Triple-Frequency Radar Retrievals

Battaglia, Alessandro; Tanelli, Simone; Tridon, Frédéric; Kneifel, Stefan; Leinonen, Jussi; Kollias, Pavlos

doi:10.1007/978-3-030-24568-9_13

Cited by 12 publications

(10 citation statements)

References 64 publications

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“…Following the definition of Z e , values measured at two wavelengths are equal if scattering from all particles and at both wavelengths can be approximated by Rayleigh scattering. If the particles increase in size, they first start to deviate from Rayleigh scattering at the shorter wavelength: this leads to a smaller Z e at the shorter wavelength compared to the longer one, where more particles are still in the Rayleigh scattering regime (Battaglia et al., 2020). As a result, quantities combining Z e values at both wavelengths can be related to the characteristic size of the underlying particle size distribution (PSD; Hogan et al., 2000; Kneifel et al., 2016; Liao et al., 2005; Matrosov et al., 2005; Szyrmer & Zawadzki, 2014; Tridon & Battaglia, 2015).…”

Section: Background: Dual‐wavelength Radar Approachmentioning

confidence: 99%

Ice Aggregation in Low‐Level Mixed‐Phase Clouds at a High Arctic Site: Enhanced by Dendritic Growth and Absent Close to the Melting Level

2022

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Low-level mixed-phase clouds (MPCs) are ubiquitous in the Arctic. They have been shown to occur widely and frequently (e.g., Mioche et al., 2015;Morrison et al., 2012) and to persist typically for several hours (de Boer et al., 2009;Shupe, 2011), with some recorded cases lasting up to several days (e.g., Zuidema et al., 2005). They are further known to introduce, on average, a strong positive surface radiative forcing (Shupe & Intrieri, 2004;Serreze & Barry, 2011;Matus & L'Ecuyer, 2017;Tan & Storelvmo, 2019). Arctic low-level MPCs display a characteristic structure with one or multiple shallow liquid layers close to cloud top, from which ice particles form and precipitate (Shupe et al., 2006). Their persistence is due to a complex interplay of several processes (Morrison et al., 2012), and they have been found to occur under a variety of conditions, including both stable and unstable

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Section: Background: Dual‐wavelength Radar Approachmentioning

confidence: 99%

Ice Aggregation in Low‐Level Mixed‐Phase Clouds at a High Arctic Site: Enhanced by Dendritic Growth and Absent Close to the Melting Level

2022

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“…Because of the variety of ice habits and shapes, the computation of scattering properties of ice crystals is much more complex than for raindrops Kuo et al, 2016;Kneifel et al, 2020, and references therein); while at small sizes backscattering cross sections are proportional to the square of the mass of the crystals (Hogan et al, 2006), when approaching large sizes the mass distribution within the particle along the direction of the impinging radiation plays a key role in affecting the particles scattering properties (e.g., Hogan & Westbrook, 2014).…”

Section: A4 Non-rayleigh Effects For Ice Crystalsmentioning

confidence: 99%

“…Multifrequency radar observations are especially valuable in ice/snow cloud conditions since ice crystals are complex with large variability in microphysical properties (e.g., density, size, shape), making the interpretation of single‐frequency radar observations extremely challenging. Dual‐frequency first (Matrosov, 1998; Hogan et al., 2000; Liao et al., 2016) and later triple‐frequency (13, 35, and 94 GHz) methods have been proposed to characterize ice microphysics (Battaglia et al., 2020; Kneifel et al., 2011; Kneifel et al., 2015; Kulie et al., 2014; Leinonen et al., 2012; Leinonen & Moisseev, 2015; Stein et al., 2015). These methods rely on the fact that, in the “non‐Rayleigh” regime, the measured reflectivity changes (typically decreases) relative to the Rayleigh reference, because the incident wave backscattered from different parts of the ice particle interferes (typically in a destructive way) with itself.…”

Section: Future Outlookmentioning

confidence: 99%

Spaceborne Cloud and Precipitation Radars: Status, Challenges, and Ways Forward

Battaglia

Kollias

Dhillon

et al. 2020

Reviews of Geophysics

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Spaceborne radars offer a unique three‐dimensional view of the atmospheric components of the Earth's hydrological cycle. Existing and planned spaceborne radar missions provide cloud and precipitation information over the oceans and land difficult to access in remote areas. A careful look into their measurement capabilities indicates considerable gaps that hinder our ability to detect and probe key cloud and precipitation processes. The international community is currently debating how the next generation of spaceborne radars shall enhance current capabilities and address remaining gaps. Part of the discussion is focused on how to best take advantage of recent advancements in radar and space platform technologies while addressing outstanding limitations. First, the observing capabilities and measurement highlights of existing and planned spaceborne radar missions including TRMM, CloudSat, GPM, RainCube, and EarthCARE are reviewed. Then, the limitations of current spaceborne observing systems, with respect to observations of low‐level clouds, midlatitude and high‐latitude precipitation, and convective motions, are thoroughly analyzed. Finally, the review proposes potential solutions and future research avenues to be explored. Promising paths forward include collecting observations across a gamut of frequency bands tailored to specific scientific objectives, collecting observations using mixtures of pulse lengths to overcome trade‐offs in sensitivity and resolution, and flying constellations of miniaturized radars to capture rapidly evolving weather phenomena. This work aims to increase the awareness about existing limitations and gaps in spaceborne radar measurements and to increase the level of engagement of the international community in the discussions for the next generation of spaceborne radar systems.

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“…Scattering properties of cloud droplets and raindrops are computed via Mie theory (e.g., see Lhermitte, 1990). An exponential drop size distribution is assumed for rain with N 0r = 8 × 10 6 m −4 (Marshall and Palmer, 1948) whereas a Gamma distribution with µ = 3 with an effective radius increasing from 3 to 15 µm from cloud base to cloud top according to Bennartz (2007) is adopted. The impact of the Marshall and Palmer assumption is discussed later.…”

Section: Forward Radar Simulatormentioning

confidence: 99%

Mind the gap – Part 2: Improving quantitative estimates of cloud and rain water path in oceanic warm rain using spaceborne radars

et al. 2020

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Abstract. The intrinsic small spatial scales and low-reflectivity structure of oceanic warm precipitating clouds suggest that millimeter spaceborne radars are best suited to providing quantitative estimates of cloud and rain liquid water paths (LWPs). This assertion is based on their smaller horizontal footprint; high sensitivities; and a wide dynamic range of path-integrated attenuations associated with warm-rain cells across the millimeter wavelength spectrum, with diverse spectral responses to rain and cloud partitioning. State-of-the-art single-frequency radar profiling algorithms of warm rain seem to be inadequate because of their dependence on uncertain assumptions about the rain–cloud partitioning and because of the rain microphysics. Here, high-resolution cloud-resolving model simulations for the Rain in Cumulus over the Ocean field study and a spaceborne forward radar simulator are exploited to assess the potential of existing and future spaceborne radar systems for quantitative warm-rain microphysical retrievals. Specifically, the detrimental effects of nonuniform beam filling on estimates of path-integrated attenuation (PIA), the added value of brightness temperature (TB) derived adopting radiometric radar modes, and the performances of multifrequency PIA and/or TB combinations when retrieving liquid water paths partitioned into cloud (c-LWPs) and rain (r-LWPs) are assessed. Results show that (1) Ka- and W-band TB values add useful constraints and are effective at lower LWPs than the same-frequency PIAs; (2) matched-beam combined TB values and PIAs from single-frequency or multifrequency radars can significantly narrow down uncertainties in retrieved cloud and rain liquid water paths; and (3) the configuration including PIAs, TB values and near-surface reflectivities for the Ka-band–W-band pairs in our synthetic retrieval can achieve an RMSE of better than 30 % for c-LWPs and r-LWPs exceeding 100 g m−2.

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Triple-Frequency Radar Retrievals

Cited by 12 publications

References 64 publications

Ice Aggregation in Low‐Level Mixed‐Phase Clouds at a High Arctic Site: Enhanced by Dendritic Growth and Absent Close to the Melting Level

Ice Aggregation in Low‐Level Mixed‐Phase Clouds at a High Arctic Site: Enhanced by Dendritic Growth and Absent Close to the Melting Level

Spaceborne Cloud and Precipitation Radars: Status, Challenges, and Ways Forward

Mind the gap – Part 2: Improving quantitative estimates of cloud and rain water path in oceanic warm rain using spaceborne radars

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