EUREC&amp;lt;sup&amp;gt;4&amp;lt;/sup&amp;gt;A's &amp;lt;i&amp;gt;Maria S. Merian&amp;lt;/i&amp;gt; ship-based cloud and micro rain radar observations of clouds and precipitation

Acquistapace, Claudia; Coulter, R. L.; Crewell, Susanne; Garcia-Benadí, Albert; Gierens, Rosa; Labbri, Giacomo; Myagkov, Alexander; Risse, Nils; Schween, Jan H.

doi:10.5194/essd-14-33-2022

Cited by 4 publications

(13 citation statements)

References 41 publications

(41 reference statements)

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“…For this reason, we derived hydrometeor fraction profiles and Contour Frequency by Altitude Diagrams (CFADs) for radar reflectivity and mean Doppler velocity for non-rainy cloud columns only. The LWP observations in rainy condition can be biased due to the wet radome of the radar, but we retain the LWP observations also in rainy conditions because all values are much smaller than 1,000 g m −2 , considered as a threshold corresponding to saturation in the MWR channels (Acquistapace, Coulter, et al, 2022). Over the cold SST, the hydrometeor profile displays two main cloudy peaks, one at the LCL, around 700 m, and the second one right below the inversion height (Figure 10b).…”

Section: Resultsmentioning

confidence: 99%

“…The vertical resolution is 7.5 m between 100 and 1,233 m, 9.2 m between 1,233 and 3,000 m, and 34.1 m between 3,000 and 10,000 m. The radar stands on a stabilization platform to reduce the impact of ship motions on its Doppler measurements. Acquistapace, Coulter, et al (2022) report a detailed description of the impact of the stabilization on the data, the setup used on the ship, and the details on the retrieval for the liquid water path (LWP). Time series of reflectivity, mean Doppler velocity and LWP are shown in Figures 2c-2e.…”

Section: W-band Cloud Radarmentioning

confidence: 99%

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Fast Atmospheric Response to a Cold Oceanic Mesoscale Patch in the North‐Western Tropical Atlantic

et al. 2022

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Low clouds over tropical oceans have a cooling impact on the Earth's radiation budget. They strongly reflect the incoming solar radiation (high albedo) and slightly reduce the terrestrial emission (Scott et al., 2020). They also impact the temperature and moisture of the marine boundary layer (Bretherton et al., 2013) and are crucial in modulating the air-sea interactions that influence the sea surface temperature (SST) patterns (Yuan et al., 2018). Stratocumulus clouds prevail where free tropospheric subsidence reinforces the atmospheric boundary layer (ABL) stability, while shallow cumuliform clouds develop where subsidence and ABL inversion are weaker, typically over warmer surfaces with a deeper ABL (Mieslinger et al., 2019). Bony and Dufresne (2005) identify such clouds as the largest source of uncertainty in climate model predictions. Most climate models cannot realistically simulate low cloud processes and strongly diverge in the feedback to global warming (Zelinka et al., 2020). Recent observational studies show that in response to surface warming,

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Section: Resultsmentioning

confidence: 99%

Section: W-band Cloud Radarmentioning

confidence: 99%

Fast Atmospheric Response to a Cold Oceanic Mesoscale Patch in the North‐Western Tropical Atlantic

et al. 2022

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“…As a post-processing step to correct for vertical heave of the vessel, a heave correction as described in Acquistapace et al (2022) was applied to the cloud radar data. Note that contrarily to Acquistapace et al (2022), the heave correction was directly applied to the full Doppler spectrum of the W-band radar, instead of to the mean Doppler velocity. Further radar data processing included signal clutter filtering as well as Doppler spectra dealiasing using pyLARDA software (Bühl et al, 2021).…”

Section: Doppler Cloud Radar Limrad94mentioning

confidence: 99%

The Virga-Sniffer – a new tool to identify precipitation evaporation using ground-based remote-sensing observations

et al. 2023

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Abstract. Continuous long-term ground-based remote-sensing observations combined with vertically pointing cloud radar and ceilometer measurements are well suited for identifying precipitation evaporation fall streaks (so-called virga). Here we introduce the functionality and workflow of a new open-source tool, the Virga-Sniffer, which was developed within the framework of RV Meteor observations during the ElUcidating the RolE of Cloud–Circulation Coupling in ClimAte (EUREC4A) field experiment in January–February 2020 in the tropical western Atlantic. The Virga-Sniffer Python package is highly modular and configurable and can be applied to multilayer cloud situations. In the simplest approach, it detects virga from time–height fields of cloud radar reflectivity and time series of ceilometer cloud base height. In addition, optional parameters like lifting condensation level, a surface rain flag, and time–height fields of cloud radar mean Doppler velocity can be added to refine virga event identifications. The netCDF-output files consist of Boolean flags of virga and cloud detection, as well as base and top heights and depth for the detected clouds and virga. The sensitivity of the Virga-Sniffer results to different settings is explored (in the Appendix). The performance of the Virga-Sniffer was assessed by comparing its results to the CloudNet target classification resulting from using the CloudNet processing chain. A total of 86 % of pixels identified as virga correspond to CloudNet target classifications of precipitation. The remaining 14 % of virga pixels correspond to CloudNet target classifications of aerosols and insects (about 10 %), cloud droplets (about 2 %), or clear sky (2 %). Some discrepancies of the virga identification and the CloudNet target classification can be attributed to temporal smoothing that was applied. Additionally, it was found that CloudNet mostly classified aerosols and insects at virga edges, which points to a misclassification caused by CloudNet internal thresholds. For the RV Meteor observations in the downstream winter trades during EUREC4A, about 42 % of all detected clouds with bases below the trade inversion were found to produce precipitation that fully evaporates before reaching the ground. A proportion of 56 % of the detected virga originated from trade wind cumuli. Virga with depths less than 0.2 km most frequently occurred from shallow clouds with depths less than 0.5 km, while virga depths larger than 1 km were mainly associated with clouds of larger depths, ranging between 0.5 and 1 km. The presented results substantiate the importance of complete low-level precipitation evaporation in the downstream winter trades. Possible applications of the Virga-Sniffer within the framework of EUREC4A include detailed studies of precipitation evaporation with a focus on cold pools or cloud organization or distinguishing moist processes based on water vapor isotopic observations. However, we envision extended use of the Virga-Sniffer for other cloud regimes or scientific foci as well.

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“…Aboard the Merian, the Institute for Geophysics and Meteorology of the University of Cologne operated a radar-radiometer system of the type RPG-FMCW-94 dual polarization (DP) of the same kind as LIMRAD which measures in the W-band (94 GHz) and includes a passive radiometer channel at 89 GHz (Küchler et al, 2017, here referred to as MSMRAD). The system was positioned on an active stabilization platform from the US-Atmospheric Radiation Measurement (ARM) program Mobile Facility 2 which keeps the radar in zenith position by adapting the table surface position to compensate for ship motions (see Acquistapace et al, 2022, for more information). As for LIMRAD, stabilization helps eliminate the effect of horizontal wind and ship roll and pitch tilting from the radar Doppler velocities.…”

Section: Merianmentioning

confidence: 99%

“…Aboard the Meteor, a 94 GHz cloud radar (Küchler et al, 2017) was installed, equipped with a passive radiometer channel measuring T B at 89 GHz (Kalesse-Los et al, 2023), here referred to as LIMRAD. A similar instrument was stationed aboard the Merian (Acquistapace et al, 2022), here referred to as MSMRAD. These single-channel measurements are suitable to retrieve IWV in cloud-free conditions, and LWP in cloudy conditions if IWV is known, e.g.…”

Section: Introductionmentioning

confidence: 99%

Ground- and ship-based microwave radiometer measurements during EUREC4A

Schnitt

Foth

Kalesse

et al. 2023

Preprint

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Abstract. During the EUREC4A field study, microwave radiometric measurements were performed at Barbados Cloud Observatory (BCO) and aboard the RV Meteor and RV Maria S Merian. We present retrieved Integrated Water Vapor (IWV), Liquid Water Path (LWP) and temperature and humidity profiles as a unified, quality-controlled, multi-site dataset on a three second temporal resolution for a core period between January 19, 2020 and February 14, 2020 in which all instruments were operational. 14-channel K- and V-band measurements were performed at BCO and aboard the RV Meteor, and combined radar-radiometer measurements of a W-band Doppler radar with a single-channel radiometer instrument were conducted at 89 GHz onboard the RV Meteor and RV Maria S Merian. Mean IWV of 31.8 kgm−2 matches independent radiosoundings at BCO with a rootmean-square difference of 1.1 kgm−2. Mean LWP conditions in confident cloudy, non-precipitating conditions ranged between 66.5 gm−2 at BCO to 40.4 gm−2 aboard the RV Maria S Merian. Aboard the ships, 90 % of LWP was below 120 gm−2 with an uncertainty of 30 % at LWP of 50 gm−2. Up to 30 % of confident cloudy profiles ranged below the LWP detection limit due to optically thin clouds. The data set comprises of processed raw-data (Level 1), full quality-controlled post-processed instrument data (Level 2), a unified temporal resolution (Level 3), and a ready-to-use multi-site time series of IWV and LWP (Level 4), available to the public via AERIS (https://doi.org/10.25326/454, Schnitt et al., 2023). The data set complements the airborne LWP measurements conducted during EUREC4A and provides a benchmark tool for model-observation studies.

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EUREC<sup>4</sup>A's <i>Maria S. Merian</i> ship-based cloud and micro rain radar observations of clouds and precipitation

Cited by 4 publications

References 41 publications

Fast Atmospheric Response to a Cold Oceanic Mesoscale Patch in the North‐Western Tropical Atlantic

Fast Atmospheric Response to a Cold Oceanic Mesoscale Patch in the North‐Western Tropical Atlantic

The Virga-Sniffer – a new tool to identify precipitation evaporation using ground-based remote-sensing observations

Ground- and ship-based microwave radiometer measurements during EUREC4A

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