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Glaciology - Coggle Diagram

- - - - Woodward et al (1997) related annual refreezing R to annual mean air temp Ta
        R = -0.69Ta + 0.0096
        
        Radic and Hock (2011) used this to calc R for all glaciers globally from 2000-2100
  - - - Pritchard et al (2009) used this for GrIS and AIS 2003-7.
      - Measures height along orbital paths and changes between
      - Found GrIS glaciers thinned at mean 0.84m/yr
      - Found many AIS outlet glaciers thinning signif e.g. 9m/yr in Amundsen Sea sector
      - Elev change =x mass change
        
        Firn compaction impact on height
        
        Apply spatial density assumptions across ice sheet
        
        Vertical bedrock adjustment (from deglaciation, recent mass loss)
    - - McMillan et al 2016 on GRIS
        
        Firn water content and refreezing assessment after 2012 melt event
        
        Radar signal confused by changing density and roughness
    - - Zwally et al (2005) GrIS MB 1992-2002
      - 90% GrIS radar altimetry
      - 3% laser altimetry, at margins
      - 7% interpolation (kriging)
  - - - GCM-ISM coupled models
      - Ice sheet-atmos feedbacks
      - ISM finer res "dynamic downscaling"
      - Ground-truth flux across GL
        
        Van den Broecke et al (2016)
        
        MB 1958-2015 GrIS from GL fluxes using InSAR and feature tracking with RACMO. MB decr since 1990s
    - - GRACE (-FO, 2019)
        
        Dimensions of distance b/w. Low-res (hundreds kms) -> "spatial leakage". Monthly data
      - Velicogna et al (2009)
      - GrIS monthly MB 2002-9. Accelerated -30+-11Gt/yr
      - AIS same period. Accel mass loss by -26+-14Gt/yr
    - - 14 gravimetry, 9 altimetry, 3 I-O models
      - Mass change bias: G +biased (in EAIS), A +biased generally, I-O -biased
- - - - S-E GrIS is sweet spot with summer melting but lots of winter accum (so pore space). Above firn layers, this forms firn aquifers at 5-50m depth (Forster et al 2013)
      - Surface lakes
        
        upper ablation area (less steep)
        
        form in depressions over ice or dense firn
        
        overtopping drainage or hydrofracture
        
        Tracking change
        
        Sneed & Hamilton (2007) used ASTER satellite reflection data and theory of light attenuation in water to calc area and depth so lake vol.change/time. Assumes uniform albedo across lake bottom. Fails on debris-covered ice.
        
        Liang et al 2012 first automated process for tracking lake area over time. MODIS 1-2day freq imagery but 250m res. Hates clouds. Proved link b/w lake duration and melt intensity.
        
        Howat et al 2012 applied Liang's algorithm to Landsat, ASTER and SPOT (10m) imagery from 1972-2012. Found progressive incr elevation of lakes over period.
        
        Fast vs slow drainage?
        
        Selmes et al 2011, 2013. Fate of lakes. Higher elevs, tend to freeze over. Otherwise unknown. Different modes by year?
        
        Benedek and Willis (2017) proved GrIS lakes drain in winter. Sudden changes in backscatter of Sentinel-1 SAR, confirmed w/ optical imagery. West central GrIS, must scale up.
        
        Hydrofracture
        
        Tedesco et al 2013 on Lake Ponting, in slush zone. 6.5days to fill to 0.5km2, drained in just 2.5hrs. Pressure sensors show rapid uplift event -> rift formed acted as moulin
        
        Filling in first place? Banwell et al 2012 used runoff testing to reconstruct water routing, showing slow filling of Lake Ponting from two up-catchment lakes. Stepped drainage then overflow
        
        Leeson et al (2015) projected lakes and drainage pathways to 2060 under RCPs. Russell & Leveret glaciers GrIS. 48-53% incr in area lake coverage for RCP4.5, 8.5 respectively.
        
        Half of these lakes may be large enough to drain according to Arnold et al's 2013 water-volume-based fracture threshold
- - - - Depth and density -> calc SWE