Conference Paper

A Brazilian Northeast Coast Wave Data Comparison: Radar vs Buoy

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Abstract

Wave buoys are well known by its accuracy in measuring sea surface elevations while wave radars were developed later. Buoy’s motions are considered direct wave measurements while microwave radars use remote sensing for tracking the sea surface. Due to sensitivity to winds, sea surface roughness, rain, etc, it is a good practice to check radar data against buoys records. Even both systems installed being 6 km apart in a deep water region offshore northeast Brazilian shelf, there were differences in wave directional spectral parameters calculated by both equipments. The wave measurements at Sergipe and Alagoas basin were in good agreement in terms of significant wave height. Hs correlation was 91% and bias was only 0.06 m. A particular behavior of radar Hs when compared to buoy Hs was overestimation in high sea states and underestimation in low ones. Tp1 correlation was 69%, bias was 0.02 s and linear regression coefficient was 0.64. The worst correlated parameter was peak direction Dp1 with 60% of correlation for E-ESE directional band. Time series matched each other and showed the typical regional wave climate with Hs 1.0–2.0 m, Tp 6–10 s and Dp1 from E-ESE. The distinction between radar and the buoy directions is related to radar susceptibility to SE trade winds during Spring and Summer seasons. However, the difference did not diverge from prevailing wave regional climate.

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Shell International Petroleum A Long-Term Intercomparison of Wave Sensors in the -Northern North Sea. Source Oceanology '88: Proceedings of an international conference
  • N M C Angevaare
DACUNHA, N.M.C. & ANGEVAARE, T.J. Shell International Petroleum, 1988. A Long-Term Intercomparison of Wave Sensors in the -Northern North Sea. Source Oceanology '88: Proceedings of an international conference, March 8 -11, 1988, Brighton, UK 3. BATSCHELET, E. 1981. Chapter 9: Circular Correlation. In: Circular Statistics in Biology. Mathematics in Biology, Academic press, p. 178-184.
MIROS System Evaluation during Storm Wind Study II
  • F W Dobson
  • E Dunlap
DOBSON, F.W. & DUNLAP, E. 1999. MIROS System Evaluation during Storm Wind Study II. Proc. WMO Workshop on Advances in Marine Climatology (CLIMAR99), 8-15
Data Comparison and Error Statistics http://www.oceanwaves.org/download/PDF/ESTAT_March2010 .pdf 10
  • Wamos Ii
  • K E Steele
  • Teng C
  • Wang And
WAMOS II, 2010. Data Comparison and Error Statistics http://www.oceanwaves.org/download/PDF/ESTAT_March2010 .pdf 10. STEELE, K.E., TENG C., AND WANG, D.W.C. 1992.
NDBC). 1996. Nondirectional and Directional Wave Data Analysis Procedures. NDBC Technical Document 96-01
  • National Data
  • Center
NATIONAL DATA BUOY CENTER (NDBC). 1996. Nondirectional and Directional Wave Data Analysis Procedures. NDBC Technical Document 96-01, 43 pp.
TRIAXYS™ Directional Wave Buoy Applications Software – User's Manual
AXYS. 2003. TRIAXYS™ Directional Wave Buoy Applications Software – User's Manual. Axys Enviromental Systems, v.00, 99pp.
Miros Waver radar MkIII -Principles of Operation
MIROS, 2004. Miros Waver radar MkIII -Principles of Operation. MIROS A/S, rev.3, 44pp.
  • E Batschelet
BATSCHELET, E. 1981. Chapter 9: Circular Correlation. In: Circular Statistics in Biology. Mathematics in Biology, Academic press, p. 178-184.
Some Comparisons Of Wave Measurements From The Norwegian Continental Shelf. The Norwegian Meteorological Institute (DNMI)
  • K A Iden
IDEN, K.A. 1996. Some Comparisons Of Wave Measurements From The Norwegian Continental Shelf. The Norwegian Meteorological Institute (DNMI), Oslo, Norway.
North Sea Severity Assessment Heal and Safety Executive -Offshore Technology Report
  • P J Owrid
OWRID P.J., 1998. North Sea Severity Assessment Heal and Safety Executive -Offshore Technology Report.