Sensitivity of PAZ LEO Polarimetric GNSS Radio-Occultation Experiment to Precipitation Events

Cardellach, Estel; Tomás, S.A.; Oliveras, S.; Padullés, Ramon; Rius, A.; Torre‐Juárez, M. de la; Turk, F. Joseph; Ao, C. O.; Kursinski, E. R.; Schreiner, B.; Ector, D.; Cucurull, Lídia

doi:10.1109/tgrs.2014.2320309

Cited by 42 publications

(65 citation statements)

References 22 publications

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“…This is due to the fact that heavy rain has more large nonspherical raindrops which can, as a result, cause more phase shift [17]. The results are also in consistent with the description by Al-Rizzo et al [33] and Cardellach et al [13]. In addition, we also note that the polarimetric phase shift's tendency is similar at different frequencies.…”

Section: Variations Of Polarimetric Phase Shift With Rain Ratesupporting

confidence: 92%

“…Extending the research by Cardellach et al [12,13], this paper intends to probe into the influencing factors on rain rate estimation by GNSS polarimetric phase shift in theory, which will play an important role in the design of measuring equipment, the implementation of experiments and the future data processing algorithms. Section 2 describes the physical-mathematical relationship model between polarimetric phase shift and rain rate using the oblate spheroid raindrop model, four different raindrop size distribution models and raindrop canting angle distribution across the Space-Earth rain path.…”

Section: Introductionmentioning

confidence: 98%

“…Moreover, a polarimetric concept employing GNSS Radio-Occultation (RO) signals to detect heavy rain was first proposed by Cardellach et al [12]. The concept will be tested on a spaceborne experiment aboard a Low Earth Orbiter, in the Radio-Occultation and Heavy Precipitation (ROHP) experiment aboard the Spanish Earth Observation satellite PAZ [13].…”

Section: Introductionmentioning

confidence: 99%

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GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

Yan

Huang

et al. 2016

Atmosphere

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Abstract:In this paper, a novel method for rain rate estimation is researched by polarimetric phase shift of the Global Navigation Satellite System (GNSS). The physical process of GNSS signals propagating through rain-filled medium is investigated, by which the cause of polarimetric phase shift is explored. Then, a theoretical model between polarimetric phase shift ∆φ and rain rate R is established and simulated, which is based on the oblate spheroid raindrop model, four different popular raindrop size distribution models and raindrop canting angle distribution across the Space-Earth rain path. Additionally, effects of raindrop size distribution, rain path length, raindrop canting angle and temperature on the ∆φ-R relation are discussed systematically. Other factors in the slant path such as ice crystals, melting particles and ionosphere are also researched preliminarily. The results show that polarimetric phase shift of GNSS signals, which has a strong correlation with rain rate, can be used to estimate the rain rate, and these influencing factors, raindrop size distribution, rain path length, raindrop canting angle and temperature, are quite important in the process of rain rate measurement. It can be also found that the effect of ice crystals can be negligible, while that of melting particles should be considered, and though ionosphere effects are not obvious, the ionospheric anomalies cannot be neglected in future experiments. This method has potential applications in real-time, continuous, extreme precipitation reconnaissance and numerical weather prediction.

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Section: Variations Of Polarimetric Phase Shift With Rain Ratesupporting

confidence: 92%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

Yan

Huang

et al. 2016

Atmosphere

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“…The material in this article involves a newly proposed measurement concept, where GNSS RO measurements are taken at two orthogonal polarizations to exploit the potential capabilities of polarimetric RO (PRO) for jointly observing and quantifying atmospheric thermodynamics and rain profiles within heavy precipitation events (Cardellach et al , 2015). These polarimetric RO measurements are predicated on the fact that, in the L band (1.5 GHz, the typical GNSS transmit frequency), the effect of clouds and precipitation on the received signal magnitude is negligible, but since GNSS receivers provide inherently high precision phase measurements they can track differential propagation phase changes very accurately.…”

Section: Introductionmentioning

confidence: 99%

Probability of intense precipitation from polarimetric GNSS radio occultation observations

Cardellach

Padullés

Tomás

et al. 2017

Quart J Royal Meteoro Soc

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There is currently a gap in satellite observations of the moisture structure during heavy precipitation conditions, since infrared and microwave sounders cannot sense water-vapour structure near the surface in the presence of intense precipitation. Conversely, Global Navigation Satellite System (GNSS) radio occultations (RO) can profile the moisture structure with high precision and vertical resolution, but cannot indicate the presence of precipitation directly. Polarimetric RO (PRO) measurements have been proposed as a method to characterize heavy rain in GNSS RO, by measuring the polarimetric differential phase delay induced by large size hydrometeors. Previous studies have shown that the PRO polarimetric phase shift is sensitive to the path-integrated rain rate under intense precipitation scenarios, but there is no current method to invert PRO measurements into quantitative estimates of the path-averaged rain rate. In this manuscript, a probabilistic inversion approach to the GNSS PRO observables is proposed, where the GPM precipitation products are used for the construction of an a priori look-up table (LUT) database. The performance of the LUTs is assessed for use in the inversion of satellite-based GNSS PRO observations, based on synthetically generated PRO data of actual events, which correspond to co-locations between GNSS RO profiles and the TRMM observations. The synthetic data include end-to-end propagation effects of the polarimetric observables and a simple separation algorithm to isolate the hydrometeor component of the observation. The assessment results in agreement better than ±1 mm h −1 between the reference LUT and the actual rain statistics of the synthetic data, proving the suitability of the GPMbased probabilistic inversion tool. These findings indicate that the GNSS PRO products are capable of extending the current GNSS RO ones by associating indications of rainrate probabilities at different altitudes, at ∼250 m vertical resolution and under intense precipitation scenarios with the standard vertical thermodynamic profiles.

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“…The values of these parameters can be obtained from measured raindrop data or radar data. This Gamma distribution is widely accepted and used by radar meteorologists and other researchers to model natural raindrop size distributions [11,29,30]. The rain rate R can be computed from [31] R mm h…”

Section: Raindrop Size Distributionmentioning

confidence: 99%

Feasibility Study of Rain Rate Monitoring from Polarimetric GNSS Propagation Parameters

Yan

Huang

et al. 2016

Atmosphere

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Abstract:In this work, the feasibility of estimating rain rate based on polarimetric Global Navigation Satellite Systems (GNSS) signals is explored in theory. After analyzing the cause of polarimetric signals, three physical-mathematical relation models between co-polar phase shift (K HH , K VV ), specific differential phase shift (K DP ), and rain rate (R) are respectively investigated. These relation models are simulated based on four different empirical equations of nonspherical raindrops and simulated Gamma raindrop size distribution. They are also respectively analyzed based on realistic Gamma raindrop size distribution and maximum diameter of raindrops under three different rain types: stratiform rain, cumuliform rain, and mixed clouds rain. The sensitivity of phase shift with respect to some main influencing factors, such as shape of raindrops, frequency, as well as elevation angle, is also discussed, respectively. The numerical results in this study show that the results by scattering algorithms T-matrix are consistent with those from Rayleigh Scattering Approximation. It reveals that they all have the possibility to estimate rain rate using the K HH -R, K VV -R or K DP -R relation. It can also be found that the three models are all affected by shape of raindrops and frequency, while the elevation angle has no effect on K HH -R. Finally, higher frequency L1 or B1 and lower elevation angle are recommended and microscopic characteristics of raindrops, such as shape and size distribution, are deemed to be important and required for further consideration in future experiments. Since phase shift is not affected by attenuation and not biased by ground clutter cancellers, this method has considerable potential in precipitation monitoring, which provides new opportunities for atmospheric research.

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Sensitivity of PAZ LEO Polarimetric GNSS Radio-Occultation Experiment to Precipitation Events

Cited by 42 publications

References 22 publications

GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

Probability of intense precipitation from polarimetric GNSS radio occultation observations

Feasibility Study of Rain Rate Monitoring from Polarimetric GNSS Propagation Parameters

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