C3S_312a Lot8: Glaciers Frank Paul, Michael Zemp Dept. of Geography, University of Zurich

Glaciers around the world

GLACIER DISTRIBUTION & INVENTORY

Main purpose of glacier monitoring The key questions How much glacier ice is out there? How (fast) do glaciers change? Glacier extent and distribution from satellite: semi-automated mapping one point in time, decadal repeat Ice thickness distribution field-based: interpolated points / models only once for bedrock topography Digital Elevation Model (DEM) orthorectifcation of satellite images drainage divides, topogr. parameters Changes in glacier extent area from satellite: decadal repeat length in the field: annual repeat Changes in thickness / volume field-based: stakes & pits (indiv. gl.) RS: DEM differencing (entire regions) RS: altimetry (along repeat tracks) Spatial inter- & extrapolation to entire glaciers (DEM), density (field) to entire regions (voids, hypsometry, upscaling, representativeness) What do we need?

Current situat ion for area & elev. change C3S Lot8 (glaciers) has a focus on area & elevation change should be a complimentary & useful service based on existing approaches lots of work is going on by other scientists, so how to add on this? largely different approaches used for monitoring area / elev. change Glacier area (GLIMS database) based on classification of (optical) satellite data and digitized maps region and approach is driven by research projects, not coordinated results are not submitted to GLIMS/RGI after publication as scientists leave or national incentives prevent sharing (Greenland, Chile) quality is sometimes not sufficient (debris, snow, water), in particular RGI Elevation change (WGMS database) field data (direct glaciological method) are regularly requested & compiled efforts are globally coordinated, standards exist, regular publication by WGMS geodetic methods (volume change) from two DEMs (rare) are increasingly applied but results are not forwarded (dh/dt grids or glacier specific changes) computational methods (voids, cell size) proposed, but not standardized

Data processing glacier outlines TM3 TM5 Ratio => Challenges (Patagonia) manual work! Mask Outlines

The main bot tleneck: Debris cover => Coherence => Sentinel 2 Landsat data: USGS Paul et al. (2015)

Measuring mass balance in the field Hot steam drilling for ablation stakes Excavating a snow pit Density measurement Extra- polated values Observational Network on Vernagtferner

Elevat ion changes from DEM dif ferencing Alaska Canada Karakoram Larsen et al. (2007) Alps Paul and Haeberli (2008) Gardelle et al. (2013) Berthier et al. (2010) => geodetic mass balance

The three pillars of our C3S approach Data production within C3S based on established methods and community needs (RGI coordination) focus on new regions and multi-temporal outlines, reprocessing wait for TanDEM-X DEM and new datasets (Arctic DEM, Greenland DEM) Improve and enrich existing datasets (GLIMS/RGI/WGMS) RGI has partly severe quality issues (snow), meta-data not consistent GLIMS database has missing attributes (topography, length, thickness) WGMS MB data difficult to extrapolate to regional scale (representative?) use of RS to extend time series (mb @ Abramov, delta l since LIA) Communication and data acquisition Reach out to scientists (conferences) & ask for their data after publication Analyse publications and try to get them, standardization? Use WGMS call for data and GLIMS executive board mailing lists

The glacier distribut ion & change service STEP 1

The glacier distribut ion & change service STEP 2 STEP 1 STEP 3

Step 1: Adaptors to integrate exist ing databases WGMS database GLIMS database RGI

Step 2:Community outreach &improvements Required corrections in the RGI 1985 2000 2011

Step 3:Integrat ion of both data streams

Work Breakdown Structure

TIMELINE Test Phase First update Second update Continuous Data Production in WP4 from M5 to M22

THE TEAM

Where everything is based on GCOS107 Requirements from Tender

The three main steps in detail