatibility rules. Speedups due to the optimization were demonstrated in single- and multiprocessing timing tests on a dedicated Cray 2 and Cray Y-MP. The enhanced physics GSM was evaluated in forecast tests, and contrasted with the simpler physics GSM used at GWC. Minimization of errors in the computation of the horizontal pressure gradient force was investigated, using a perturbation temperature instead of full temperature in the integration of the hydrostatic equation. Several schemes were tested in an idealized model atmosphere.

Results from the first year of a three-year contract to prototype a local thunderstorm forecast model are presented. This model seeks to use single Doppler radar data to continuously update a mesoscale forecast model which will predict crucial thunderstorm forecast parameters. Previous research has shown that assimilating Doppler wind information alone will not produce accurate model forecasts; a compatible temperature analysis must also be generated and assimilated alongside. We present results from an Observing System Simulation Experiment confirming these results and outlining a new assimilation and forecast system. This system will generate a quality 3-dimensional wind analysis from the single Doppler radar data, and will generate a compatible temperature analysis consistent with the wind analysis. It will then use the wind and temperature analyses to continuously nudge a mesoscale model toward the evolving boundary layer wind and temperature field.

This report summarizes results of a basic research program to investigate and develop advanced techniques for obtaining and applying meteorological parameters from spaceborne lidars. The focus of this program was to identify potentially inexpensive lidar sensor concepts which provide maximum paybacks in improvements to numerical weather prediction (NWP) model performance. As the result of a trade-off of potential lidar systems for measuring meteorological parameters such as temperature, moisture, and winds, it was determined that maximum payback for NWP could be achieved by improving the accuracy and coverage of wind observations. Since they will be available from a polar orbiter, coverage will be increased, especially for extratropical areas. The lidar will produce winds wherever there is a cloud and will likely provide boundary layer winds from maritime aerosol backscatter. The assessment of the impact of candidate satellite lidar observation concepts on numerical weather analysis and prediction models was performed through a series of observing system simulation experiments (OSSEs). In addition to NWP model impacts, the fusion of potential lidar sensor system data with that from the current Defense Meteorological Satellite Program (DMSP) suite of passive sensors was considered. Special emphasis was placed on investigating active/passive data fusion approaches for improving the retrieval of atmospheric temperature and moisture profiles and the analysis of clouds (i.e. nephanalysis) in support of tactical and strategic operations.

This reports documents the development and testing of an advanced geophysical parameter retrieval, analysis and prediction system for global numerical weather prediction. The additions and improvements to the existing data assimilation system at the Phillips Laboratory are the following: a new surface pressure analysis, modifications for high resolution analysis, an optimal retrieval of SSM/T data based on Bayesian estimation, use of precipitation data to improve the moisture and divergence analysis and as input to a diabatic nonlinear normal mode initialization. The system uses a version of the advanced physics global spectral model of PL. The results of simulation tests show a significant improvement of the moisture analyses, especially in the tropics and Southern Hemisphere, and a smaller, but detectable improvement of the other variables, except in the stratosphere.

FFTSCAN is a computer program which uses Fourier Transforms to convolve a spectrum with an instrument spectral scanning function. This technique mimics the operation of Fourier transform spectroscopy and preserves the full extent of the scanning function, which is particulary important for functions with large side lobes, like sin(x)/x. Five scanning functions commonly used in Fourier transform spectroscopy are available: sinc, sinc2, Beer, Hamming, and Hanning, plus triangle and gauss. The program is specifically adapted to process spectra created by the atmospheric transmittance/radiance program FASCODE. A special, disk-based Fourier transform routine allows FFTSCAN to handle spectra of any size. FFTSCAN is more accurate and as or more efficient that the existing equivalent FASCODE routines. This report describes the mathematical basis for spectral smoothing in the Fourier domain and gives the user instructions for FFTSCAN. It gives examples of spectral smoothing, including estimates of error limits and computational times, and provides guidance on implementing the program on different computers., Sponsored in part by Contracts F19628-86-C-0182, OptiMetrics, Inc., Ann Arbor, MI and F19628-83-C-0056, Stewart Radiance Lab.

This report summarizes work that was performed under a research contract with the Satellite Meteorology Branch of the Phillips Laboratory (Geophysics Directorate) Atmospheric Sciences Division. The topic addressed is the use of the Air Force Interactive Meteorological System (AIMS) as a research tool for the acquisition, processing, display and management of large sets of satellite data obtained from different platforms and sensors. Of particular importance is the foundation that AIMS provides for establishing an optimal satellite data processing system based on a systematic and integrated approach to data handling and manipulation. This foundation is composed of four functional areas: (1) access to meteorological data sources including: direct broadcast NOAA, DMSP, and GOES satellite data; global surface and upper air reports from the NWS Family of Services; and lightning data from the SUNY-Albany lightning detection network, (2) data visualization and processing that employs both 8-bit and 24-bit full color imaging workstations, and (3) interactive development, data analysis, and batch processing capabilities supported by mid- range performance minicomputers. This report includes a historical perspective of AIMS, its current configuration, a review of scientific applications supported by AIMS, ongoing work to provide an integrated approach to data management, analysis and processing, and a discussion of current short term needs and long range planning issues., Original contains color plates: All DTIC and NTIS reproductions will be in black and white.

RADTRAN is a model and computer program for computing atmospheric transmittance and radiance in the microwave region. The previous version of RADTRAN assumed a plane parallel non-refracting atmosphere for computing the amounts of absorbers and scatterers (e.g. oxygen, water vapor, clouds, rain) along the optical path. However, the plane-parallel assumption breaks down for zenith angles greater than about 80 degrees, leading to large errors in the calculated radiance and transmittance. The standard Phillips Lab atmospheric raytrace model FSCATM has been incorporated into RADTRAN as an option to calculate the absorber amounts. FSCATM uses spherical. refractive geometry to compute the layer-by-layer absorber amounts and density-weighted pressure and temperature for any slant path through the atmosphere. The atmospheric profiles from RADTRAN are retained. In the new program, called RADTRANS, the spherical-refractive geometry is available as an option, otherwise the program retains all the capabilities of the original version. However, the spherical geometry is incompatible with the multiple scattering model so the multiple scattering calculations must still be run using the plane-parallel geometry. Sample calculations are shown for the case of a satellite sensor scanning the nadir from 890 km. The radiance and the transmittance are calculated for 37, 90, and 150 GHz for both spherical and plane-parallel geometries. The results show differences of up to 70 K in brightness temperature at 37 GHz out near the horizon.... Microwave Radiation, Air mass, Atmospheric radiation, Transmittance/radiance models.

This study investigates the derivation of reentry-vehicle erosion parameter estimates based on the inference of rain rate and hydrometeor liquid water content from microwave imagery data from the Defense Meteorological Satellite Program (DMSP) sensors. Specifically, This research focuses on evaluation of Special Sensor Microwave/Imager (SSM/I) brightness temperature data to obtain a climatology of intense atmospheric precipitation at selected relevant land based sites for a four month summer period. An integral element of the study is identification of convective cloud models to support the analysis of hydrometeor liquid water content from the inferred surface rainfall rates. Tasks include: (1) development of SSM/I rain rate climatology; (2) development of hydrometeor liquid water content parameterization; (3) application of liquid water parameterization; and (4) documentation. Software was implemented to: (a) read the SSM/I TDRs from the acquired SSM/I data tapes; (b) calibrate and antenna pattern correct the data to obtain brightness temperatures; (c) bin the data according to the location of each desired site by latitude and longitude; (d) apply the rain rate retrieval algorithm to the data; and (e) evaluate relevant climatologies. The latter included four month summer time series of average rainfall rate, spatial standard deviation, and hydrometeor integrated liquid water content for eleven Eurasian sites.

Three topics are addressed: mesoscale prediction modeling, improvements and modifications to the Air Force real-time nephanalysis program, and on-site support for maintenance and enhancements to the Air Force Interactive Meteorological Processing System (AIMS). Mesoscale model work centered on the GL/LYP prediction model. An investigation of the model revealed several problems and inconsistencies when attempting to reproduce the Aster results. Numerous procedural changes were made to the model program to facilitate operation and interpretation of model results. Nephanalysis work was in a number of areas including: satellite data ingest and data base management, remapping of satellite data, and development of an atmospheric transmission band model to characterize infrared water vapor attenuation. Band model results were inconclusive due to model sensitivity to input data field quality, particularly surface temperature and vertical moisture profiles. AIMS support consisted of system management, technical support, and software development over a time of explosive system growth. During the period of the contract, 11 processing nodes were added to the cluster in addition to numerous peripheral devices and software upgrades., Original contains color plates: All DTIC/NTIS reproductions will be in black and white.

We have simulated the wind measurements which might be obtained from a low power doppler wind lidar (DWL) sensor. Wind profiles obtained from such an instrument will not be as complete as those expected from planned higher energy sensors (e.g.LAWS), with measurements only from cirrus clouds, the tops of other clouds, and from marine boundary layer aerosol. The potential impact of such a scaled down DWL system has been assessed by inserting the simulated measurements into the Air Force Phillips Laboratory Global Data Assimilation System (GDAS). Results from the observing system simulation experiment (OSSE) indicate that significant improvement in the analysis and forecast of geopotential height, horizontal wind, and relative humidity may be expected in the southern hemisphere extratropics. Comparison of impacts with those obtained in a previously conducted OSSE which assumed a full blown DWL instrument (WINDSAT) indicate that the low energy lidar yields improvements which are 1/2 to 3/4 magnitude of improvements with WINDSAT. Thus, if the development cost of a simple lidar is found to be substantially less than a LAWS-type sensor, such an instrument may warrant consideration in the planning of future space-based observing systems.

An observing system simulation experiment (OSSE) is conducted using simulated DMSP microwave sensor data, surrogate data for cloud imagery (all based on a natural run), and the application of the unified retrieval (UR) method for DMSP to obtain meteorological variables as proposed by Isaacs (23). Both the DMSP SSM/T-1 temperature sounder and SSM/T-2 moisture sounder data are simulated. The unified retrieval uses physical considerations based on a forecast or other first guess by comparing the sensor data with those simulated using the first guess profiles. Although the preliminary UR did not perform better than the statistical retrieval, enhanced UR are found to be more accurate in terms of integrated water vapor amounts. The retrieved variables, primarily temperature and moisture, are used to construct initial conditions for input to the AFGL global spectral numerical weather prediction model. The resulting analyses and forecasts based on the present statistical retrieval scheme. The impact of the preliminary UR used in this experiment was small. However the enhanced UR should provide improved humidity analyses. (JHD)

The objective of this study is the development of a vectorized, multiprocessing global spectral model (GSM) with enhanced physical parameterizations. The starting point for this work is the current Geophysics Laboratory (GL) GSM. Described is the multitasking and vectorization design for the GSM. One proposes to implement the latitude tasking scheme for multiprocessing the loop over latitude in the calculation of spectral tendencies and adjusted model variables. The general truncation version of the hydrodynamics code will be used. Wavenumber calculations will be multiprocessed and vectorized over wavenumber. All gridpoint calculations will be vectorized over longitude. The physics packages will be modified to bring them into close compliance with the plug compatibility rules.

Two forecast techniques were developed based on trend extrapolation of storm boundary represented by a fixed level contour) attributes. The two techniques differ in the selection of attributes upon which the forecast is based. The first technique performs an extrapolation of spatial characteristics of the system in order to predict position and shape. The second technique treats the storm boundary coordinates as periodic functions represented through Fourier transformation as a series of phase and amplitude coefficients. The magnitude of the coefficients, along with some physical constraints such as area or aspect ratio, are extrapolated to produce the forecast. The accuracy of the two techniques is currently under evaluation and results will be presented in a separate report.... Interactive data analysis, Satellite meteorology, Short term forecasting, Radar meteorology, Remote sensing.

This report has described the results of a study undertaken at AER to identify and implement a state of the art nonlinear retrieval approach to characterize line of sight variability of atmospheric thermal and constituent environments. This path characterization capability was designed to interface with the existing Geophysics Laboratory (GL) line-by-line radiance/transmittance code, FASCODE. Accomplishments of the study include: (a) a review of the relevant literature concerning potential path characterization retrieval algorithms, selection of a physical least squares (PLS) nonlinear retrieval approach for implementation based on criteria including flexibility within the context of FASCODE and a certain degree of robustness in application; (b) development of a stand alone, preprocessing screening procedure to identify potential channels for path characterization based on user requirements; (c) formulation and implementation of the path characterization retrieval algorithm including suitable interfaces with FASCODE; (d) inclusion of a comprehensive error analysis capability as an integral part of the retrieval procedure; (e) demonstration of the approach for the retrieval of temperature, water vapor and ozone; and (f) comprehensive documentation of the path characterization code implementations.

An evaluation of available approaches to treat the coupled processes of multiple-scattering due to atmospheric molecules and aerosols, and nongray absorption due to atmospheric gases is performed. Based on the evaluation and consideration of the requirements of efficiency, accuracy and code structure of LOWTRAN and FASCODE models, we recommend that an approach based on the stream approximation together with the k-distribution method is best suited for implementation into these models. The parameterization is unique in the sense that the k-distribution method decouples the multiple-scattering from the treatment of non-gray gaseous absorption so that the stream approximation can be used to treat multiple scattering in both the LOWTRAN and FASCODE models. The stream approximation is extremely attractive since it retains the analytical simplicity(and hence, efficiency) of single scattering while improving the treatment of multiple-scattering(and hence, accuracy).

A one-dimensional model has been developed to calculate densities and diurnal behavior of background trace gases as well as metal neutral and ionic species between 60 and 120 km. Particular attention has been given to the modeling of sodium species, given the availability of both observational and kinetic data.

An extensive literature review showed a disparity between the large amount of satellite data currently or potentially available for meteorological parameters and the relatively small amount that is actually utilized. The review also documented the various existing data retrieval techniques. Algorithms were developed and modified to retrieve temperature and moisture profiles from satellite infrared and millimeter/microwave radiances. Tools were developed, based on existing Air Force computer codes, to include and test the effect of satellite data in numerical weather prediction. The use of the logarithm of specific humidity as a forecast variable was investigated. The FGGE level II and III data sets existing at AFGL were completed to include all of the special observing periods and to form the basis of data assimilation tests. Finally, an attempt was made to optimize a cloudiness parameterization scheme on the basis of satellite retrievals. A number of recommendations are made for further work in satellite data retrieval, data assimilation and numerical weather prediction. They include the continuation of some of the items presented here, as well as suggestions for new avenues of research.

This report summarizes the results of an initial study to investigate the retrieval of water vapor profiles over land from several combinations of millimeter wave frequency channels, to compare the results obtained over land to performance expected over the ocean, and to assess the feasibility of obtaining cloud information from 183 GHz measurements. Brightness temperatures were simulated for four hypothetical millimeter wave moisture sounders using a recently developed sensor simulation model. Channel frequency selecton was investigated by comparing results from individual instrumental channel sets. In performing these simulations atmospheric data sets consisting of 400 radiosonde temperature and moisture profiles obtained over both land and ocean were used. The effect of beam-filling cloud on brightness temperatures was evaluated by incorporating physical cloud submodles. For representative cloud types within the simulation algorithm. Retrievals of vertical moisture profiles were accomplished by implementing a general statistical regression method which minimizes the mean square of interest. Retrieval statistics evaluated from a dependent subset of channel brightness temperatures and vertical water vapor profiles were applied subsequently to infer water vapor profiles from an independent set of brightness temperatures.

Concurrent visible and infrared cloud imagery from four satellite sensors (DMSP OLS, NOAA AVHRR, GOES VISSR, Landsat MSS) have been intercompared. Inherent differences in cloud field analyses are noted due to sensor characteristics such as spatial and spectral resolution and scene/sensor geometry. Digital data were manipulated to simulate one sensor's data from that of another. Recommendations for further analysis of the collected data set are provided.

A simulation model applicable to the design specification of a millimeter wave moisture sounder is described. The algorithm is capable of treating the response of a multifrequency radiometer to realistic variations in vertical profiles of atmospheric temperature and moisture, surface emissivity, cloud and precipitation. Analyses were performed to investigate the sensitivity of proposed moisture sounder channels to changes in the vertical distribution of atmospheric water vapor and the presence of cloud and rain. Preliminary studies based on statistical inversion methods demonstrate moisture retrieval capabilities in clear, cloudy, and precipitating cases. Results indicate that cloud and precipitation will most likely degrade moisture sounder performance. Investigation of moisture retrieval methodologies which explicitly treat cloud effects is recommended. Keywords: Atmospheric precipitation; Satellite meteorology; Computer codes; Multiple scattering; Radiative transfer; Clouds.

This report documents the results of our two-year Phase II effort to investigate the application of data from the proposed DMSP microwave moisture sounder (SSM/T-2) to the inference of water vapor profiles, temperature profiles, cloud, precipitation, and the properties of the underlying surface. The goal of this research is to provide a unified retrieval scheme capable of processing microwave and millimeter wave sensor (i.e., sounder and imager) data which extends the adopted operational algorithm based on a purely statistically based retrieval of temperature profiles from the SSM/T-1, moisture profiles from the SSM/T-2, and surface and atmospheric parameters such as precipitation and integrated cloud liquid water from the SSM/I. The approach uses two concepts to increase retrieval accuracy. First, physical considerations based on the application of the radiative transfer equation are used to quality control the statistically derived first guess retrievals. Second, data sources from colocated microwave mission sensors (i.e., the SSM/T-1, SSM/T-2, and SSM/I) are combined when necessary to more completely characterize the spectral dependence of the observed brightness temperatures on the meteorological properties of the surface and atmosphere. By combining data from all available sensors, the desired meteorological parameters can be more accurately determined. Based on our evaluation of cloud effects on millimeter wave brightness temperatures and water vapor retrievals (Isaacs and Deblonde, 1987), we have suggested use of the visible and infrared Operational Linescan System (OLS) to provide information on cloud presence.

We study the inference of humidity profiles from cloud data, using the 3DNEPH database as the source of the cloudiness information. The 3DNEPH (now RTNEPH) is a high resolution cloud database produced operationally by the USAF Global Weather Central. A colocation study of cloud data with radiosonde measurements of relative humidity over North America is used to develop and test a statistical method for inferring humidity profiles; a global data impact study is used to assess the utility of this moisture information. We review some previously developed methods for inferring humidity from cloud cover data, describe the database and processing used in our colocation study, and discuss the development and testing of the new method for inferring humidity. Regression equations were developed for the first two empirical orthogonal functions of relative humidity, using vertically compacted and horizontally averaged 3DNEPH cloud cover values as predictors. The regression equations were found to have smaller errors than existing level-to-level cloud to humidity conversion techniques in tests in which no attempt was made to tune the existing methods for optimal performance. The utility of the bogus RH data for operational data assimilation was studied in a global observing system experiment, using the AGGL global data assimilation system. The impact of the additional RH data was evident in analyses in the early part of the assimilation runs but was lost in the noise of the assimilation system at later times.

This report documents changes to and experiments designed to test the impact of these changes on the AFGL Statistical Analysis Program (ASAP) of heights and winds on the model sigma surfaces. Key enhancements include a new, simpler and more efficient method of converting pressure layer temperatures into sigma level heights, a corrected and improved handling of the least squares equations and a new solver for these systems of equations based on standard LINPACK routines. We conducted several offline tests of the new versions of procedures SATLTMP and ASAP2 which embody these enhancements to verify their correctness, to compare their results to results of the earlier versions and to tune certain control constants. We then conducted a one week data assimilation experiment, using simulated data to examine the impact of the enhanced ASAP. The changes made to ASAP have enhanced its consistency and operation. Separate studies of the satellite profile data preprocessing and the specification and solution of the normal equations demonstrated that the changes made are desirable. The overall positive impact of the enhancements is small as measured by a one week data assimilation experiment based on simulated data. Keywords: Data assimilation; Numerical weather prediction; Objective analysis; Optimal interpolation.

A preliminary exploration is made of the uses of multiprocessing computers for large scale NWP using spectral models. In general if global communication between processors is relatively fast and easy, then implementing spectral models is feasible. The global spectral model is recast in terms of latitude and wavenumber tasks. This approach has a number of advantages: The entire algorithm is macrotasked. Only a handful of crucial pointers need to be locked. The spectral transform calculations are localized so that arithmetic always follows the same ordering and all results are exactly reproducible. The latitude wavenumber tasking scheme is implemented and tested on the Sequent Balance, a shared memory multiple instruction multiple data device. It is argued that this scheme could be easily extended and applied to larger machines of this class and provide a good starting point for distributed memory machines. The potential of single instruction multiple data machines is huge. A proposed algorithm for this class of machine uses a processor for each horizontal grid point. Keywords: Numerical weather prediction; Multiprocessors; Atmosphere models; Weather forecasting.

Observing system simulation experiments (OSSEs) are conducted to assess the impact of the Special Sensor Microwave 183 GHz (SSM/T-2) water vapor sounder and the associated SSM/T-1 temperature sounder. Analyzed and forecast meteorological fields are improved by the addition of the SSM/T-1,2 temperature and humidity profiles. The greatest impacts occur in the Southern Hemisphere in the scenario when the civilian infrared sounder data are not available, i.e., when TOVS data are not assimilated. To calibrate the OSSE results, comparisons are made with real data observing system experiments (OSEs). These comparisons indicate that the expected impact of adding actual SSM/T-1,2 data with the stated geographic coverage and error characteristics, in the absence of TOVS data, would improve 500 mb height forecasts by approximately 12 hours in the Southern Hemisphere. However adding SSM/T-1,2 would have smaller impacts (8 h or less) in the Southern Hemisphere if added to the available TOVS data. Improvements for 200 mb wind forecasts in the tropics are: 36 hours for SSM/T-1, 2 alone and 12 hours for SSM/T-1,2 and TOVS together. Little impact was seen in moisture forecasts from the addition of the SSM data, but moisture and cloud analysis were clearly improved when the SSM data was assimilated; a decrease in global root mean square error of about 5% was indicated. Keywords: Meteorological data processing; Atmospheric temperature sounding; Weather forecasting data assimilation; Meteorological satellite observations.

Observing system simulation experiments (OSSEs) are conducted to assess the impact of a space borne Doppler wind lidar sensor. Analyzed and forecast meteorological fields are greatly improved by the addition of the lidar wind profiles. The greatest impacts are in the Southern Hemisphere height and wind fields and the tropical wind fields. In order to calibrate the OSSE results, comparisons are made with real data observing system experiments (OSEs) . These comparisons indicate that the expected impact of an actual lidar with the stated geographic coverage (equivalent to that of the current operational temperature sounders) and error characteristics (random, 1 m/s rms) would improve forecasts by approximately 36 hours in the Southern Hemisphere.

We have made substantial progress in areas related to improving NWP, especially the analysis and forecast of moisture and cloudiness, through spaceborne observing systems. We have: developed, implemented and evaluated techniques for retrieving geophysical parameters from satellite observations for use in NWP; tested the impact of these data and data from other sources in a series of observing system experiments (OSEs); developed and applied a comprehensive data simulation methodology; and conducted a series of observing system simulation experiments to evaluate the impact of new observing systems. Work in techniques development focused on retrieving relative humidity profiles from 3 distinct sources: the civilian infrared sounder (TOVS), the operational nephanalysis (3DNEPH) and the DMSP microwave sounder (SSM/T-1,2). The real data sources, TOVS and 3DNEPH, provided only marginally useful data, while in simulation, the SSM/T retrievals were significantly useful. A series of real data OSEs was conducted to measure the impact of retrieved humidity profile data as well as the impact of other satellite data. Two data denial experiments examined the effect of using limited surface-based data or of using satellite observations only. Such data systems are clearly inferior to the full operational system.

A basic research program is described to investigate weather effects on microwave sensors used to remote sounding and to enhance our knowledge of microwave propagation through clouds and precipitation. In this report, we describe the current RADTRAN algorithm, enumerate its deficiencies, and provide corrective solutions. The latter include; (a) updating the code structure providing user friendly menus and internal comments, (b) providing for consistency with standardized input model atmospheres currently implemented within other AFGL transmission/radiance models, (c) undertaking a comparison of the current algorithm with contemporary state-of-the-art transmittance/radiance codes to insure its fidelity and representativeness, (d) enhancing RADTRAN to treat multiple scattering, (e) providing calculations of polarized surface emissivities based on user specified surface types, and (f) document the code. Finally, we describe appropriate statistical retrieval schemes for inclusion in the code so that users can perform sensor simulation/retrieval studies. (RRH)

Part A of the report presents results from our model calculation of the diurnal behavior of the neutral and ionic sodium species. It is shown that the concentration of Na(+) above 90 km exerts a direct influence on the topside scale height of the atomic sodium layer in the mesosphere. The abundance of Na(+) is controlled by the reaction rate for the clustering reaction which is the rate limiting step for the conversion of Na(+) to Na. Downward transport of Na(+) due to ion drift is also effective in reducing the sodium abundance around 90 km. The model can successfully simulate the observed topside scale height of the sodium layer by either using a slow rate for the clustering reaction or incorporating transport of Na(+). Part B assesses the possible impact of sodium species on the stratospheric chlorine cycle. Recent measurements of kinetic rates suggest that the bulk of the sodium psecies could be in the form of NaCl in the stratosphere. Since the sodium abundance is three orders of magnitude smaller than that of chlorine, NaCl is not likely to be an important chlorine reservoir. Photolysis of NaCl could provide a mechanism for recycling HCl to Cl in the lower stratosphere if it is as fast as 0.001/s. However, the mechanism would not be effective if there exists another more stable form of sodium compound, such as NaHC03 or polymers of NaCl. Keywords: Ionospheric chemistry; Photochemistry; Ion chemistry; Upper atmosphere; Ionospheric models; D region; E region.

A study is made to calculate the diurnal behavior of the neutral sodium species (Na, NaO, NaO2, and NaOH) in the mesosphere using a one-dimensional photochemical model. The calculated results for Na are compared with available observations. The model results show that NaO2 is an important reservior for the sodium species in the atmosphere, and that the diurnal variation of Na in the mesosphere is, to a large extent, determined by the diurnal behavior of atomic oxygen. The role of NaOH as a temporary reservior for sodium and its possible effect on stratospheric chlorine chemistry remains unclear, as there is insufficient information from observation of Na to determine the rate for the atmospheric production of NaOH.

A mathematical model is described and documented which simulates the sensitivity of satellite incident visible and near infrared radiances (0.4-1.1 micron wavelength spectral interval) to variations in the meteorological variables (such as relative humidity and wind speed) characterizing the environment near the ocean surface. Potential applications include support of meteorological analysis of DMSP visible imagery and operational satellite-based retrieval of the aerosol contribution to optical range degradation. Attributes of the model include: (a) calculation of solar/satellite sub-point and scan line pixel location based on nominal DMSP orbital characteristics (b) choice of aerosol optical properties from among tropospheric, maritime, rural and urban models, (c) surface reflectivity based on statistics of wind-driven, rough ocean, and (d) approximate radiative transfer calculation of satellite incident radiances. The theoretical basis of each model subcomponent is fully discussed. A variety of supporting calculations are provided including radiance simulations in sunglint regions, DMSP imagery simulation, and comparison of simulated DMSP radiances to hardcopy imagery. The model is implemented in the form of a user-oriented, computationally efficient computer algorithm for a desk-top mini-computer. Documentation, listings, and sample test runs are provided.

This report presents major accomplishments and significant findings of atmospheric research performed under AFGL contract F19628-81-C-0016 for the period December 1980 - June 1982. The following topics are discussed: Review of recent developments in stratospheric chemistry; Modeling results on ozone perturbation studies; Results of the zonal-mean model calculations covering calculated species concentrations and atmospheric lifetimes; Role of meteoric metal in atmospheric chemistry. (Author)

An efficient modeling approach is described to simulate the dependence of remotely sensed radiances at visible and near infrared wavelengths (04.-1.1 microns) on meteorological variables such as relative humidity, wind speed, and visual range. Model elements include: (1) atmospheric opacity due to Rayleigh scattering and gaseous absorption; (2) physical modeling of aerosol size distribution; (3) aerosol optical properties calculations; and (4) implementation of radiative transfer theory. Sensitivity analyses are performed for these variables in the context of examining modeled meteorological influences in the marine environment on the DMSP VHR and LF sensors. The sensitivity of emergent radiances in the near infrared spectral windows to the presence of relative humidity and wind speed dependent coarse mode aerosols of oceanic origin is demonstrated.