Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

Brath, Manfred; Fox, Stuart; Eriksson, Patrick; Harlow, Chawn; Burgdorf, M.; Buehler, Stefan A.

doi:10.5194/amt-11-611-2018

Cited by 46 publications

(36 citation statements)

References 39 publications

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“…The observations of MWI, which cover the frequency range from 19 GHz up to 183 GHz, will provide additional sensitivity to liquid and frozen precipitation as well as water vapor.The advent of space-borne sub-millimeter radiometry of clouds brings with it great potential for the study ice in the atmosphere. The information content and retrieval performance from radiometer observations alone has been studied in detail for 50 column-integrated ice mass (Jiménez et al, 2007;Wang et al, 2017;Brath et al, 2018) as well as for the vertical distribution of ice in the atmosphere (Birman et al, 2017;Grützun et al, 2018;Aires et al, 2019). Also the concept of combining millimeter and sub-millimeter radiometer observations with active observations from a cloud radar has been investigated (Evans et al, 2005; Jiang et al, 2019).This work applies the concept of synergistic radar and sub-millimeter radiometer retrievals to the upcoming ICI and MWI 55 sensors by combining them with a conceptual W-band cloud radar.…”

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confidence: 99%

Synergistic radar and radiometer retrievals of ice hydrometeors

Pfreundschuh¹,

Eriksson²,

Buehler³

et al. 2019

Preprint

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Abstract. The upcoming Ice Cloud Imager (ICI) radiometer, to be launched on board the second generation of European operational meteorological satellites (Metop-SG), will be the first microwave imager to provide sub-millimeter observations of the atmosphere. The Microwave Imager (MWI) radiometer will be flown on the same satellites and complement the ICI sensor with observations at traditional millimeter wavelengths. The addition of these two new passive microwave sensors to the global system of earth observation satellites opens up opportunities for synergistic satellite missions aiming to maximize the scientific return of the Metop-SG program. This study analyzes the potential benefits of combining observations of the MWI and ICI radiometers with a 94-GHz cloud radar for the retrieval of frozen hydrometeors. Starting from a simplified numerical experiment, it is shown that the complementary information content in the radar and radiometer observations can help to better constrain the particle size distribution of ice particles in the atmosphere. The feasibility of the combined retrieval is demonstrated by applying a one-dimensional, variational cloud-retrieval algorithm to simulated observations from a high-resolution atmospheric model. Comparison of the results with passive- and radar-only versions of the retrieval algorithm confirms that synergies between the active and passive observations allow an improved retrieval of microphysical properties of frozen hydrometeors. The effect of the assumed ice particle shape on the results is analyzed and found to be critical for obtaining good retrieval performance. In addition to this, the synergistic retrieval shows improved sensitivity to liquid water in both warm and supercooled clouds. The results of this study clearly demonstrate the potential of the combined observations to constrain the microphysical properties of ice hydrometeors which can help to reduce errors in retrieved profiles of mass- and number densities.

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confidence: 99%

Synergistic radar and radiometer retrievals of ice hydrometeors

Pfreundschuh¹,

Eriksson²,

Buehler³

et al. 2019

Preprint

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“…ARTS is a freely available software package, which has been designed for radiative transfer simulations for the mm and sub-mm spectral range, including polarization capabilities. ARTS has been comprehensively tested by comparison to a range of other MW radiative transfer models [59,60] and its performance has been demonstrated in various applications [11,12,14,44]. It can be operated in spherical geometry for 1D, 2D, and 3D atmospheres, and thus, it can be employed for a wide range of remote sensing applications.…”

Section: Atmospheric Radiative Transfer Simulatormentioning

confidence: 99%

“…Toward that end, the upcoming Ice Cloud Imager (ICI) instrument, which covers frequencies between 183.31 GHz and 668 GHz, on board the Meteorological Operational Satellite-Second Generation (Metop-SG) [9] operated by the European Organization of Meteorological Satellites (EUMETSAT), is going to fill this gap [10]. The performance of the sub-mm wavelengths in terms of retrieving ice properties has been manifested by airborne and limb sounding instruments; e.g., the International Submillimetre Airborne Radiometer (ISMAR) [11,12], the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) [13], Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES), and the Odin-Sub-Millimetre Radiometer (Odin-SMR) [14]. Accordingly, ICI, with frequencies sensitive to the size, content, shape, and orientation of ice hydrometeors, aims at improving the representation of ice-containing clouds in NWP models.…”

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Three Dimensional Radiative Effects in Passive Millimeter/Sub-Millimeter All-sky Observations

Barlakas

Eriksson

2020

Remote Sensing

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This study was conducted to quantify the errors prompted by neglecting three-dimensional (3D) effects, i.e., beam-filling and horizontal photon transport effects, at millimeter/sub-millimeter wavelengths. This paper gives an overview of the 3D effects that impact ice cloud retrievals of both current and proposed (Ice Cloud Imager) satellite instruments operating at frequencies of ≈186.3 and ≈668 GHz. The 3D synthetic scenes were generated from two-dimensional (2D) CloudSat (Cloud Satellite) observations over the tropics and mid-latitudes using a stochastic approach. By means of the Atmospheric Radiative Transfer Simulator (ARTS), three radiative transfer simulations were carried out: one 3D, one independent beam approximation (IBA), and one-dimensional (1D). The comparison between the 3D and IBA simulations revealed a small horizontal photon transport effect, with IBA simulations introducing mostly random errors and a slight overestimation (below 1 K). However, performing 1D radiative transfer simulations results in a significant beam-filling effect that increases primarily with frequency, and secondly, with footprint size. For a sensor footprint size of 15 km, the errors induced by neglecting domain heterogeneities yield root mean square errors of up to ≈4 K and ≈13 K at 186.3 GHz and 668 GHz, respectively. However, an instrument operating at the same frequencies, but with a much smaller footprint size, i.e., 6 km, is subject to smaller uncertainties, with a root mean square error of ≈2 K at 186.3 GHz and ≈7.1 K at 668 GHz. When designing future satellite instruments, this effect of footprint size on modeling uncertainties should be considered in the overall error budget. The smallest possible footprint size should be a priority for future sub-millimeter observations in light of these results.

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“…6,7 ISMAR is installed onboard the FAAM BAe-146 Atmospheric Research Aircraft which is operated by the a) Electronic mail: arvid.hammar@omnisys.se. UK Met Office.…”

Section: Introductionmentioning

confidence: 99%

Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR)

Hammar

Sobis

Drakinskiy

et al. 2018

Review of Scientific Instruments

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We report on the development of two 874 GHz receiver channels with orthogonal polarizations for the International Submillimetre Airborne Radiometer. A spline horn antenna and dielectric lens, a Schottky diode mixer circuit, and an intermediate frequency (IF) low noise amplifier circuit were integrated in the same metallic split block housing. This resulted in a receiver mean double sideband (DSB) noise temperature of 3300 K (minimum 2770 K, maximum 3400 K), achieved at an operation temperature of 40 °C and across a 10 GHz wide IF band. A minimum DSB noise temperature of 2260 K at 20 °C was measured without the lens. Three different dielectric lens materials were tested and compared with respect to the radiation pattern and noise temperature. All three lenses were compliant in terms of radiation pattern, but one of the materials led to a reduction in noise temperature of approximately 200 K compared to the others. The loss in this lens was estimated to be 0.42 dB. The local oscillator chains have a power consumption of 24 W and consist of custom-designed Schottky diode quadruplers (5% power efficiency in operation, 8%–9% peak), commercial heterostructure barrier varactor (HBV) triplers, and power amplifiers that are pumped by using a common dielectric resonator oscillator at 36.43 GHz. Measurements of the radiation pattern showed a symmetric main beam lobe with full width half maximum <5° and side lobe levels below −20 dB. Return loss of a prototype of the spline horn and lens was measured using a network analyzer and frequency extenders to 750–1100 GHz. Time-domain analysis of the reflection coefficients shows that the reflections are below −25 dB and are dominated by the external waveguide interface.

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Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

Cited by 46 publications

References 39 publications

Synergistic radar and radiometer retrievals of ice hydrometeors

Synergistic radar and radiometer retrievals of ice hydrometeors

Three Dimensional Radiative Effects in Passive Millimeter/Sub-Millimeter All-sky Observations

Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR)

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