Sea‐surface emissivity parametrization from microwaves to millimetre waves

Prigent, Catherine; Aires, Filipe; Wang, Dié; Fox, Stuart; Harlow, Chawn

doi:10.1002/qj.2953

Cited by 52 publications

(33 citation statements)

References 17 publications

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“…The proposed methodology involves a series of coupling tools. The Tool to Estimate Land Surface Emissivities from Microwave to Sub-millimeter waves (TELSEM2; Wang et al, 2016) and the Tool to Estimate Sea Surface Emissivity from Microwave to Sub-millimeter waves (TESSEM2; Prigent et al, 2016) are used to determine land and ocean surface emissivities respectively. TELSEM2 provides the emissivity (V and H components) for any location, month and incidence angle with a spatial resolution of 0.25 • .…”

Section: The Radiative Transfer Model: Artsmentioning

confidence: 99%

Analysis and evaluation of WRF microphysical schemes for deep moist convection over south-eastern South America (SESA) using microwave satellite observations and radiative transfer simulations

et al. 2017

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Abstract. In the present study, three meteorological events of extreme deep moist convection, characteristic of southeastern South America, are considered to conduct a systematic evaluation of the microphysical parameterizations available in the Weather Research and Forecasting (WRF) model by undertaking a direct comparison between satellite-based simulated and observed microwave radiances. A research radiative transfer model, the Atmospheric Radiative Transfer Simulator (ARTS), is coupled with the WRF model under three different microphysical parameterizations (WSM6, WDM6 and Thompson schemes). Microwave radiometry has shown a promising ability in the characterization of frozen hydrometeors. At high microwave frequencies, however, frozen hydrometeors significantly scatter radiation, and the relationship between radiation and hydrometeor populations becomes very complex. The main difficulty in microwave remote sensing of frozen hydrometeor characterization is correctly characterizing this scattering signal due to the complex and variable nature of the size, composition and shape of frozen hydrometeors. The present study further aims at improving the understanding of frozen hydrometeor optical properties characteristic of deep moist convection events in south-eastern South America. In the present study, bulk optical properties are computed by integrating the singlescattering properties of the Liu (2008) discrete dipole approximation (DDA) single-scattering database across the particle size distributions parameterized by the different WRF schemes in a consistent manner, introducing the equal mass approach. The equal mass approach consists of describing the optical properties of the WRF snow and graupel hydrometeors with the optical properties of habits in the DDA database whose dimensions might be different (D max ) but whose mass is conserved. The performance of the radiative transfer simulations is evaluated by comparing the simulations with the available coincident microwave observations up to 190 GHz (with observations from Tropical Rainfall Measuring Mission's (TRMM) Microwave Imager (TMI), Microwave Humidity Sounder (MHS) and Special Sensor Microwave Imager/Sounder (SSMI/S)) using the χ 2 test. Good agreement is obtained with all observations provided special care is taken to represent the scattering properties of the snow and graupel species.

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Section: The Radiative Transfer Model: Artsmentioning

confidence: 99%

Analysis and evaluation of WRF microphysical schemes for deep moist convection over south-eastern South America (SESA) using microwave satellite observations and radiative transfer simulations

et al. 2017

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“…In that direction, the recently developed parameterization of sea surface emissivity generated by the Tool to Estimate Sea Surface Emissivity from Microwave to sub-Millimeter waves (TESSEM2) [85] was selected. Moreover, lambertian reflection was assumed.…”

Section: Radiative Transfer Simulationsmentioning

confidence: 99%

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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“…Liu et al (2011) tested FASTEM up to 150 GHz. Prigent et al (2016) compared FASTEM with the Tool to Estimate Sea-Surface Emissivity from Microwaves to sub-Millimeter waves (TESSEM2) and with ISMAR measurements from two low-level flights at low wind speeds. They showed that FASTEM tends to underestimate the emissivity at 243.3 GHz leading to errors of order 5 K in the upwelling brightness temperature close to the surface (flight altitudes < 300 m).…”

Section: Radiative Transfer Simulationsmentioning

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.

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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.

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Sea‐surface emissivity parametrization from microwaves to millimetre waves

Cited by 52 publications

References 17 publications

Analysis and evaluation of WRF microphysical schemes for deep moist convection over south-eastern South America (SESA) using microwave satellite observations and radiative transfer simulations

Analysis and evaluation of WRF microphysical schemes for deep moist convection over south-eastern South America (SESA) using microwave satellite observations and radiative transfer simulations

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

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

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