Universität zu Köln

Mroz, Kamil, Battaglia, Alessandro ORCID: 0000-0001-9243-3484, Kneifel, Stefan ORCID: 0000-0003-2220-2968, von Terzi, Leonie, Karrer, Markus and Ori, Davide ORCID: 0000-0002-9964-2200 (2021). Linking rain into ice microphysics across the melting layer in stratiform rain: a closure study. Atmos. Meas. Tech., 14 (1). S. 511 - 530. GOTTINGEN: COPERNICUS GESELLSCHAFT MBH. ISSN 1867-8548

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Abstract

This study investigates the link between rain and ice microphysics across the melting layer in stratiform rain systems using measurements from vertically pointing multi-frequency Doppler radars. A novel methodology to examine the variability of the precipitation rate and the mass-weighted melted diameter (D-m) across the melting region is proposed and applied to a 6 h long case study, observed during the TRIPEx-pol field campaign at the Julich Observatory for Cloud Evolution Core Facility and covering a gamut of ice microphysical processes. The methodology is based on an optimal estimation (OE) retrieval of particle size distributions (PSDs) and dynamics (turbulence and vertical motions) from observed multi-frequency radar Doppler spectra applied both above and below the melting layer. First, the retrieval is applied in the rain region; based on a one-to-one conversion of raindrops into snowflakes, the retrieved drop size distributions (DSDs) are propagated upward to provide the mass-flux-preserving PSDs of snow. These ice PSDs are used to simulate radar reflectivities above the melting layer for different snow models and they are evaluated for a consistency with the actual radar measurements. Second, the OE snow retrieval where Doppler spectra are simulated based on different snow models, which consistently compute fall speeds and electromagnetic properties, is performed. The results corresponding to the best-matching models are then used to estimate snow fluxes and D-m, which are directly compared to the corresponding rain quantities. For the case study, the total accumulation of rain (2.30 mm) and the melted equivalent accumulation of snow (1 93 mm) show a 19 % difference. The analysis suggests that the mass flux through the melting zone is well preserved except the periods of intense riming where the precipitation rates were higher in rain than in the ice above. This is potentially due to additional condensation within the melting zone in correspondence to high relative humidity and collision and coalescence with the cloud droplets whose occurrence is ubiquitous with riming. It is shown that the mean mass-weighted diameter of ice is strongly related to the characteristic size of the underlying rain except the period of extreme aggregation where breakup of melting snowflakes significantly reduces D-m. The proposed methodology can be applied to long-term observations to advance our knowledge of the processes occurring across the melting region; this can then be used to improve assumptions underpinning spaceborne radar precipitation retrievals.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mroz, Kamil UNSPECIFIED UNSPECIFIED UNSPECIFIED Battaglia, Alessandro UNSPECIFIED orcid.org/0000-0001-9243-3484 UNSPECIFIED Kneifel, Stefan UNSPECIFIED orcid.org/0000-0003-2220-2968 UNSPECIFIED von Terzi, Leonie UNSPECIFIED UNSPECIFIED UNSPECIFIED Karrer, Markus UNSPECIFIED UNSPECIFIED UNSPECIFIED Ori, Davide UNSPECIFIED orcid.org/0000-0002-9964-2200 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-579067
DOI:	10.5194/amt-14-511-2021
Journal or Publication Title:	Atmos. Meas. Tech.
Volume:	14
Number:	1
Page Range:	S. 511 - 530
Date:	2021
Publisher:	COPERNICUS GESELLSCHAFT MBH
Place of Publication:	GOTTINGEN
ISSN:	1867-8548
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language RADAR DOPPLER SPECTRA; SIZE DISTRIBUTIONS; WIDESPREAD PRECIPITATION; WATER-CONTENT; CLOUD RADAR; PART III; BAND; RETRIEVAL; AGGREGATE; MULTIFREQUENCY Multiple languages Meteorology & Atmospheric Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/57906