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Reading GPS Time Series Plots Roger Groom, UNAVCO Master Teaching-in-Residence Shelley Olds UNAVCO.

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Presentation on theme: "Reading GPS Time Series Plots Roger Groom, UNAVCO Master Teaching-in-Residence Shelley Olds UNAVCO."— Presentation transcript:

1 Reading GPS Time Series Plots Roger Groom, UNAVCO Master Teaching-in-Residence Shelley Olds UNAVCO

2 GPS Basics Need 3 satellite signals to locate the receiver in 3D space 4th satellite used for time accuracy Calculate position within sub-centimeter

3 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

4 Movement of GPS stations GPS station positions change as plates move. How will these stations’ positions change relative to one another?

5 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 DateNorth (mm)East (mm) Vertical (mm) 1/1/ /2/ /3/ /4/ /5/ ………… 1/1/ /1/ /1/

6 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

7 Units of measurement X Axis  Typically in 10ths of year Y Axis  Usually millimeters (but always check)

8 Gaps in Data Causes Power outages Snow coverage Equipment failure Vandalism Wildlife Etc.

9 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

10 Gum-drop stations in action

11 Date North (mm) East (mm) Height (mm) ……… What direction is GPS monument A moving? GPS Monument A

12 Time (years) North (mm) Date North Position (mm) …… GPS Monument A Plotting the GPS Position over time: North North vs Time

13 Time (years) North (mm) Date North Position (mm) …… GPS Monument A Plotting the GPS Position over time: North North vs Time

14 Time (years) East (mm) Date East Position (mm) …… GPS Monument A Plotting the GPS Position over time: East East vs Time

15 Time (years) East (mm) Date East Position (mm) …… GPS Monument A Plotting the GPS Position over time: East East vs Time

16 Time (years) Height (mm) Date Height (mm) …… GPS Monument A Plotting the GPS Position over time: Height Height vs Time

17 Time (years) Height (mm) Date Height (mm) …… GPS Monument A Plotting the GPS Position over time: Height Height vs Time

18 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 North (mm) East (mm) Height (mm) Time

19 Date North (mm ) East (mm) ……… Plot North and East together 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? north east

20 Date North (mm ) East (mm) ……… 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? north east

21 Date North (mm ) East (mm) ……… 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? north east

22 What direction is GPS monument B moving? Date North (mm) East (mm) 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?

23 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 north east Date (Year)North (mm)East (mm)

24 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 B Date (Year)North (mm)East (mm)

25 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 B Date (Year)North (mm)East (mm) north east

26 Moving south and west Negative slope  North-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 North (mm) East (mm) Height (mm) Time

27 What direction is this GPS station moving? Zero slope Is the GPS station moving? Time North (mm) Time

28 What direction is this GPS station moving? Zero slope The station isn’t moving. How is GPS monument BURN moving? Time North (mm) Time

29 Which car matches the graphs? What Direction? ________ Which car? (letter) ________ North Time (Hours) North (miles) East East (miles) Time (Hours) 1) A B C E D North

30 Which car matches the graphs? What Direction? ________ Which car? (letter) ________ North Time (Hours) North (miles) East East (miles) Time (Hours) 1) A B C E D North

31 Which car matches the graphs? What Direction? ________ Which car? (letter) ________ North Time (Hours) North (miles) East East (miles) Time (Hours) 1) A B C E D North

32 Which car matches the graphs? What Direction? North- Northeast Which car? (letter) _Car A__ 1) A B C E D North Time (Hours) North (miles) East East (miles) Time (Hours)

33 Which car matches the graphs? What Direction? _______ Which car? (letter) ________ North Time (Hours) North (miles) East East (miles) Time (Hours) 2) A B C E D North

34 Which car matches the graphs? What Direction? _South_ Which car? (letter) __Car C__ North Time (Hours) North (miles) East East (miles) Time (Hours) 2) A B C E D North

35 Which car matches the graphs? What Direction? ______ Which car? (letter) ________ North Time (Hours) North (miles) East East (miles) Time (Hours) 3) A B C E D North

36 Which car matches the graphs? What Direction? Northwest_ Which car? (letter) ___Car B_ 3) A B C E D North Time (Hours) North (miles) East East (miles) Time (Hours)

37 Which car matches the graphs? What direction is Car E moving? __________ 4) A B C E D North Time (Hours) North (miles) East East (miles) Time (Hours) Draw the North and East Graphs

38 Which car matches the graphs? What direction is Car E moving? ___East___ 4) A B C E D North Time (Hours) North (miles) East East (miles) Time (Hours) Draw the North and East Graphs

39 Which car matches the graphs? What direction is Car D moving? _____________ 5) A B C E D North Time (Hours) North (miles) East East (miles) Time (Hours) Draw the North and East Graphs

40 Which car matches the graphs? What direction is Car D moving? Southeast 5) A B C E D North Time (Hours) North (miles) East East (miles) Time (Hours) Draw the North and East Graphs

41 Reference Key

42 What does GPS tell us about Iceland ? REYK HOFN

43 GPS Monument REYK North (mm) East (mm) What direction is Monument REYK moving?

44 GPS Monument HOFN North (mm) East (mm) What direction is Monument HOFN moving?

45 What directions are Monument REYK and HOFN moving? REYK HOFN North (mm) East (mm) North (mm) East (mm) towards each other, away from each other, or in the same direction? REYK HOFN

46 How quickly is REYK moving? Average position on 1/1/1997 = ______ mm Average position on 1/1/2007 = ______ mm Speed of REYK north = ___ mm / 10 years = ____ / yr to the North or South North (mm)

47 How quickly is REYK moving? Average position on 1/1/1997 = _-135__ mm Average position on 1/1/2007 = __70____ mm Speed of REYK north = ( ) 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). North (mm)

48 How are quickly are REYK and HOFN moving? North (mm) East (mm) North (mm) East (mm) REYKHOFN REYK North = 20.5___ mm/year REYK EAST = __ mm/year HOFN North = 15.0 ____ mm/year HOFN EAST = 13.0 __ mm/year

49 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.

50 Plotting vectors: east Now draw a vector arrow blocks (mm) along the East axis:

51 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: √ = 23 mm / yr to the WNW

52 Draw the vectors on your map

53 What is happening to Iceland?

54 Icelandic rift eruption (Photo: National Geographic Magazine) Vestmanneyjar, Heimaey, Iceland January 1973.

55 Source: USGS Sites of surface eruptions

56 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

57 ICELAND Mid-Atlantic Ridge

58 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.

59 Other tools to explore UNAVCO GPS, Earthquake, Volcano Viewer  Google Earth: Learn about Plate Tectonics  Plate_Tectonics.kmz Plate_Tectonics.kmz IRIS Earthquake Browser  er/map.do er/map.do 59

60 Thank you Contact: Shelley Olds olds unavco.org Follow UNAVCO on facebook Facebook Twitter


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