Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472393
Yong Han, S. Melfi, J. Snider, R. Ferrare, E. Westwater
In radiometric remote sensing of the atmosphere, the ability to calculate radiances from underlying state variables is fundamental. Traditionally, such "forward model" calculations have coupled radiosonde observations of the state variables with detailed absorption and radiative transfer models to compare with radiance observations. However, for a variety of reasons, radiosondes are not always satisfactory, especially during low humidity conditions, or when there are large horizontal or temporal gradients in the humidity structure. The use of Raman lidar is an alternative method of measuring humidity profiles, and has the added advantage of providing knowledge that the atmosphere above the instruments is clear. In November-December 1991, a substantial number of remote sensor and in situ instruments were operated together in Coffeyville, Kansas, USA, during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE II). Included in the suite of instruments were (a) the NOAA Environmental Technology Laboratory's (ETL) three channel microwave radiometer; (b) the NASA/Goddard Space Flight Center's (GSFC) Raman lidar; (c) ETL's Radio Acoustic Sounding System (RASS) (7); and (d) frequent research-quality radiosondes. The authors present results of simultaneous microwave radiometer measurements with collocated Raman lidar measurements of water vapor. Information on temperature profiles was obtained from composite data from radiosondes and RASS. The Raman lidar soundings of humidity routinely reach 8.5 km during clear nighttime conditions, but reach only to 3-4 km during the day. During the presence of liquid-bearing clouds, the Raman lidar may not penetrate much beyond cloud base. However, a suite of ground-based sensors, such as Raman lidar, RASS, and microwave radiometers, could perhaps provide soundings during both day and night and during cloudy conditions that are also useful for meteorological remote sensing. Such an array of sensors has been operated on an experimental basis by the Department of Energy's Atmospheric Radiation Program, and further deployment by the ARM program is also planned.<>
{"title":"Comparison of measurements of water vapor by a microwave radiometer and Raman lidar","authors":"Yong Han, S. Melfi, J. Snider, R. Ferrare, E. Westwater","doi":"10.1109/COMEAS.1995.472393","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472393","url":null,"abstract":"In radiometric remote sensing of the atmosphere, the ability to calculate radiances from underlying state variables is fundamental. Traditionally, such \"forward model\" calculations have coupled radiosonde observations of the state variables with detailed absorption and radiative transfer models to compare with radiance observations. However, for a variety of reasons, radiosondes are not always satisfactory, especially during low humidity conditions, or when there are large horizontal or temporal gradients in the humidity structure. The use of Raman lidar is an alternative method of measuring humidity profiles, and has the added advantage of providing knowledge that the atmosphere above the instruments is clear. In November-December 1991, a substantial number of remote sensor and in situ instruments were operated together in Coffeyville, Kansas, USA, during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE II). Included in the suite of instruments were (a) the NOAA Environmental Technology Laboratory's (ETL) three channel microwave radiometer; (b) the NASA/Goddard Space Flight Center's (GSFC) Raman lidar; (c) ETL's Radio Acoustic Sounding System (RASS) (7); and (d) frequent research-quality radiosondes. The authors present results of simultaneous microwave radiometer measurements with collocated Raman lidar measurements of water vapor. Information on temperature profiles was obtained from composite data from radiosondes and RASS. The Raman lidar soundings of humidity routinely reach 8.5 km during clear nighttime conditions, but reach only to 3-4 km during the day. During the presence of liquid-bearing clouds, the Raman lidar may not penetrate much beyond cloud base. However, a suite of ground-based sensors, such as Raman lidar, RASS, and microwave radiometers, could perhaps provide soundings during both day and night and during cloudy conditions that are also useful for meteorological remote sensing. Such an array of sensors has been operated on an experimental basis by the Department of Energy's Atmospheric Radiation Program, and further deployment by the ARM program is also planned.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116023640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472373
V. M. Zemlianskii, F.J. Yanovsky
Presents a strategy for sizing aerosols and water droplets in air using multiwavelength and multisensor technology. The proposed optical-microwave measurement method is based upon the assumptions that the particles to be sized are spherical and traverse a uniform field of plane waves. The optical-microwave system with fixed differential frequency shift f/sub m/ between two beams of different wavelength has two microwave detectors and two detector receiving optics. Mie and Rayleigh theory are used in this analysis.<>
{"title":"Phase optical-microwave method for sizing droplets in air. Theory and numerical treatment","authors":"V. M. Zemlianskii, F.J. Yanovsky","doi":"10.1109/COMEAS.1995.472373","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472373","url":null,"abstract":"Presents a strategy for sizing aerosols and water droplets in air using multiwavelength and multisensor technology. The proposed optical-microwave measurement method is based upon the assumptions that the particles to be sized are spherical and traverse a uniform field of plane waves. The optical-microwave system with fixed differential frequency shift f/sub m/ between two beams of different wavelength has two microwave detectors and two detector receiving optics. Mie and Rayleigh theory are used in this analysis.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116827273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472377
J. Bosenberg, T. Schaberl, C. Senff
Exchange processes of trace gases in the troposphere play an important role in atmospheric dynamics and chemistry. In particular, the vertical transport of water vapor governs a major part of the energy balance, both through direct latent heat transport and through modification of the radiation field by cloud formation. Vertical mixing is most efficiently performed by convective processes, where latent heat release is one of the main driving forces. Ozone is an example for a chemically reactive gas, the importance of which has been increasingly recognized. While many measurements of this gas have been performed on ground stations, and of course in the stratosphere, there is relatively little knowledge about it's vertical distribution in the troposphere. The redistribution of this gas by convective mixing in the boundary layer has a large impact e.g. on the actual surface concentration. While in situ methods certainly can have adequate accuracy and resolution to study convective exchange processes, the available platforms for measurements throughout the boundary layer, e.g. aircraft or tethered balloons, require a rather big effort, both financially and with respect to manpower. In addition, tethered balloons are generally restricted in height and can only be operated in light to moderate minds, and with severe restrictions on the sites of operation. From aircraft it is almost impossible to derive true vertical profiles. Therefore, the authors have started the development of adequate remote sensing methods, some results of which are presented.<>
{"title":"Remote measurement of trace gas fluxes in the convective boundary layer using differential absorption lidar and radar/Rass","authors":"J. Bosenberg, T. Schaberl, C. Senff","doi":"10.1109/COMEAS.1995.472377","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472377","url":null,"abstract":"Exchange processes of trace gases in the troposphere play an important role in atmospheric dynamics and chemistry. In particular, the vertical transport of water vapor governs a major part of the energy balance, both through direct latent heat transport and through modification of the radiation field by cloud formation. Vertical mixing is most efficiently performed by convective processes, where latent heat release is one of the main driving forces. Ozone is an example for a chemically reactive gas, the importance of which has been increasingly recognized. While many measurements of this gas have been performed on ground stations, and of course in the stratosphere, there is relatively little knowledge about it's vertical distribution in the troposphere. The redistribution of this gas by convective mixing in the boundary layer has a large impact e.g. on the actual surface concentration. While in situ methods certainly can have adequate accuracy and resolution to study convective exchange processes, the available platforms for measurements throughout the boundary layer, e.g. aircraft or tethered balloons, require a rather big effort, both financially and with respect to manpower. In addition, tethered balloons are generally restricted in height and can only be operated in light to moderate minds, and with severe restrictions on the sites of operation. From aircraft it is almost impossible to derive true vertical profiles. Therefore, the authors have started the development of adequate remote sensing methods, some results of which are presented.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128299922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472317
B. M. Kendall, Michael C. Bailey, L. Schroeder
Microwave measurements of soil moisture are not being obtained at the required spatial Earth resolution with current technology. The Low Earth Orbit Microwave Radiometry Workshop held in Hampton, Virginia, identified measurements of soil moisture at a resolution of 10 km as the general science driver. Recently, new novel designs for lightweight reflector systems have been developed using deployable inflatable antenna structures which could enable lightweight real-aperture radiometers. In consideration of this, a study was conducted at the NASA Langley Research Center to determine the feasibility of developing a microwave radiometer system using inflatable reflector antenna technology to obtain high spatial resolution radiometric measurements of soil moisture from low Earth orbit and which could be used with a small and cost effective launch vehicle. The required high resolution with reasonable swath width coupled with the L-band measurement frequency for soil moisture dictated the use of a large (30 meter class) real aperture antenna in conjunction with a pushbroom antenna beam configuration and noise-injection type radiometer designs at 1.4 and 4.3 GHz to produce a 370 kilometer cross-track swath with a 10 kilometer resolution that could be packaged for launch with a Titan II class vehicle. This study includes design of the inflatable structure, control analysis, structural and thermal analysis, antenna and feed design, radiometer design, payload packaging, orbital analysis, and electromagnetic losses in the thin membrane inflatable materials.<>
{"title":"Inflatable antenna microwave radiometer for soil moisture measurement","authors":"B. M. Kendall, Michael C. Bailey, L. Schroeder","doi":"10.1109/COMEAS.1995.472317","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472317","url":null,"abstract":"Microwave measurements of soil moisture are not being obtained at the required spatial Earth resolution with current technology. The Low Earth Orbit Microwave Radiometry Workshop held in Hampton, Virginia, identified measurements of soil moisture at a resolution of 10 km as the general science driver. Recently, new novel designs for lightweight reflector systems have been developed using deployable inflatable antenna structures which could enable lightweight real-aperture radiometers. In consideration of this, a study was conducted at the NASA Langley Research Center to determine the feasibility of developing a microwave radiometer system using inflatable reflector antenna technology to obtain high spatial resolution radiometric measurements of soil moisture from low Earth orbit and which could be used with a small and cost effective launch vehicle. The required high resolution with reasonable swath width coupled with the L-band measurement frequency for soil moisture dictated the use of a large (30 meter class) real aperture antenna in conjunction with a pushbroom antenna beam configuration and noise-injection type radiometer designs at 1.4 and 4.3 GHz to produce a 370 kilometer cross-track swath with a 10 kilometer resolution that could be packaged for launch with a Titan II class vehicle. This study includes design of the inflatable structure, control analysis, structural and thermal analysis, antenna and feed design, radiometer design, payload packaging, orbital analysis, and electromagnetic losses in the thin membrane inflatable materials.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128788384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472325
S. Ismail, E. Browell
The Lidar Atmospheric Sensing Experiment (LASE) is a highly engineered and autonomous Differential Absorption Lidar (DIAL) system developed at NASA Langley Research Center (LaRC) to measure high-resolution water vapor and aerosol profiles in the troposphere. LASE is being developed as a precursor to the deployment of a spaceborne DIAL system for global measurement of high-resolution water vapor profiles. The LASE system uses a tunable Ti:sapphire laser that is frequency locked to pre-selected water vapor lines in the 815-nm region. LASE is undergoing a series of engineering test flights onboard a high-altitude ER-2 aircraft to evaluate its initial performance before deployment on field programs. During the first engineering test flight conducted near NASA Ames Research Center in May 1994, LASE was operated in the backscattered lidar mode and obtained high-quality aerosol profiles in the 0-20 km altitude region. During a subsequent engineering flight series conducted near NASA Wallops Flight facility in September 1994, water vapor and aerosol profiles were obtained simultaneously under a variety of cloud and background conditions. This paper discusses the results of the water vapor and aerosol measurements made during these flights. These measurements will be used to evaluate the performance of the instrument and for comparison with predicted values of atmospheric signals and water vapor profiles derived from in situ measurements from radiosondes launched in the vicinity of LASE measurements. These results will be used to refine the LASE system for a final engineering test series planned for early 1995. Plans for the validation of the LASE instrument with other in situ and remote sensors and the anticipated field program participation are also discussed.<>
{"title":"NASA LASE water vapor differential absorption lidar measurements and performance evaluation","authors":"S. Ismail, E. Browell","doi":"10.1109/COMEAS.1995.472325","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472325","url":null,"abstract":"The Lidar Atmospheric Sensing Experiment (LASE) is a highly engineered and autonomous Differential Absorption Lidar (DIAL) system developed at NASA Langley Research Center (LaRC) to measure high-resolution water vapor and aerosol profiles in the troposphere. LASE is being developed as a precursor to the deployment of a spaceborne DIAL system for global measurement of high-resolution water vapor profiles. The LASE system uses a tunable Ti:sapphire laser that is frequency locked to pre-selected water vapor lines in the 815-nm region. LASE is undergoing a series of engineering test flights onboard a high-altitude ER-2 aircraft to evaluate its initial performance before deployment on field programs. During the first engineering test flight conducted near NASA Ames Research Center in May 1994, LASE was operated in the backscattered lidar mode and obtained high-quality aerosol profiles in the 0-20 km altitude region. During a subsequent engineering flight series conducted near NASA Wallops Flight facility in September 1994, water vapor and aerosol profiles were obtained simultaneously under a variety of cloud and background conditions. This paper discusses the results of the water vapor and aerosol measurements made during these flights. These measurements will be used to evaluate the performance of the instrument and for comparison with predicted values of atmospheric signals and water vapor profiles derived from in situ measurements from radiosondes launched in the vicinity of LASE measurements. These results will be used to refine the LASE system for a final engineering test series planned for early 1995. Plans for the validation of the LASE instrument with other in situ and remote sensors and the anticipated field program participation are also discussed.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125867541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472394
A. Fung, D. Gibbs, Z. Li, C. Betty
In modeling of electromagnetic (EM) interaction with terrain one must first examine the geometry of the scatterers relative to the incident wavelength and the electromagnetic properties of the terrain in the frequency region of interest. The purpose of this study is to examine the similarities and differences in developing scattering models for soil and leaves in the optical and microwave regions. For interpretation of remotely sensed data, the scattering model should be a function of geometric and EM parameters which in turn may depend on other physical, biological and physiological parameters of interest. The authors discuss the anticipated sources of scattering, the absorption properties that are known and the geometry of the scattering problem appropriate for each frequency region.<>
{"title":"Modeling considerations of EM scattering from soil and leaves in the optical and microwave regions","authors":"A. Fung, D. Gibbs, Z. Li, C. Betty","doi":"10.1109/COMEAS.1995.472394","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472394","url":null,"abstract":"In modeling of electromagnetic (EM) interaction with terrain one must first examine the geometry of the scatterers relative to the incident wavelength and the electromagnetic properties of the terrain in the frequency region of interest. The purpose of this study is to examine the similarities and differences in developing scattering models for soil and leaves in the optical and microwave regions. For interpretation of remotely sensed data, the scattering model should be a function of geometric and EM parameters which in turn may depend on other physical, biological and physiological parameters of interest. The authors discuss the anticipated sources of scattering, the absorption properties that are known and the geometry of the scattering problem appropriate for each frequency region.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122767166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472389
K. Sassen
Joint cloud remote sensing research using radar, lidar, and passive optical and microwave techniques began over 25 years ago, not long after the development of field-worthy laser systems. Concurrent field measurements of thunderstorm clouds and anvils were made in 1970 by a polarization ruby (0.69 /spl mu/m) lidar transported from New York University and a scanning 10-cm radar system from the South Dakota School of Mines and Technology near Rapid City. At about the same time, a program was initiated at the NOAA Wave Propagation Laboratory in Boulder, CO, primarily from laser eye-safety concerns, to coalign a K-band radar with a scanning mirror assembly used to point the laser beam. Although polarization lidar findings from this early research phase were published (1), serious intercomparisons with the radar data were not attempted. However, since that time the multiple remote sensor approach has steadily gained acceptance in the cloud physics research community with the recognition of the synergistic qualities of diverse, multiwavelength datasets. Examples of the integration of active and passive optical and microwave remote sensing methods, which currently constitute a major meteorological research emphasis, as applied to cloud research programs are reviewed.<>
{"title":"Combined microwave and optical remote sensing of clouds: a review","authors":"K. Sassen","doi":"10.1109/COMEAS.1995.472389","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472389","url":null,"abstract":"Joint cloud remote sensing research using radar, lidar, and passive optical and microwave techniques began over 25 years ago, not long after the development of field-worthy laser systems. Concurrent field measurements of thunderstorm clouds and anvils were made in 1970 by a polarization ruby (0.69 /spl mu/m) lidar transported from New York University and a scanning 10-cm radar system from the South Dakota School of Mines and Technology near Rapid City. At about the same time, a program was initiated at the NOAA Wave Propagation Laboratory in Boulder, CO, primarily from laser eye-safety concerns, to coalign a K-band radar with a scanning mirror assembly used to point the laser beam. Although polarization lidar findings from this early research phase were published (1), serious intercomparisons with the radar data were not attempted. However, since that time the multiple remote sensor approach has steadily gained acceptance in the cloud physics research community with the recognition of the synergistic qualities of diverse, multiwavelength datasets. Examples of the integration of active and passive optical and microwave remote sensing methods, which currently constitute a major meteorological research emphasis, as applied to cloud research programs are reviewed.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121545850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472337
M. Keller, B. Gotwols, W. Plant, W. Keller
Microwave backscatter from the ocean surface has long been assumed to be proportional to the spectral density of windwaves at the Bragg-resonant wavelength. Although the spectral density of gravity-capilary waves is primarily a function of wind forcing, interactions with longer waves are also an important factor in wave-wave energy transfer. Thus, the microwave backscatter should be affected by the presence of longer waves as well. Any effort to measure the effects of longer waves on the backscatter, usually referred to as the modulation transfer function, or mtf: should include both direct measurement of the backscatter and direct measurement of the short-wave spectral density. The authors have used microwave and millimeter-wave scatterometers at 10 GHz (X-band), 35 GHz (K/sub /spl alpha// band), and 70 GHz (V band) to measure the backscatter. All three microwave instruments are CW Doppler systems. The X-band scatterometer offsets the Doppler by 400 Hz so both the upwind and downwind peaks can recorded. The remaining systems are I&Q instruments, where the RF signal modulates a 60 MHz carrier wave, and the I&Q are retrieved from the 60 MHz carrier in a separate section. The microwave signals are sampled at 3 kHz using a Data Translation A/D card in a PC, and the data are stored on 8 mm EXABYTE type. The microwave and optical systems were all aligned to view the same spot on the water, at a fetch of 16.5 meters.<>
{"title":"Wave-wave interactions in a wind-wavetank as measured with microwave and optical systems","authors":"M. Keller, B. Gotwols, W. Plant, W. Keller","doi":"10.1109/COMEAS.1995.472337","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472337","url":null,"abstract":"Microwave backscatter from the ocean surface has long been assumed to be proportional to the spectral density of windwaves at the Bragg-resonant wavelength. Although the spectral density of gravity-capilary waves is primarily a function of wind forcing, interactions with longer waves are also an important factor in wave-wave energy transfer. Thus, the microwave backscatter should be affected by the presence of longer waves as well. Any effort to measure the effects of longer waves on the backscatter, usually referred to as the modulation transfer function, or mtf: should include both direct measurement of the backscatter and direct measurement of the short-wave spectral density. The authors have used microwave and millimeter-wave scatterometers at 10 GHz (X-band), 35 GHz (K/sub /spl alpha// band), and 70 GHz (V band) to measure the backscatter. All three microwave instruments are CW Doppler systems. The X-band scatterometer offsets the Doppler by 400 Hz so both the upwind and downwind peaks can recorded. The remaining systems are I&Q instruments, where the RF signal modulates a 60 MHz carrier wave, and the I&Q are retrieved from the 60 MHz carrier in a separate section. The microwave signals are sampled at 3 kHz using a Data Translation A/D card in a PC, and the data are stored on 8 mm EXABYTE type. The microwave and optical systems were all aligned to view the same spot on the water, at a fetch of 16.5 meters.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134511852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472374
T. D. Stevens, C. R. Philbrick
The scattering of optical radiation in the visible, ultraviolet and infrared regions of the spectrum has a major impact on commercial air traffic and on many military systems. It has become critically important, with modern systems, that the electro-optical environment be properly characterized. Lidar techniques show great promise for describing the electro-optical scattering environment. Most of the past applications of lidar have failed to provide satisfactory results because the techniques have generally focused on measurements of the backscattered radiation at the laser fundamental wavelength. The authors have been able to demonstrate that the rotational and vibrational Raman backscatter can be used to determine the extinction profile through optical scattering regions containing aerosols and cloud layers. They have developed a secondary bi-static remote receiver designed to collect scattering angle and polarization information from a laser remote sensing system. This instrument collects an image of the radiation scattered from the first few kilometers of the atmospheric path to help determine atmospheric particle size distributions. By collecting data at different angles from the laser transmitter, additional information contained in the scattering angle phase function can be obtained. The Raman lidar extinction together with the backscatter phase function and polarization provide information on the particle size distribution that should allow extension of the extinction and transmission calculations to a wider range of wavelengths.<>
{"title":"Atmospheric extinction from Raman lidar and a bi-static remote receiver","authors":"T. D. Stevens, C. R. Philbrick","doi":"10.1109/COMEAS.1995.472374","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472374","url":null,"abstract":"The scattering of optical radiation in the visible, ultraviolet and infrared regions of the spectrum has a major impact on commercial air traffic and on many military systems. It has become critically important, with modern systems, that the electro-optical environment be properly characterized. Lidar techniques show great promise for describing the electro-optical scattering environment. Most of the past applications of lidar have failed to provide satisfactory results because the techniques have generally focused on measurements of the backscattered radiation at the laser fundamental wavelength. The authors have been able to demonstrate that the rotational and vibrational Raman backscatter can be used to determine the extinction profile through optical scattering regions containing aerosols and cloud layers. They have developed a secondary bi-static remote receiver designed to collect scattering angle and polarization information from a laser remote sensing system. This instrument collects an image of the radiation scattered from the first few kilometers of the atmospheric path to help determine atmospheric particle size distributions. By collecting data at different angles from the laser transmitter, additional information contained in the scattering angle phase function can be obtained. The Raman lidar extinction together with the backscatter phase function and polarization provide information on the particle size distribution that should allow extension of the extinction and transmission calculations to a wider range of wavelengths.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133084155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472319
G. Skofronick-Jackson, A. Gasiewski
An appropriate level of detail in the microphysical parameterization of clouds and rain cells is essential to the development of realistic atmospheric forward radiative transfer models. Too much detail can inflate computation time and complexity by supporting meaningless degrees of freedom, while too little detail can result in an inadequate model. The particle phase, size distribution, aggregate density, shape, and dielectric constant govern the absorption and scattering properties of a hydrometeor-laden atmosphere. In order to evaluate hydrometeor parameterizations for wideband (10-325 GHz) RT modelling a statistical comparison was performed between brightness temperatures observed over a mature oceanic convective storm and those calculated for a similar storm using two- and five-phase hydrometeor parameterizations in a planar-stratified RT model. While general agreement is obtained, the comparisons suggest that neither the two-phase nor five-phase model is entirely satisfactory for wideband brightness temperature simulations.<>
{"title":"A statistical comparison of calculated brightness temperatures with aircraft-based observations from 10 to 325 GHz","authors":"G. Skofronick-Jackson, A. Gasiewski","doi":"10.1109/COMEAS.1995.472319","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472319","url":null,"abstract":"An appropriate level of detail in the microphysical parameterization of clouds and rain cells is essential to the development of realistic atmospheric forward radiative transfer models. Too much detail can inflate computation time and complexity by supporting meaningless degrees of freedom, while too little detail can result in an inadequate model. The particle phase, size distribution, aggregate density, shape, and dielectric constant govern the absorption and scattering properties of a hydrometeor-laden atmosphere. In order to evaluate hydrometeor parameterizations for wideband (10-325 GHz) RT modelling a statistical comparison was performed between brightness temperatures observed over a mature oceanic convective storm and those calculated for a similar storm using two- and five-phase hydrometeor parameterizations in a planar-stratified RT model. While general agreement is obtained, the comparisons suggest that neither the two-phase nor five-phase model is entirely satisfactory for wideband brightness temperature simulations.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"57 6 Suppl 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116518939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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