Guoqi Hanl, John Loder2, Brian Petrie2, Jianyong Lil, and . Charles O'Reilly2. INorthwest ... John Loder, Brian Petrie, Jianyong and Charles O'Reilly. 2004. Geo- ...
GEO-REFERENCEDSEASURFACE TOPOGRAPHY FOR TIlE SCOTIAN SHELF FROM SATELLITE ALTIMETRY Guoqi Hanl, John Loder2, Brian Petrie2, Jianyong Lil, and . Charles O'Reilly2 INorthwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John's, NL, Canada 2Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, NS, Canada
2004
Can. Tech. Rep. Hydrogr. Ocean Sci. 237
1"'1 .",.
Fisheries and Oceans Peches et Oceans
Canada Canada
C anad ·a..·
•
Canadian Technical Report of Hydrography and Ocean Sciences
•,
Technical reports contain scientific and technical infOimation that contlibutes to existing knowledge but which is not nonnally appropliate for primary literature. The subject matter is related generally to programs and interests of the Ocean Science and Surveys (OSS) sector of the Depaltment of Fishelies and Oceans . Technical reports may be cited as full publications. The correct citation appears above the abstract of each repolt. Each report is abstracted in Aquatic Sciences and Fisheries Abstracts and indexed in the Depaltment's annual index to scientific and technical publications. Technical repOits are produced regionally but are numbered nationally. Requests for individual reports will be filled by the issuing establishment listed on the front cover and title page. Out of stock reports will be supplied for a fee by commercial agents. Regional and headqualters establishments of Ocean Science and Surveys ceased publication of their valious rep0l1 series as of December 1981. A complete listing of these publications is published in the Canadian loumal of Fisheries and Aquatic Sciences, Volume 39: Index to Publications of 1982. The current series, which begins with report number 1, was initiated in January 1982.
Rapport technique canadien sur I'hydrographie et les sciences oceaniques Les rapports techniques contiennent des reseignements scientifiques et techniques qui constituent une contribution aux connaissances actuelles, mais qui ne sont pas nOimalement appropries pour la publication dans un journal scientifique. Le sujet est generalement lie aux programmes et interets du service des Sciences et leves oceaniques (SLO) du ministere des Peches et des Oceans. Les rapport techniques peuvent etre cites comme des publications completes. I.e titre exact parait au-des sus du resume de chaque rapport. Les rapports techniques sont resumes dans la revue Resume des sciences aquatiques et halieutiques, et ils sont classes dans l'index annuel des publications scientifiques et techniques du Ministere. Les rapports techniques sont produits a l'echelon regional , mais numerotes a I'echelon national. Les demandes de rapports seront satisfaites par l'etablissement auteur dont Ie nom figure sur la couve11ure et la page du titre. Les rapp0l1s epuises seront fournis contre rettibution par des agents commerciaux. Les etablissements des Sciences et leves oceaniques dans les regions et aI' administration centrale ont cesse de publier leurs diverses series de rapports en decembre 1981. Vne Iiste complete de ces publications figure dans Ie volume 39, Index des publications 1982 du loumal canadien des sciences halieutiques et aquatiques. La serie actuelle a commence avec la publication du rapport numero 1 en janvier 1982.
Can. Tech. Rep. Hydrogr. Ocean Sci. 237
2004
Geo-Referenced Sea Surface Topography for the Scotian Shelf from Satellite Altimetry
by
Guoqi Hanl, John
, Brian Petrie 2 , Jianyong O'Reilly2
INorthwest Atlantic Fisheries Canada, St. John'
, and Charles
Fisheries and Oceans Canada
2Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, NS, Canada
Minister of Supply and Services
Cat No. 97
citation
this publication:
John Loder, Brian Petrie, Jianyong and Charles O'Reilly. 2004. Geo-Referenced
Topography for Scotian Shelf from Satellite Altimetry. Hydrogr. + p.
ii
~.
TABLE OF CONTENTS
PAGE
List of Tables ................................................................................................................................. iv
List of Figures ..................................................................................................................................v
..••.........•..............•...........••....•....•......•........•....................•...•.......•.......................••...•..... VI
1. Introduction .................................................................................................................................. 1
2. Methodology ................................................................................................................................ 1
3. Results ..........................................................................................................................................2
Summary ................................................................................................................................... .
Acknowledgements ..................................................................................................................... .
References ........................................................................................................................................ 8
iii
List of Tables Table 1. Annual cycles of sea level derived from the TIP data. Amplitudes are sea leveL .................................... 4 metres phases day at (a) the raw lO-d sea level data, (b) with the annual cycle Table The RMS values (m) removed, and (c) with an additional applied ........................................ 4 TIP (in braces) for 8 constants major semi-diurnal and diurnal constituents at North Sydney, Halifax and Yarmouth. Amplitudes are in meters and Greenwich are in degrees ........................................ 5 RMS between the and in situ observations. The In braces are Han et al.'s (1996) Amplitudes are meters and phases are in degrees ...................................................................................................................................... 6
List of Figures 1. Map the and adjacent waters. The numerical labeled (thin dashed) are selected ground tracks on which the analysis is performed. 200-, lOOO-, 2000-, 3000- and 4000-m isobaths (grey lines) are also shown. SEC: Shelf-edge . Sable .............................................................................................. 9
sea height (m) relative to the TIP ellipsoid from the data for period August 1992 to June 2002. The 200-m isobath (thin white lines) (thick white lines) are also displayed ..................................................................................... lO Figure 3. Long-term seasonal-mean sea height (m) from data. The thick black lines depict zero contours. The 200-m isobath (thin white lines) TIP tracks (thick white lines) are also .................................................................................................................. 11 Figure Seasonal-mean sea surface anomalies (m) for (a) 1994, (b) and (c) 2000 . ....v~"v, zero contours. The 200-m isobath (thin white lines) and (thick white are also displayed .......................................................................... . Figure 5. Seasonal-mean sea level anomalies (solid lines) at along the Nova Scotia coast estimated from TIP data. dashed lines are the with the annual and cycles and subsequently smoothed with a ....................... 15 6. Comparison of TIP and observations of seasonal-mean sea height anomalies. RMSD: RMS difference ............................................................................ 16 7. for annual and semi-annual cycles removed and smoothed with a five-point moving .............................................. 17 Figure 8. TIP SSH anomalies on (a) 050, (b) 088 and (c) 126 for the period August 1992 to 2002 ................................................................................................................ .. 9. Co-amplitude and altimetry (a) M2, (b) S2, (c) N2, Cd) (e) . The thick black line corresponds to 0.5, O. 0.1, 0.08, and 0.04 m for M2, S2, N2, , and 01, respectively ....................................................................................................... 21 10. of and bottom pressure where TIP are with tide-gauge observations (Table 4) ........................................... . Figure 11. Predicted tidal sea level at (a) Yannouth, (b) Halifax, and (c) North Sydney using and tide-gauge derived parameters constituents .............................................. ..
v
s
ABSTRACT Guoqi Han, John Loder, Brian Surface for the Ocean Sci. 237: vi + 29 p.
O'Reilly. 2004. Altimetry. Can. Tech. Rep.
Altimetry data from the TOPEXIPoseidon (TIP) mission are to provide seasonal-mean sea surface topography for the Scotian Shelf and Slope, and the to data are also used to approaches to the Bay of Fundy during the period ~ova Scotia coast. Comparisons with sea level sea level along measurements from gauges are carried out to evaluate the potential of altimetry data for coastal sea level monitoring. diurnal tidal are an older version of TIP data in which tidal signals have not been removed. present altimetric tides agree with in situ observations, but with notable discrepancies some constituents at some A tool using tidal constituents is implemented to Scotian Shelf online ,=.:.=..;;.;..;...;;:;...;;==....t-===" Halifax and ~orth Sydney. The resulting fields are ==..:...::...:=.:..:.:.::=::...:.=-:.....::::.:..=:...;::.:..:.c:=c:..::.:...t==-=..i=-:-':'-:::::::'==':'-:::===; and are available to research and
Guoqi John Loder, Brian Petrie, Jianyong Li, and Surface Topography the Shelf Ocean Sci. vi + p.
O'Reilly. 2004. Geo-Referenced Altimetry. Tech. Rep.
donnees altimetriques obtenues la mission utilisees fournir des la topographie la plate-forme et du talus neo-ecossais, ainsi que pour les abords de la mer pour regIOn donnees TIP servent a estimer baie Fundy, au cours de la peri ode 1992 a 2002. Nouvelle-Ecosse. les moyennes du niveau la mer, Ie long de la cote de avec mesures du niveau la mer, maregraphes, permettent altimetriques en du de mer Ie d'evaluer Ie potentiel des du littoral. Huit compos antes diurnes et d'une version plus ancienne de donnees donnees altimetriques actuelles sur situ, Un outil de prevision utilisant composantes derivees des donnees reuvre afin de prevoir les niveaux des maH~es pour la plate-forme Yarmouth, et North Sydney. champs qui en en et sont a la
vi
1. Introduction altimetry provides reliable measurements of offshore sea level variations, particularly amplitude variations such as with (Han et , 1996), major currents and ocean (Han, 2002). Estimation of associated sea level at sites from altimetry is more challenging because of data degradation and near land. Nevertheless there is high potential that altimetry can contribute to coastal sea level monitoring, particularly in areas with spatially-varying sea and in remote areas. The altimetry data of near-decade length now available from TIP mission allow an extraction of important seasonal and interannual variations in sea level which are of to coastline variability, other Atlantic Canada. In this report we used altimetry data for the period from 1992-2002 to study sea variability over Scotian Shelf. Our objectives are: to sea topography over the Shelf and adjacent by season and compare estimates of mean and seasonal/interannual variations in coastal sea level from TIP with those from GPS-positioned tide data at selected along the Nova Scotia to evaluate the potential of satellite for coastal sea level and 3) to provide improved observational of the tidal variations in sea surface topography over the Scotian Shelf. The should useful to research and coastal communities in various applications such as and other data, improving bathymetric for areas of Atlantic Canada. datums, and evaluating implications of climate
techniques.
report consists of four 3
Section 2 briefly describes data sets and processing is given in
2. Methodology 2.1 TIP data and processing for seasonal means ~~
~~~~d
~~
are to study sea The a nominal repeat cycle of 10 ideally there are 360 observations at each location. There are (SW-NE) and descending (NW -SE) tracks with spacing of about 200 on the Shelf (Fig. 1). The along-track resolution is about 6 km. data were corrected based primarily on the principles in Benada (1997) for various atmospheric and oceanographic effects, including: 1) wet troposphere delay measured by the microwave radiometer; 2) dry troposphere delay determined from the European Centre Medium-Range Weather surface pressure model; 3) ionosphere delay on the altimeter measurement; 4) (due to ocean wave influences) using 2% of the significant wave height; ocean, load, solid pole
1
standard NASA (Goddard Flight Center) orbit based on the Joint Gravity Model-3 (JGM-3) was used to produce the sea surface height data to the TIP with equatorial radius 6378.1363 km and a flattening coefficient of 1/298.257. digital filter with a to altimetric sea surface height data. presented are on smoothed height data unless indicated otherwise. A time-mean sea surface was constructed from the data. We then calculate the sea relative to the mean sea Both the marine and mean oceanic topography are removed by this procedure. 2.2 TIP data and tidal analysis
The data for analysis are the same, for duration and some of the geophysical corrections applied. The data period is from August 1992 to December 2001. were no ocean, load and tide corrections, but the inverse barometric of sea to atmospheric was to These data are hpYH,,,,fnrth tide-in TIP data. A
method (Han et al., 1996) was to extract eight major tide from the tide-in TIP data. A tidal tool was implemented to tidal levels based on the altimetric tidal information.
2.3
data and processing
Water level data at three along the Scotia coast (North Sydney, Halifax and Yarmouth) were obtained from Marine Environmental and Oceans Canada. One-hour water level are quality controlled, (MEDS) of detided using the Godin 25_24_24 filter and averaged to produce monthly mean sea levels. data from North Sydney were suspect and not included in this 2002 data for the two other received no or only minimal quality control by of good quality.
3. Results 3.1 Altimetric mean surface topography Mean sea levels at locations were calculated over period from 1992 to 2002 relative to the TIP ellipsoid. We also interpolated the by GSFCOO mean topography (Wang, 2001) onto the track locations. The the GSFCOO mean sea levels (the former minus the latter) were computed location by location. We then mapped the onto a 0.2° by 0.2° grid an optimal linear interpolation method
2
2004) with a correlation scale of and 3° in the longitudinal The mapped differences were onto the GSFCOO mean sea the TIP mean sea topography averaged over the period
3.2 Altimetric seasonal-mean sea-surface topography anomalies Fig. 3 shows 10ng-tenTI seasonal-mean topography averaged from 1992 to 2002. They were constructed the optimal linear interpolation· method. We can see the coastal sea level is highest in fall except for winter west of Halifax and lowest in spring. Over the open shelf the sea is late summer and fall lowest early The seasonal variability is enhanced over the continental slope, presumably ~~_,~~, and/or meandering of the Gulf Stream and pinched from it. annual sea level range from 10 cm near the coast to cm over the lower slope. The present results and expand an study et (2002). Relatively low sea level in summer is probably with coastal upwelling under alongshore wind and relatively high sea level off the southwestem Nova Scotia in winter may be associated with of the peak Nova Scotian Current (Han et aJ., 1997). 4 presents seasonal-mean sea-surface topography anomalies by season for selected years, constructed using the linear interpolation method. In addition to seasonal variations, we also see significant interannual fluctuations. The sea level over the Scotian Shelf was low around 1994, in 1996/97, close to nonnal in 1990s (Han, 2002). The variability over the Scotian is out of phase with that over the Scotian Shelf. for seasonal-mean sea surface topography anomalies for the
~~~~~~~~~~~~~~~~~~~~~~~~~
3.3 Seasonal and interannual sea level anomalies at tide-gauge stations and offshore An important aspect of this report is to evaluate of altimetic estimates of coastal sea levels. Fig. 5 presents seasonal-mean sea level estimates at selected along the Nova Scotia coast, extrapolated from the altimetry data using the aforementioned optimal interpolation method. are significant interannual variations at all the In the sea level was low in the early 1990s, high in mid 1990s and close to nonnal the late 1990s and early 2000s. The range is about 10 cm. 6 compares altimetric estimates with measurements at three pennanent sites (North Sydney, Halifax Yarmouth). correlation (RMS) differences are cm, The removal of the annual and semiannual cycles significantly enhances the (the RMS difference: 1.5 cm), and slightly so at other two sites (the RMS 1.9 cm) 7). appears to be some systematic gauge and satellite observations, for the half of the record the difference (satellite minus gauge) is generally negative, for the second half mostly positive at all 3 correlation and TIP for this RMS difference at North Sydney are with
3
To provide further infonnation on the along-shelf and cross-shelf structure of sea level anomalies, four along-track bands were selected based on bathymetry: (i) coast to mid-shelf, (ii) mid-shelf to 200 m, (iii) 200-2000m and (iv) 2000-4000m. For Tracks 050, 088 and 126, we average sea level anomalies band by band every cycle. Fig. 8 presents time series of the averaged sea level anomalies. Least squares fit is carried out to derive the annual cycle from the sea level anomalies (Table l). Table 1. Annual cycles of sea level derived from the segment-averaged TIP data. Amplitudes are in metres and phases indicate the year day at the maximum sea level. 050 088 Segment Amplitude Phase Amplitude Phase 0.049 Shore to Mid-shelf 0.037 8 Mid-shelf to 200-m 0.013 0.052 343 200-m to 2000-m 0.046 252 0.055 0.052 266 2000-m to 3000-m 0.063
314 300 272 275
126 Amplitude Phase 0.035 0.050 0.048 0.071
290 297 280 264
Table 2. The RMS values (m) of (a) the raw 10-d sea level data, (b) with the annual cycle removed, and (c) with an additional 37-point moving filter applied.
(a) Shore to Mid-shelf 0.118 Mid-shelf to 200-m 0.097 200-m to 2000-m 0.107 2000-m to 3000-m 0.125
050 (b) 0.115 0.097 0.101 0.119
(c) 0.022 0.014 0.019 0.040
(a) 0.116 0.107 0.114 0.127
088 (b) 0.110 0.100 0.107 0.118
(c) 0.028 0.021 0.027 0.037
(a) 0.108 0.113 0.109 0.117
126 (b) 0.104 0.106 0.104 0.105
(c) 0.030 0.032 0.029 0.024
Over the inner shelf, the amplitude of the annual cycle is about 5 cm, decreasing towards both the northeastern and southwestern ends of shelf (Table 1). The phase pattern shows a -2 month lag from east to west, suggesting a southwestward propagation of the sea level signal. The amplitude of the annual cycle is larger over the continental slope. The sea level is highest in September/October, probably mainly associated with steric effects due to thennal expansion of the upper ocean in response to the surface heating and cooling. The outer Scotian Shelf and the shelf edge show transitional features between those of the slope and the inner shelf. The RMS sea level values (Table 2) indicate the higher-frequency variability dominates over the annual and interannual cycles over the Scotian Shelf Slope, as can be seen from Fig. 8. Off the central and western Nova Scotia, the interannual variability increases notably towards the deep ocean (Table 2).
3.4 Major tidal constituents We have derived eight major semi-diurnal (M2, S2, N2, K 2) and diurnal (K I, 0 1, PI. QI) tidal constituents from the tide-in TIP data using a response analysis method. The altimetric tides
4
on
ascending and tracks are interpo!atedJextrapolated onto a 0.20 by 0.20 an optimal linear interpolation method (Hendry and He, 2004) with a correlation scale of and latitudinal 9 Greenwich 3° in the ofM2, S2, N2, K, and 01. The major are with et aI., 1996). the semidiumal has small amplitude and phase from the east to west, Scotian Shelf. The diumal amphidromic points near the eastem Scotian Shelf. with in We have compared observations from coastal at the 3 stations (Table 3). Halifax North Sydney, same optimal interpolation method (Hendry and 2004) is to Yarmouth, a linear extrapolation scheme is used, with the altimetric tidal data on Track 033 only. 3. Harmonic constants from estimates and observations (in braces) for the 8 major semi-diumal and diumal constituents at North Sydney, Halifax and Yarmouth. Amplitudes are in meters lags are in
M2 S2 lN2 IK2 IK1 :01 PI Ql
Yarmouth Amplitude Phase 1.658( 1.652) 62(61) 0.272(0.287) 96(89) 0.351 (0.336) 34(35) 0.082(0.059) 98(90) 0.14(0.137)1 183(183) 0.108(0.124) 165(169) 0.048(0.050)' 182(183) 0.016(0.019) 160(124)
Halifax Amplitude Phase 0.584 (0.633) 342(351)' 17(23) 0.139 (0.139) 0.139 (0.14) 333(327) 19(16) 0.035 (0.039) 0.088 (0.109) 123(123) 0.018 (0.04) 127(94) 0.024(0.032) 122(124) 0.014(0.006) 128(335)
North Sydney Phase Amplitude 0.368(0.510) 353(349) 0.109(0.143) 37(24) 0.076(0.106) 330(320) 32(27) 0.03(0.035) 325(27) 0.077(0.043) 0.082(0.029) 287(332) 0.026(0.015) 315(29) 250(286)1 0.01l(0.012)
is good between data and estimates at Yarmouth. This is mainly due to Track 033 closely passes by Yarmouth. largest amplitude (phase) difference is 0.023 m (36°) with RMS over 8 constituents of 0.012 m (9°).
low by about 0.01
M2 is low about 0.04 m, and are within 0.001 m. Kl 01 are 0.02 m. There is generally good agreement in phase except for 01.
At North Sydney, altimetric tide is high by O. m for M2, low by 0.03 m for S2 and N2 and high by 0.04 and 0.05 m for 01. There are larger at this than at Yarmouth or Halifax. As we can see, the nearest altimetric data points are North Sydney. For the diumals, the presence of amphydromic points limits the accuracy of extrapolation of altimetric onto the coastal The altimetric tidal results are evaluated other coastal tide-gauge pelagic bottom measurements (see Fig. 10). A comparison of the
5
and
altimetric tide solutions with Han et al.'s (1996) altimetric estimates indicates overall improvement for the diurnal tides (Table 4). The nearly doubled record length is now sufficient to get the aliased Kl tide (which has an aliasing period of 172.3 d) separated from the semi annual cycle, which improves the estimation of the tidal admittance at each frequency of the diurnal species. Table 4. The RtVIS differences between the altimetric tides and in situ observations. The values in braces are from Han et al.'s (1996) solutions. Amplitudes are in meters and phases are in degrees.
M2 S2 N2 Kl 01
Coastal Amplitude 0.031 (0.040) 0.017 (0.031) 0.014 (0.015) 0.014 (0.017) 0.019 (0.031)
Pelagic Amplitude 0.012 (0.008) 0.015 (0.016) 0.012 (0.009) 0.013 (0.014) 0.018 (0.017)
Phase 11 (7) 13 (15) 17 (17) 15 (48) 29 (69)
Phase 4 (4) 10 (9) 8 (8) 10 (17) 21 (28)
A tidal prediction tool is implemented for the Scotian Shelf based on the harmonic constants for the eight tidal constituents. The 24-h forecast results are presented online and updated daily (http://sultry.nfl.dfo-mpo.gc.ca/intemecsite/engiish/guoqi/topex.html). A comparison of predicted tidal levels from the 8 tidal constituents using altimetry and tide-gauge analysis respectively is made at the three pennanent tide-gauge sites (Fig. 11), showing good agreement at Yannouth and Halifax, and large discrepancies at North Sydney. For the time period considered, the RMS difference from the hourly prediction is 1.5,3.2 and 16.2 cm for Yarmouth, Halifax and North Sydney.
4. Summary We have derived seasonal-mean sea levels and major tidal constituents over the Scotian Shelf from TIP data. The sea level along the coast is highest in fall and lowest in spring, and over the open shelf, highest in late summer and lowest in early spring. The magnitude increases over the Scotian Slope. The sea level over the Scotian shelf was low in the early 1990s, highest in 1996/97, and close to normal in the late 1990s. A comparison of TIP estimates and tide-gauge measurements at the coastal stations indicates fair agreement at seasonal and interannual scales. Eight major semi-diurnal and diurnal constituents are derived from the tide-in TIP data. Comparison with tide-gauge data and bottom pressure gauge data indicate overall good agreement. The present tidal solutions are in better agreement with tide-gauge data than Han et al.' s (1996) for the Kl and 01 tides, but nearly the same for M2, S2 and N2. Detailed comparisons for the three pennanent tide-gauge stations indicate good agreement at Yarmouth and Halifax, but with notable discrepancies at North Sydney. For estimating coastal sea levels from satellite altimetry, higher spatial resolution is demanded. It is apparent that the close agreement between altimetric estimates and tide-gauge measurements at Yarmouth and Halifax can be partly attributed to better data coverage near the
6
The tandem missions of TIP and Jason-1 will provide sea data wi th doubled crosstrack resolution. It is expected that the coastal sea levels can using the data from two missions, when combined with those from other satellite altimetry missions.
Acknowledgements was funded by the Canadian Space the Climate Change and Sector subprogram of the federal Program on Energy, (PERD), and and Canada. Mel Newhook and analysis. The TIP data were obtained from the NASA Pathfinder Project.
7
on
References Benada, R., 1997. Merged GDR (TOPEXlPoseidon) User Handbook, JPL D-J1007, Jet Propul. Lab., Pasadena, Calif. 2002. sea level variations in the Scotia-Maine region the 1990s. J. ofRemote Sensing, 581-587, 2002. Han G., M. Ikeda and Smith, 1996. Oceanic on Newfoundland and Scotian from TOPEXIPOSEIDON altimetry. Atmosphere-Ocean, 34(4), 589-604. Hannah, P.e. Smith, and lW. 1997. variation of dimensional circulation over the Scotian Shelf, J. Geophys. 102(CI), 1011-1025. Han and Smith, 2002. Annual variations of sea surface currents Oceanogr., 1794-1810. over Shelf and Slope, J. Hendry, and 1. He, 2004. Technical Report on Objective Analysis (OA) Project. In Can. Rep. Hydrog. Ocean Sci. mean sea surface, anomaly, and vertical gravity gradient Wang, YM., 2001. J. ,106(C 31,167-31,174. from satellite altimeter
8
46 ; I
\
\
;
\
\
an so I-darbour I \
I
\ S~ .7).'\:\
/SbO\\
\
/
\! / \
'urphy's Cove Halifax; \ \ 0\\
,( nenburgo (
\
I
\
/
SIB /
/ /
\ / /
42
;
\
\ \
/
\
!
\ \
/
41~------~····~~-f-~----------------~·~~----------~~~-~------~--~
-68
-62 LongitudeOW
1. Map showing the Scotian Shelf and waters. The TIP ground tracks on which the are 2000-, 3000- and 4000-m isobaths (grey lines) are also shown. Sable Island Bank.
9
labeled lines (thin 200-, 1000-,
0
-2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -22 -24
-26 -28
LongitudeOW
2. Mean sea height (m) period from August 1992 to June 2002. The (thick white lines) are also displayed.
to the TIP ellipsoid the TIP data the isobath (thin white lines) and TIP tracks
.:..v,", .u
10
-30
Winter 47,---~~~--~~
O. i
46
o
-0.1
-62 LongitudeOW
LongitudeOW
Summer
Fall
47r---~'-~--~-'
46
z
z 45 o
°(l)
(l)
45
o:a 44
-g 44 -
j 43
~
.....J
43
42 41
-68
-66
-64
-62
-60
-58 LongitudeOW
LongitudeOW
3. Long-term seasonal-mean sea surface (m) from TIP data. The thick black depict zero contours. The 200-m isobath (thin white lines) and TIP tracks (thick white lines) are also displayed.
11
1994 Spring
0.2 47r---~~~--~~
47~----~~--~--
46
46
0.2
o
-62 1994 Summer
-60
-0.2
-0.2
LongitudeOW
LongitudeOW 0.2
1994 Fall
0.2
47.---~~~--~~
46
o
42 -0.2
(a)
sea surface height anomalies (m) for (a) 1994, (b) 1997, and (c) 2000. depict zero contours. The 200-m isobath (thin white lines) and TIP tracks (thick white lines) are also displayed.
12
1997 Winter
0.2
47
1997 Spring 47
0.2
46
46
z 45 0
Q)
-
0
0544 Cil ....J 43 42 41 -68
-66
-64
-62
-60
-58
-0.2 02
47
46
46
z 45 0
Q)
~44 ~
....J
43 42
42
LongitudeOW
LongitudeOW
(b) 4. (continued).
13
2000 Winter
0.2
47 46
2000 Spring 47
0.2
46
z 45 0
Q)
~ 44
j
0
43 42 41 -68
-66
-64
-62
-60
-58
-64
-0.2
LongitudeOW
2000 Summer 47
-62
-0.2
LongitudeOW 0.2
2000 47
46
46
z 45
z 45
0
0
Q)
Q)
O~ 44
~ 44
ro 43
j
....J
0
43
42
42
-0.2
LongiludeOW
LongitudeoW
(c) 4. (continued).
14
0.06
a -0.06
0.06
a -0.06
0.06
a -0.06
0.06
a -0.06'-· .
0.06
o -0.06
0.06
o -0.06
0.06
a -0.06
Year
5. Seasonal-mean sea anomalies (solid lines) at along the Nova Scotia coast TIP data. dashed are the with annual and semi-annual cycles removed and subsequently smoothed with a five-point moving filter.
15
RMSD=4.47 em·
0.00
:r: (j) (j)
-0.10
Halifax
-0 .20 =~=r::==-=~r::.-=-=-:-L-:-::-=--L-,-=-=-,,---L-1:-:9-==-97~-1-:-:9:-:9-::-8-'--:-:19=-=9-==-9--L--=-20=-=0:-::0-L.-::-2-=-00=--c1:-L--::2-=-00=2,-J 0.20 r;=::=:::::r=::=:::::::r:::=::::=::r:=:::=::::c;---.--r--'---r;::=::::=:::r:==::=::::::r=::=::=;l RMSD==3.49 em 0.10
0.00
:r:
(j) (j)
-0.10
Yarmouth -0.20
1992
1993
1994
1995
1997 Year
1998
1999
2000
2001
2002
Figure 6. Comparison of TIP estimates and tide-gauge observations of seasonal-mean sea surface anomalies. RMSD: RMS difference.
16
RMSD=2.28 em 0.04
-
0.00
.-.
---. -.- .-..\\'- ._. -~,
..........
,, '
.,;:
-0.04
,- , 0.00
.
I
... I
,.., ....;. ...,..,..,.-:-.. .;,..~."C'....,.
-0.04
-0.08 -=;;:;:::c::~:;::r:~~..L..,-~,--L---:-::-::~~~. .~:-:::-=-=---..L--:-::-=-=--..L....,--::-::-::c-....L-:::-::-::-:----=--=~ 0.08 r.====::c::====:c======::r:::====::::c:-::----,--,-------,----r,:============r==::==::l
0.04
0.00
-0.04
Yarmouth
-0.08 ~~:::::c~:;:;=e.-=-:::-:--'--:'1799=5:-l--:1-=-9=g6:-l--:1=g=g7::----'--:1:-=g7g8:----L-1:-::g=g-=-g--'--2=-=O:-=0-=0--L.2::-:0=-=0:-:-1---L2::-:0=-=0-=2-.J Year
Figure as 7, except annual and semi-annual cycles being removed and subsequently being smoothed with a five-point moving fi1ter.
shore-->rnid-shelf 0.2
o -0.2
•-
050
0.2
o :r:
(f) (f)
-0.2
200rn-->2000rn 0.2
o :r:
(f) (f)
.J
-0.2.
2000rn-->4000rn 0.2
o :r:
(f) (f)
-0.2 1995
1992
1996
1997
1999
2001
Year
(a) 8. TIP
anomalies on
(a) 050, (b) 088 and (c) 1
1992 to June 2002.
18
for the
from
shore-->mid-shelf 0.2
o I
U) U)
-0.2
mid-shelf-->200m 0.2
o I
U) U)
-0.2. I
..~... ---.JI'--_---'-_
200m-->2000m 0.2
2000m-->4000m
I
U) U)
-0.2
(b) 8. (continued).
19
shore-->mid-shelf 0.2
° -0.2
mid-shelf-->200m 0.2
I (f) (f)
-0.2
200m-->2000m 0.2
° I
(f) (f)
-0.2.
0.2
o I
(f) (f)
-0.2. 1997
Year
(c) Figure 8. (continued).
20
1998
1999
2000
2001
126
~----,
Amplitude (m,gray scale) and phase (degree,white line)
1.8
'---11.7 1----11.6 f-----I1.5
46
1------11,4
1.3 1.2
45
1.1
0.9
44
0.8 0.7
43
0.6 0.5 0,4
42
0.3 0.2
41
-68
-66
-64
-62
Longitude"W
-60
-58
0.1
o
(a)
9. Co-amplitude co-phase charts from altimetry for (a) M2, (b) S2, (c) N2, (d) Kl, and (e) 01. The thick black line corresponds to 0.5,0.12,0.1,0.08, and 0.04 m M2, S2, N2, Kl, and 01, respectively.
21
.---~
0.3
.------1
0.27
Amplitude (m,gray scale) and phase (degree,white line) 47,-------~------~~------~-------
1------1 0.24
46
0.21
45 0.18
0.15
0.12
43
42
41
-68
-66
-64
-62 LongitudeOW
(b)
9. (continued),
22
-60
-58
o
,-----, 0.35
Amplitude (m,gray scale) and phase (degree,white line)
1-------1
0.3
0.2
0.1
41 -68
-66
-64
-62 LongitudeOW (c)
Figure
(continued).
-60
-58
~-0.16
Amplitude (m,gray scale) and phase (degree,white line) 47 0.14
46
K1 0.12
45
0.1
0.08
0.06
0.04
0.02
LongitudeOW
(d)
Figure 9. (continued).
o
----,0.16
Amplitude (m,gray scale) and phase (degree,white line) 47 0.14
46
°1
0.12
45
0.1
0.08
0.06
0.04
LongitudeOW
(e)
Figure 9. (continued).
25
o
0'
I
~\
I \
I , I
/' /
\
\ I I
\
\
I
\
\ \
42
I
/
I
\
/
\
\
/
-60
-58
LongitudeOW gauges and ..,~,~""'~ 10. Locations estimates are compared with tide-gauge
26
i.lL'-,,'"''.'''''
!'.a'..
!'.~,,:> where TIP
Yarmouth( -66.12,43.84)
4
.....
tide-gauge
o~·==========~
11/21
11/22
_____ ______ ~
11/23
. . ________L -_ _ _ _ _ _
~ ~
11/24
~
11/26
2003 (a)
11. Predicted tidal sea at (a) Yannouth, (b) Halifax, and (c) North Sydney using TIP and tide-gauge derived parameters for the constituents.
Halifax( -63.60,44.67) 2rr========c==~----'---~--~--~r---'---~--~
1.8 1.6 1.4
1.2
0.8
0.6
11/24
11 2003
(b)
11. (continued).
28
11/25
North Sydney(-60
I
1.4
,
."'
'i I . I I
I 1
I
I
••
I
I
I I .
I
I
.
... 1 I
I
. II '•·
.'
.....
I ,
...,'I
I
..•
..
.
,' I
I·· .
"I
o~======~~----~----------~--------~---------~ 11/21 11 11/23 11/24 11/25 11/26
2003 (c) Figure 11. (continued).
..
.
