Boemre 2008 Extended Hindcast Calculation of Gulf of Mexico Circulation: Model Development, Comparisons with Observations
Lugo-Fernández, A. and A. Badan, 2007: On the vorticity cycle of the Loop Current. J. Mar. Res. 65, 471-489
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- Appendix 1: Comparison of QuikScat/NCEP blended winds with CCMP3 winds, and also the resulting simulated surface ocean currents
Lugo-Fernández, A. and A. Badan, 2007: On the vorticity cycle of the Loop Current. J. Mar. Res. 65, 471-489.Mellor, G. L., and T. Yamada, 1982: Development of a turbulence closure model for geophysical fluid problems, Rev. Geophys., 20, 851– 875. Mellor, G. L., 2002: User Guide for a Three-Dimensional, Primitive Equation, Numerical Ocean Model (Jul/2002 Version), 42 pp., Atmos. & Oceanic Sci. Prog., Princeton Univ. NJ, USA. (http://www.aos.princeton.edu/WWWPUBLIC/htdocs.pom/PubOnLine/POL. html). Mellor, G.L. and Ezer, T., 1991: A Gulf Stream model and an altimetry assimilation scheme. J. Geophys. Res, 96: 8779-8795. Mellor, G. L., M. A. Donelan, and L-Y. Oey, 2008: A surface wave model for coupling with numerical ocean circulation models. J.Atmos. Oceanic Tech., 25, 1785-1807. Minobe, S., A.K. Yoshida, N. Komori, S.-P. Xie and R.J. Small, 2008: Influence of the Gulf Stream on the troposphere. Nature 452, 206-209 (13 March 2008) | doi:10.1038/nature06690. Nowlin, W.D., Jr., 1972. Winter circulation pattern and property distributions. Contributions on the Physical Oceanography of the Gulf of Mexico, Vol. II, L.R.A. Capurro and J.L. Reid, Eds., Gulf Publishing Co., 3–64. Oey, L.-Y., 1996: Simulation of Mesoscale Variability in the Gulf of Mexico: Sensitivity Studies, Comparison with Observations, and Trapped Wave Propagation., J. Phys. Oceanogr, 26, 145–175. Oey, L.-Y., 2004: A Circulation Model of the Gulf of Mexico and the Caribbean Sea, Part I: Development of the Princeton Regional Ocean Forecast (& Hindcast) System - PROFS, and Hindcast Experiment for 1992-1999. Final Report to U.S. DOI Minerals Management Service, Herndon, Virginia, Contract# 1435-01-00-CT-31076, by Princeton University, AOS Program, Sayre Hall, Princeton, NJ 08544, Dec/2003. 167pp, 51 figures. Oey, L.-Y., 2008: Loop Current and Deep Eddies. J. Phys. Oceanogr. 38, 1426-1449. Oey, L.-Y., and P. Chen. 1992a: A model simulation of circulation in the north-east Atlantic shelves and seas. J. Geophy. Res. 97:20,087-20,115. Oey, L.-Y., and P. Chen. 1992b: A Nested-Grid Ocean Model: With Application to the Simulation of Meanders and Eddies in the Norwegian Coastal Current. J. Geophy. Res. 97: 20,063–20,086. Oey, L.-Y. and Lee, H.-C, 2002: Deep Eddy Energy and Topographic Rossby Waves in the Gulf of Mexico. J. Phys. Oceanogr., 32(12):3499-3527. Oey, L.-Y. and H.-C. Zhang, 2004. A mechanism for the generation of subsurface cyclones and jets. Cont. Shelf Res., 24, 2109-2131. Oey, L.-Y., H.-C. Lee and W. J. Schmitz Jr., 2003. Effects of Winds and Caribbean Eddies on the Frequency of Loop Current Eddy Shedding: A Numerical Model Study, JGR, 108 (C10), 3324, doi:10.1029/2002JC001698, 2003. Oey L.-Y., T. Ezer and H.J. Lee, 2005a: Loop Current, Rings and Related Circulation in the Gulf of Mexico: A Review of Numerical Models and Future Challenges. In “Circulation in the Gulf of Mexico: Observations and Models,” W. Sturges, A. Lugo-Fernandez, Eds, Geophysical Monograph Series, Vol.161, 360pp, 2005. Oey L.-Y., T. Ezer, G. Forristall, C. Cooper, S. DiMarco, S. Fan, 2005b: An exercise in forecasting loop current and eddy frontal positions in the Gulf of Mexico, Geophys. Res. Lett., 32, L12611, doi:10.1029/2005GL023253. Oey L.-Y., T. Ezer, D.-P. Wang, S. Fan and X.-Q. Yin, 2006: Loop Current warming by Hurricane Wilma, Geophys. Res. Lett. 33, L08613, doi:10.1029, 2006GL025873. Oey, L.-Y., T. Ezer, D.-P. Wang, X.-Q. Yin and S.-J. Fan, 2007: Hurricane-induced motions and interaction with ocean currents. Cont. Shelf Res. 27, 1249-1263. Oey, L.-Y., M. Inoue, R. Lai, X.-H. Lin, S. Welsh and L. Rouse Jr. 2008: Stalling of near-inertial waves in a cyclone. Geophys. Res. Lett., 35, L12604, doi:10.1029/2008GL034273.Oey, L.-Y., Y.-L. Chang, Z.-B. Sun & X.-H. Lin, 2009: Topocaustics. Ocean Modelling, 29, 277-286.Schmitz, W. J., Jr., 1996: On the world ocean circulation, vol. I, Some global features/North Atlantic circulation, WHOI Tech. Rep. WHOI-96-03, 141 pp., Woods Hole Oceanogr. Inst., Woods Hole, Mass., 1996. Sheinbaum J., J. Candela, A. Badan and J. Ochoa, 2002: Flow structure and transport in the Yucatan Channel, Geophy. Res. Let., 29, 10.1029/2001GL013990. Smagorinsky, J., 1963: General circulation experiments with the primitive equations, part I, The basic experiment, Mon. Weather Rev., 91, 99 – 164. Sturges, W., and R. Leben, 2000: Frequency of ring separations from the Loop Current in the Gulf of Mexico: A revised estimate, J. Phys. Oceanogr., 30, 1814– 1818. Sturges, W., and K.E. Kenyon, 2008: Mean flow in the Gulf of Mexico, J. Phys. Oceanogr., 38, 1501–1514. Wang, D.-P. & L.-Y. Oey, 2008: Hindcast of Waves and Currents in Hurricane Katrina. Bulletin of the American Meteorological Society (BAMS). DOI:10.1175/BAMS-89-4-487. Wang, D-P., L-Y. Oey, T. Ezer, and P. Hamilton, 2003: Near-surface currents in DeSoto Canyon (1997–99): Comparison of current meters, satellite observation, and model simulation. J. Phys. Oceanogr., 33(1), 313-326. Worthington, L.V., 1976: On the North Atlantic circulation, Oceanographic Studies, The John Hopkins University, Baltimore, MD, 6, 1-110. Wϋst, G., 1964: Stratification and circulation in the Antillean-Caribbean basins, Part 1. Columbia Univ. Press, New York . Yin, X.-Q. and L.-Y. Oey, 2007: Bred-ensemble ocean forecast of Loop Current and rings, Ocean Modelling, doi:10.1016/j.ocemod.2007.02.005. Appendix 1: Comparison of QuikScat/NCEP blended winds with CCMP3 winds, and also the resulting simulated surface ocean currents In the first draft of this report, we erroneously stated that CCMP3 winds were used instead of the QuikScat/NCEP (hereinafter Qblend) winds that were proposed and available (for this project) at that time for use in the model results delivered to BOEMRE. Since the delivery of those results, the newer CCMP3 winds became available and these were then used in the 2010 Oil Spill trajectory calculations [Chang et al. 2011] as well as in all later calculations we did, and are now doing for BOEMRE. In view of the possible confusion that these changing events may cause, we compare here both wind products focusing on the period Dec/1999-Feb/2000 when differences (between Qblend and CCMP3) were noted by BOEMRE scientists after our first draft. There were concerns that the Qblend winds may not be of sufficiently good quality and therefore may in turn degrade the quality of the simulated currents delivered to BOEMRE. The purpose of this Appendix is to attempt to address these concerns. It should be emphasized again, however, that the Qblend wind was the “best” wind product available to us when we did the calculations some three years ago. Our goal here is to simply evaluate its quality and, as a secondary goal, how it compares with the newer CCMP3wind product. Both wind products are blended from satellite and NCEP reanalysis model runs. They contain errors. Since we do not know the truths, the best we could do is to inter-compare them, and also compare them against actual observations at buoy locations in the Gulf of Mexico. Two locations are chosen, NDBC 42019 (27.9 N 95.4 W) and 42040 (29.2 N 88.2 W) closest to the region where BOEMRE scientists found largest discrepancies at one 6-hourly record (near end of December 1999). Before we make the above-mentioned comparisons, we check in Fig. A1.1 (as an example) that the model interpolated correctly the Qblend wind onto the curvilinear grid. The date chosen is Dec/21/1999 at 06:00 GMT, the time when BOEMRE scientists reported of the discrepancy between Qblend and CCMP3 winds (see below). This shows that the two wind vectors almost overlay each other. We have made similar comparisons for other times also and arrive at the conclusion that the model correctly interpolated the Qblend wind onto the model’s curvilinear grid. Note the strong wind over the LATEX shelf which will be discussed below. 
Fig.A1.1. A comparison of the wind used in the model with the Qnblend wind on Dec/21/06:00GMT, 1999. Locations of three NDBC stations 42019 (27.9 N 95.4 W), 42035 (29.2 N 94.4 W) and 42040 (29.2 N 88.2 W) are also shown. Qnblend and CCMP3 Wind & Ocean Current Comparisons at Buoy 42019 & 42040: Figs.A1.2 and A1.3 compare the time-series of Qnblend and CCMP3 winds at the NDBC buoy locations 42019 and 42040, respectively. In each figure, the black line in the time-series plots of U and V in the first 2 panels is for CCMP3, while the red line is for Qnblend. Stick plot in the third panel is for CCMP3 and that in the fourth panel is for Qnblend. The agreements are in general very good. At NDBC buoy 42019, the vector correlation between the 2 time series [see Lin et al. 2007] give R = 0.91 and angle = -7.8 deg (=1 and 0 respectively for a perfect match). The means of U are -1.91 m/s and -2.08 m/s for CCMP3 and Qnblend respectively, and those of V are 0.36 m/s and 0.1 m/s respectively. The standard deviations of U are 4.05 m/s and 4.25 m/s for CCMP3 and Qnblend respectively, and those of V are both 6 m/s. These also show very good agreements. Similarly good agreements are also seen at NDBC buoy 42040 (Fig.A1.3). There are discrepancies between the two winds, most notably near Dec/21/06:00 in 1999. These will be detailed below where we will show the existence of strong gusts with wind speeds exceeding 15 m/s. 
Fig.A1.2. Qnblend and CCMP3 wind comparisons at NDBC buoy 42019. The black line in the time-series plots of U and V in the first 2 panels is for CCMP3 wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for CCMP3 while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for CCMP3 and that in the fourth panel is for Qnblend. Time is from Nov/1999 through Feb/2000 (in GMT). 
Fig.A1.3. Qnblend and CCMP3 wind comparisons at NDBC buoy 42040. The black line in the time-series plots of U and V in the first 2 panels is for CCMP3 wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for CCMP3 while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for CCMP3 and that in the fourth panel is for Qnblend. Time is from Nov/1999 through Feb/2000 (in GMT). Similar comparisons are also made for the ocean’s surface currents simulated using the CCMP3 wind with those obtained using the Qnblend wind. Figs.A1.4 and A1.5 compare them at the NDBC buoy locations 42019 and 42040, respectively. The agreements are also generally good. The R’s and ’s, as well as the means and standard deviations indicate quite good agreements. The agreements are not as good those for the wind comparisons. However, this is to be expected because of the chaotic nature of the ocean (in which the slightest differences in the forcing can lead to large deviations in the simulated currents). In this case, however, the near-surface currents appear to be largely wind-forced. 
Fig.A1.4. Comparisons of simulated ocean’s surface currents at NDBC buoy 42019 forced by Qnblend and CCMP3 winds. The black line in the time-series plots of U and V in the first 2 panels is for CCMP3 wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for CCMP3 while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for CCMP3 and that in the fourth panel is for Qnblend. Time is from Nov/1999 through Feb/2000 (in GMT). 
Fig.A1.5. Comparisons of simulated ocean’s surface currents at NDBC buoy 42040 forced by Qnblend and CCMP3 winds. The black line in the time-series plots of U and V in the first 2 panels is for CCMP3 wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for CCMP3 while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for CCMP3 and that in the fourth panel is for Qnblend. Time is from Nov/1999 through Feb/2000 (in GMT). BOEMRE scientists reported that Qnblend and CCMP3 winds differ on Dec/21/06:00/ 1999. This difference shows up as short “blips” lasting for about 12 hours (two data points, since both wind data are 6-hourly) with speed difference of approximately 1~2 m/s on the time-series comparisons at buoys 42019 and 42040 in Figs.A1.2 and A1.3, respectively. Strong wind-gusts with speeds exceeding 15 m/s (see e.g. the V-component in Fig.A1.2, also see below) passed through the northern Gulf during that time period. Such transient differences between the two wind datasets occur throughout the time-series, and are perhaps not too surprising (because the two datasets are different). They also produce transient differences in the simulated surface currents as seen in Figs.A1.4 and A1.5, degrading the vector correlations R and . Given the errors in the model physics (turbulence parameterizations, absence of wind waves, effects of bottom roughness etc), resolution errors (which lead to errors in simulating small-scale eddies, topography etc), as well as other forcing errors (rivers, heat/evaporative fluxes, and winds!), we would argue that the differences in the simulated currents due to the different wind datasets are probably within the uncertainties of these other errors. As noted previously, despite the tendency for chaos to develop in the model ocean, the high values of R > 0.8 and small values of || < 6 deg between the two simulated currents in Figs.A1.4 and A1.5 support this conclusion. Qnblend, CCMP3 and Buoy Wind Comparisons at Buoy 42035: Figs.A1.1 shows that on Dec/21/06:00/ 1999, the strong winds occurred near the coast over the central LATEX shelf. We therefore compare the Qnblend and CCMP3 winds with buoy 42035 (Fig.A1.6). The black and red lines are again CCMP3 and Qnblend winds respectively (as in Figs.A1.2 and A1.3). In addition, we also plot the buoy wind time series in blue, and also the buoy wind gust time series in purple. The agreements amongst all 4 datasets are good. On Dec/21/06:00/1999, wind gusts with speeds exceeding 15 m/s are observed. There are again instances when the Qnblend and CCMP3 winds differ, but the vector correlation between them remains good, with R 0.88 and || < 10 deg. We cannot say which wind dataset is more superior from this (and previous) plots. However, since CCMP3 wind is a newer dataset, it is probably a better dataset to use. In another BOEMRE-supported study for the Mid-Atlantic region, we have conducted a more thorough comparison study amongst various wind datasets, and have concluded that CCMP3 is a good dataset to use. Qnblend, CCMP3 and Buoy Wind Comparisons at Buoys 42019, 42035 and 42040: To complete the comparisons, we compare in Figs.A1.7, A1.8 and A1.9 the Qnblend wind data with buoy data over a 2-year period from Sep/1999- Sep/2001. Table A1.1 compares the R and , as well as the means and standard deviations including also the CCMP3 wind. 
Fig.A1.6. Qnblend, CCMP3 and buoy wind comparisons at NDBC buoy 42035. The black line in the time-series plots of U and V in the first 2 panels is for CCMP3 wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for CCMP3 while red are for Qnblend. The blue line is buoy wind data while the purple line is buoy wind-gust data assuming the same directions as the wind data. Stick plot (plotted every 2days for clarity) in the third panel is for CCMP3 and that in the fourth panel is for Qnblend. Time is from Nov/1999 through Feb/2000 (in GMT). 
Fig.A1.7. Qnblend and buoy wind comparisons at NDBC buoy 42019. The black line in the time-series plots of U and V in the first 2 panels is for the buoy wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for buoy data while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for buoy wind and that in the fourth panel is for Qnblend. Time is from Sep/1999 through Sep/2001 (in GMT). 
Fig.A1.8. Qnblend and buoy wind comparisons at NDBC buoy 42035. The black line in the time-series plots of U and V in the first 2 panels is for the buoy wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for buoy data while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for buoy wind and that in the fourth panel is for Qnblend. Time is from Sep/1999 through Sep/2001 (in GMT). 
Fig.A1.9. Qnblend and buoy wind comparisons at NDBC buoy 42040. The black line in the time-series plots of U and V in the first 2 panels is for the buoy wind, while the red line is for Qnblend wind. Similarly, black numbers across the top are for buoy data while red are for Qnblend. Stick plot (plotted every 2days for clarity) in the third panel is for buoy wind and that in the fourth panel is for Qnblend. Time is from Sep/1999 through Sep/2001 (in GMT). Table A1.1. Comparisons between observed, Qnblend and CCMP3 winds at NDBC buoys 42019, 42035 and 42040 in the northern Gulf of Mexico. The “R” and “” are the vector correlation (with respect to the observed) coefficient and angle respectively.
It can be seen from these figures and table that the Qnblend wind that is used for this project agrees quite well with the observed buoy wind data. However, the CCMP3 wind dataset appears to be a more superior dataset. Unfortunately, this latter dataset was only available after this project was completed. 1 These ADPC instruments are owned and operated by the oil companies on drilling and production facilities in deep water in the Gulf of Mexico. The data are transmitted to NODC in compliance with an BOEMRE Notice to Lessees. 2 In Oey et al. (2006), the coefficient for |ua| 2 was erroneously rounded off to 0.0002. 3 Note that the sign of the principal component is meaningful because the eigenvectors are in the same directions for both observation and model. Directory: ftp -> lyo -> chiming ftp -> Tr-41. 4-03-05-024 Telecommunications ftp -> Message Race Detection for Web Services by an smt-based Analysis ftp -> A proposal submitted to the ftp -> National reports on data buoy activities ftp -> Louisiana barrier island comprehensive monitoring program (bicm) Volume 1: Barrier Shoreline Post-Storm Assessment ftp -> Jcomm expert team on chiming -> T jpo, 2011, in press he origin of along-shelf pressure gradient in the Middle Atlantic Bight Download 265.82 Kb. Share with your friends:
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