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Robert Conrick, Joseph P. Zagrodnik, and Clifford F. Mass

during different storm sectors of midlatitude cyclones impacting the Olympic Peninsula of Washington State. In addition, they found that periods warm-rain enhancement were associated with DSDs having a large number of small drops. The development of machine learning techniques and their implementations (e.g., the “scikit-learn” Python package; Pedregosa et al. 2011 ) provide new opportunities for the atmospheric sciences, particularly with regard to statistical weather forecasting ( Herman and

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Qian Cao, Thomas H. Painter, William Ryan Currier, Jessica D. Lundquist, and Dennis P. Lettenmaier

development of techniques that merge the two data sources, for example, mean field bias ( Berndt et al. 2014 ; Nikolopoulos et al. 2015 ), probability density function matching ( Nikolopoulos et al. 2015 ; Hasan et al. 2016 ), and geostatistical approaches including kriging, cokriging, and kriging with external drift (KED; Velasco-Forero et al. 2009 ; Berndt et al. 2014 ; Rabiei and Haberlandt 2015 ). Despite the fact that integration of radar and gauge data exploits both of their strengths, its

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David J. Purnell and Daniel J. Kirshbaum

(>3 km) typically exceeds the freezing level. For the WF3 example, the MFB correction is strongly positive over the KLGX2 and UPPER regions ( Figs. 5c,d ), yielding a more physically plausible precipitation field over the Olympics with a maximum on its southwestern slopes. b. 2D-VAR Additional small-scale corrections are carried out in close proximity to each surface gauge measurement using 2D variational data assimilation (2D-VAR), an optimal-estimation technique that accounts for errors in both

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Zeinab Takbiri, Ardeshir Ebtehaj, Efi Foufoula-Georgiou, Pierre-Emmanuel Kirstetter, and F. Joseph Turk

) developed a statistical approach that partitions high-frequency brightness temperatures (≥89 GHz) into two distinct warm and cold weather regimes by thresholding the brightness temperature at 53 GHz. Another class of empirical approaches relies on Bayesian techniques. These techniques use a database or a lookup table that relates brightness temperatures of snowing clouds to the radar snowfall observations along with the atmospheric temperature profile. As an example, Liu and Seo (2013) used matched

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Bin Pei and Firat Y. Testik

2002 ; Thurai et al. 2012 ). In the development of a typical category I algorithm, the dual-polarization radar observables and the corresponding theoretical rain rates are first calculated using either the simulated or measured DSDs. The calculation of the dual-polarization radar observables relies on an accurate description of the electromagnetic scattering by particles. Computational techniques, such as the T-matrix method ( Mishchenko et al. 1996 ), the discrete dipole approximation ( Draine

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Ali Tokay, Leo Pio D’Adderio, David A. Marks, Jason L. Pippitt, David B. Wolff, and Walter A. Petersen

rely on radar rainfall estimates for flood forecasting and the majority of the comparative studies use rain gauges as a reference ( Cunha et al. 2013 ). The accuracy of Z H / Z DR couples should therefore independently be evaluated prior to radar rainfall estimation. The envelope of Z H / Z DR presented here could be used a reference in these studies. Reflectivities Z H and Z DR are vital radar measurements for radar rainfall mapping. The study presented here showed the presence of surface

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Andrew Heymsfield, Aaron Bansemer, Norman B. Wood, Guosheng Liu, Simone Tanelli, Ousmane O. Sy, Michael Poellot, and Chuntao Liu

for Medium-Range Weather Forecasts (ECMWF) that have been collocated to the CloudSat radar profiles. The CloudSat snowfall data were produced via a retrieval method similar to that used by the CloudSat 2C-SNOW-PROFILE (2C-SP) version release 4 (R04) algorithm ( Wood et al. 2013 ), but modified to perform retrievals above the melting layer when rain or mixed-phase precipitation is reaching the surface. As does the unmodified algorithm, this 2C-SP-mod retrieval algorithm estimates vertical

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Yagmur Derin, Emmanouil Anagnostou, Marios Anagnostou, and John Kalogiros

methods to validate satellite constellation measurements with surface rainfall measured by dense rain gauge and disdrometer networks at various sites. One such campaign was OLYMPEX, which was conducted in the Pacific Northwest. The goal of OLYMPEX was to validate rain and snow measurements in midlatitude frontal systems as they moved from ocean to coast to mountains and determine how remotely sensed measurements of precipitation by GPM could be applied to a range of hydrological, weather forecasting

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Joseph P. Zagrodnik, Lynn A. McMurdie, Robert A. Houze Jr., and Simone Tanelli

. (2015) and Zagrodnik et al. (2018) the rain PSDs are described using the median volume diameter D o and normalized intercept parameter N w as derived in Testud et al. (2001) . This technique is particularly useful because a given PSD with an approximately gamma distribution can be characterized using only D o and N w . The value of D o is computed from the binned PSDs by determining the two drop size bins in which the cumulative liquid water content reaches 50% and linearly

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