Deriving Surface Winds from Satellite Observations of Low-Level Cloud Motions

1985 ◽  
Vol 24 (8) ◽  
pp. 758-769 ◽  
Author(s):  
James C. Sadler ◽  
B. J. Kilonsky
Keyword(s):  
Satellite Observations ◽  
Surface Winds ◽  
Low Level

scholarly journals The 6 May 2010 Elevated Supercell during VORTEX2

2017 ◽  
Vol 145 (7) ◽  
pp. 2635-2657 ◽  
Author(s):  
Christopher W. MacIntosh ◽  
Matthew D. Parker
Keyword(s):  
Cold Pool ◽  
Surface Winds ◽  
Stable Layer ◽  
Low Level ◽  
Stable Inversion ◽  
Idealized Modeling ◽  
Weak Surface ◽  
Negatively Buoyant

An elevated supercell from the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) on 6 May 2010 is investigated. Observations show that the supercell formed over a stable inversion and was likely decoupled from the surface. Quintessential features of a supercell were present, including a hook echo (albeit bent anticyclonically) and midlevel mesocyclone, and the storm was quasi steady during the observing period. A weak surface cold pool formed, but it was apparently devoid of air originating from midlevels. Idealized modeling using near-storm soundings is employed to clarify the structure and maintenance of this supercell. The simulated storm is decoupled from the surface by the stable layer. Additionally, the reflectivity structure of the simulated supercell is strikingly similar to the observed storm, including its peculiar anticyclonic-curving hook echo. Air parcels above 1 km reached their LFCs as a result of the simulated supercell’s own dynamic lifting, which likely maintained the main updraft throughout its life. In contrast, low-level air in the simulation followed an “up–down” trajectory, being lifted dynamically within the stable layer before becoming strongly negatively buoyant and descending back to the surface. Up–down parcels originating in the lowest 100 m are shown to be a potential driver of severe surface winds. The complementary observations and simulations highlight a range of processes that may act in concert to maintain supercells in environments lacking surface-based CAPE.

scholarly journals Characteristics of Ocean Surface Winds in the Lee of an Isolated Island Observed by Synthetic Aperture Radar

2010 ◽  
Vol 139 (6) ◽  
pp. 1744-1761 ◽  
Author(s):  
Osamu Isoguchi ◽  
Masanobu Shimada ◽  
Hiroshi Kawamura
Keyword(s):  
Synthetic Aperture Radar ◽  
Atmospheric Stability ◽  
Ocean Surface ◽  
Synthetic Aperture ◽  
Leeward Side ◽  
Surface Winds ◽  
Low Level ◽  
Ocean Surface Winds ◽  
Low Level Jet ◽  
Aperture Radar

Abstract Characteristics of ocean surface winds around an isolated island are examined in relation to atmospheric stability using a synthetic aperture radar (SAR) and rawinsonde sounding observations. The SAR-derived winds on 22 May 2009 indicate a low-level jet extending over 30 km behind the island. Around the time of SAR acquisition, winds intensified on the leeward side in association with the stabilization of stratified flows, which suggests the connection of the SAR-derived jet with downslope winds. A number of SAR-derived winds elucidate typical wind patterns and their transitions depending on the nondimensional mountain height . For cases of large (>2), a wake is formed in the lee of the island and low-level jets produce strong wind shear on both sides of the wake. For cases of relatively small (<1.75), although a weak wind region is formed behind the mountain, no wind jets develop. As a transition of the above two cases , a low-level jet develops in the lee of the island, as in the case on 22 May 2009. These wake configurations and their -dependent transitions seem to correspond to major regimes for hydrostatic flow over topography with constant upstream speed and buoyancy frequency: small-amplitude waves , wave breaking , and flow splitting . It is noted that the ocean surface winds behind the island are very sensitive to around the transition point, changing up and down. The occurrence of each wind pattern shows clear seasonal features dependent on atmospheric stability.

scholarly journals Satellite Observations of Ocean Surface Winds and Currents

Eos ◽  
2018 ◽  
Vol 99 ◽  
Author(s):  
Mark Bourassa ◽  
Ernesto Rodriguez ◽  
Sarah Gille
Keyword(s):  
Ocean Surface ◽  
Satellite Observations ◽  
Florida State University ◽  
State University ◽  
Surface Winds ◽  
Ocean Surface Winds ◽  
La Jolla

Florida State University workshop on Satellite Observations of Ocean Surface Winds & Currents; La Jolla, California, 18–19 May 2018

scholarly journals Verification of a coupled atmosphere-ocean model using satellite observations over the Adriatic Sea

2008 ◽  
Vol 26 (7) ◽  
pp. 1935-1954 ◽  
Author(s):  
V. Djurdjevic ◽  
B. Rajkovic
Keyword(s):  
Boundary Conditions ◽  
Adriatic Sea ◽  
Weather Forecasting ◽  
Horizontal Resolution ◽  
Satellite Observations ◽  
Forecast Skill ◽  
Primary Data ◽  
Surface Winds ◽  
Operating Cycle ◽  
Verification Period

Abstract. Verification of the EBU-POM regional atmosphere-ocean coupled model (RAOCM) was carried out using satellite observations of SST and surface winds over the Adriatic Sea. The atmospheric component has a horizontal resolution of 0.125 degree (approximately 10 km) and 32 vertical levels, while the ocean component has a horizontal resolution of approximately 4 km with 21 sigma vertical levels. Verification of the forecasted SST was performed for 15 forecasts during 2006, each of them seven days long. These forecasts coincide with the operating cycle of the Adriatic Regional Model (AREG), which provided the initial fields and boundary conditions for the ocean component of EBU-POM. Two sources of data were used for the initial and boundary conditions of the atmosphere: primary data were obtained from the European Center for Medium-Range Weather Forecasting (ECMWF), while data from National Centers for Environmental Prediction (NCEP) were used to test the sensitivity to boundary conditions. Forecast skill was expressed in terms of BIAS and root mean square error (RMSE). During most the of verification period, the model had a negative BIAS of approximately −0.3°, while RMSE varied between 1.1° and 1.2°. Interestingly, these errors did not increase over time, which means that the forecast skill did not decline during the integrations. The 10-m wind verification was conducted for one period of 17 days in February 2007, during a strong bora episode, for which satellite estimates of surface winds were available. During the same period, SST measurements were conducted twice a day, which enabled us to verify diurnal variations of SST simulated by the RAOCM model. Since ECMWF's deterministic forecasts do not cover such a long period, we decided to use the ECMWF analysis, i.e. we ran the model in hindcast mode. The winds simulated in this analysis were weaker than the satellite estimates, with a mean BIAS of −0.8 m/s.

scholarly journals Analysis of a Destructive Wind Storm on 16 November 2008 in Brisbane, Australia

2014 ◽  
Vol 142 (9) ◽  
pp. 3038-3060 ◽  
Author(s):  
Harald Richter ◽  
Justin Peter ◽  
Scott Collis
Keyword(s):  
Ambient Air ◽  
Surface Winds ◽  
Near Surface ◽  
Low Level ◽  
Ball Size ◽  
Close Proximity ◽  
Forcing Mechanisms ◽  
Set Up ◽  
Perturbation Pressure ◽  
Lapse Rates

During the late afternoon on 16 November 2008 the Brisbane (Queensland, Australia) suburb of “The Gap” experienced extensive wind damage caused by an intense local thunderstorm. The CP2 research radar nearby detected near-surface radial velocities exceeding 43 m s−1 above The Gap while hail size reports did not exceed golf ball size, and no tornadoes were reported. The storm environment was characterized by a layer of very moist near-surface air and strong storm-relative low-level flow, whereas the storm-relative winds aloft were weak. While the thermodynamic storm environment contained a range of downdraft-promoting ingredients such as a ~4-km-high melting level above a ~2-km-deep layer with nearly dry-adiabatic lapse rates mostly collocated with dry ambient air, a ~1-km-deep stable layer near the ground would generally lower expectations of destructive surface winds based on the downburst mechanism. Once observed reflectivities exceed 70 dBZ, downdraft cooling due to hail melting and downdraft acceleration based on hail loading are found to likely become nonnegligible forcing mechanisms. The event featured the close proximity of a hydrostatically and dynamically driven mesohigh at the base of the downdraft to a dynamically driven mesolow associated with a low-level circulation. This proximity was instrumental in the anisotropic horizontal acceleration of the near-ground outflow and the ultimate strength of the Gap storm surface winds. Weak storm-relative midlevel winds are speculated to have allowed the downdraft to descend close to the low-level circulation, which set up this strong horizontal perturbation pressure gradient.

Satellite Observations of Organizational Regimes in Low-Level Mixed-Phase Clouds over the Southern Ocean

2020 ◽  
Author(s):  
Jessica Danker ◽  
Odran Sourdeval ◽  
Isabel L. McCoy ◽  
Robert Wood ◽  
Anna Possner
Keyword(s):  
Southern Ocean ◽  
Radiative Forcing ◽  
Ocean Surface ◽  
Satellite Observations ◽  
Mixed Phase ◽  
Pure Liquid ◽  
Data Set ◽  
Radiative Balance ◽  
Low Level ◽  
Mixed Phase Clouds

<p>On average stratocumulus clouds cover about 23% of the ocean surface and are important for Earth’s radiative balance. They typically self-organize into cellular patterns and thus are often referred to as mesoscale-cellular convective (MCC) cloud systems. In the Southern Ocean (SO), low-level clouds cover between 20% to 40% of the ocean surface in the mid-latitudes where they exert a substantial radiative cooling. In a previous study, McCoy et al (2017) demonstrated that different MCC regimes may be associated with different cloud albedos and thus different cloud radiative forcing.<br>Many of the MCC clouds in the SO are not pure liquid but contain a mixture of liquid and ice. Here we investigate whether the formation of ice within these mixed-phase clouds influences MCC organization and thus the cloud-radiative effect.<br>To investigate the cloud phase we use the raDAR-liDAR (DARDAR) data product (version 1) from Cloud-Aerosol-Water-Radiation Interactions (ICARE) Data and Services Center which provides collocated data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), CloudSat and Moderate Resolution Imaging Spectroradiometer (MODIS). The “Simplified DARMASK Categorization Flag” of DARDAR is used to categorize the vertically resolved cloud phase into a single cloud phase per data point: clear, multi-layer, liquid, mixed or ice. In order to distinguish between open and<br>closed MCC regimes, we collocate the DARDAR product with an MCC classification data set from McCoy et al (2017) which is based on a neural network algorithm applied to MODIS Aqua data.<br>Our preliminary results confirm previous ground-based observations that most mixed-phase clouds are composed of a supercooled liquid top and ice underneath. Furthermore, our preliminary analysis suggests open MCCs occur more frequently as mixed-phase clouds (57% (DJF), 55% (JJA)) in the SO compared to liquid clouds (39% (DJF), 37% (JJA)) during both summer (DJF) and winter (JJA). In contrast, closed MCCs are more likely to appear as liquid clouds (58%) in comparison to mixed-phase clouds (40%) during winter, whereas during summer there seems to be no tendency for closed MCCs to be either liquid (51%) or mixed (49%).</p>

Sign in / Sign up

Export Citation Format

Share Document