The first global 883 GHz cloud ice survey: IceCube Level 1 data calibration, processing and analysis

Gong, Jie; Wu, Dong L.; Eriksson, Patrick

doi:10.5194/essd-13-5369-2021

Cited by 7 publications

(2 citation statements)

References 39 publications

(39 reference statements)

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“…This indicates poor calibration for low IWPs. This was not unexpected as the passive microwave instruments in the millimetre (mm) range are sensitive to IWPs greater than ∼0.2 kg m −2 (See Figure 1 of [70]). Overall, Q-IWP overestimated the low IWP values (thin ice clouds) and slightly underestimated the larger IWPs (thick ice clouds).…”

Section: Basic Retrieval Performancementioning

confidence: 81%

“…While such cases occurred frequently, the accuracy was limited by the sensitivity of the satellite observations on which the retrievals were based. The passive microwave instruments in the mm range were sensitive to IWPs greater than ∼200 g m −2 (See Figure 1 of [70]). For cases with lower IWPs, the ML model only had the a priori information at its disposal.…”

Section: Other Factors Affecting Retrieval Performancementioning

confidence: 99%

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Fast Radiative Transfer Approximating Ice Hydrometeor Orientation and Its Implication on IWP Retrievals

et al. 2022

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The accurate simulation of microwave observations of clouds and precipitation are computationally challenging. A common simplification is the assumption of totally random orientation (TRO); however, studies have revealed that TRO occurs relatively infrequently in reality. A more appropriate assumption is that of azimuthally random orientation (ARO), but so far it has been a computationally expensive task. Recently a fast approximate approach was introduced that incorporates hydrometeor orientation into the assimilation of data from microwave conically scanning instruments. The approach scales the extinction in vertical (V) and horizontal (H) polarised channels to approximate ARO. In this study, the application of the approach was extended to a more basic radiative transfer perspective using the Atmospheric Radiative Transfer Simulator and the high-frequency channels of the Global Precipitation Measurement Microwave Imager (GMI). The comparison of forward simulations and GMI observations showed that with a random selection of scaling factors from a uniform distribution between 1 and 1.4–1.5, it is possible to mimic the full distribution of observed polarisation differences at 166 GHz over land and water. The applicability of this model at 660 GHz was also successfully demonstrated by means of existing airborne data. As a complement, a statistical model for polarised snow emissivity between 160 and 190 GHz was also developed. Combining the two models made it possible to reproduce the polarisation signals that were observed over all surface types, including snow and sea ice. Further, we also investigated the impact of orientation on the ice water path (IWP) retrievals. It has been shown that ignoring hydrometeor orientation has a significant negative impact (∼20% in the tropics) on retrieval accuracy. The retrieval with GMI observations produced highly realistic IWP distributions. A significant highlight was the retrieval over snow covered regions, which have been neglected in previous retrieval studies. These results provide increased confidence in the performance of passive microwave observation simulations and mark an essential step towards developing the retrievals of ice hydrometeor properties based on data from GMI, the Ice Cloud Imager (ICI) and other conically scanning instruments.

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Section: Basic Retrieval Performancementioning

confidence: 81%

Section: Other Factors Affecting Retrieval Performancementioning

confidence: 99%