Airborne Dual-Polarization Observations of the Sea Surface NRCS at C-Band in High Winds

Sapp, Joseph; Frasier, Stephen J.; Dvorsky, J.; Chang, Paul; Jelenak, Zorana

doi:10.1109/lgrs.2012.2220118

Cited by 4 publications

(3 citation statements)

References 11 publications

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“…External calibration is achieved by combining ground calibration measurements with a final adjustment computed from a scatterometer geophysical model function using collocated SFMR measurements. For a description of the external calibration method, see Sapp et al (2013Sapp et al ( , 2016.…”

Section: A Iwrapmentioning

confidence: 99%

Coherent Turbulence in the Boundary Layer of Hurricane Rita (2005) during an Eyewall Replacement Cycle

Guimond

Zhang

Sapp

et al. 2018

Journal of the Atmospheric Sciences

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The structure of coherent turbulence in an eyewall replacement cycle in Hurricane Rita (2005) is presented from novel airborne Doppler radar observations using the Imaging Wind and Rain Airborne Profiler (IWRAP). The IWRAP measurements and three-dimensional (3D) wind vector calculations at a grid spacing of 250 m in the horizontal and 30 m in the vertical reveal the ubiquitous presence of organized turbulent eddies in the lower levels of the storm. The data presented here, and the larger collection of IWRAP measurements, currently are the highest-resolution Doppler radar 3D wind vectors ever obtained in a hurricane over the open ocean. Coincident data from NOAA airborne radars, the Stepped Frequency Microwave Radiometer, and flight-level data help to place the IWRAP observations into context and provide independent validation. The typical characteristics of the turbulent eddies are the following: radial wavelengths of ~1–3 km (mean value is ~2 km), depths from the ocean surface up to flight level (~1.5 km), aspect ratio of ~1.3, and horizontal wind speed perturbations of 10–20 m s−1. The most intense eddy activity is located on the inner edge of the outer eyewall during the concentric eyewall stage with a shift to the inner eyewall during the merging stage. The evolving structure of the vertical wind shear is connected to this shift and together these characteristics have several similarities to boundary layer roll vortices. However, eddy momentum flux analysis reveals that high-momentum air is being transported upward, in contrast with roll vortices, with large positive values (~150 m2 s−2) found in the turbulent filaments. In the decaying inner eyewall, elevated tangential momentum is also being transported radially outward to the intensifying outer eyewall. These results indicate that the eddies may have connections to potential vorticity waves with possible modifications due to boundary layer shear instabilities.

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Section: A Iwrapmentioning

confidence: 99%

Coherent Turbulence in the Boundary Layer of Hurricane Rita (2005) during an Eyewall Replacement Cycle

Guimond

Zhang

Sapp

et al. 2018

Journal of the Atmospheric Sciences

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“…With its aircraft field campaigns, DIAMET joins worldwide efforts to sample weather systems through aircraft observations (e.g., Sch€ afler et al 2011;Sapp et al 2013). To the authors' knowledge there have only been two previous research flights into an intense cyclone of this type, crossing the strong wind regions near the cyclone center.…”

Section: Introductionmentioning

confidence: 99%

Distinguishing the Cold Conveyor Belt and Sting Jet Airstreams in an Intense Extratropical Cyclone

Martínez‐Alvarado

Baker

Gray

et al. 2014

Monthly Weather Review

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Strong winds equatorward and rearward of a cyclone core have often been associated with two phenomena: the cold conveyor belt (CCB) jet and sting jets. Here, detailed observations of the mesoscale structure in this region of an intense cyclone are analyzed. The in situ and dropsonde observations were obtained during two research flights through the cyclone during the Diabatic Influences on Mesoscale Structures in Extratropical Storms (DIAMET) field campaign. A numerical weather prediction model is used to link the strong wind regions with three types of ''airstreams'' or coherent ensembles of trajectories: two types are identified with the CCB, hooking around the cyclone center, while the third is identified with a sting jet, descending from the cloud head to the west of the cyclone. Chemical tracer observations show for the first time that the CCB and sting jet airstreams are distinct air masses even when the associated low-level wind maxima are not spatially distinct. In the model, the CCB experiences slow latent heating through weak-resolved ascent and convection, while the sting jet experiences weak cooling associated with microphysics during its subsaturated descent. Diagnosis of mesoscale instabilities in the model shows that the CCB passes through largely stable regions, while the sting jet spends relatively long periods in locations characterized by conditional symmetric instability (CSI). The relation of CSI to the observed mesoscale structure of the bent-back front and its possible role in the cloud banding is discussed.

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“…All of these calibration adjustments are on the same order of magnitude as in previous years (e.g., [5], [14]). HH-polarization results are not shown here since Sentinel-1B was not measuring HH NRCS at the time.…”

Section: Calibrationmentioning

confidence: 99%

Comparison of the Sentinel-1B Synthetic Aperture Radar With Airborne Microwave Sensors in an Extra-Tropical Cyclone

Sapp

Mouche

Jelenak

et al. 2020

IEEE Trans. Geosci. Remote Sensing

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Airborne Dual-Polarization Observations of the Sea Surface NRCS at C-Band in High Winds

Cited by 4 publications

References 11 publications

Coherent Turbulence in the Boundary Layer of Hurricane Rita (2005) during an Eyewall Replacement Cycle

Coherent Turbulence in the Boundary Layer of Hurricane Rita (2005) during an Eyewall Replacement Cycle

Distinguishing the Cold Conveyor Belt and Sting Jet Airstreams in an Intense Extratropical Cyclone

Comparison of the Sentinel-1B Synthetic Aperture Radar With Airborne Microwave Sensors in an Extra-Tropical Cyclone

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