Scaling Current Patterns¶
Since the current patterns created in CATS only indicate the direction of the current and the relative speeds, these current patterns need to be scaled in order to be useful with the trajectory model. For example, consider a fictitious current pattern with only two triangles, A and B. The velocity in triangle A is 1.2 to the east and the velocity in triangle B is 1.8 to the north. Observations indicate that the velocity in triangle A should be 3.0 knots to the east, so we must scale the current pattern by the ratio of these velocities in triangle A, or (3.0 knots ÷ 1.2 = 2.5 knots). That is, multiplying the velocity in triangle A in the current pattern (1.2) by the scale factor (2.5 knots) yields the observed velocity (3.0 knots). The direction did not change. To find the velocity in triangle B, we multiply the velocity in triangle B in the current pattern (1.8) by the scale factor (2.5 knots) to get a velocity of 4.5 knots. The velocity in triangle B is still to the north, since the direction does not change in the current pattern. GNOME is quite helpful in scaling current patterns. At a given reference point in the current pattern, GNOME tells you what the flow is. You then input into GNOME what you would like the velocity to be at the reference point, and GNOME calculates the scaling coefficient for the pattern for you!
The direction of the flow in the current fields in GNOME can reverse by multiplying the pattern by a negative scaling coefficient. The ebb and flow of tides are simulated this way, through a time-series of positive and negative scaling values. You can scale currents with either a constant value or a time-series. The acceptable file formats for time-series are outlined below.
Time-Series File Formats¶
Current patterns in GNOME can be scaled to be time dependent with two different file types:
a time-series of current magnitude or
a “SHIO mover” that contains data for GNOME to use in calculating tidal current magnitudes.
All data in this section were created by the NOAA SHIO application (“shio” comes from Japanese for “tide”).
The South Bend, Washington, U.S.A. station on the Willapa River was chosen for all the examples in this section. Below is the information found in the SouthBend.text file to illustrate the information GNOME needs in order to calculate the tidal currents at this station. This particular file is not a data file for GNOME. Those data are represented in data files presented later in this discussion.
Example – Filename: SouthBend.text¶
Tidal currents at South Bend, Willapa River, WASHINGTON COAST
Station No. CP1009
Meter Depth: n/a
Latitude: 46˚0' N
Longitude: 123˚47' W
Maximum Flood Direction: 90˚
Maximum Ebb Direction: 270˚
Time offsets Hour:Min
Min Before Flood 0:19am
Flood 0:20am
Min Before Ebb 0:24am
Ebb -0:06am
Flood Speed Ratio: 0.6
Ebb Speed Ratio: 0.5
Speed(kt) Direction(deg.)
Min Before Flood 00.0 n/a
Flood 01.2 090
Min Before Ebb 00.0 n/a
Ebb 01.4 270
Based on Grays Harbor Ent.
Local Standard Time
------------------------------------------------------------------
Mon, Aug 24, 1998--Sunrise -- 6:09am Sunset -- 7:55pm
0:38am +01.2 Max Flood
3:31am +00.0 Min Before Ebb
6:29am -01.6 Max Ebb
9:59am +00.0 Min Before Flood
1:08pm +01.4 Max Flood
4:12pm +00.0 Min Before Ebb
6:56pm -01.4 Max Ebb
10:17pm +00.0 Min Before Flood
Time Series of Current Magnitude¶
Time series file for currents have the format
dd, mm, yy, hr, min, u, 0.0
where dd is the day, mm is the month, yy is the year, hr is the hour, min is the minute, u is the magnitude of the velocity, and 0.0 is a number to indicate that the file is in a magnitude format rather than a U,V format. The direction is left blank because the current pattern supplies the individual current vectors. There is an optional header:
The first line lists the station name.
The second line lists the station position.
The third line provides the units.
For example, the SouthBend.ossm file contains one day of tidal information for South Bend, Washington, U.S.A.
Example – Filename: SouthBend.ossm¶
South Bend
-123.78,46
knots
24, 8, 98, 0, 37, 1.2, 0.0
24, 8, 98, 3, 30, 0.0, 0.0
24, 8, 98, 6, 28, -1.6, 0.0
24, 8, 98, 9, 58, 0.0, 0.0
24, 8, 98, 13, 7, 1.4, 0.0
24, 8, 98, 16, 11, 0.0, 0.0
24, 8, 98, 18, 55, -1.4, 0.0
24, 8, 98, 22, 16, 0.0, 0.0
Annotated Version of the File
# Day, Month, Year, Hour, Min., Speed, Direction # (Dummy Value)
24, 8, 98, 0, 37, 1.2, 0.0
24, 8, 98, 3, 30, 0.0, 0.0
24, 8, 98, 6, 28, -1.6, 0.0
24, 8, 98, 9, 58, 0.0, 0.0
24, 8, 98, 13, 7, 1.4, 0.0
24, 8, 98, 16, 11, 0.0, 0.0
24, 8, 98, 18, 55, -1.4, 0.0
24, 8, 98, 22, 16, 0.0, 0.0
SHIO Movers: Using Tidal Constituents¶
GNOME can use both tidal height and tidal current constituent data to scale current patterns. In the case of tidal height station data. GNOME will take the time derivative of the tidal heights, and request the user to scale that derivative to calculate the tidal currents. For the tidal current station data (below), GNOME will use the calculated currents directly. The constituent record data are rather complex, so we have provided information about the data fields and then provided an example file.
Tidal Heights Constituent Record:
Line 1 [StationInfo]
Line 2 Type=H station type for heights is “H”
Line 3 staName station name
Line 4 Latitude=latStr decimal degrees
Line 5 Longitude=longStr decimal degrees
Line 6 [Constituents]
Line 7 DatumControls.datum=datum mean sea level
Line 8 DatumControls.FDir=0 bug. Type as seen. Will be fixed in 1.2.7
Line 9 DatumControls.EDir=0 bug. Type as seen. Will be fixed in 1.2.7
Line 10 DatumControls.L2Flag=0 bug. Type as seen. Will be fixed in 1.2.7
Line 11 DatumControls.HFlag=0 bug. Type as seen. Will be fixed in 1.2.7
Line 12 DatumControls.RotFlag=0 bug. Type as seen. Will be fixed in 1.2.7
Lines 13-17 constituent amplitudes in order M2, S2, N2, K1, M4, O1, M6, MK3, S4, MN4, NU2, S6, MU2, 2N2, OO1, LAM2, S1, M1, J1, MM, SSA, SA, MSF, MF, RHO, Q1, T2, R2, 2Q1, P1, 2SM2, M3, L2, 2MK3, K2, M8, MS4 [feet]
Lines 18-23 constituent phases in order see above, lines 13-17 [degrees]
Line 24 [Offset]
Note: Lines 25-30 use a second integer to indicate to GNOME whether there is valid data in the field. “0” indicates no data, so GNOME can skip the calculation. “1” indicates valid data exists (that may be zero).
Line 25 HighTime=highTime 1 high water time adjustment (minutes)
Line 26 LowTime=lowTime 1 low water time adjustment
Line 27 HighHeight_Mult=highHeightScalar 1 high water height multiplier
Line 28 HighHeight_Add=highHeightAdd 1 high water height addend
Line 29 LowHeight_Mult=lowHeightScalar 1 low water height multiplier
Line 30 LowHeight_Add=lowHeightAdd 1 low water height addend
Example – Filename: HornIslandPass.shio.txt¶
[StationInfo]
Type=H
Name=Horn Island Pass
Latitude=30.2167
Longitude=-88.483333
[Constituents]
DatumControls.datum=0.620000
DatumControls.FDir=0
DatumControls.EDir=0
DatumControls.L2Flag=0
DatumControls.HFlag=0
DatumControls.RotFlag=0
H=0.066000 0.022000 0.013000 0.468000 0.000000 0.460000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.020000 0.000000 0.000000 0.033000 0.036000 0.000000 0.120000 0.299000 0.000000 0.000000 0.018000 0.099000 0.000000 0.000000 0.012000 0.139000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
kPrime=358.500000 355.700012 0.000000 327.000000 0.000000 324.200012 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 329.799988 0.000000 0.000000 325.500000 328.399994 0.000000 32.099998 151.800003 0.000000 0.000000 323.000000 314.100006 0.000000 0.000000 321.299988 331.899994 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
[Offset]
HighTime=-0.516667 1
LowTime=-0.883333 1
HighHeight_Mult=1.300000 1
HighHeight_Add=0.000000 1
LowHeight_Mult=1.300000 1
LowHeight_Add=0.000000 1
Tidal Currents Constituent Record¶
Line 1 [StationInfo]
Line 2 Type=C station type for currents is “C”
Line 3 staName station name
Line 4 Latitude=latStr decimal degrees
Line 5 Longitude=longStr decimal degrees
Line 6 [Constituents]
Line 7 DatumControls.datum=datum datum
Line 8 DatumControls.FDir=floodDirection flood direction
Line 9 DatumControls.EDir=ebbDirection ebb direction
Line 10 DatumControls.L2Flag=L2Flag L2Flag
Line 11 DatumControls.HFlag=hydraulicFlag hydraulic flag
Line 12 DatumControls.RotFlag=0 For non-rotary tides, use “0”. For rotary tides defined relative to North or East, use “1”. For rotary tides defined by major and minor axes, use “2”.
Lines 13-17 constituent amplitudes in order M2, S2, N2, K1, M4, O1, M6, MK3, S4, MN4, NU2, S6, MU2, 2N2, OO1, LAM2, S1, M1, J1, MM, SSA, SA, MSF, MF, RHO, Q1, T2, R2, 2Q1, P1, 2SM2, M3, L2, 2MK3, K2, M8, MS4 [knots]
Lines 18-23 constituent phases in order see above, lines 13-17 [degrees]
Line 24 [Offset]
Note: Lines 25-38 use a second integer to indicate to GNOME whether there is valid data in the field. “0” indicates no data, so GNOME can skip the calculation. “1” indicates valid data exists (that may be zero).
Line 25 MinBefFloodTime= minBefFloodTime 1 minimum before flood time adjustment
Line 26 FloodTime= floodTime 1 flood time adjustment
Line 27 MinBefEbbTime= minBefEbbTime 1 minimum before ebb time adjustment
Line 28 EbbTime= ebbTime 1 ebb time adjustment
Line 29 FloodSpdRatio=floodSpeedRatio 1 flood speed ratio
Line 30 EbbSpdRatio=ebbSpeedRatio 1 ebb speed ratio
Line 31 MinBFloodSpd=minBefFloodAvgSpeed 0 average speed - minimum before flood
Line 32 MinBFloodDir=minBefFloodAvgDir 0 average direction - minimum before flood
Line 33 MaxFloodSpd=maxFloodAvgSpeed 0 average speed - flood
Line 34 MaxFloodDir=maxFloodAvgDir 0 average direction - flood
Line 35 MinBEbbSpd=minBefEbbAvgSpeed 0 average speed - minimum before ebb
Line 36 MinBEbbDir=minBefEbbAvgDir 0 average direction - minimum before ebb
Line 37 MaxEbbSpd=maxEbbAvgSpeed 0 average speed – ebb
Line 38 MaxEbbDir=maxEbbAvgDir 0 average direction – ebb
Example – Filename: StJohnsRiver.shio.txt¶
[StationInfo]
Type=C
Name=ST. JOHNS RIVER ENT. (between jetties)
Latitude=30.400000
Longitude=-81.383333
[Constituents]
DatumControls.datum=-0.350000
DatumControls.FDir=275
DatumControls.EDir=100
DatumControls.L2Flag=0
DatumControls.HFlag=0
DatumControls.RotFlag=0
H=1.993000 0.333000 0.404000 0.216000 0.293000 0.174000 0.092000 0.000000 0.000000 0.000000 0.078000 0.000000 0.000000 0.054000 0.000000 0.014000 0.000000 0.012000 0.014000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.034000 0.020000 0.000000 0.000000 0.071000 0.000000 0.000000 0.054000 0.000000 0.091000 0.044000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
kPrime=227.199997 244.399994 208.800003 98.800003 131.100006 122.699997 238.699997 0.000000 0.000000 0.000000 211.199997 0.000000 0.000000 190.300003 0.000000 235.199997 0.000000 110.699997 86.800003 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 134.600006 244.600006 0.000000 0.000000 99.199997 0.000000 0.000000 245.699997 0.000000 244.000000 100.800003 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
[Offset]
MinBefFloodTime=0.000000 1
FloodTime=0.000000 1
MinBefEbbTime=0.000000 1
EbbTime=0.000000 1
FloodSpdRatio=1.000000 1
EbbSpdRatio=1.000000 1
MinBFloodSpd=0.000000 0
MinBFloodDir=0.000000 0
MaxFloodSpd=0.000000 0
MaxFloodDir=0.000000 0
MinBEbbSpd=0.000000 0
MinBEbbDir=0.000000 0
MaxEbbSpd=0.000000 0
MaxEbbDir=0.000000 0
Example – Filename: Edmonds.shio.txt
[StationInfo]
Type=C
Name=Edmonds, 2.7 miles WSW of
Latitude=47.800000
Longitude=-122.450000
[Constituents]
DatumControls.datum=-0.500000
DatumControls.FDir=180
DatumControls.EDir=5
DatumControls.L2Flag=0
DatumControls.HFlag=0
DatumControls.RotFlag=0
H=1.954000 0.460000 0.402000 0.847000 0.000000 0.421000 0.000000 0.000000 0.000000 0.000000 0.078000 0.000000 0.000000 0.054000 0.018000 0.013000 0.000000 0.030000 0.033000 0.000000 0.000000 0.000000 0.000000 0.000000 0.016000 0.081000 0.028000 0.000000 0.000000 0.280000 0.000000 0.000000 0.055000 0.000000 0.125000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
kPrime=66.400002 84.099998 39.400002 72.500000 0.000000 66.199997 0.000000 0.000000 0.000000 0.000000 43.000000 0.000000 0.000000 12.300000 78.800003 74.599998 0.000000 69.300003 75.800003 0.000000 0.000000 0.000000 0.000000 0.000000 63.500000 63.000000 84.400002 0.000000 0.000000 73.199997 0.000000 0.000000 93.400002 0.000000 83.400002 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
[Offset]
MinBefFloodTime=0.733333 1
FloodTime=0.100000 1
MinBefEbbTime=0.216667 1
EbbTime=0.316667 1
FloodSpdRatio=0.100000 1
EbbSpdRatio=0.200000 1
MinBFloodSpd=0.000000 1
MinBFloodDir=0.000000 0
MaxFloodSpd=0.200000 1
MaxFloodDir=170.000000 1
MinBEbbSpd=0.000000 1
MinBEbbDir=0.000000 0
MaxEbbSpd=0.500000 1
MaxEbbDir=0.000000 1
Hydrology Time-Series¶
Hydrology time-series files for currents have the format per the bulleted list below. An example hydrology time-series file, Hillsbourgh.HYD, is also provided.
The first line lists the station name.
The second line contains the reference point position for scaling the current pattern with the hydrology volume transport time-series.
- The third line provides the units for the volume transport:
cubic feet per second (CFS)
kilo cubic feet per second (KCFS) Defined as 1,000 cubic feet of water passing a given point for an entire second.
cubic meters per second (CMS)
kilo cubic meters per second (KCMS) Defined as 1,000 cubic meters of water passing a given point for an entire second.
The data are given in the same time-series format as the currents, except that the magnitude of the current is changed to the volume transport.
Example – Filename: Hillsbourgh.HYD
HILLSBOURGH STATION
28.029534,-82.688080
CMS
01,10,2002,0,0,432,0
02,10,2002,0,0,309,0
03,10,2002,0,0,310,0
04,10,2002,0,0,312,0
05,10,2002,0,0,311,0
06,10,2002,0,0,287,0
07,10,2002,0,0,234,0
08,10,2002,0,0,235,0
09,10,2002,0,0,232,0
10,10,2002,0,0,177,0
Annotated Version of the File
HILLSBOURGH STATION # Station Name
28.029534,-82.688080 # Position (latitude, longitude)
CMS Units
# Day, Month, Year, Hour, Min., Transport, Direction (Dummy Value)
01, 10, 2002, 0, 0, 432, 0
02, 10, 2002, 0, 0, 309, 0
03, 10, 2002, 0, 0, 310, 0
04, 10, 2002, 0, 0, 312, 0
05, 10, 2002, 0, 0, 311, 0