Upload
azis-ali-wibowo
View
89
Download
2
Embed Size (px)
Citation preview
Dr. Parluhutan ManurungNational Coordinating Agency for Survey and Mapping (BAKOSURTANAL)
INDONESIA
INTRODUCTION TO TIDE MODELLING
Training Course on Satellite Altimetry and Its ApplicationCibinong, 12-16 October 2009
Outline
• Observed sea level• Mean Sea Level• Tidal Level• Extreme Level• Exercise: Sea Level Processing
Time Varying Sea Level
X (t) = Zo (t) + T (t) + S (t)
• T (t) = Tidal Level
• X (t) = Observed sea level
• Zo (t) = Mean Sea Level
• S (t) = Surge (extreme) Level
Basic Equation of Sea Level
How do we observe?X (t) = Observed sea level
Tsunami December 26th, 2004
Indonesia Tide Gauge Network
Before• 54 stations• 34 analog and 20 digital • Delayed mode communication
After• 90 stations• 10 analog and 80 digital• 57 tsunami capable (real time)• 22 near real time
German Support for InaTEWS
USA/NOAA – IOC/UNESCO Support for InaTEWS
Sea Level Recording
Pressure gauge based on measure of water level column difference
Radar gauge; direct measure to sea surface
Digital float gauge; capable of performing real time data transmission
Graphical float gauge; direct measurement via floating mass
InstrumentationsBasic Concept
Platform Transmission rate
Coverage in Indonesia
Com. direction
PowerConsumption
Cost/yr (USD)
VSAT IP C-band flexible good 2-ways high 6,000
GTS/Meteosat 15’ (5’?) good 1-way low free
BGAN flexible good 2-ways low > 3,000GSM/GPRS flexible none in remote 2-ways low < 400
PSTN flexible none in remote 2-ways low 1000
Radio flexible inter visibility 2-ways high No air time cost
• VSAT is currently the best choice for a real time data transmission and its flexibility to add data transmission of other sensors: GPS and Meteo Sensor
• PASTI/BGAN would be the most preferable if a special rate is available
• Radio requires tower due to inter station visibility
GTS/Meteosat Pasti Radio
Data Communication Options
Database Server
OBSERVATION PROCESSING CENTER DISPLAY
InaTEWS CentreSea Level Centre
VSAT PASTI
GSM
BGAN
GTS
VSAT/VPN IP
InaTEWS Sea Level Data Work Flow
Public Access
Dedicated Access
Station distribution
Data Communication
Real Time Multigraph Display
Zo (t) = Mean Sea Level
• Tidal Datum • Sea level rise due to Global change
Where the sea level refer to?
Tsunami ; an extreme sea level..
Tidal Datum
Chart Datum = Lowest Astronomic Height
Long Term Datum Change
Global sea level rise ~ 10-20 cm for 100 years Semarang
Jepara
Tanjung Priuk
Sorong
T (t) = Tidal Level
• Astronomical Generating Force• Tide Prediction
Tide Generating Force
MoonEarth
Astronomical constellation of Moon, Sun and other planets toward the Earth generating sea tide
Tidal Description
• High Water : a water level maximum (High Tide)• Low Water : A water level minimum (Low Tide)• Mean Tide Level : the mean water level, relative to A reference point , averaged over a long ttime• Tidal Range: High and Low Tide difference• Daily Inequality: two successive low or high tide difference• Spring Tide: the tide following full and new Moon• Neap Tide: the tide following the first and last quarter of the Moon phases
Tide as function of time
Tides produced by the Moon• M2 (semidiurnal Lunar) ½ Lunar
day= 12 H 25 Min• O1 (Diurnal Lunar) 1 Lunar DAY=
12 h 25 min
Tides produced by the Sun• S2 (Semidiurnal Solar) ½ Solar
day= 12• K1 (Diurnal Solar) 1 Solar day=
24
Tidal Types (cont)
F Category
0 - 0.25 Semidiurnal: two high and low waters each day
0.25-1.5 Mixed, mainly semidiurnal two high and low waters each day during most of the time, only one high and low water during neap tides
1.5-3 Mixed, mainly diurnal 1 dominant high and low water per day, 2 high and low waters during spring tide.
>3 Diurnal one high and low water each day
F = (K1 + 01)/(M2 + S2)
Tidal Analysis
• Tides can be represented as the sum of tidal constituents, each has its amplitude, period and phase
• The amplitude, period and phase of each tidal constituent can be extracted from observations by harmonic analysis
• Practical tidal prediction uses more then 60 of tidal constituents derived from 1 year observations
Name DescriptionZ0 Mean Sea Level (MSL)M2 Principal lunar
semidiurnal constituent. S2 Principal solar
semidiurnal constituent.K1 Lunisolar diurnal
constituentO1 Lunar diurnal constituent. N2 Larger lunar elliptic semi
diurnal constituent. K2 Smaller lunar elliptic
semi diurnal constituent.
Harmonic Constants Description
MSM, MM, MSF, MF Long period
ALP1, Q1, SIG1, Q1, RHO1, O1, TAU1,BET1, NO1, CHI1, P1, K1, PHI1, THE1J1, SO1, OO1
,Diurnal
OQ2, EPS2, 2N2, MU2, N2, NU2, M2,MKS2, LDA2, L2, S2, , MSN2, ETA2
Semi diurnal
MO3, M3, SO3, MK3, SK3 Third Diurnal
MN4, M4, SN4, MS4, MK4, S4, SK4 Fourth Diurnal
MK5, SK5 Fifth DiurnalMN6, M6, MS6, MK6, SM6, MSK6 Sixth Diurnal
Harmonic Constants
Major Constants
Tide Prediction
• Quality data time series results in good model• Better identification of error budget
JAKARTA
S (t) = Surge (extreme) level
Tsunami, extreme sea level
• Tsunami; extreme and destructive sea level• Storm surge, other less destructive sea level
Showing Tsunami Signals
• Sea state during tsunami: Sea Level = tide + (atmospheric + current + local factor + tsunami signal)
• Removing tide effect from the record• Need to introduce low pass digital filters• The remaining is approximately turbulence
generated by tsunami• MATLAB Script is written by: Walters, R. A. and Heston,
C., 1982. Removing the tidal-period variations from time-series data using low-pass digital filters. Journal of Physical Oceanography, 12 112-115
• The source is available in:http://woodshole.er.usgs.gov/operations/sea-mat/index.html
Tend to occur at least once in a year
POL Liverpool, 3 December 2008
2004
2005
2006
2007
2008
17 Nov 2008
It happens at least once in a year……
2009
The Latest Tsunami: Manokwari’s Earthquake
3rd January 2009
Exercise: Sea Level Data Processing
Sample of Hourly Tide Data Harmonic Constants after tide data processing
Data Processing
Tide Processing
Graphics of Tide Processing
Tide Prediction
Thanks …..