Improved Cloud Motion Wind Vector and Altitude Assignment Using VAS

Menzel, W. Paul; Smith, William L.; Stewart, Tod R.

doi:10.1175/1520-0450(1983)022<0377:icmwva>2.0.co;2

Cited by 260 publications

(197 citation statements)

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“…This allows uncertainties associated with retrieval methodology and instrument characteristics to be isolated. Two established methods for retrieving cloud height using spectrally resolved infrared instruments, the minimum local emissivity variance (MLEV) technique (Huang et al, 2004) and the CO 2 slicing (e.g., Menzel et al, 1983;Mahesh et al, 2001) and sorting (Holz et al, 2006) technique, are further developed and intercompared here. Although these have been compared for satellite-based retrievals from upwelling radiances (Holz et al, 2006), they have not been compared for retrievals from downwelling radiances or with consideration of variability in noise characteristics and spectral sampling between different types of spectrometers, which are key engineering barriers to developing an autonomous surface-based system.…”

Section: Introductionmentioning

confidence: 99%

Toward autonomous surface-based infrared remote sensing of polar clouds: cloud-height retrievals

2016

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Abstract. Polar regions are characterized by their remoteness, making measurements challenging, but an improved knowledge of clouds and radiation is necessary to understand polar climate change. Infrared radiance spectrometers can operate continuously from the surface and have low power requirements relative to active sensors. Here we explore the feasibility of retrieving cloud height with an infrared spectrometer that would be designed for use in remote polar locations. Using a wide variety of simulated spectra of mixed-phase polar clouds at varying instrument resolutions, retrieval accuracy is explored using the CO 2 slicing/sorting and the minimum local emissivity variance (MLEV) methods. In the absence of imposed errors and for clouds with optical depths greater than ∼ 0.3, cloud-height retrievals from simulated spectra using CO 2 slicing/sorting and MLEV are found to have roughly equivalent high accuracies: at an instrument resolution of 0.5 cm −1 , mean biases are found to be ∼ 0.2 km for clouds with bases below 2 and −0.2 km for higher clouds. Accuracy is found to decrease with coarsening resolution and become worse overall for MLEV than for CO 2 slicing/sorting; however, the two methods have differing sensitivity to different sources of error, suggesting an approach that combines them. For expected errors in the atmospheric state as well as both instrument noise and bias of 0.2 mW/(m 2 sr cm −1 ), at a resolution of 4 cm −1 , average retrieval errors are found to be less than ∼ 0.5 km for cloud bases within 1 km of the surface, increasing to ∼ 1.5 km at 4 km. This sensitivity indicates that a portable, surface-based infrared radiance spectrometer could provide an important complement in remote locations to satellite-based measurements, for which retrievals of low-level cloud are challenging.

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Section: Introductionmentioning

confidence: 99%

Toward autonomous surface-based infrared remote sensing of polar clouds: cloud-height retrievals

2016

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“…The technique for the retrieval of cloud height and effective cloud amount (the product of cloud fraction and cloud emissivity at 11 μm) has been previously described in detail [3,4]. Multi-years of high cloud statistics obtained from a series of satellite sensors of National Oceanic and Atmospheric Administration (NOAA) have been reported [4].…”

Section: Introductionmentioning

confidence: 99%

Cloud Remote Sensing Using Midwave IR CO2 and N2O Slicing Channels near 4.5 μm

Gao

Shettle

2011

Remote Sensing

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Narrow channels located in the longwave IR CO 2 absorption region between approximately 13.2 and 14.5 μm, the well known CO 2 slicing channels, have been proven to be quite effective for the estimates of cloud heights and effective cloud amounts as well as atmospheric temperature profiles. The designs of some of the near-future multi-channel earth observing satellite sensors cannot accommodate these longwave IR channels. Based on the analysis of the multi-channel imaging data collected with the NASA Moderate Resolution Imaging SpectroRadiometer (MODIS) instrument and on theoretical cloud radiative transfer modeling, we have found that narrow channels located at the midwave IR region between approximately 4.2 and 4.55 μm, where the combined CO 2 and N 2 O absorption effects decrease rapidly with increasing wavelength, have similar properties as the longwave IR CO 2 slicing channels. The scattering of solar radiation by clouds on the long wavelength side of the 4.3 μm CO 2 absorption makes only a small contribution to the upwelling radiances. In order to retain the crucial cloud and temperature sensing capabilities, future satellite sensors should consider including midwave IR CO 2 and N 2 O slicing channels if the longwave IR channels cannot be implemented on the sensors. The hyperspectral data covering the 3.715.5 m wavelength range and measured with the Infrared Atmospheric Sounding Interferometer (IASI) can be used to further assess the utility of midwave IR channels for satellite remote sensing. OPEN ACCESSRemote Sens. 2011, 3 1007

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“…His method is based on the assumption that the effective emissivities of the two channels are equal. Menzel et al (1983) has developed the CO2 absorption method which combines infrared longwave-window channel data with CO2 absorption channel data of VISSR Atmospheric Sounder (VAS) to specify a cloud height including cirrus clouds.…”

Section: Introductionmentioning

confidence: 99%

“…These infrared methods of Szejwach (1982) and Menzel et al (1983) have obliged to use slightly low spatial resolution data. In this paper, semi-transparent cirrus clouds are studied using the Advanced Very High Resolution Radiometer (AVHRR) channel 4 and channel 5 data whose central wavelength is 11 *m and 12 *m respectively and spatial resolution is 1.1km at the nadir.…”

Section: Introductionmentioning

confidence: 99%

On the Temperature and Effective Emissivity Determination of Semi-Transparent Cirrus Clouds by Bi-Spectral Measurements in the 10μm Window Region

Inoue¹

1985

Journal of the Meteorological Society of Japan

310

245

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By inspection of the image constructed from the brightness temperature difference between the 11 *m and 12 *m satellite data, semi-transparent cirrus clouds where brightness temperature in 11 *m and visible reflectivity are relatively low are identified clearly as having a bigger brightness temperature difference area than that of cloud free areas.Effective emissivity is determined for semi-transparent cirrus clouds using the simple cloud model where scattering is neglected and only absorption is considered.Cirrus clouds often have 'black' parts in this wavelength. The radiance of the 'black' part of the cirrus clouds whose temperature is assumed to be equal to that of semi-transparent part and the clear radiance just off the cirrus clouds which is assumed to be equal to the radiance at the bottom of the cloud are used for effective emissivity calculation. A simple relationship between the effective emissivity for 11 *m and 12 *m has been determined empirically from 860 satellite measurements for eight cirrus clouds cases which have 'black' parts. The bi-spectral method has been developed to retrieve cloud temperature and effective emissivity for semi-transparent cirrus clouds using the effective emissivity relationship between 11 *m and 12 *m. We have compared the retrieved cloud temperature and effective emissivity by our method with those estimated from the 'black' part of the cirrus cloud. It shows reasonable agreement for the cirrus cloud whose effective emissivity is larger than 0.4.

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Improved Cloud Motion Wind Vector and Altitude Assignment Using VAS

Cited by 260 publications

References 5 publications

Toward autonomous surface-based infrared remote sensing of polar clouds: cloud-height retrievals

Toward autonomous surface-based infrared remote sensing of polar clouds: cloud-height retrievals

Cloud Remote Sensing Using Midwave IR CO2 and N2O Slicing Channels near 4.5 μm

On the Temperature and Effective Emissivity Determination of Semi-Transparent Cirrus Clouds by Bi-Spectral Measurements in the 10μm Window Region

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Improved Cloud Motion Wind Vector and Altitude Assignment Using VAS

Cited by 260 publications

References 5 publications

Toward autonomous surface-based infrared remote sensing of polar clouds: cloud-height retrievals

Toward autonomous surface-based infrared remote sensing of polar clouds: cloud-height retrievals

Cloud Remote Sensing Using Midwave IR CO2 and N2O Slicing Channels near 4.5 μm

On the Temperature and Effective Emissivity Determination of Semi-Transparent Cirrus Clouds by Bi-Spectral Measurements in the 10&mu;m Window Region

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On the Temperature and Effective Emissivity Determination of Semi-Transparent Cirrus Clouds by Bi-Spectral Measurements in the 10μm Window Region