Mesoscale Near-Surface Wind Speed Variability Mapping with Synthetic Aperture Radar

This work discusses the accuracy of C-2PO (C-band cross-polarized ocean backscatter) and CMOD4 (C-band model) geophysical model functions (GMF) for sea surface wind speed retrieval from satellite-born Synthetic Aperture Radar (SAR) images over in the Northwest Pacific off the coast of China. In situ observations are used for comparison of the retrieved wind speed using two established wind retrieval models: C-2PO model and CMOD4 GMF. Using 439 samples from 92 RADARSAT-2 fine quad-polarization SAR images and corresponding reference winds, we created two subset wind speed databases: the training and testing subsets. From the training data subset, we retrieve ocean surface wind speeds (OSWSs) from different models at each polarization and compare with reference wind speeds. The RMSEs of SAR-retrieved wind speeds are: 2.5 m/s: 2.11 m/s (VH-polarized), 2.13 m/s (HV-polarized), 1.86 m/s (VV-polarized) and 2.26 m/s (HH-polarized) and the correlation coefficients are 0.86 (VH-polarized), 0.85(HV-polarized), 0.87(VV-polarized) and 0.83 (HH-polarized), which are statistically significant at the 99.9% significance level. Moreover, we found that OSWSs retrieved using C-2PO model at VH-polarized are most suitable for moderate-to-high winds while CMOD4 GMF at VV-polarized tend to be best for low-to-moderate winds. A hybrid wind retrieval model is put forward composed of the two models, C-2PO and CMOD4 and sets of SAR test data are used in order to establish an appropriate wind speed threshold, to differentiate the wind speed range appropriate for one model from that of the other. The results show that the OSWSs retrieved using our hybrid method has RMSE of 1.66 m/s and the correlation coefficient are 0.9, thereby significantly outperforming both the C-2PO and CMOD4 models.

Download Full-text

Sea Surface Wind Speed Retrieval From Textures in Synthetic Aperture Radar Imagery

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.2021.3062401 ◽

2021 ◽

pp. 1-11

Author(s):

Lizhang Zhou ◽

Gang Zheng ◽

Jingsong Yang ◽

Xiaofeng Li ◽

Bin Zhang ◽

...

Keyword(s):

Wind Speed ◽

Synthetic Aperture Radar ◽

Surface Wind ◽

Surface Wind Speed ◽

Sea Surface ◽

Synthetic Aperture ◽

Sea Surface Wind Speed ◽

Sea Surface Wind ◽

Radar Imagery ◽

Synthetic Aperture Radar Imagery

Download Full-text

Validation of Sentinel-1 offshore winds and average wind power estimation around Ireland

Wind Energy Science ◽

10.5194/wes-5-1023-2020 ◽

2020 ◽

Vol 5 (3) ◽

pp. 1023-1036 ◽

Cited By ~ 1

Author(s):

Louis de Montera ◽

Tiny Remmers ◽

Ross O'Connell ◽

Cian Desmond

Keyword(s):

Wind Speed ◽

Synthetic Aperture Radar ◽

Wind Power ◽

Surface Wind ◽

Synthetic Aperture ◽

Synthetic Aperture Radar Data ◽

Average Wind ◽

Level 2 ◽

Aperture Radar

Abstract. In this paper, surface wind speed and average wind power derived from Sentinel-1 Synthetic Aperture Radar Level 2 Ocean (OCN) product were validated against four weather buoys and three coastal weather stations around Ireland. A total of 1544 match-up points was obtained over a 2-year period running from May 2017 to May 2019. The match-up comparison showed that the satellite data underestimated the wind speed compared to in situ devices, with an average bias of 0.4 m s−1, which decreased linearly as a function of average wind speed. Long-term statistics using all the available data, while assuming a Weibull law for the wind speed, were also produced and resulted in a significant reduction of the bias. Additionally, the average wind power was found to be consistent with in situ data, resulting in an error of 10 % and 5 % for weather buoys and coastal stations, respectively. These results show that the Sentinel-1 Level 2 OCN product can be used to estimate the wind resource distribution, even in coastal areas. Maps of the average and seasonal wind speed and wind power illustrated that the error was spatially dependent, which should be taken into consideration when working with Sentinel-1 Synthetic Aperture Radar data.

Download Full-text

Encounter of Foehn Wind with an Atmospheric Eddy over the Black Sea as Observed by the Synthetic Aperture Radar Onboard Envisat

Monthly Weather Review ◽

10.1175/mwr-d-11-00074.1 ◽

2011 ◽

Vol 139 (12) ◽

pp. 3992-4000 ◽

Cited By ~ 10

Author(s):

Werner Alpers ◽

Andrei Yu. Ivanov ◽

Knut-Frode Dagestad

Keyword(s):

Synthetic Aperture Radar ◽

Black Sea ◽

Surface Wind ◽

Quantitative Information ◽

Synthetic Aperture ◽

The Black Sea ◽

Sar Image ◽

Wind Fields ◽

Near Surface ◽

Aperture Radar

Abstract Foehn wind blowing through the Kolkhida (Kolkheti) Lowland in the southwestern Caucasus (western Georgia) was observed on an Envisat synthetic aperture radar (SAR) image as it encountered an atmospheric cyclonic eddy over the Black Sea on 13 September 2010. This SAR image reveals unprecedented finescale features of the near-surface wind fields that cannot be resolved by other sensors. It shows, among others, the deflection of the foehn wind by the atmospheric eddy. Quantitative information on the near-surface wind field over the sea is extracted from the SAR image.

Download Full-text

Ocean Surface Wind Speed Retrieval Using Simulated RADARSAT Constellation Mission Compact Polarimetry SAR Data

Remote Sensing ◽

10.3390/rs11161876 ◽

2019 ◽

Vol 11 (16) ◽

pp. 1876

Author(s):

He Fang ◽

William Perrie ◽

Guosheng Zhang ◽

Tao Xie ◽

Shahid Khurshid ◽

...

Keyword(s):

Wind Speed ◽

Synthetic Aperture Radar ◽

Wind Direction ◽

Surface Wind ◽

Ocean Surface ◽

Synthetic Aperture ◽

Ocean Surface Wind ◽

Sar Data ◽

Relative Wind ◽

Aperture Radar

We investigated the use of C-band RADARSAT Constellation Mission (RCM) synthetic aperture radar (SAR) for retrieval of ocean surface wind speeds by using four new channels (right circular transmit, vertical receive (RV); right circular transmit, horizontal receive (RH); right circular transmit, left circular transmit (RL); and right circular transmit, right circular receive (RR)) in compact polarimetry (CP) mode. Using 256 buoy measurements collocated with RADARSAT-2 fine beam quad-polarized scenes, RCM CP data was simulated using a “CP simulator”. Provided that the relative wind direction is known, our results demonstrate that wind speed can be retrieved from RV, RH and RL polarization channels using existing C-band model (CMOD) geophysical model function (GMF) and polarization ratio (PR) models. Simulated RR-polarized radar returns have a strong linear relationship with speed and are less sensitive to relative wind direction and incidence angle. Therefore, a model is proposed for the RR-polarized synthetic aperture radar (SAR) data. Our results show that the proposed model can provide an efficient methodology for wind speed retrieval.

Download Full-text

Recurrence Characteristics Analysis of Near-Surface Wind Speed Signal with Different Sampling Frequencies

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.599-601.1605 ◽

2014 ◽

Vol 599-601 ◽

pp. 1605-1609 ◽

Cited By ~ 1

Author(s):

Ming Zeng ◽

Zhan Xie Wu ◽

Qing Hao Meng ◽

Jing Hai Li ◽

Shu Gen Ma

Keyword(s):

Wind Speed ◽

Surface Wind ◽

Surface Wind Speed ◽

Recurrence Plot ◽

Sampling Frequency ◽

Near Surface ◽

Gas Leakage ◽

Time Period ◽

Characteristics Analysis ◽

Quantification Analysis

The wind is the main factor to influence the propagation of gas in the atmosphere. Therefore, the wind signal obtained by anemometer will provide us valuable clues for searching gas leakage sources. In this paper, the Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) are applied to analyze the influence of recurrence characteristics of the wind speed time series under the condition of the same place, the same time period and with the sampling frequency of 1hz, 2hz, 4.2hz, 5hz, 8.3hz, 12.5hz and 16.7hz respectively. Research results show that when the sampling frequency is higher than 5hz, the trends of recurrence nature of different groups are basically unchanged. However, when the sampling frequency is set below 5hz, the original trend of recurrence nature is destroyed, because the recurrence characteristic curves obtained using different sampling frequencies appear cross or overlapping phenomena. The above results indicate that the anemometer will not be able to fully capture the detailed information in wind field when its sampling frequency is lower than 5hz. The recurrence characteristics analysis of the wind speed signals provides an important basis for the optimal selection of anemometer.

Download Full-text

Effectiveness of WRF wind direction for retrieving coastal sea surface wind from synthetic aperture radar

Wind Energy ◽

10.1002/we.1526 ◽

2012 ◽

Vol 16 (6) ◽

pp. 865-878 ◽

Cited By ~ 10

Author(s):

Yuko Takeyama ◽

Teruo Ohsawa ◽

Katsutoshi Kozai ◽

Charlotte Bay Hasager ◽

Merete Badger

Keyword(s):

Synthetic Aperture Radar ◽

Wind Direction ◽

Surface Wind ◽

Sea Surface ◽

Synthetic Aperture ◽

Sea Surface Wind ◽

Coastal Sea ◽

Aperture Radar

Download Full-text

A Synthetic Aperture Radar–Based Climatology of Open-Cell Convection over the Northeast Pacific Ocean

Journal of Applied Meteorology and Climatology ◽

10.1175/2010jamc2624.1 ◽

2011 ◽

Vol 50 (3) ◽

pp. 594-603 ◽

Cited By ~ 10

Author(s):

Todd D. Sikora ◽

George S. Young ◽

Caren M. Fisher ◽

Matthew D. Stepp

Keyword(s):

Pacific Ocean ◽

Synthetic Aperture Radar ◽

Vertical Wind Shear ◽

Heat Fluxes ◽

Synthetic Aperture ◽

Cold Pool ◽

Near Surface ◽

Open Cell ◽

Northeastern Pacific ◽

Aperture Radar

Abstract This paper presents an 8-yr (1999–2006) climatology of the frequency of open-cell convection over the northeastern Pacific Ocean and the thermodynamic and kinematic environment associated with its development. The climatology is based on synthetic aperture radar–derived wind speed images and reanalysis data. The climatology shows that open-cell convection was a cold-season phenomenon, having occurred in environments in which the difference in temperature between the near-surface air and the sea surface is negative and in environments with positive surface sensible and latent heat fluxes. Within the region between the surface and 500 hPa, the 700–850-hPa layer median static stability was near moist adiabatic while that for the remainder was conditionally unstable. The median magnitude of the vertical wind shear was largest in the 925-hPa–near-surface and 500–700-hPa layers while that at midlevels was relatively weak. Similarities are highlighted between the organization of open-cell convection over the northeastern Pacific Ocean and tropical deep moist maritime convection in terms of cold-pool dynamics. Avenues for future work are discussed.

Download Full-text