APMIR: airborne polarimetric microwave imaging radiometer

Bobak, J.P.; Dowgiallo, David J.; McGlothlin, N.R.; Germain, Karen M. St.

doi:10.1109/igarss.2001.976204

Cited by 9 publications

(5 citation statements)

References 3 publications

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“…Observations of brightness temperature of the ocean surface T B were made with two microwave radiometers operating at 10.7 and 37 GHz, V and H polarizations. The radiometers are a subset of the Airborne Polarimetric Microwave Imaging Radiometer (APMIR) built at Naval Research Laboratory [ Bobak et al ., , ]. The T B time series at 10.7 GHz synchronized to Coordinated Universal Time (UTC) are used in this study.…”

Section: Instrumentationmentioning

confidence: 99%

Whitecap lifetime stages from infrared imagery with implications for microwave radiometric measurements of whitecap fraction

Potter¹,

Smith²,

Snow

et al. 2015

JGR Oceans

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Quantifying active and residual whitecap fractions separately can improve parameterizations of air‐sea fluxes associated with breaking waves. We use data from a multi‐instrumental field campaign on Floating Instrument Platform (FLIP) to simultaneously capture the signatures of active and residual whitecaps at visible, infrared (IR), and microwave wavelengths using, respectively, video camera, mid‐IR camera, and a radiometer at 10 GHz. We present results from processing and analyzing IR images and correlating this information with radiometric time series of brightness temperature at horizontal and vertical polarizations TBH and TBV. The results provide evidence that breaking crests and decaying foam appear in mid‐IR as bright and dark pixels clearly distinguishing active from residual whitecaps. We quantify the durations of whitecap lifetime stages from the IR images and identify their corresponding signatures in TB time series. Results show that TBH and TBV vary in phase during the active and in antiphase during the residual whitecap stages. A methodology to distinguish active and residual whitecaps in radiometric time series without a priori IR information has been developed and verified with corresponding IR and video images. The method uses the degree of polarization P (the ratio between the sum and difference of TBV and TBH) to capture whitecaps as prominent spikes. The maximum and zero‐crossing of the first derivative of P serve to identify the presence of active whitecaps, while the minimum of dP marks the transition from active to residual whitecap stage. The findings have implications for radiometric measurements of active and total whitecap fractions.

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Section: Instrumentationmentioning

confidence: 99%

Whitecap lifetime stages from infrared imagery with implications for microwave radiometric measurements of whitecap fraction

Potter¹,

Smith²,

Snow

et al. 2015

JGR Oceans

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show abstract

“…We chose a cylinder over a sphere for practicality of calibration, smaller size, and easier gimbal design, despite some aerodynamic advantages of a sphere. AESMIR's 65-cm cylinder is in-between the sizes of PSR's 50-cm cylinder and APMIR's 90-cm sphere [2,3].…”

Section: Sensor Designmentioning

confidence: 99%

The Airborne Earth Science Microwave Imaging Radiometer (AESMIR) - NASA's new passive microwave airborne imager

Kim

2009

2009 IEEE Sensors

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NASA's Airborne Earth Science Microwave Imaging Radiometer (AESMIR) is a new sensor for satellite calibration, geophysical algorithm studies, and technology development. Its unique single-package design covers 6 microwave bands (6, 10, 18, 23, 36, 89 GHz) with 4-Stokes capability (except at 23 GHz). Separate parallel filters enable simultaneous simulation of the passbands of multiple satellite sensors. Various aircraft installations options are available. Design and flight details are presented.

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“…A detailed description of APMIR can be found in [23]. During the RASSI experiment, vertically and horizontally polarized microwave brightness temperatures T B at 6.6, 6.8, and 7.2 GHz; vertically polarized microwave brightness temperature at 10.7 GHz; and fully polarimetric data at 19.35 and 37.0 GHz (hereafter referred to as 19 and 37 GHz) were measured.…”

Section: B Radiometric Measurementsmentioning

confidence: 99%

Aerial Radiometric and Video Measurements of Whitecap Coverage

Bobak

Asher

Dowgiallo

et al. 2011

IEEE Trans. Geosci. Remote Sensing

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This paper presents the results of high-altitude microwave radiometric and video measurements in the presence of breaking waves made during the passage of Hurricane Dean on August 21, 2007, over the Gulf of Mexico. Previous measurements of foam fraction and radiometric brightness temperature have focused on the small scale, in which individual foam patches were of the same scale as the radiometer footprint. To work with data from spaceborne microwave radiometers, which have footprints on the scale of tens of kilometers, the knowledge of how the foam fraction sensitivity of brightness temperature scales when footprints increase from meters to kilometers is necessary. Video images of the sea surface recorded with a high-resolution monochrome digital camera were used to determine the foam fraction. Ocean-surface brightness temperature was measured with the Airborne Polarimetric Microwave Imaging Radiometer (APMIR) of the Naval Research Laboratory at frequencies of 6.6 [vertical and horizontal (VH) polarizations], 6.8 (VH), 7.2 (VH), and 10.7 GHz (V), with full polarimetric brightness temperatures measured at 19.35 and 37.0 GHz. Collocated nearly contemporaneous brightness temperatures were available from WindSat, Special Sensor Microwave Imager/Sounder, and Special Sensor Microwave/Imager satellite radiometer overpasses. Oceanographic and meteorological data were taken from buoys located along the flight track. There was good correlation between brightness temperatures measured with APMIR and satellite-borne radiometers with absolute differences largely within the expected uncertainty of the data. An analysis of the video imagery provided the fractional area coverage of the actively breaking waves on the ocean surface. The increase in brightness temperature from each of the microwave sensors was correlated with the whitecap coverage measured by the camera.The experiment not only serves as an important bridge between measurements made with spatial scales on the order of tens of meters and data collected from satellites with spatial scales of tens of kilometers but also provides guidance for improving future field measurements on this topic.

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APMIR: airborne polarimetric microwave imaging radiometer

Cited by 9 publications

References 3 publications

Whitecap lifetime stages from infrared imagery with implications for microwave radiometric measurements of whitecap fraction

Whitecap lifetime stages from infrared imagery with implications for microwave radiometric measurements of whitecap fraction

The Airborne Earth Science Microwave Imaging Radiometer (AESMIR) - NASA's new passive microwave airborne imager

Aerial Radiometric and Video Measurements of Whitecap Coverage

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