Upload
agalia
View
57
Download
0
Embed Size (px)
DESCRIPTION
Reading GPS Time Series Plots. Roger Groom, UNAVCO Master Teaching-in-Residence Shelley Olds UNAVCO . GPS Basics. Need 3 satellite signals to locate the receiver in 3D space 4th satellite used for time accuracy Calculate position within sub-centimeter. Anatomy of a GPS Station . - PowerPoint PPT Presentation
Citation preview
Reading GPS Time
Series PlotsRoger Groom, UNAVCO Master Teaching-in-Residence
Shelley Olds UNAVCO
GPS Basics
• Need 3 satellite signals to locate the receiver in 3D space
• 4th satellite used for time accuracy
• Calculate position within sub-centimeter
Anatomy of a GPS Station
GPS antenna inside of dome, solidly attached into the ground with braces. If the ground moves, the station moves.
Solar panel for power
Equipment enclosure • GPS receiver• Power/batteries• Communications/ radio/ modem• Data storage/ memory
Movement of GPS stations
GPS station positions change as plates move.
How will these stations’ positions change
relative to one another?
Processed GPS Data
SBCC GPS STATION
• Located near Mission Viejo, CA • Position data collected every 30
seconds• One position estimate developed
for each day North East Vertical
Date North (mm) East (mm)Vertical
(mm)
1/1/2004 -37.67 36.57 2.33
1/2/2004 -38.04 35.73 5.63
1/3/2004 -37.16 35.83 4.69
1/4/2004 -37.34 36.34 5.36
1/5/2004 -37.59 36.44 9.11
… … … …
1/1/2005 -9.43 9.63 2.36
1/1/2006 16.48 -18.09 7.35
1/1/2007 45.98 -43.42 -6.43
Starting with the basics: GPS Time Series Plot
Y-axis:• North (N/S)• East (E/W)• Height (up/down)
(sometimes called Vertical)
• In millimeters
X-axis: Date of the measurement In 10ths of year or months
Red data points are rapid position estimates
Units of measurement
• X AxisTypically in 10ths of year
• Y AxisUsually millimeters (but always check)
Gaps in Data
Causes• Power outages• Snow coverage• Equipment failure• Vandalism• Wildlife• Etc.
Gum drop GPS station
Build a gum-drop model of a GPS Monument 1 gum drop for the receiver = GPS Receiver 4 toothpicks (3 legs, one center post) = Monument braces 3 small Playdoh feet = Cement Small piece of transparency paper = ‘see-through’ Earth’s plate
Gum-drop stations in action
DateNorth(mm)
East(mm)
Height (mm)
2000 0 0 02001 1 1 02002 2 2 02003 3 3 02004 4 4 02005 5 5 0
… … …
What direction is GPS monument A moving?
GPS Monument A
5432102000 2001 2002 2003 2004 2005
Time (years)
Nor
th (m
m)
DateNorth Position
(mm)2000 02001 12002 22003 32004 42005 5
… …
GPS Monument A
Plotting the GPS Position over time: North
North vs Time
543210
Time (years)
Nor
th (m
m)
DateNorth Position
(mm)2000 02001 12002 22003 32004 42005 5
… …
GPS Monument A
Plotting the GPS Position over time: North
North vs Time
2000 2001 2002 2003 2004 2005
543210
Time (years)
Eas
t (m
m)
DateEast Position
(mm)2000 02001 12002 22003 32004 42005 5
… …
GPS Monument A
Plotting the GPS Position over time: East
East vs Time
2000 2001 2002 2003 2004 2005
543210
Time (years)
Eas
t (m
m)
DateEast Position
(mm)2000 02001 12002 22003 32004 42005 5
… …
GPS Monument A
Plotting the GPS Position over time: East
East vs Time
2000 2001 2002 2003 2004 2005
543210
Time (years)
Hei
ght (
mm
)
DateHeight(mm)
2000 02001 02002 02003 02004 02005 0
… …
GPS Monument A
Plotting the GPS Position over time: Height
Height vs Time
2000 2001 2002 2003 2004 2005
543210
Time (years)
Hei
ght (
mm
)
DateHeight(mm)
2000 02001 02002 02003 02004 02005 0
… …
GPS Monument A
Plotting the GPS Position over time: Height
Height vs Time
2000 2001 2002 2003 2004 2005
Summary
• Positive slope (numbers getting larger)North-south time
series: The station is moving north
East-west time series: The station is moving east
Height time series: The station is moving up
Nor
th (m
m)
Eas
t (m
m)
Hei
ght
(mm
)
Time
DateNorth(mm)
East(mm)
19992000
01
01
2001 2 22002 3 32003 4 42005 5 5
… … …
Plot North and East togetherGPS Monument A
• Plot the location of the GPS station each year. • Draw an arrow from the first data point to the last data point.• Move your gum-drop GPS monument from year 2000’s position toward
2005’s position. What direction is your GPS monument moving?
543210
1 2 3 4 5
north
east
DateNorth(mm)
East(mm)
19992000
01
01
2001 2 22002 3 32003 4 42005 5 5
… … …
Step 2) What direction is GPS monument A moving?
GPS Monument A
• Plot the location of the GPS station each year. • Draw an arrow from the first data point to the last data point.• Move your gum-drop GPS monument from year 2000’s position toward
2005’s position. What direction is your GPS monument moving?
54321
1 2 3 4 5
north
east
DateNorth(mm)
East(mm)
19992000
01
01
2001 2 22002 3 32003 4 42005 5 5
… … …
Step 2) What direction is GPS monument A moving?
GPS Monument A
• Plot the location of the GPS station each year. • Draw an arrow from the first data point to the last data point.• Move your gum-drop GPS monument from year 2000’s position toward
2005’s position. What direction is your GPS monument moving?
54321
1 2 3 4 5
north
east
What direction is GPS monument B moving?
DateNorth(mm)
East(mm)
2000 0 02001 -1 -22002 -2 -42003 -3 -62004 -4 -82005 -5 -10
GPS Monument B
Focus on the data for the North data• Is Monument B moving in a more positive or negative direction?• What direction is GPS Monument B moving? North or South?
Now, focus on the data for the East data• Is Monument B moving in a more positive or negative direction?• What direction is GPS Monument B moving? East or West?
Plotting North and East Positions Together
• Plot the location of the GPS station each year. • Draw an arrow from the first data point to the last data point.• Move your gum-drop GPS monument from year 2000’s position toward
2005’s position. What direction is your GPS monument moving?
GPS Monument B
-1-2-3-4-5
-5 -4 -3 -2 -1
north
east
Date (Year) North (mm) East (mm)2000 0 02001 -1 -22002 -2 -4
2003 -3 -62004 -4 -82005 -5 -10
-1-2-3-4-5
-5 -4 -3 -2 -1
north
east
Plotting North and East Positions Together
• Plot the location of the GPS station each year. • Draw an arrow from the first data point to the last data point.• Move your gum-drop GPS monument from year 2000’s position toward
2005’s position. What direction is your GPS monument moving?
GPS Monument BDate (Year) North (mm) East (mm)
2000 0 02001 -1 -22002 -2 -4
2003 -3 -62004 -4 -82005 -5 -10
-1-2-3-4-5
-5 -4 -3 -2 -1
north
east
Plotting North and East Positions Together
• Plot the location of the GPS station each year. • Draw an arrow from the first data point to the last data point.• Move your gum-drop GPS monument from year 2000’s position toward
2005’s position. What direction is your GPS monument moving?
GPS Monument BDate (Year) North (mm) East (mm)
2000 0 02001 -1 -22002 -2 -4
2003 -3 -62004 -4 -82005 -5 -10
-1-2-3-4-5
-5 -4 -3 -2 -1
north
east
Moving south and west
Negative slopeNorth-south time
series: The station is moving south
East-west time series: The station is moving west
Height time series: The station is moving down
Nor
th (m
m)
Eas
t (m
m)
Hei
ght (
mm
)
Time
What direction is this GPS station moving?
Zero slope
Is the GPS station moving?
Time
Nor
th (m
m)
Time
What direction is this GPS station moving?
Zero slope
The station isn’t moving.
How is GPS monument BURN moving?
Time
Nor
th (m
m)
Time
Which car matches the graphs?
WhatDirection?
________
Which car? (letter)
________
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
1)
AB
C
E
D
North
Which car matches the graphs?
WhatDirection?
________
Which car? (letter)
________
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
1)
AB
C
E
D
North
Which car matches the graphs?
WhatDirection?
________
Which car? (letter)
________
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
1)
AB
C
E
D
North
Which car matches the graphs?
WhatDirection?
North-Northeast
Which car? (letter)
_Car A__
1)
AB
C
E
D
North
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
Which car matches the graphs?
WhatDirection?
_______
Which car? (letter)
________
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
2)
AB
C
E
D
North
Which car matches the graphs?
WhatDirection?
_South_
Which car? (letter)
__Car C__
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
2)
AB
C
E
D
North
Which car matches the graphs?
WhatDirection?
______
Which car? (letter)
________
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
3)
AB
C
E
D
North
Which car matches the graphs?
WhatDirection?
Northwest_
Which car? (letter)
___Car B_
3)
AB
C
E
D
North
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
Which car matches the graphs?
What direction is Car E moving?
__________
4)
AB
C
E
D
North
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
Draw the North and East Graphs
Which car matches the graphs?
What direction is Car E moving?
___East___
4)
AB
C
E
D
North
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
Draw the North and East Graphs
Which car matches the graphs?
What direction is Car D moving?
_____________
5)
AB
C
E
D
North
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
Draw the North and East Graphs
Which car matches the graphs?
What direction is Car D moving?
Southeast
5)
AB
C
E
D
North
North
Time (Hours)
Nor
th (m
iles)
East
Eas
t (m
iles)
Time (Hours)
Draw the North and East Graphs
Reference Key
What does GPS tell us about Iceland ?
REYK
HOFN
GPS Monument REYKN
orth
(mm
)E
ast (
mm
)
What direction is Monument REYK moving?
GPS Monument HOFNN
orth
(mm
)E
ast (
mm
)
What direction is Monument HOFN moving?
What directions are Monument REYK and HOFN moving?
REYKHOFN
Nor
th (m
m)
Eas
t (m
m)
Nor
th (m
m)
Eas
t (m
m)
towards each other, away from each other, or in the same direction?
REYK HOFN
How quickly is REYK moving?
Average position on 1/1/1997 = ______ mmAverage position on 1/1/2007 = ______ mm
Speed of REYK north = ___ mm / 10 years = ____ / yr to the North or South
Nor
th (m
m)
How quickly is REYK moving?
Average position on 1/1/1997 = _-135__ mmAverage position on 1/1/2007 = __70____ mm
Speed of REYK north = (70 - -135) mm / 10 years = 205 mm/ 10 yr = 20.5 mm / yr to the North
Calculate the speed of REYK for in the east-west direction and the speed of HOFN for both north-south and east-west directions (hint, use 1998 and 2008 for HOFN).
Nor
th (m
m)
How are quickly are REYK and HOFN moving?
Nor
th (m
m)
Eas
t (m
m)
Nor
th (m
m)
Eas
t (m
m)
REYK HOFN
REYK North = 20.5___ mm/year
REYK EAST = -11.0 __ mm/year
HOFN North = 15.0 ____ mm/year
HOFN EAST = 13.0 __ mm/year
Plotting vectors: north
• Number each axis using the same scale.• Vector: magnitude and direction
Tail is the GPS monument location Length of arrow is the magnitude Shows direction on a map
• GPS Monument REYK has moved 20.5 mm to the North per year• On your graph paper, each block represents 1 mm.
Draw a vector arrow 20.5 blocks along the north axis.
Plotting vectors: east
• Now draw a vector arrow -11.0 blocks (mm) along the East axis:
Adding the vectors together• To add the vectors together,
Re-draw the East arrow by placing its tail at the arrow head of the North arrow
Then draw a new vector from the tail of the North vector to the arrow head of the East vector.
GPS Monument C moves at: √20.52 + -112 = 23 mm / yr to the WNW
Draw the vectors on your map
What is happening to Iceland?
Icelandic rift eruption(Photo: National Geographic Magazine)
Vestmanneyjar, Heimaey, Iceland January 1973.
Source: USGS
Sites of surface eruptions
The fracture pictured here occurs over the Mid-Atlantic Ridge. The photo by R. Stull was taken immediately after the largest earthquake in the area since 1917.
www.calstatela.edu/dept/geology/HotSpots.htm
ICELAND
Mid-Atlantic Ridge
Conclusion
What you can do:• Explain the components of GPS data. • Determine velocity vectors from GPS
time series plots• Identify uses of GPS in applications
other than driving and hiking.
Other tools to explore
• UNAVCO GPS, Earthquake, Volcano Viewerhttp://geon.unavco.org/unavco/GEV.php
• Google Earth: Learn about Plate Tectonicshttp://geon.unavco.org/unavco/GE/Learn_about_
Plate_Tectonics.kmz
• IRIS Earthquake Browserhttp://www.iris.washington.edu/servlet/eventserv
er/map.do
59
Thank you
Contact: Shelley Oldsolds unavco.org
http://www.unavco.org/
Follow UNAVCO on facebookFacebook Twitter