Appendix B

Sea-Level Rise in the Northeast Pacific Ocean

Sea-level rise along the west coast of the United States can be estimated using tide gage records from coastal stations or satellite altimetry data from the northeast Pacific Ocean. Appendix A estimated sea-level rise along the coast by correcting tide gage records for total vertical land motions—including tectonics, glacial isostatic adjustment (GIA), and fluid withdrawal and recharge—using Global Positioning System data. This Appendix estimates sea-level rise using tide gage records corrected for the GIA component of vertical land motion, then compares the estimates with regional altimetry data, which are also corrected for GIA.

It is well established that sea-level rise varies geographically and that this geographical pattern can be measured using satellite altimetry. However, satellite altimetry records are short (< 20 years), and the estimated sea-level trend is significantly influenced by ocean variability at interannual or longer timescales. On the other hand, satellite altimetry is much less affected by GIA than tide gages, and it is unaffected by vertical land motions caused by tectonics or fluid extraction or recharge. This appendix examines the extent to which tide gages and satellite altimetry measure the same sea-level variations at the seasonal and interannual scales in the northeast Pacific. This analysis differs from previous studies, which compared satellite altimetry with island tide gage data for calibration and validation purposes (e.g., Chambers et al., 2003; Mitchum et al., 2010). Such studies show that sea-level trends determined from tide gages are similar to trends determined from altimetry measurements made near the tide gage station (averaged within 220–330 km), as long as the vertical motion of the tide gage benchmark is known. The analysis below compares records from 21 tide gages and altimetry data from the northeast Pacific Ocean over the same timespan, 1992–2008. This exercise is intended (1) to assess confidence in both types of sea-level measurements, (2) to provide an independent check on the GPS-corrected tide gage sea-level estimates presented in Appendix A, and (3) to possibly discern the source of vertical land motion at the tide gage benchmarks along the coasts of California, Oregon, and Washington.

CORRECTIONS

Sea-level data from the TOPEX/Poseidon, Jason-1, and Jason-2 altimeters were obtained for 1992–2010 from JPL PODAAC,1 and tide gage data were obtained from the Permanent Service for Mean Sea Level (PSMSL). To compare the tide gage and regional altimetry sea-level trends, the altimetry data were first corrected for instrument, media, and geophysical effects, and the gage data were corrected for atmosphere barotropic effects using the inverted barometer assumption. Both types of data were then corrected for the effect of GIA, assuming that GIA is the only geophysical process affecting motion of either the land or the seafoor, for tide gage or altimetry records, respectively. The corrections to the data and the conversion to geocentric sea-level trends are described below.

__________

1 See <http://podaac.jpl.nasa.gov>.



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Appendix B Sea-Level Rise in the Northeast Pacific Ocean S ea-level rise along the west coast of the United station (averaged within 220330 km), as long as the States can be estimated using tide gage records vertical motion of the tide gage benchmark is known. from coastal stations or satellite altimetry data The analysis below compares records from 21 tide gages from the northeast Pacific Ocean. Appendix A esti- and altimetry data from the northeast Pacific Ocean mated sea-level rise along the coast by correcting tide over the same timespan, 19922008. This exercise gage records for total vertical land motions--including is intended (1) to assess confidence in both types of tectonics, glacial isostatic adjustment (GIA), and fluid sea-level measurements, (2) to provide an indepen- withdrawal and recharge--using Global Positioning dent check on the GPS-corrected tide gage sea-level System data. This appendix estimates sea-level rise estimates presented in Appendix A, and (3) to pos- using tide gage records corrected for the GIA com- sibly discern the source of vertical land motion at the ponent of vertical land motion, then compares the tide gage benchmarks along the coasts of California, estimates with regional altimetry data, which are also Oregon, and Washington. corrected for GIA. It is well established that sea-level rise varies CORRECTIONS geographically and that this geographical pattern can be measured using satellite altimetry. However, satel- Sea-level data from the TOPEX/Poseidon, lite altimetry records are short (< 20 years), and the Jason-1, and Jason-2 altimeters were obtained for estimated sea-level trend is significantly influenced by 19922010 from JPL PODAAC, 1 and tide gage ocean variability at interannual or longer timescales. On data were obtained from the Permanent Service for the other hand, satellite altimetry is much less affected Mean Sea Level (PSMSL). To compare the tide gage by GIA than tide gages, and it is unaffected by vertical and regional altimetry sea-level trends, the altimetry land motions caused by tectonics or fluid extraction or data were first corrected for instrument, media, and recharge. This appendix examines the extent to which geophysical effects, and the gage data were corrected tide gages and satellite altimetry measure the same for atmosphere barotropic effects using the inverted sea-level variations at the seasonal and interannual barometer assumption. Both types of data were then scales in the northeast Pacific. This analysis differs from corrected for the effect of GIA, assuming that GIA previous studies, which compared satellite altimetry is the only geophysical process affecting motion of with island tide gage data for calibration and validation either the land or the seafloor, for tide gage or a ltimetry purposes (e.g., Chambers et al., 2003; Mitchum et al., records, respectively. The corrections to the data and 2010). Such studies show that sea-level trends deter- the conversion to geocentric sea-level trends are mined from tide gages are similar to trends determined described below. from altimetry measurements made near the tide gage 1 See . 163

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164 APPENDIX B The sea-level data from TOPEX/Poseidon (ground are directly comparable. For the tide gages, the sea-level tracks from the original mission and the tandem mis- trend was calculated by subtracting the GIA predicted sion phase), Jason-1, and Jason-2 were processed by relative sea-level trend from the tide gage estimated subtracting a mean sea surface from the corrected sea linear trend. The GIA predicted relative sea-level trend surface topography measurements, and applying cross- (absolute sea-level change minus the height change track and along-track gradient corrections. Relative of the solid earth surface) at the gage benchmark is altimeter biases between the three different altimeters effectively a predicted vertical land motion estimate, were estimated globally with respect to TOPEX then with an opposite sign, if GIA is the only geophysical applied to the regional study. The altimeter sea surface process. For altimetry, the geocentric sea-level trend topography measurements were corrected for media was calculated by subtracting the GIA-model predicted (ionosphere, dry, and wet troposphere), instrument, and absolute sea-level change from the altimeter sea-level geophysical (solid Earth, pole and ocean tides, sea state trend (Peltier, 2001, Tamisiea, 2011). Table B.2 shows bias, and atmosphere barotropic response) conditions. long-term tide gage estimated sea-level trends, cor- The altimeter sea-level time series were cor- rected using the van der Wal GIA model, and the GIA rected for dynamic atmosphere response using the model corrections from various GIA models. AVISO dynamic atmosphere response model ( Carrre and Lyard, 2003) and for atmospheric pressure (in- RESULTS verse barometer [IB]) using the European Centre for Medium-Range Weather Forecasts surface pressure Figure B.1 shows the GIA-model predicted rela- model. These corrections were applied to the along- tive sea-level change (computed by subtracting the track sea-level data from each altimeter, and the data crustal uplift from absolute sea-level change) from were averaged around each tide gage site into monthly an ensemble of eight GIA models in western North measurements. The monthly tide gage sea-level data America. Predicted values differ significantly from one were corrected for IB effects using the National another in Washington and Canada, but are similar O ceanic and Atmospheric Administration Earth along the coast. In the study region where the tide System Research Laboratory (NOAA ESRL) 20th gages are located, the spread of GIA predicted values Century Reanalysis V2 (Table B.1).2 is between 1 mm yr-1 and 2 mm yr-1, mostly dominated Semiannual and annual signals for both the by the difference in the predicted uplift rate of the solid altimetry and tide gage sea-level time series were re- earth. moved. Removal of these signals improved the correla- Figure B.2 shows the tide gage estimated long-term tion between the altimetry and tide gage sea-level data sea-level trends, ~19002009, corrected for GIA using and reduced their root mean square (RMS) differences. an ensemble of 17 models, as a function of latitude. Application of the atmosphere correction further re- The discrepancy in sea-level trend due to the choice duced the sea-level variability of both the altimetry and of different GIA models is approximately 1 mm yr-1 tide gage data. The IB corrections had little impact on for the southern tide gages and up to 2 mm yr-1 for the the linear sea-level trend estimated from the tide gage Washington gages (Figure B.2). records, however they slightly reduced the correlation Figure B.3 compares the estimated sea-level trends between the tide gage and altimetry sea-level data from for both tide gages and satellite altimetry for 1992 0.79 to 0.64 (Table B.1). 2008. Both records were corrected for IB and for GIA Both the tide gage and the altimetry sea-level data using the van der Wal GIA model (van der Wal et al., were corrected for GIA, and thus their estimated trends 2009). The sea-level trend determined from satellite altimetry (background color) and from the tide gages (color-coded circles) is in reasonable agreement along 2 The National Centers for Environmental Prediction (NCEP) the coast. Figure B.3 shows that the sea-level trend is Reanalysis Derived Data (Kalnay et al., 1996), which is valid for 19482011 and has a spatial resolution of 2.5 2.5, can also nonuniform geographically, and that satellite altimetry be used to correct for inverse barometer. Tests showed that the can measure the sea-level trends much further away performance of both the NOAA ESRL and NCEP models was from the coastal regions where tide gages reside. almost identical.

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APPENDIX B 165 Absolute sea-level - Uplift (Sasgen-Klemann-Martinec) Absolute sea-level - Uplift (Paulson-Zhong-Wahr) 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 70 70 70 70 60 60 60 60 50 50 50 50 40 40 40 40 30 30 30 30 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 mm/yr mm/yr -4 -3 -2 -1 0 1 2 3 4 -4 -3 -2 -1 0 1 2 3 4 Absolute sea-level - Uplift (Wang_Wu ICE4G) Absolute sea-level - Uplift (Wang_Wu ICE5G) 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 70 70 70 70 60 60 60 60 50 50 50 50 40 40 40 40 30 30 30 30 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 mm/yr mm/yr -4 -3 -2 -1 0 1 2 3 4 -4 -3 -2 -1 0 1 2 3 4 Absolute sea-level - Uplift (Peltier ICE4G) Absolute sea-level - Uplift (Peltier ICE5GVM2) 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 70 70 70 70 60 60 60 60 50 50 50 50 40 40 40 40 30 30 30 30 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 mm/yr mm/yr -4 -3 -2 -1 0 1 2 3 4 -4 -3 -2 -1 0 1 2 3 4 Absolute sea-level - Uplift (Peltier ICE5GVM4) Absolute sea-level - Uplift (van der Wal) 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 70 70 70 70 60 60 60 60 50 50 50 50 40 40 40 40 30 30 30 30 200 210 220 230 240 250 260 270 200 210 220 230 240 250 260 270 mm/yr mm/yr -4 -3 -2 -1 0 1 2 3 4 -4 -3 -2 -1 0 1 2 3 4 FIGURE B.1 Selected GIA model predicted relative sea-level rise (absolute sea-level change minus height change) in western North America. Tide gage locations are shown as blue dots. For the Paulson-Zhang-Wahr model, only the absolute sea level is available, so a theoretical predicted relationship between absolute sea-level change and uplift (Wahr et al., 1995) was used to compute the associated relative sea-level change.

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166 APPENDIX B Sea Level Trends Estimated by NE Paci c Tide Gages, Data Spans: 24~110 yrs 5 4 GIA Corrected Sea Level Trend (mm yr -1) ICE4GVM2 3 ICE4GVM2L90NR ICE4GVM2L90 2 ICE4GVM2L120 ICE5GVM2 ICE5Gv1.3f_VM2_L90 1 ICE5GVM4 ICE5Gv1.3f_VM5b ICE6Gv2.04_VM5a 0 ICE6Gv2.04_VM5aD1 ICE6Gv2.04_VM5b -1 ICE6Gv3.0_VM5aD1 Paulson-Zhong-Wahr Wang Wu ICE4G -2 Wang Wu ICE5G van der Wal Sasgen-Klemann-Martinec -3 32 34 36 38 40 42 44 46 48 50 Latitude of Tide Gage Sites (deg) FIGURE B.2 Tide gage estimated long-term sea-level trends, corrected for GIA using an ensemble of 17 models at 21 locations from south (San Diego, 32.72N) to north (Friday Harbor, 48 55N). 220 230 240 250 50 FRIDAY HARBOR 50 CHERRY POINT NEAH BAY PORT TOWNSEND SEATTLE TOKE POINT ASTORIA SOUTH BEACH CHARLESTON II PORT ORFORD CRESCENT CITY N. SPIT 40 40 POINT REYES ALAMEDA SAN FRANCISCO MONTEREY PORT SAN LUIS SANTA MONICA LOS ANGELES LA JOLLA SAN DIEGO 30 30 220 230 240 250 mm/yr -10 -5 0 5 10 FIGURE B.3 Comparison of geocentric sea-level trends, in mm yr-1, for 19922008 from 21 tide gages along the coast of Cali- fornia, Oregon, and Washington (color-coded circles) and from TOPEX/Poseidon, Jason-1, and Jason-2 satellite altimetry missions (background colors).

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APPENDIX B 167 TABLE B.1 Effect of Inverted Barometer Corrections on Estimated Sea-Level Trends in the Northeast Pacific Ocean Without IB Correction to IB Correction Using NOAA ESRL Tide Gage or Altimetry Data 20th Century Reanalysis V2 Model Linear sea-level trend averaged from 21 tide gages, 19062008 0.71 0.04 mm yr-1 0.76 0.04 mm yr-1 RMS difference of average sea level, altimetry minus tide gage, 19922008 3.3 cm 3.3 cm Correlation, 19922008 79.2% 63.7% Figure B.4 compares the tide gage and altimetry tide gages and altimetry with the long-term (extending sea-level time series for 19922008 at each tide gage back to 1900) variation in sea level determined from site in the northeast Pacific study region. Note than tide gages. The stated reasons for the trend difference the trend estimates for both data types are probably between altimetry and gage is further confirmed by in error, primarily because of the short data spans and the differences in the short-term (19922008) and the large sea-level variability at interannual or longer long-term (19002009) gage trend estimates, at -2.0 timescales. RMS differences and correlations are given 0.7 mm yr-1 and 0.76 0.04 mm yr-1, respectively. The at the top of each figure, and the sea-level trends are latter represents a more robust sea-level trend estimate indicated by the straight lines. The figures show that over the study region. seasonal variations between the altimetry and tide gage The above analysis indicates that both altimetry sea-level time series are largely coherent (as indicated and tide gage observed sea-level variations are coherent by RMS differences and correlations), indicating that at seasonal and interannual timescales. The difference the two independent sea-level measurement systems in trend estimates of ~2 mm yr-1 over the timespan observed the same sea-level variations at seasonal and (19922008), correcting for vertical motion assuming interannual timescales during 19922008. However, an ongoing GIA process, could be caused by the short some estimated trends of individual tide gages are data span or by non-GIA related vertical motion at substantially different from the altimetry trend, likely some of tide gages in the study region. because of the poor trend determination due to short data spans and/or because vertical land motion at some REFERENCES of these tide gage sites is dominated by non-GIA pro- cesses, such as tectonics. Carrre, L., and F. Lyard, 2003, Modelling the barotropic response of the global ocean to atmospheric wind and pressure forcing Next, the estimated gage and altimetry trends Comparisons with observations, Geophysical Research Letters, were averaged to further examine whether these two 30, 1275. independent types of data measure the same sea level Chambers, D., S.A. Hayes, J.C. Ries, and T. Urban, 2003, New at the same location. The top panel of Figure B.5 TOPEX sea state bias models and their effect on global mean sea level, Journal of Geophysical Research, 108, 3305, shows the averaged tide gage and altimetry sea-level doi:10.1029/2003JC001839. time series for 19922008. The estimated trends are Kalnay, E., M. Kanamitsu, R. Kistler, W. Collins, D. Deaven, L. -2.0 0.7 mm yr-1 for the tide gages and 0.0 0.4 mm Gandin, M. Iredell, S. Saha, G. White, J. Woollen, Y. Zhu, M. Chelliah, W. Ebisuzaki, W. Higgins, J. Janowiak, K.C. Mo, C. yr-1 for altimetry. Although these trend estimates are Ropelewski, J. Wang, A. Leetmaa, R. Reynolds, R. Jenne, and significantly different (because of short data spans and D. Joseph, 1996, The NCEP/NCAR 40-year reanalysis project, possibly non-GIA related uplift or subsidence at the Bulletin of the American Meteorological Society, 77, 437-470. tide gage benchmarks), both time series show good Mitchum, G., R. Nerem, M. Merrifield, and W. Gehrels, 2010, Modern sea level estimates, in Understanding Sea-Level Rise and coherence at seasonal and interannual timescales. They Variability, J. Church, P. Woodworth, T. Aarup, and W. Wilson, have an averaged RMS difference of 3.2 cm and an eds., Wiley-Blackwell, UK, pp. 122-428. averaged correlation of 65.9 percent, indicating that Paulson, A., S.J. Zhong, and J. Wahr, 2007, Inference of mantle they measure essentially the same sea level. The bot- viscosity from GRACE and relative sea level data, Geophysical Journal International, 171, 497-508. tom panel of Figure B.5 compares the short-term (last few decades) variation in sea level determined from

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168 APPENDIX B TABLE B.2 Sea-Level Trends and Different GIA Corrections for 21 Tide Gages van der Wala Peltier ICE4G VM2 Tide Gage (mm yr-1) (mm yr-1) Geocentric Sea-Level Absolute Relative Absolute Relative Trendb Sea-Level Sea-Level Sea-Level Sea-Level Name Latitude Longitude Period (mm yr-1) Trend Trendc Trend Trend Cherry Point 48.867 -122.750 19852009 -0.03 -0.23 -0.50 0.05 -1.10 Friday Harbor 48.550 -123.000 19342009 1.13 -0.25 -0.17 0.03 -0.83 Neah Bay 48.367 -124.617 19342009 -1.63 -0.28 0.32 0.00 -0.40 Port Townsend 48.117 -122.750 19722009 1.48 -0.26 0.12 0.01 -0.53 Seattle 47.760 -122.333 18992009 2.11 -0.28 0.43 -0.01 -0.21 Toke Point 46.717 -123.967 19732009 1.04 -0.33 1.04 -0.06 0.50 Astoria 46.217 -123.767 19252009 -0.29 -0.35 1.07 -0.07 0.64 South Beach 44.633 -124.050 19672009 2.42 -0.38 0.91 -0.11 0.80 Charleston II 43.350 -124.317 19702009 0.82 -0.40 0.58 -0.13 0.61 Port Orford 42.733 -124.500 19852009 1.49 -0.40 0.45 -0.14 0.50 Crescent City 41.750 -124.200 19332009 -0.67 -0.41 0.22 -0.15 0.29 North Spit 40.767 -124.217 19852009 4.39 -0.41 0.13 -0.16 0.20 Point Reyes 38.000 -122.983 19752009 1.68 -0.43 0.04 -0.18 0.06 San Francisco 37.800 -122.467 18542009 1.98 -0.43 -0.01 -0.17 0.02 Alameda 37.767 -122.300 19392009 0.81 -0.43 -0.03 -0.17 0.01 Monterey 36.600 -121.883 19732009 1.11 -0.44 0.05 -0.18 0.04 Port San Luis 35.167 -120.750 19452009 0.78 -0.45 0.08 -0.19 0.05 Santa Monica 34.017 -118.500 19332009 1.44 -0.45 0.01 -0.19 0.00 Los Angeles 33.717 -118.267 19232009 0.83 -0.45 0.03 -0.19 0.01 La Jolla 32.867 -117.250 19242009 2.06 -0.45 0.05 -0.19 0.03 San Diego 32.717 -117.167 19062009 2.09 -0.45 0.06 -0.19 0.03 Average 1.19 -0.38 0.23 -0.11 0.03 SOURCE: ICE4G VM2 (Peltier, 2002), ICE5G VM2, and ICE5G VM4 (Peltier, 2004) models are from . ICE5G predictions were computed by R. Peltier (personal communication, 2011). GIA model results (Wang and Wu, 2006; Paulson et al., 2007; van der Wal et al., 2009; Sasgen et al., 2012; H. Wang, personal communication, 2011) were provided by the respective authors. a Model includes rotational feedback. b Tide gage geocentric sea-level trend = tide gage relative sea-level trend minus GIA predicted relative sea-level trend. The van der Wal model was used for the GIA correction. Tide gage relative sea-level trend was estimated by fitting a trend simultaneously with terms modeling semiannual and annual variations. c GIA predicted relative sea-level trend = absolute sea-level change minus height change of the solid earth surface. Peltier, W., 2001, Global glacial isostatic adjustment and modern Tamisiea, M., 2011, Ongoing glacial isostatic contributions to ob- instrumental records of relative sea level history, in Sea Level servations of sea level change, Geophysical Journal International, Rise: History and Consequences, B. Douglas, M. Kearney, and S. 186, 1036-1044. Leatherman, eds., International Geophysics Series, 75, Aca- van der Wal, W., A. Braun, P. Wu, and M. Sideris, 2009, Prediction demic Press, pp. 65-95. of decadal slope changes in Canada by glacial isostatic adjust- Peltier, W.R., 2002, On eustatic sea level history: Last Glacial Max- ment modeling, Canadian Journal of Earth Sciences, 46, 587-595. imum to Holocene, Quaternary Science Reviews, 21, 377-396. Wahr, J.M., D. Han, and A. Trupin, 1995, Predictions of vertical Peltier, W., 2004, Global glacial isostasy and the surface of the ice- uplift caused by changing polar ice volumes on a viscoelastic age Earth: The ICE-5G (VM2) model and GRACE, Annual Earth, Geophysical Research Letters, 22, 977-980. Review of Earth and Planetary Sciences, 32, 111-149. Wang, H., and P. Wu, 2006, Effects of lateral variations in litho- Sasgen, I., V. Klemann, and Z. Martinec, 2012, Towards the joint spheric thickness and mantle viscosity on glacially induced inversion of GRACE gravity fields for present-day ice-mass surface motion on a spherical, self-gravitating Maxwell Earth, changes and glacial-isostatic adjustment in North America and Earth and Planetary Science Letters, 244, 576-589. Greenland, Journal of Geodynamics, in press.

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APPENDIX B 169 Peltier ICE5G VM2a Peltier ICE5G VM4a Wang-Wu ICE4G Wang-Wu ICE5G Sasgen-Klemann- (mm yr-1) (mm yr-1) (mm yr-1) (mm yr-1) Martinec (mm yr-1) Absolute Relative Absolute Relative Absolute Relative Absolute Relative Absolute Relative Sea-Level Sea-Level Sea-Level Sea-Level Sea-Level Sea-Level Sea-Level Sea-Level Sea-Level Sea-Level Trend Trend Trend Trend Trend Trend Trend Trend Trend Trend -0.91 0.23 -0.81 -0.42 0.25 -1.12 0.37 0.22 0.08 -0.23 -0.93 0.61 -0.83 -0.09 0.22 -0.84 0.33 0.42 0.03 -0.22 -0.96 1.18 -0.85 0.40 0.18 -0.45 0.26 0.63 -0.04 0.04 -0.96 0.88 -0.85 0.14 0.20 -0.60 0.31 0.61 -0.01 -0.06 -0.99 1.16 -0.87 0.37 0.18 -0.32 0.28 0.82 -0.06 0.09 -1.04 1.82 -0.91 0.90 0.11 0.19 0.17 1.19 -0.16 0.60 -1.06 1.79 -0.92 0.85 0.09 0.32 0.15 1.27 -0.17 0.59 -1.09 1.53 -0.95 0.52 0.03 0.59 0.06 1.44 -0.19 0.80 -1.10 1.23 -0.96 0.24 -0.01 0.65 -0.01 1.44 -0.18 0.72 -1.11 1.15 -0.96 0.17 -0.03 0.67 -0.03 1.44 -0.18 0.72 -1.11 0.95 -0.96 0.03 -0.05 0.62 -0.06 1.34 -0.16 0.60 -1.12 0.90 -0.97 0.04 -0.07 0.60 -0.09 1.28 -0.15 0.66 -1.13 0.76 -1.00 0.10 -0.10 0.49 -0.14 1.06 -0.12 0.47 -1.13 0.69 -1.00 0.05 -0.10 0.45 -0.14 1.01 -0.12 0.35 -1.13 0.67 -1.00 0.03 -0.10 0.44 -0.14 0.99 -0.12 0.30 -1.14 0.68 -1.01 0.12 -0.11 0.43 -0.15 0.96 -0.11 0.41 -1.14 0.61 -1.02 0.13 -0.12 0.40 -0.17 0.87 -0.10 0.40 -1.14 0.45 -1.03 0.04 -0.11 0.31 -0.17 0.75 -0.09 0.26 -1.14 0.45 -1.03 0.06 -0.12 0.31 -0.17 0.75 -0.08 0.32 -1.14 0.44 -1.03 0.09 -0.12 0.27 -0.17 0.70 -0.08 0.29 -1.14 0.44 -1.03 0.10 -0.12 0.27 -0.17 0.69 -0.08 0.29 -1.08 0.89 -0.95 0.19 0.01 0.18 0.02 0.95 -0.10 0.35

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170 APPENDIX B Figure continues FIGURE B.4 Comparisons for 19922008 between the sea-level time series for 21 tide gages and averaged altimetry (TOPEX, Jason-1, and Jason-2) in the northeast Pacific study region.

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APPENDIX B 171 Figure continues FIGURE B.4Continued

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172 APPENDIX B Figure continues FIGURE B.4Continued

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APPENDIX B 173 FIGURE B.4Continued

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174 APPENDIX B 150 Tide Gage Observed Sea-Level Trend = -2.0 0.7 mm/yr Multi-altimetry (TP, J1 & J2) Observed Trend = 0.0 0.4 mm/yr 100 Sea Level Variation [mm] 50 0 -50 -100 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year 300 Tide Gage Observed Sea-Level Trend = +0.76 0.04 mm/yr Multi-altimetry (TP, J1 & J2) Observed Trend = -0.05 0.37 mm/yr 250 200 Sea Level Variation [mm] 150 100 50 0 -50 -100 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year FIGURE B.5 Averaged tide gage and altimetry sea-level time series for 19922008 (top), and the averaged tide gage time series for 19002008 shown also with altimetry sea-level time series (bottom). Inverted barometer and GIA corrections have been applied to both tide gage and altimetry sea-level records. The bottom panel also shows yearly averages, solid blue and red lines for tide gage and altimetry sea level, respectively, and estimated tide gage sea-level uncertainty in gray shades.