ESA GlobSnow - project overview GCW 1 st Implementation meeting Geneve, 23 Nov. 2011 K. Luojus & J. Pulliainen (FMI) + R. Solberg (NR) Finnish Meteorological Institute 1.12.2011 1
ESA GlobSnow ESA-GlobSnow project: Production of novel hemispherical snow extent (SE) and snow water equivalent (SWE) climate data records. Generation of long time-series employing FMI supercomputing facilities at Helsinki (daily, weekly and monthly maps of SE and SWE for northern hemisphere) Near-real-time GlobSnow processing system and data archives located in Sodankylä. Consortium members: Finnish Meteorological Institute (FMI) with ENVEO IT GmbH (Austria), GAMMA Remote Sensing (Switzerland), Norwegian Computing Center, Finnish Environment Institute (SYKE), and Environment Canada (EC). Details and products available at www.globsnow.info Finnish Meteorological Institute 1.12.2011 2
30 year-long CDR time-series on snow conditions of Northern Hemisphere (ESA-GlobSnow SWE) First time reliable daily spatial information on SWE (snow cover): - Snow Water Equivalent (SWE) - Snow Extent and melt (+grain size) - 25 km resolution (EASE-grid) - Time-series for 1979-2011 Passive microwave radiometer data combined with ground-based synoptic snow observations - Variational data-assimilation Available at open data archive (www.globsnow.info) Demonstration of NRT processing started on October 2010 Greenland, glaciers & mountains masked out
SWE algorithm selection & validation SWE estimates from 5 algorithms evaluated for Eurasia (1994-1997) FMI Assimilation algorithm (Pulliainen 2006) EC SWE suite (Goodison, Walker, Goita, Derksen et al. 1993-2009) Chang et al. 1987 (original channel difference algorithm) SPD-algorithm (Asbacher 1989) Armstrong and Brodzik 2001-algorithm (Improved channel difference) SWE algorithm evaluation for 09/1994 and 12/1997 (SSM/I data) Evaluations for North America and Finland were carried out in addition to the analyses for Eurasia Finnish Meteorological Institute 1.12.2011 4
Validation data INTAS SSCONE data INTAS SSCONE data (from the former USSR and Russia) There are 1294 snow path stations with data from the USSR Manual (0.5 2km) transects measuring snow depth There were 450 path stations with data for 1994-1997 Finnish Meteorological Institute 1.12.2011 5
Overall performance for SWE algorithms Eurasia 09/1994 12/1997 Reference data: independent snow transects Name RMSE bias Corr.coeff Unbiased RMSE Samples FMI algorithm used for GlobSnow) 43.2 mm -3.1 mm 0.611 43.1 mm 26063 EC algorithm 67.6 mm -28.2 mm 0.210 61.5 mm 18109 Chang et al. 1987 (asc node) Chang et al. 1987 (desc node) 71.6 mm 70.7 mm -8.4 mm 1.6 mm 0.011 0.029 71.1 mm 70.8 mm 26726 27521 SPD algorithm (asc node) SPD algorithm (desc node) 67.1 mm 63.9 mm -12.7 mm -3.1 mm 0.052 0.121 65.9 mm 63.9 mm 29559 29451 Armstrong et al. 2001 (asc node) Armstrong et al. 2001 (desc node) 72.3 mm 73.7 mm -44.1 mm -42.9 mm 0.044 0.029 57.3 mm 59.9 mm 21796 24791 Finnish Meteorological Institute 1.12.2011 6
SWE retrieval (data assimilation vs. channel diff.) Density scatterplot (assimilated vs. satellite only SWE) Ground truth data is INTAS SCCONE SWE transect data
Consistency of SWE retrieval 1980-2009 RMS error and retrieval bias calculated independently for each year 1980-2009 Reference data: snow transects from Russia (INTAS-SCCONE) SMMR F 8 SSM/I F 11 SSM/I F 13 SSM/I F 17 SSM/I SMMR F 8 SSM/I F 11 SSM/I F 13 SSM/I F 17 SSM/I SWE<150 mm
GlobSnow SE Dataset SE retrieval using ERS-2 ATSR-2 and Envisat AATSR data - Finnish Environment Institute s SCAmod algorithm. - Norwegian Linear Reflectance (NLR) fractional snow cover (FSC) algorithm; - 15 years SE data record has been produced using optical imagery from ATSR-2 (1995-) and AATSR (2002-) on a hemispherical scale. yellow clouds green bare ground white snow cover Finnish Meteorological Institute 1.12.2011 9
Daily, weekly and monthly products Optical data ~ 1km spatial resolution 310 March April 2003 2010 119 March April 2003 2010 March April 2003 2010 Finnish Meteorological Institute 1.12.2011 10
Examples of monthly products, 2010
Examples of monthly products, 2010 April 2003 May 2003 June 2003
Example: Trend analysis using SWE product Apr 4 2011
Snow clearance date Example for year 2008 Time series of 30 years processed and distributed along the SWE product Apr 4 2011
Frost tube measurements in Finland Operated by Finnish environmental institute Default configuration: Three frost tubes in three different locations: Open area, Forest and Bog site. Manually recorder three times per month (usually 6 th, 16 th and 26 th ). During freezing and thawing 5 times. Almost 40 manually recorded frost tube stations. In Sodankylä, automatic temperature profile measurements installed next to frost tubes for comparison.
Frost tube locations Typically three tubes in three main land classes: forest, bog, open Forest Bog Open
Two winter time-series: ELBARA-II and frost/snow Inc. angle: 50 Snow Snow Frost Frost
Hemispherical trend of snow extent (PMW ~25km) Finnish Meteorological Institute 1.12.2011 19
Hemispherical trend of snow mass Finnish Meteorological Institute 1.12.2011 20
GlobSnow - Summary Production of novel global snow extent (SE) and snow water equivalent (SWE) climate data records (15 and 30 years of snow cover information) - coarse resolution (25km) SWE and SE for 1979 2011 - medium resolution (1km) SE for 1995 2011 Additionally, near-real-time GlobSnow processing demonstration is ongoing with open data access (started on October 2010) Additional information and all GlobSnow products available at www.globsnow.info Finnish Meteorological Institute 1.12.2011 21
Any Questions? (GlobSnow-handouts available ) Finnish Meteorological Institute 1.12.2011 22