Quarterly Progress Report Form - Oil Spill Recovery Institute
This report may be submitted by mail, fax or e-mail
P.O. Box 705 - Cordova, AK99574 - Fax: (907) 424-5820 - E-mail:
Deadline for this report: All grants over $25,000 shall submit this report within 30 days of the end of the quarter.
Today’s date: 10/31/2006
Name of awardee/grantee:University of Miami, Rosenstiel School of Marine and Atmospheric Science, PI: Professor Christopher N.K. Mooers
OSRI Contract Number:06-10-01
Project title: How Does a Semi-Enclosed Sea Respond to External and Internal Forcings?
This report covers _ Oct.-Dec.1st quarter
Jan.-March2nd quarter
_ April-June3rd quarter
X July-Sept.4th quarter
PART I - Progress Report on Activities
In a short paragraph (3-10 sentences), please describe project activities since your last report.
2006 Annual Report on Activities:
Xinglong Wu
31 October 2006
ABSTRACT: EPWS/NFS1 and PWS/NFS2 provide daily operational updates through the Internet, along with available observations for PWS from NOS3 tide gauges, NDBC4 buoys and C-MAN5 stations. RAMS6 and Global-NCOM7 continue to be effective in providing surface forcings and OBCs8, respectively, for EPWS-POM9, which is the modeling backbone of EPWS/NFS. As the second stage for comprehensive assessments of EPWS/NFS versus PWS/NFS versus observations, vertical velocity profiles at HE and MS, as well as at NDBC buoy 46060, are investigated. Coastal sea levels, surface temperature at NDBC and NOS stations, and the seasonal cycle of monthly-mean temperature profiles at GAK110 are also examined. These studies document the superiority of EPWS/NFS over its predecessor. EPWS/NFS products are then applied to explore the coherence and phase between total transports through HE and MS, emulation of monthly-mean transport through HE, seasonal mesoscale variability in the Central Sound, and the spatial structure of the monthly mean flow and mass fields at HE for one year..
1: Prince William Sound/Nowcast-Forecast System
2: Extended Prince William Sound/Nowcast-Forecast System
3: NationalOcean Service
4: NationalDataBuoyCenter
5: Coastal-Marine Automated Network
6: Regional Atmospheric Modeling System
7: Global - Navy Coastal Ocean Model
8: Open Boundary Conditions
9: PrincetonOcean Model
10: A hydrographic station located at the mouth of ResurrectionBay near Seward, Alaska and sampled by UAF.
STATUS OF OBJECTIVES:At the end of my second OSRI Fellowship year performing the proposed research, the status of my objectives is summarized below,
1) Numerical models: alternative versions of PWS-POM and EPWS-POM implemented with a curvilinear grid, increased horizontal resolution, and a smaller domain (but with the Alaska Shelf included for EPWS-POM) for conducting process studies; Completed
2) Assistance in assessing Global-NCOM as a source of open boundary conditions for EPWS-POM; Completed
3) Assistance in assessing RAMS as a source of surface forcing for EPWS-POM; Completed
3) Assistance in the real-time operation of PWS/NFS; Completed
4) Assistance in the real-time operation of EPWS/NFS; Completed
5) Assessments of PWS/NFS versus EPWS/NFS versus observations:
i) Comparison of velocity profiles at HE and MS, as well as NDBC buoy 46060; Completed
ii) Comparison of coastal sea levels at tide gauges, surface temperatures at NDBC and NOS stations, as well as monthly-mean temperature profile at GAK1; Completed
iii) Detection of Helmholtz Resonance of Prince William Sound; Completed
iv) Analysis of the coherence and phase between total transports through HE and MS; Completed
v) Emulation of monthly-mean transport through HE; Completed
vi) Description of simulated seasonal mesoscale variability in Central Sound; Completed
ROADBLOCKS ENCOUNTERED:The new dataset of two-point high-resolution ADCP measurements at both HE and MS in 2005 ( ?region=PWS) provides, for the first time, deep insight into the cross-sectional velocity structures, which are known to be crucial to understanding and calculating the circulation in the Central Sound. However, no performance information for these measurements has been provided, and the quality control of the data is unknown.
The ADCP measurements at NDBC buoy 46060 are invaluable for the validation of EPWS/NFS performance. However, the discontinuance of the data on 25 AUG 05 without prior announcement on the NDBC Website is a big loss, and makes it impossible to assess the complete seasonal cycle of variability of EPWS/NFS velocity in the Central Sound (note that EPWS/NFS starts on 23 FEB 05).
Access to OSRI's planned Lagrangian field experiment for AUG 07 is essential for skill assessment of EPWS-POM.
HIGHLIGHTS OF ACCOMPLISHMENTS:
1) A student seminar entitled as “Helmholtz Resonance of Semi-enclosed Seas” was presented in February 2006 in RSMAS. The seminar was focused on the physical mechanism and application of barotropic and baroclinic Helmholtz resonances in semi-enclosed seas. As an example, the Helmholtz resonance in PWS was studied and detected from both observed and simulated coastal sea levels and transport through HE. The Helmholtz resonance model can also be used to determine the response of PWS spatial mean sea level to atmospheric pressure loading, which indicates a maximum response near the Helmholtz resonance frequency (period ca. 6 hrs), an isostatic response for lower frequencies, and almost no response for higher frequencies .
2) Assistance with the real-time operation of both PWS/NFS and EPWS/NFS has continued, and the latest forecasts are updated daily via Internet at
3) To first order, the simulated CSLs generally agree well with NOS tide gauge observations at Cordova, Valdez and Seward (Fig. 1). However, the differences between observations and simulations may have amplitudes of 0.5 m or more during spring tides (Fig. 2), a phenomenon that requires further analysis to be understood. The most energetic peaks in the power spectra of CSLs, corresponding to diurnal and semi-diurnal tides, are consistent between observations and simulations with nearly the same magnitude (Fig. 3). The peak for diurnal tides is broader in the observations than that in the simulations. Other than tidal periods and the Helmholtz resonance, EPWS/NFS produces less energetic variations in CSL by an order of magnitude.
4) Observed seasonal cycles of SST at all NOS stations and NDBC buoys are well simulated by EPWS/NFS with the occurrence of maximum SST in AUG and minimum SST in MAR (Fig. 4). At 46060, PWS/NFS, on the other hand, underestimates the observed SST by a maximum of 5 Co difference (Fig. 5). During summer 2005, one significant surface cooling event is misrepresented in PWS/NFS simulation, which in contrast, is precisely followed by EPWS/NFS. At GAK1, the EPWS/NFS monthly-mean temperature profile has structure similar to that of the observed monthly climatology for the upper 150 m (Fig. 6). Both indicate the progressive delay of the occurrence of maximum temperature with water depth during seasonal warming. In the middle of October, a temperature inversion; i.e., a layer of warmer water under cooler water, occurs in both the simulations and the climatology, consistent with freshening in the upper layer that maintains hydrostatic stability on the monthly time scale.
5) The transports through HE and MS are nearly balanced, highly coherent, and generally out of phase for periods longer than ca. 30 hrs (Fig. 7). At periods shorter than ca. 10 hrs, the HE and MS transports are generally in phase and not perfectly coherent. There is a transition period band between 10 and 30 hrs where coherence is relatively low and phase varies rapidly.
6) As another application, EPWS/NFS time-depth velocity structure at a single point in HE was used to emulate a single moored ADCP moored. The results indicate that a single ADCP might not be sufficient to estimate HE transport. On the other hand, two moored ADCPs significantly improves the accuracy of the estimated HE transport (Fig. 8).
7) The subtidal EPWS/NFS simulated surface currents in Central PWS are dominated by mesoscale variability. A typical cyclonic eddy on 1MAR05 and an anticyclonic eddy on 1SEP05 (Fig. 9) are displayed.as examples of synoptic (“snapshot”) surface current maps, From preliminary examination of synoptic maps on a day-by-day basis for a year, the mesoscale variability changes rapidly: eddies typically form in Central Sound, translate northwestward, and dissipate in 20 to 30 da.
8) Cross-sectional monthly mean temperature, salinity, density, and velocity structures at HE are examined (Fig. 10). Surface warming and freshening commences in MAY and continues until AUG; then the surface water begins to cool and become saltier The water column remains stratified throughout the year in temperature, salinity, and density, though it is weaker in the surface layer in winter than summer, as is to be expected.The isopycnals are tilted from the horizontal (indicative of baroclinic flow) and in different directions (indicative of subsurface extrema in the flow). In most months, there is three-layered flow: inflow in the surface and bottom layers and outflow in the intermediate layer. These flow structures are fundamental to the dynamics of PWS, including the ventilation (i.e., renewal or exchange) of its waters.
PRELIMINARY CONCLUSIONS
1) Both PWS/NFS and EPWS/NFS continue to be fully operational in a highly automated fashion with real-time atmospheric forcings from RAMS and OBCs from Global-NCOM.
2) The Helmholtz resonance model can be used to determine the response of PWS spatial mean sea level to spatially-averaged atmospheric pressure loading, which crucially depends on the Helmholtz resonance frequency (period of ca. 6 hrs) of PWS.
3) EPWS/NFS is superior to PWS/NFS, based on comparisons of surface temperature and time series of vertical profiles of horizontal velocity in Central Sound.
4) Overall, EPWS/NFS agrees well with observed coastal sea levels and surface temperatures at NDBC and NOS stations, as well as the climatological monthly temperature profiles at GAK1.
5) Coherence and phase of EPWS/NFS volume transports at HE and MS indicates a dependence on period: nearly balanced and out of phase at periods greater than 30 hrs, nearly in phase at periods less than 10 hrs, and a phase transition band between 10 to 30 hrs of low coherence.
6) Emulation of moored ADCPs with detailed EPWS/NFS velocity structure at HE suggests that using two ADCPs (rather than one) significantly improves the estimation accuracy.
7) The subtidal EPWS/NFS simulated surface currents in Central Sound are dominated by mesoscale variability with a life cycle of the order of 1 mo.
8) At HE, the simulated monthly mean transects of velocity components and the mass field (i.e., temperature, salinity, and density) for 2005 indicate that three-layer flow (viz., into PWS in the surface and bottom layers and out of PWS in the intermediate layer) is typical throughout most of the year, and that the upper layer stratification is stronger in summer than winter, as is to be expected.
Figure 1: Comparisons of Coastal Sea Levels (CSLs) between observations at NOS tide gauges (red) and EPWS/NFS (blue) during 07/19 - 08/18/2005: (a) Cordova; (b) Valdez; and (c) Seward.
Figure 2: Differences between simulated and observed CSLs during 07/19 - 08/18/2005: (a) Cordova, (b) Valdez, and (c) Seward.
Figure 3: Power spectra for CSLs: (a) Cordova; (b) Valdez; and (c) Seward.
Figure 4: Comparisons between observed (red) and EPWS/NFS simulated (blue) SST at selected locations: (a) NOS Valdez; (b) NOS Cordova; (c) NDBC buoy 46060; (d) NDBC buoy 46061; (e) NDBC buoy 46081; (f) NDBC buoy 46076.
Figure 5: Comparisons between observed (red), EPWS/NFS (blue) and PWS/NFS (green) simulated (blue) SST at 46060.
Figure 6: Observed (upper) and simulated (bottom) monthly-mean temperature at various depths at GAK1. Observed monthly climatology is based on 30-year CTD measurements, and simulated monthly-mean is from EPWS/NFS running during MAR2005-MAR2006.
Figure 7: Coherence of one-year original volume transports (blue) between HE and MS: (a) magnitude; (b) phase. For comparison, coherence of one-year detided volume transports (red) is also shown: (c) magnitude; (d) phase.
Figure 8: Monthly-mean volume transport through HE: (1) EPWS/NFS simulated; (2) one-point ADCP estimated (as in Vaughan et al. 1997); (3) one-point ADCP emulated (full depth); (4) one-point ADCP emulated (partial depth); and (5) two-point ADCP emulated. EPWS/NFS simulated monthly-mean volume transport through MS (6) is also shown.
Figure 9: EPWS/NFS simulated surface current in Central Sound on 01 March (upper) and 01 September (bottom) 2005;
Figure 10.1: EPWS/NFS simulated monthly-mean temperature transect at HE in 2005.
NOTE: JAN & FEB are from 2006 because the present implementation (w/Global NCOM OBCs)of EPWS did not start until FEB 2005.
Figure 10.2: Same as above but for salinity.
Figure 10.3: Same as above but for density.
Figure 10.4: Same as above but for northward velocity.
OSRI Quarterly Progress Report
(JUL through SEP 2006)
Part II - Budget Report 06-10-01
QuarterCumulative Balance
Budget CategoryBudgetExpenses Expenses Remaining
Direct Costs
Personnel 20,000 3159.00 20000.00 0
Travel 0 0 0 0
Contractual 0 0 0 0
Commodities 0 0 0 0
Equipment 0 0 0 0
Subtotal Direct Costs 20,000 3159.00 20000.00 0
Indirect 5,000 789.75 5000.00 0
Project Total 25,000 3948.75 25000.00 0