1. Department of Geography and Urban Studies, Temple University GUS 0265/0465 Applications in GIS/Geographic Data Analysis Lecture 7: Case Study: Interpolation of Glacier Elevation and Analysis of Glacier Area and Volume Change

2. Purpose To create a spatio-temporal glacier database to support glacier change analysis To integrate various historic and contemporary data sources on glaciers Issues –Representation of 2-D and 3-D glacier geometry –Representation of glaciers at different times –Support for multi-path data retrieval (by glacier, location, time) –Integration of data with varying scales and data quality

3. Pilot Study: Mount Rainier, Washington Mount Rainier National Park

4. Spatial Data Layers Glacier ExtentDebris ExtentOriginal Contour

5. Spatial Data Layers Appended ContourElevation PointsGlacier Surface

6. Spatial Data Layers Glacier Slope Glacier Aspect Glacier Hillshade

7. Spatial Data Layers Terminus Position Terminus Position (detail)

8. Interpolation: Trend vs. IDW

9. Interpolation: Kriging vs. Spline

10. Interpolation: Spline Weighting

11. Managing the Temporal Component of the Spatial Data The ‘Snapshot’ Approach Time t1t1 tntn

12. Managing the Temporal Component of the Attribute Data The ‘time-normalization’ approach to representing time in the relational data model (Navathe and Ahmed, 1993) Define three types of attribute data: –Feature-based data –Glacier-based, time-dependent data –Glacier-Based, time-independent data

13. Feature Based Data ablation203818141020201913 accum.280926831020201913 ZONEM_ELEVMETAKEYLENGTH Carbon Glacier, 1913 Carbon Glacier, 1913 Polygon Attribute Table Data that describe the properties of a single feature (i.e. individual polygon) of a glacier at a given time of record

14. Glacier Based, Time Dependent Data Data that describe the properties of an entire, individual glacier that vary over time 21360.681020271913102027 22510.461020201913102020 13 ELAAARWGMSMETAKEY Nisqually Carbon NAME 20590.551020201971102020Carbon Carbon Glacier, 1913 Morphology Table 1913 YEAR 1971

15. Glacier Based, Time Independent Data Data that describe the properties of an entire, individual glacier that remain invariant over time Carbon Glacier, all times WACascadeMt. Rainier102027 WACascadeMt. Rainier102020 STATERANGEWGMSMOUNT WACascadeMt. Rainier102025 Tahoma Carbon NAME Cowlitz Location Table

16. Relational Schema ablation203818141020201913 accum.280926831020201913 ZONEM_ELEVMETAKEYLENGTH Carbon Glacier, 1913 Polygon Attribute Table 21360.681020271913102027 22510.461020201913102020 13 ELAAARWGMSMETAKEY Nisqually Carbon NAME 20590.551020201971102020Carbon Morphology Table 1913 YEAR 1971 WACascadeMt. Rainier102027 WACascadeMt. Rainier102020 STATERANGEWGMSMOUNT WACascadeMt. Rainier102025 Tahoma Carbon NAME Cowlitz Location Table

17. Glacier Area Change 1913 – 1971

18. Calculating Glacier Volume Glacier Surface Layer Basal Topography Layer -- = Glacier Isopach Layer

19. Calculating Glacier Volume Carbon Glacier, 1971 Glacier Isopach Data Layer

20. Calculating Glacier Volume 13 17 COUNT 12 10 14 THICKNESS 17 36 23 56 20 21 33 45 14 67 34 37 39 34 59 42 45 K Grid Attribute Table for a Glacier Isopach Layer ∑ T j ∙ A j ∙ C j K j = 1 V = Where: V is the glacier volume; K is the total number of records in the grid attribute table; T is the THICKNESS value of record j; A is the area of a grid cell (400 m 2) ; C is the COUNT value of record j.

21. Glacier Area and Volume Change, 1913 - 1971

22. Data Quality: A Comparison Our 1971 Area and Volume Calculation Results Versus Driedger and Kennard (1986)

23. Data Quality: Area Measurements Surveying Errors Digitizing Consistency Errors Registration Errors

24. Data Quality: Volume Measurements

27. Data Quality: Metadata Buyer Beware! Maintain metadata table (Glacier Based, Time Dependent) –Map Quality –Survey Date –Person Digitizing –Date of Data Digitization