Journal ArticleDOI
Sea State Impacts on Wind Speed Retrievals From C-Band Radars
TLDR
Analysis of data from advanced scatterometer (ASCAT) aboard MetOp-A and the advanced synthetic aperture radar (ASAR) aboard Envisat against the in situ buoy wind speeds finds that the sea state dominates the wind speed errors and these trends increase with the significant wave height.Abstract:
Scatterometers, a proven technology, provide ocean wind speeds and directions that are essential in operational forecasts, monitoring of the climate, and scientific applications. While the missions and geophysical model functions are performing well, challenges remain. We analyze data from advanced scatterometer (ASCAT) aboard MetOp-A and the advanced synthetic aperture radar (ASAR) aboard Envisat, both of which operate in the C-band, against the in situ buoy wind speeds. We observe large variability in the wind speed residuals. Through analysis of these residuals, we find that they are related to sea state effects and atmospheric stability. The sea state dependence created by low-frequency swells is more pronounced for the lower incidence angles in ASCAT. In ASAR with a fixed angle of $23^{\circ }$ , the sea state dominates the wind speed errors and these trends increase with the significant wave height. We observe that wind speeds from ASAR and ASCAT have a close resemblance, which helps us to extrapolate our findings. The synergy between the two technologies can be further exploited to improve wind speed retrievals. Future scatterometer missions, such as the next MetOp, will operate with the wider range of incidence angles (including lower angles) to increase their coverage together, have higher spatial resolution, and obtain measurements closer to the coasts. In these cases, high-resolution SAR data can aide in the understanding of the radar response.read more
Citations
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Journal ArticleDOI
Calibration of the Normalized Radar Cross Section for Sentinel-1 Wave Mode
TL;DR: Based on the global data set acquired by S-1A WV, assessment of normalized radar cross section (NRCS) is carried out through comparison with CMOD5.N predictions over open ocean and the necessity for recalibration and comparable correction factors for WV1 and WV2 is shown.
Journal ArticleDOI
Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network
TL;DR: In this article, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016-2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights.
Journal ArticleDOI
Impact of Sea State on Wind Retrieval From Sentinel-1 Wave Mode Data
TL;DR: The possibility to compensate the sea state impact by including azimuth cutoff in the geophysical model function of the normalized radar cross section of Sentinel-1 wave mode is demonstrated.
Journal ArticleDOI
Characterizing Buoy Wind Speed Error in High Winds and Varying Sea State with ASCAT and ERA5
TL;DR: In this article, a triple collocation (TC) exercise comparing buoy winds to winds from ASCAT and ERA5 was conducted, where the residuals by anemometer height and testing under high wind-wave and swell conditions were analyzed.
Journal ArticleDOI
Evaluation of CFOSAT Scatterometer Wind Data in Global Oceans
Haijun Ye,Junmin Li,Bo Li,Junliang Liu,Danling Tang,Chen Wuyang,Hongqiang Yang,Fenghua Zhou,Rongwang Zhang,Sufen Wang,Shilin Tang +10 more
TL;DR: In this paper, the authors evaluated the performance of wind retrievals under the passage of tropical cyclones and showed that the results satisfy the accuracy requirements of scientific research, although some improvements are needed to enhance the performance.
References
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Journal ArticleDOI
The NCEP Climate Forecast System Reanalysis
Suranjana Saha,Shrinivas Moorthi,Hua-Lu Pan,Xingren Wu,Jiande Wang,Sudhir Nadiga,Patrick Tripp,Robert Kistler,John S. Woollen,David Behringer,Haixia Liu,Diane Stokes,Robert Grumbine,George Gayno,Jun Wang,Yu-Tai Hou,Hui-ya Chuang,Hann-Ming Henry Juang,Joe Sela,Mark Iredell,Russ Treadon,Daryl T. Kleist,Paul van Delst,Dennis Keyser,John Derber,Michael Ek,Jesse Meng,Helin Wei,Rongqian Yang,Stephen J. Lord,Huug van den Dool,Arun Kumar,Wanqiu Wang,Craig S. Long,Muthuvel Chelliah,Yan Xue,Boyin Huang,Jae-Kyung E. Schemm,Wesley Ebisuzaki,Roger Lin,Pingping Xie,Mingyue Chen,Shuntai Zhou,Wayne Higgins,Cheng-Zhi Zou,Quanhua Liu,Yong Chen,Yong Han,Lidia Cucurull,Richard W. Reynolds,Glenn Rutledge,Mitch Goldberg +51 more
TL;DR: The NCEP Climate Forecast System Reanalysis (CFSR) was completed for the 31-yr period from 1979 to 2009, in January 2010 as mentioned in this paper, which was designed and executed as a global, high-resolution coupled atmosphere-ocean-land surface-sea ice system to provide the best estimate of the state of these coupled domains over this period.
Journal ArticleDOI
The NCEP climate forecast system version 2
Suranjana Saha,Shrinivas Moorthi,Xingren Wu,Jiande Wang,Sudhir Nadiga,Patrick Tripp,David Behringer,Yu-Tai Hou,Hui Ya Chuang,M. Iredell,Michael Ek,Jesse Meng,Rongqian Yang,Malaquías Peña Mendez,Huug van den Dool,Qin Zhang,Wanqiu Wang,Mingyue Chen,Emily Becker +18 more
TL;DR: The second version of the NCEP Climate Forecast System (CFSv2) was made operational at the National Center for Environmental Prediction (NCEP) in 2011 as discussed by the authors.
Journal ArticleDOI
A proposed spectral form for fully developed wind seas based on the similarity theory of S. A. Kitaigorodskii
TL;DR: In this article, the authors used the data for the spectra of fully developed seas obtained for wind speeds from 20 to 40 knots as measured by anemometers on two weather ships.
Journal ArticleDOI
How Much More Rain Will Global Warming Bring
TL;DR: Observations suggest that precipitation and total atmospheric water have increased at about the same rate over the past two decades, compared with the climate models and satellite observations.
Journal ArticleDOI
An improved C-band scatterometer ocean geophysical model function: CMOD5
TL;DR: In this article, a new C-band geophysical model function (GMF) is derived on the basis of measurements from the scatterometer on board of the European Remote Sensing Satellite ERS-2.