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Geodynamics www.helsinki.fi/yliopisto Geodynamics Climatic, geomorphic and geodynamic processes Lecture 13.1 - Climate-tectonic coupling I Lecturer: David Whipp [email protected] 1
Geodynamics www.helsinki.fi/yliopisto
Geodynamics
Climatic, geomorphic and geodynamic processes Lecture 13.1 - Climate-tectonic coupling I
Lecturer: David Whipp [email protected]
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Goals of this lecture
• Introduce the relationships between climate, erosion, topography and tectonics
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Plate tectonics builds topography
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http://www.lpi.usra.edu/
Tectonics
Topography
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Erosion shapes topography
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Houses
Erosion shapes topography
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Houses
Tectonics
Topography
Erosion
Erosion shapes topography
Topography influences climate
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Tibetan Plateau (NASA image)
Tibetan Plateau
Tarim Basin
Himalaya
Topography influences climate
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Tibetan Plateau (NASA image)
Tibetan Plateau
Tarim Basin
Himalaya
Why does topography affect climate?
Topography influences climate
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Tibetan Plateau (NASA image)
Tibetan Plateau
Tarim Basin
Himalaya
that represents a continuous rainfall-time series [Barros etal., 2000; Lang and Barros, 2002]. Thus, we utilize therelationship between field measurements and single-cellTRMM-derived rainfall amounts to scale our satellite-derived rainfall amounts (Figure 2). Interestingly, thissimple linear fit between TRMM-derived Indian summermonsoon rainfall intensities and absolute rain-gaugeamounts yields consistent results. This indicates that, de-spite non-continuous TRMM-rainfall time series, relativevalues represent a valid rainfall distribution. Consequently,we apply a constant scaling factor to the satellite data toderive an estimate of the absolute rainfall amount. Thisrelationship, however, holds true only when integrating oversatellite rainfall series at least one month long. We suggestthis represents a more valid calibration method than com-parisons of basin-wide TRMM-derived runoff with rivergauges, because a) discharge measurements are more inac-curate than rainfall measurements, b) discharge in theHimalaya is strongly influenced by snowmelt with un-known but likely significant temporal offsets from theprecipitation events, and c) very few continuous, reliabledischarge measurements are available that account for the
Figure 1. (a) Calibrated TRMM-based monsoon rainfall amounts averaged from January 1998 to December 2005. Thedata comprises instantaneous rainfall measurement with a spatial resolution of !5 " 5 km. Note the two pronouncedrainfall bands in the central Himalaya. (b) 5-km-radius relief calculated from topographic data merged from SRTM V2,DTED, and ASTER-DEM imagery with a spatial resolution of 90 m. Note the high-relief band !75–100 km from themountain front in the central Himalaya. White polygons indicate the location of 20 swath profiles, of which 4 examples areshown in Figure 3. A simplified N-S geologic profile depicts the major geologic units and faults separating them: MainFrontal Thrust (MFT), Main Boundary Thrust (MBT), Main Central Thrust (MCT).
Figure 2. Calibration curve for TRMM-rainfall datautilizing the half-hour rainfall measurement of the centralNepal (Marsyandi) gauge network for the years 2001–2004[Barros et al., 2000]. Each dot represents the cumulativeTRMM-measured rainfall intensity over 4 months (June toSeptember) for one grid cell (!5 " 5 km) vs. the (point-)gauge network measurement. Despite the large differencesin spatial and temporal resolution, the data sets agree well.We show only stations that are within 250 m elevation ofthe corresponding TRMM gridcell.
L08405 BOOKHAGEN AND BURBANK: HIMALYAN TOPOGRAPHY, RELIEF, AND RAINFALL L08405
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Bookhagen and Burbank, 2006
Tibetan Plateau
Himalaya
Topography influences climate
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Tibetan Plateau (NASA image)
Tibetan Plateau
Tarim Basin
Himalaya
Bookhagen and Burbank, 2006
Tibetan Plateau
Himalaya
Tectonics
Topography
Erosion
Climate
Let’s see what you’ve learned…
• If you’re watching this lecture in Moodle, you will now be automatically directed to the quiz!
• Reference(s):
Bookhagen, B., & Burbank, D. W. (2006). Topography, relief, and TRMM-derived rainfall variations along the Himalaya. Geophysical Research Letters, 33(8), L08405. doi:10.1029/2006GL026037
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