ISMAR: an airborne submillimetre radiometer

Fox, Stuart; Lee, Clare; Moyna, B.; Philipp, Martin; Rule, Ian; Rogers, Stuart; King, Robert R.; Oldfield, M.; Rea, Simon; Henry, M.; Wang, Hui; Harlow, Chawn

doi:10.5194/amt-10-477-2017

Cited by 36 publications

(42 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

View full text Add to dashboard Cite

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.

show abstract

“…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

View full text Add to dashboard Cite

show abstract

“…However, in this work we use only the near-vertical nadir view in order to eliminate any polarization differences. For further details on ISMAR see Fox et al (2017). Polarization differences are not expected in the vertical view as both polarizations are orthogonal to both the surface and the clouds, and the sensed medium is likely to be random in the azimuth direction.…”

Section: Ismarmentioning

confidence: 99%

“…The International Submillimetre Airborne Radiometer (ISMAR) is an airborne radiometer that measures at several frequencies between 118 and 664 GHz of the electromagnetic spectrum. One of the main tasks of ISMAR is to serve as a satellite demonstrator for ICI (Fox et al, 2017). Apart from ISMAR, another airborne radiometer that measures in a similar region of the electromagnetic spectrum is the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR).…”

Section: Introductionmentioning

confidence: 99%

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

Brath¹,

Fox

Eriksson

et al. 2018

Atmos. Meas. Tech.

Self Cite

View full text Add to dashboard Cite

Abstract. A neural-network-based retrieval method to determine the snow ice water path (SIWP), liquid water path (LWP), and integrated water vapor (IWV) from millimeter and submillimeter brightness temperatures, measured by using airborne radiometers (ISMAR and MARSS), is presented. The neural networks were trained by using atmospheric profiles from the ICON numerical weather prediction (NWP) model and by radiative transfer simulations using the Atmospheric Radiative Transfer Simulator (ARTS). The basic performance of the retrieval method was analyzed in terms of offset (bias) and the median fractional error (MFE), and the benefit of using submillimeter channels was studied in comparison to pure microwave retrievals. The retrieval is offset-free for SIWP > 0.01 kg m to 30 % at LWP = 1 kg m −2 . The MFE of IWV for IWV > 3 kg m −2 is 5 to 8 %. The SIWP retrieval strongly benefits from submillimeter channels, which reduce the MFE by a factor of 2, compared to pure microwave retrievals. The IWV and the LWP retrievals also benefit from submillimeter channels, albeit to a lesser degree. The retrieval was applied to ISMAR and MARSS brightness temperatures from FAAM flight B897 on 18 March 2015 of a precipitating frontal system west of the coast of Iceland. Considering the given uncertainties, the retrieval is in reasonable agreement with the SIWP, LWP, and IWV values simulated by the ICON NWP model for that flight. A comparison of the retrieved IWV with IWV from 12 dropsonde measurements shows an offset of 0.5 kg m −2 and an RMS difference of 0.8 kg m −2 , showing that the retrieval of IWV is highly effective even under cloudy conditions.

show abstract

“…Above 200 GHz, the frequencies are mainly governed by the channels of the planned Ice Cloud Imager (ICI) mission (Kangas et al, 2012). The upper end at 886.4 GHz was set in order to support the ISMAR (Fox et al, 2017) and IceCube (Wu et al, 2015) instruments.…”

mentioning

confidence: 99%

A general database of hydrometeor single scattering properties at microwave and sub-millimetre wavelengths

Eriksson¹,

Ekelund²,

Mendrok³

et al. 2018

Preprint

View full text Add to dashboard Cite

Abstract. A main limitation today in simulations and inversions of microwave observations of ice hydrometeors (cloud ice, snow, hail . . . ) is the lack of data describing the interaction between electromagnetic waves and the particles. To improve the situation, the development of a comprehensive dataset of such "scattering properties" has been started. The database aims at giving a broad coverage in both frequency (1 to 886 GHz) and temperature (190 to 270 K), to support both passive and active current and planned measurements, and to provide data corresponding to the full Stokes vector. This first version of the database 5 is restricted to totally random particle orientation. Data for 34 particle sets, i.e. habits, have been generated. About 17 of the habits can be classified as single crystals, three habits can be seen as heavily rimed particles, and remaining habits are aggregates of different types, representing e.g. snow and hail. The particle sizes considered vary between the habits, but a maximum diameter of 10 and 20 mm are typical values for the largest single crystal and aggregate particles, respectively, and the number of sizes per habit is at least 30. Particles containing liquid water are also inside the scope of the database, but this phase of water is 10 so far only represented by a liquid sphere habit. The database is built upon the netCDF4 file format. Interfaces to browse, extract and convert data for selected radiative transfer models are provided in Matlab and Python. The database and associated tools are publically available from Zenedo (https://doi.org/10.5281/zenodo.1175572 and https://doi.org/10.5281/zenodo.1175588, respectively). Planned extensions include non-spherical rain drops, melting particles and a second orientation case that can be denoted as azimuthally random.

show abstract

ISMAR: an airborne submillimetre radiometer

Cited by 36 publications

References 22 publications

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

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

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

A general database of hydrometeor single scattering properties at microwave and sub-millimetre wavelengths

Contact Info

Product

Resources

About