An Airborne Spectral Albedometer with Active Horizontal Stabilization

Wendisch, Manfred; Müller, Dörthe; Schell, D.; Heintzenberg, Jost

doi:10.1175/1520-0426(2001)018<1856:aasawa>2.0.co;2

Cited by 137 publications

(128 citation statements)

References 38 publications

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“…Ten HALO research flights from Barbados are envisioned, each with a duration of 9 h bracketing two 4-h flights of the ATR-42 (with a refuelling in between). (Wirth et al 2009) SMART Up-and downward-looking spectral (300-2200 nm) radiance and irradiance measurements (Wendisch et al 2001;Ehrlich et al 2008) SpecMACS Downward-looking hyper-spectral (400-2500 nm) line imager Thermal imager Downward-looking (10.8 and 12 lm) two channel line imager (in development) Dropsondes AVAPs system with four-channel receiver supporting Vaisala RD94 Sondes (ten channel receiver in development)…”

Section: Aircraft Measurementsmentioning

confidence: 99%

“…SMART (Spectral Modular Airborne Radiation Measurement System) consists of a set of spectral solar radiation sensors including radiances and irradiances (Wendisch et al 2001;Ehrlich et al 2008). All quantities are obtained for the wavelength range of 0.3-2.2 lm with spectral resolution of 2-16 nm full width of half maximum (FWHM), which is sufficient to analyse the spectral characteristics of spectral absorption bands of ice and liquid water.…”

Section: The Halo Aircraft and Its Instrumentationmentioning

confidence: 99%

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EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

et al. 2017

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Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. 123Surv Geophys (2017) 38:1529-1568 https://doi.org/10.1007/s10712-017-9428-0 cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of tradecumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air-sea interactions and convective organization.

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Section: Aircraft Measurementsmentioning

confidence: 99%

Section: The Halo Aircraft and Its Instrumentationmentioning

confidence: 99%

EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

et al. 2017

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“…The system is extensively described in Wendisch et al (2001) and Ehrlich et al (2008). In this paper the focus is on I N S measurements which are available for the four HALO missions introduced above.…”

Section: The Smart Instrumentmentioning

confidence: 99%

“…With a maximum ceiling altitude of around 15 km HALO is capable of operating in and above SVC and cirrus at mid-latitudes and in polar regions for in situ measurements. The airborne observations are obtained with the Spectral Modular Airborne Radiation measurement sysTem (SMART) (Wendisch et al, 2001) and the Differential Optical Absorption Spectrometer (mini-DOAS) (Hüneke, 2016) both assembled on HALO. The instrumentation is introduced in Sect.…”

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confidence: 99%

Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles

et al. 2017

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Abstract. Spectral radiance measurements collected in nadir and sideward viewing directions by two airborne passive solar remote sensing instruments, the Spectral Modular Airborne Radiation measurement sysTem (SMART) and the Differential Optical Absorption Spectrometer (mini-DOAS), are used to compare the remote sensing results of cirrus optical thickness τ . The comparison is based on a sensitivity study using radiative transfer simulations (RTS) and on data obtained during three airborne field campaigns: the North Atlantic Rainfall VALidation (NARVAL) mission, the MidLatitude Cirrus Experiment (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems (ACRIDICON) campaign. Radiative transfer simulations are used to quantify the sensitivity of measured upward radiance I with respect to τ , ice crystal effective radius r eff , viewing angle of the sensor θ V , spectral surface albedo α, and ice crystal shape. From the calculations it is concluded that sideward viewing measurements are generally better suited than radiance data from the nadir direction to retrieve τ of optically thin cirrus, especially at wavelengths larger than λ = 900 nm. Using sideward instead of nadir-directed spectral radiance measurements significantly improves the sensitivity and accuracy in retrieving τ , in particular for optically thin cirrus of τ ≤ 2.The comparison of retrievals of τ based on nadir and sideward viewing radiance measurements from SMART, mini-DOAS and independent estimates of τ from an additional active remote sensing instrument, the Water Vapor Lidar Experiment in Space (WALES), shows general agreement within the range of measurement uncertainties. For the selected example a mean τ of 0.54 ± 0.2 is derived from SMART, and 0.49 ± 0.2 by mini-DOAS nadir channels, while WALES obtained a mean value of τ = 0.32 ± 0.02 at 532 nm wavelength, respectively. The mean of τ derived from the sideward viewing mini-DOAS channels is 0.26 ± 0.2. For the few simultaneous measurements, the mini-DOAS sideward channel measurements systematically underestimate (−17.6 %) the nadir observations from SMART and mini-DOAS. The agreement between mini-DOAS sideward viewing channels and WALES is better, showing the advantage of using sideward viewing measurements for cloud remote sensing for τ ≤ 1. Therefore, we suggest sideward viewing measurements for retrievals of τ of thin cirrus because of the significantly enhanced capability of sideward viewing compared to nadir measurements.

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“…First steps towards hyperspectral techniques for cloud remote sensing were done with instruments like the Solar Spectral Flux Radiometer (SSFR, Pilewskie et al, 2003) or the Spectral Modular Airborne Radiation measurement sysTem (SMART, Wendisch et al, 2001;Wendisch and Mayer, 2003) from a ground-based (McBride et al, 2011;Chiu et al, 2012; Jäkel et al, 2013) or an airborne perspective (Ehrlich et al, 2008;Eichler et al, 2009;Schmidt et al, 2007;Coddington et al, 2010). All of these methods are based on non-imaging sensors; i.e., only one measurement is taken at a time and one line of measurements is constructed by sensor motion or cloud motion over a ground-based measurement.…”

Section: Introductionmentioning

confidence: 99%

Design and characterization of specMACS, a multipurpose hyperspectral cloud and sky imager

Ewald

Kölling²,

Baumgartner

et al. 2016

Atmos. Meas. Tech.

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Abstract. The new spectrometer of the Munich Aerosol Cloud Scanner (specMACS) is a multipurpose hyperspectral cloud and sky imager designated, but is not limited to investigations of cloud-aerosol interactions in Earth's atmosphere. With its high spectral and spatial resolution, the instrument is designed to measure solar radiation in the visible and shortwave infrared region that is reflected from, or transmitted through clouds and aerosol layers. It is based on two hyperspectral cameras that measure in the solar spectral range between 400 and 2500 nm with a spectral bandwidth between 2.5 and 12.0 nm. The instrument was operated in ground-based campaigns as well as aboard the German High Altitude LOng Range (HALO) research aircraft, e.g., during the ACRIDICON-CHUVA campaign in Brazil during summer 2014.This paper describes the specMACS instrument hardware and software design and characterizes the instrument performance. During the laboratory characterization of the instrument, the radiometric response as well as the spatial and spectral resolution was assessed. Since the instrument is primarily intended for retrievals of atmospheric quantities by inversion of radiative models using measured radiances, a focus is placed on the determination of its radiometric response. Radiometric characterization was possible for both spectrometers, with an absolute accuracy of 3 % at their respective central wavelength regions. First measurements are presented which demonstrate the wide applicability of the instrument. They show that key demands are met regarding the radiometric and spectral accuracy which is required for the intended remote sensing techniques.

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An Airborne Spectral Albedometer with Active Horizontal Stabilization

Cited by 137 publications

References 38 publications

EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles

Design and characterization of specMACS, a multipurpose hyperspectral cloud and sky imager

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