Pub Date : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430702
D. Draper, D. Newell
The Global Precipitation Measurement (GPM) Microwave Imager (GMI) launched aboard the GPM Core Observatory as a joint mission between the National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA) has operated with high stability for four years. The noise equivalent delta temperature (NEDT) for each channel has be exceptionally stable. Non-linearity as measured using the 4-point calibration technique has been shown to be stable within +/-0.02K. Calibration features such as the hot load, cold sky reflector and main reflector coating continue to provide high quality calibration with no discernable degradation of performance. The on-orbit trending of calibration is facilitated using the on-board noise sources. The antenna was calibrated on-orbit to within 0.25K 1-sigma over the ocean.
{"title":"Global Precipitation Measurement (GPM) Microwave Imager (GMI) After Four Years On-Orbit","authors":"D. Draper, D. Newell","doi":"10.1109/MICRORAD.2018.8430702","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430702","url":null,"abstract":"The Global Precipitation Measurement (GPM) Microwave Imager (GMI) launched aboard the GPM Core Observatory as a joint mission between the National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA) has operated with high stability for four years. The noise equivalent delta temperature (NEDT) for each channel has be exceptionally stable. Non-linearity as measured using the 4-point calibration technique has been shown to be stable within +/-0.02K. Calibration features such as the hot load, cold sky reflector and main reflector coating continue to provide high quality calibration with no discernable degradation of performance. The on-orbit trending of calibration is facilitated using the on-board noise sources. The antenna was calibrated on-orbit to within 0.25K 1-sigma over the ocean.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127862526","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430697
C. Lewis-Beck, Jarad Niemi, Petruta Caragea, B. Hornbuckle, Victoria A. Walker
The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite has recently been shown to measure variables containing information relevant to agronomists. SMOS was initially intended to monitor the water content of soil. However, a combination of SMOS's antenna technology and data processing algorithms make it possible to estimate the mass of water contained in vegetation tissue. Recent work by Hornbuckle et al. shows this new variable Τ roughly mirrors the growth and senescence of crops [1]. In this paper we analyze SMOS data from an intensively cultivated agricultural region in the Midweset to provide new information about crop phenology. In addition to modeling the seasonal pattern of crop growth, we estimate the day of the year when Τ reaches its peak. Because SMOS has a fine temporal resolution, the ability to model Τ during a growing season could be useful to understanding changes in crop development, climate conditions, as well as forecasting future growth cycles.
{"title":"Monitoring Crop Growth in the Us Corn Belt with SMOS Level 2 Tau","authors":"C. Lewis-Beck, Jarad Niemi, Petruta Caragea, B. Hornbuckle, Victoria A. Walker","doi":"10.1109/MICRORAD.2018.8430697","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430697","url":null,"abstract":"The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite has recently been shown to measure variables containing information relevant to agronomists. SMOS was initially intended to monitor the water content of soil. However, a combination of SMOS's antenna technology and data processing algorithms make it possible to estimate the mass of water contained in vegetation tissue. Recent work by Hornbuckle et al. shows this new variable Τ roughly mirrors the growth and senescence of crops [1]. In this paper we analyze SMOS data from an intensively cultivated agricultural region in the Midweset to provide new information about crop phenology. In addition to modeling the seasonal pattern of crop growth, we estimate the day of the year when Τ reaches its peak. Because SMOS has a fine temporal resolution, the ability to model Τ during a growing season could be useful to understanding changes in crop development, climate conditions, as well as forecasting future growth cycles.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132520018","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430700
G. Lagerloef, D. Carey, H. Kao
The Aquarius satellite mission was developed to measure the ocean's sea surface salinity (SSS) field and to investigate the links between changes in the global water cycle, ocean circulation and climate variability. The mission ended in June 2015 because of a power supply malfunction on the satellite. A recent data re-calibration and re-processing as produced Aquarius data version V5.0, released in December 2017. Key Aquarius science objectives were to (1) map the mean SSS field, (2) measure the annual SSS cycle, and (3) document interannual variations, within a three-year minimum duration. This study addresses objectives (2) and (3) by using co-located in situ data to verify that there is no significant spurious radiometer calibration drift on these time scales. The analysis converts the in situ salinity and temperature data (primarily from Argo floats) to an expected radiometer brightness temperature (TB), and computes the differences of these from the Aquarius radiometer-derived TB. The crux of the analysis is separating the sensor drift from the varying environmental corrections in the retrieval algorithm. The approach is to aggregate these co-located Tb differences within geographical zones (for example northern and southern hemispheres, ascending and descending passes), and then comparing the differences between these zones (double-difference). Next, regression analyses isolate the sensor variations from the environmental ones. The key assumption is that the long term (seasonal to interannual) radiometer calibration drift is a common signal among the various zones. This report explains this calculation and presents the results achieved with Aquarius V5.0 ocean salinity data release. Calibration histories for each of the six Aquarius radiometer channels are derived. The residuals are attributed to environmental model errors within each zone. Understanding these remains more problematic. The future study will be to adapt the technique to SMAP, and eventually SMOS measurements to enable a systematic cross-calibration of the different satellite systems and obtain a reliable combined multi-year time series for studying ocean trends.
{"title":"Verifying Aquarius Radiometer Calibration Drift Using in Situ Data","authors":"G. Lagerloef, D. Carey, H. Kao","doi":"10.1109/MICRORAD.2018.8430700","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430700","url":null,"abstract":"The Aquarius satellite mission was developed to measure the ocean's sea surface salinity (SSS) field and to investigate the links between changes in the global water cycle, ocean circulation and climate variability. The mission ended in June 2015 because of a power supply malfunction on the satellite. A recent data re-calibration and re-processing as produced Aquarius data version V5.0, released in December 2017. Key Aquarius science objectives were to (1) map the mean SSS field, (2) measure the annual SSS cycle, and (3) document interannual variations, within a three-year minimum duration. This study addresses objectives (2) and (3) by using co-located in situ data to verify that there is no significant spurious radiometer calibration drift on these time scales. The analysis converts the in situ salinity and temperature data (primarily from Argo floats) to an expected radiometer brightness temperature (TB), and computes the differences of these from the Aquarius radiometer-derived TB. The crux of the analysis is separating the sensor drift from the varying environmental corrections in the retrieval algorithm. The approach is to aggregate these co-located Tb differences within geographical zones (for example northern and southern hemispheres, ascending and descending passes), and then comparing the differences between these zones (double-difference). Next, regression analyses isolate the sensor variations from the environmental ones. The key assumption is that the long term (seasonal to interannual) radiometer calibration drift is a common signal among the various zones. This report explains this calculation and presents the results achieved with Aquarius V5.0 ocean salinity data release. Calibration histories for each of the six Aquarius radiometer channels are derived. The residuals are attributed to environmental model errors within each zone. Understanding these remains more problematic. The future study will be to adapt the technique to SMAP, and eventually SMOS measurements to enable a systematic cross-calibration of the different satellite systems and obtain a reliable combined multi-year time series for studying ocean trends.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134070318","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430715
Alamgir Hossan, M. Jacob, W. Linwood Jones, Harriet Medrozo
This paper describes a novel ocean vector wind (OVW) retrieval algorithm that uses Ku-band Precipitation Radar (PR) and the multi-frequency TRMM Microwave Imager (TMI), both on board the Tropical Rainfall Measuring Mission (TRMM) satellite. The basis of this algorithm is the anisotropic nature of ocean backscatter (sig-0) and brightness temperature (Tb), which are used in a maximum likelihood estimation procedure to infer wind speed and wind direction. For this paper, we leverage from previous research that characterized the Geophysical Model Functions (GMF) for both TMI and PR observations. NOAA Numerical Weather Product (GDAS) was used as a nature run, to perform a Monte Carlo simulation to conduct trade studies and predict the OVW retrieval performance over the TRMM orbit. Examples of retrieved ocean winds and statistics of WS and WD differences are presented.
{"title":"An Active/Passive Microwave Retrieval Algorithm for Inferring Ocean Vector Winds from TRMM","authors":"Alamgir Hossan, M. Jacob, W. Linwood Jones, Harriet Medrozo","doi":"10.1109/MICRORAD.2018.8430715","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430715","url":null,"abstract":"This paper describes a novel ocean vector wind (OVW) retrieval algorithm that uses Ku-band Precipitation Radar (PR) and the multi-frequency TRMM Microwave Imager (TMI), both on board the Tropical Rainfall Measuring Mission (TRMM) satellite. The basis of this algorithm is the anisotropic nature of ocean backscatter (sig-0) and brightness temperature (Tb), which are used in a maximum likelihood estimation procedure to infer wind speed and wind direction. For this paper, we leverage from previous research that characterized the Geophysical Model Functions (GMF) for both TMI and PR observations. NOAA Numerical Weather Product (GDAS) was used as a nature run, to perform a Monte Carlo simulation to conduct trade studies and predict the OVW retrieval performance over the TRMM orbit. Examples of retrieved ocean winds and statistics of WS and WD differences are presented.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121693854","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430720
S. Cruz-Pol, Liese Van Zee, N. Kassim, W. Blackwell, D. L. Le Vine, Agnes Scott
The ever-increasing demand for the radio frequency (RF) spectrum is transforming radio regulations at national and international levels at an increasingly frenzied pace. Observations collected with radio-astronomy and Earth remote sensing instruments can easily be rendered unusable due to Radio Frequency Interference (RFI) whether it is from out-of-band (OOBE) or spurious emissions in the bands used by these sensors. The RFI could originate from a single transmitter or the aggregate effects of a collection of many transmitting sources using the same frequency (e.g. spurious radiation from a poorly designed TV receiver) or different frequencies, e.g., OOBE. The aggregate case is particularly problematic because the collective signal can be indistinguishable from natural radiation. The Committee on Radio Frequencies (CORF) is a standing committee of the United States' National Academy of Sciences (NAS), that represents the scientific users of the radio spectrum at national and international fora. This paper will present a brief overview of spectrum management within the USA and the role of CORF. It will also describe some of the important issues to be dealt with at thr World Radiocommunication Conference-2019 (WRC19) and their potential impact on radio astronomy and passive remote sensing.
{"title":"Spectrum Management and the Impact of RFI on Science Sensors","authors":"S. Cruz-Pol, Liese Van Zee, N. Kassim, W. Blackwell, D. L. Le Vine, Agnes Scott","doi":"10.1109/MICRORAD.2018.8430720","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430720","url":null,"abstract":"The ever-increasing demand for the radio frequency (RF) spectrum is transforming radio regulations at national and international levels at an increasingly frenzied pace. Observations collected with radio-astronomy and Earth remote sensing instruments can easily be rendered unusable due to Radio Frequency Interference (RFI) whether it is from out-of-band (OOBE) or spurious emissions in the bands used by these sensors. The RFI could originate from a single transmitter or the aggregate effects of a collection of many transmitting sources using the same frequency (e.g. spurious radiation from a poorly designed TV receiver) or different frequencies, e.g., OOBE. The aggregate case is particularly problematic because the collective signal can be indistinguishable from natural radiation. The Committee on Radio Frequencies (CORF) is a standing committee of the United States' National Academy of Sciences (NAS), that represents the scientific users of the radio spectrum at national and international fora. This paper will present a brief overview of spectrum management within the USA and the role of CORF. It will also describe some of the important issues to be dealt with at thr World Radiocommunication Conference-2019 (WRC19) and their potential impact on radio astronomy and passive remote sensing.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120975869","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430713
Cheng Zhang, Hao Liu, Ji Wu
Clock Scanning Microwave Interferometric Radiometer (CS-MIR) is a new concept of synthetic aperture radiometer. It has the advantages of simple array structure, easy deployment and resultingly being able to achieve high spatial resolution. Recently a ground-based prototype of CS-MIR working at L-band has been developed. This paper presents the calibration method of this instrument. Compared with the SMOS/MIRAS system, the calibration of the CS-MIR is much simple. The simplicity is mainly lies in three aspects: It does not need quadrature error correction because of the digital I/Q demodulation, not need PMS subsystem for visibility demoralization and not need correlated noise injection for phase calibration.
{"title":"Calibration of Clock Scanning Microwave Interferometric Radiometer","authors":"Cheng Zhang, Hao Liu, Ji Wu","doi":"10.1109/MICRORAD.2018.8430713","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430713","url":null,"abstract":"Clock Scanning Microwave Interferometric Radiometer (CS-MIR) is a new concept of synthetic aperture radiometer. It has the advantages of simple array structure, easy deployment and resultingly being able to achieve high spatial resolution. Recently a ground-based prototype of CS-MIR working at L-band has been developed. This paper presents the calibration method of this instrument. Compared with the SMOS/MIRAS system, the calibration of the CS-MIR is much simple. The simplicity is mainly lies in three aspects: It does not need quadrature error correction because of the digital I/Q demodulation, not need PMS subsystem for visibility demoralization and not need correlated noise injection for phase calibration.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117220403","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430704
D. Burrage, Magdalena D. Angulelova, David W. Wang, J. Wesson
Many previous laboratory, field and remote sensing studies have empirically quantified whitecap (WC) parameters such as coverage and scale, foam layer thickness, and bubble plume profiles, but only a few have simulated foam layer or WC microwave reflectivity and emissivity using analytical and numerical electro-magnetic (E-M) models. We report the development and application of a Finite-Difference Time-Domain (FDTD) E-M model to investigate the emissivity, reflectivity and detectability of WCs. The model solves Maxwell's equations directly for an arbitrary free space and dielectric configuration. It is applied to multiple dielectric layers representing foam and spray overlying a rough sea surface. The foam layer profiles are adapted from Anguelova's L-band radiative transfer model (RTM), and the rough surface is a statistical realization of the Kudryavtsev wave spectrum model. The accuracy and precision of model emissivity estimates, the roughness emissivity increment, and detectability of WCs using L-band radiometry, are assessed under various wind conditions. Possible enhancements using Monte-Carlo simulation and more deterministic simulations of active breakers with WCs of various void fractions, shapes and scales, are also considered.
{"title":"Predicting L-Band Emissivity of a Wind-Roughened Sea with Foam Layers or Whitecaps and Overlying Spray, Using a Finite-Difference Time-Domain Model","authors":"D. Burrage, Magdalena D. Angulelova, David W. Wang, J. Wesson","doi":"10.1109/MICRORAD.2018.8430704","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430704","url":null,"abstract":"Many previous laboratory, field and remote sensing studies have empirically quantified whitecap (WC) parameters such as coverage and scale, foam layer thickness, and bubble plume profiles, but only a few have simulated foam layer or WC microwave reflectivity and emissivity using analytical and numerical electro-magnetic (E-M) models. We report the development and application of a Finite-Difference Time-Domain (FDTD) E-M model to investigate the emissivity, reflectivity and detectability of WCs. The model solves Maxwell's equations directly for an arbitrary free space and dielectric configuration. It is applied to multiple dielectric layers representing foam and spray overlying a rough sea surface. The foam layer profiles are adapted from Anguelova's L-band radiative transfer model (RTM), and the rough surface is a statistical realization of the Kudryavtsev wave spectrum model. The accuracy and precision of model emissivity estimates, the roughness emissivity increment, and detectability of WCs using L-band radiometry, are assessed under various wind conditions. Possible enhancements using Monte-Carlo simulation and more deterministic simulations of active breakers with WCs of various void fractions, shapes and scales, are also considered.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128196627","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430698
I. Corbella, F. Torres, N. Duffo, I. Durán, R. Oliva, M. Martín-Neira
Using land-sea transitions as two-level targets, the gain parameter of the three Noise Injection Radiometers (NIR) installed in instrument MIRAS onboard ESA's SMOS satellite are independently estimated. The reference data for this calibration is the average antenna temperature measured simultaneously by the other MIRAS receivers operating as total power radiometers. Individually, the retrieved parameters show similar values to the nominal sky-calibrated ones, but long-term series of data reveal different seasonal behavior, suggesting that external maneuvers may have a non-negligible impact on the NIR front-end stability.
{"title":"Self-Consistent Amplitude Calibration of Miras-SMOS","authors":"I. Corbella, F. Torres, N. Duffo, I. Durán, R. Oliva, M. Martín-Neira","doi":"10.1109/MICRORAD.2018.8430698","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430698","url":null,"abstract":"Using land-sea transitions as two-level targets, the gain parameter of the three Noise Injection Radiometers (NIR) installed in instrument MIRAS onboard ESA's SMOS satellite are independently estimated. The reference data for this calibration is the average antenna temperature measured simultaneously by the other MIRAS receivers operating as total power radiometers. Individually, the retrieved parameters show similar values to the nominal sky-calibrated ones, but long-term series of data reveal different seasonal behavior, suggesting that external maneuvers may have a non-negligible impact on the NIR front-end stability.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126555618","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430710
M. Aksoy, P. Racette
Absolute calibration of radiometers is implemented onboard using one hot and one cold external calibration targets. However, two-point calibration methods are unable to differentiate calibration drifts and associated errors from fluctuations in receiver gain and offset. This paper investigates the use of onboard three-point calibration algorithm for microwave radiometers to track calibration drifts and characterize associated errors in Earth and Space measurements of the radiometer.
{"title":"Tracking Radiometer Calibration Stability Using Three-Point Onboard Calibration","authors":"M. Aksoy, P. Racette","doi":"10.1109/MICRORAD.2018.8430710","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430710","url":null,"abstract":"Absolute calibration of radiometers is implemented onboard using one hot and one cold external calibration targets. However, two-point calibration methods are unable to differentiate calibration drifts and associated errors from fluctuations in receiver gain and offset. This paper investigates the use of onboard three-point calibration algorithm for microwave radiometers to track calibration drifts and characterize associated errors in Earth and Space measurements of the radiometer.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"164 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131444930","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 : 2018-03-01DOI: 10.1109/MICRORAD.2018.8430696
T. Dillon, Andrew A. Wright, D. Mackrides, S. Shi, J. Murakowski, P. Yao, C. Schuetz, D. Prather
Nano-satellites are gaining in popularity due to their low cost and ease of deployment. Reaching orbit as secondary payload to larger spacecraft enables science grade missions at disruptively low cost. Such miniaturized platforms impose severe constraints on the size, weight, and power (SWaP) of the payload, however, making large antenna apertures difficult to realize. Meanwhile, relatively large apertures are needed to achieve desired spatial resolution for earth observing sensors at microwave frequencies. To this end, our distributed aperture array technology dramatically reduces the SWaP of such sensors, thus enabling deployment of large radio frequency apertures on spaceborne platforms. The sensor performs optical upconversion of the upwelling microwave radiation to optical frequencies, using high-speed, broadband electro-optic mixers, and subsequent coherent optical reconstruction of the passive thermal microwave scene, without the need for bulky and power hungry digital correlation engines or substantial post-processing. Notably, the optical processing technique images all of the beams in the array concurrently, forming a real-time video stream of radiometric brightness temperatures. Herein, we describe a spaceborne, 1-D pushbroom passive millimeter wave sensor utilizing optical upconversion and aperture synthesis, at a nominal detection frequency of 36 GHz, and deployed on a 12U CubeSat for remote sensing and earth science applications.
{"title":"Microwave Photonic Imaging Radiometer","authors":"T. Dillon, Andrew A. Wright, D. Mackrides, S. Shi, J. Murakowski, P. Yao, C. Schuetz, D. Prather","doi":"10.1109/MICRORAD.2018.8430696","DOIUrl":"https://doi.org/10.1109/MICRORAD.2018.8430696","url":null,"abstract":"Nano-satellites are gaining in popularity due to their low cost and ease of deployment. Reaching orbit as secondary payload to larger spacecraft enables science grade missions at disruptively low cost. Such miniaturized platforms impose severe constraints on the size, weight, and power (SWaP) of the payload, however, making large antenna apertures difficult to realize. Meanwhile, relatively large apertures are needed to achieve desired spatial resolution for earth observing sensors at microwave frequencies. To this end, our distributed aperture array technology dramatically reduces the SWaP of such sensors, thus enabling deployment of large radio frequency apertures on spaceborne platforms. The sensor performs optical upconversion of the upwelling microwave radiation to optical frequencies, using high-speed, broadband electro-optic mixers, and subsequent coherent optical reconstruction of the passive thermal microwave scene, without the need for bulky and power hungry digital correlation engines or substantial post-processing. Notably, the optical processing technique images all of the beams in the array concurrently, forming a real-time video stream of radiometric brightness temperatures. Herein, we describe a spaceborne, 1-D pushbroom passive millimeter wave sensor utilizing optical upconversion and aperture synthesis, at a nominal detection frequency of 36 GHz, and deployed on a 12U CubeSat for remote sensing and earth science applications.","PeriodicalId":423162,"journal":{"name":"2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130486607","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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