1. WMO GCW Advisory Group Meeting “Snow Watch” group of Products task team Update on activities Kari Luojus (FMI, Finland) Ross Brown (Ouranos, Canada) Barry Goodison, Jeff Key, Chris Derksen (EC) 23-24 January 2014 – WMO GCW Advisory Group Meeting IMO, Reykjavik, Iceland

2. Contents 1) A brief background of Snow Watch (Toronto GCW meeting) 2) Snow intercomparison project ESA SnowPEX 3) Development of Hemispheric snow ”anomaly” trackers for SE & SWE 4) An inventory of snow datasets 5) Additional items - Memberships for the different actions? - Budget & upcoming meetings?

3. Brief background of GCW Snow Watch The Snow Watch project was initiated as an invited expert workshop at EC premises, Toronto, January 2013, with goals to: 1. determine the current state of snow data, products and information, particularly concerning satellite products (and relevant ground data) 2. identify any critical issues that need to be addressed (in regard to item 1) 3. make recommendations on the initial content and structure of the “project” (“Snow Watch group” within “Products task team”) The team chose to focus on a single piece of the overall puzzle - a single parameter to keep activities manageable (for a limited team without much funding) and still get moving forward “quickly” Tackling all the parameters & issues …? (more time & budget is needed)

4. 1st Snow Watch meeting, Toronto, Jan. 2013 First workshop on implementing a Snow Watch component of GCW hosted by Environment Canada at Toronto, Canada from January 28-30, 2013. Twenty-eight scientists from nine countries (Austria, Canada, Finland, Italy, France, Norway, Switzerland, United Kingdom and USA) participated Aim: to determine the current state of global snow monitoring to identify critical issues affecting the ability to provide authoritative information on the current state of snow cover to initiate “GCW Snow Watch sub-projects” to address priority areas Approach: Questionnaire, discussions at the meeting & hooking up key actors for the identified priority areas

5. 1st Snow Watch meeting, Toronto, Jan. 2013 The initial actions of the Snow Watch group, defined at the 1 st meeting were: initiate a satellite snow products evaluation/intercomparison activity initiate a principal investigator self-assessment for snow products initiate a global snow data rescue activity develop hemispheric “snow anomaly trackers" for SE and SWE develop inventory of existing snow datasets initiate activity to standardize snow-related nomenclature improve NRT snow depth obs on GTS (zero value reporting, missing regions) …

6. Snow intercomparison project – ESA SnowPEX Toronto Snow Watch meeting agreed that comprehensive evaluation/ intercomparison of snow cover products was a high priority (one of the highest identified tasks from questionnaire) for GCW given the increase in the number of products in recent years and the need to provide uncertainty estimates for assimilation of data into operational snow analysis schemes ESA offered to initiate a “Satellite Snow Products intercomparison and evaluation EXercise – SnowPEX” project to be carried out by a team of international experts beginning in 2014 (2 year project) Relevant for CryoNet as independent and integrated CryoNet sites could serve as important independent data sources for such intercomparisons of not only snow but also other cryosphere components

7. Snow intercomparison project – ESA SnowPEX The project will intercompare and evaluate current global/ hemispheric satellite snow products for assessing their quality and for better quantifying the uncertainty of long term trends of the seasonal snow pack deduced from satellite data. Parameters: snow extent (SE) and snow water equivalent (SWE) Lead: ESA T.O: B. Bojkov (ESA/ESRIN), PI: T. Nagler (Enveo, Austria) Team: C. Derksen (EC), R. Brown (Ouranos), K. Luojus (FMI), S. Metsämäki (SYKE), R. Fernandes (CCRS) 2 International workshops to be arranged (summer 2014 Canada/USA & summer 2015 Europe Innsbruck?)

8. Snow intercomparison project – ESA SnowPEX Compilation of generally available reference datasets suitable for algorithm and product evaluation (for SE & SWE) Assess & gather the reference data High to very high resolution optical data (Landsat, SPOT, …) Distributed data: snow courses/snow transects Different spatial scales Different temporal scales (climate & trend analyses) Goal: provide the reference data (where possible) to the whole snow community – for self-assessment & development purposes

9. Snow intercomparison project – ESA SnowPEX Example: various SE datasets for 2011

10. PI-led self assessment for snow products An initiative for a PI self-assessment of snow cover products was proposed (in parallel to ESA SnowPEX) to provide quick feedback on the strengths and weakness of current snow cover products to the user community. This may help avoid situations where products with known weaknesses contribute to misleading conclusions Lead: R. Fernandes (CCRS); Team: D. Hall (NASA) & K. Luojus (FMI)

11. Development of Hemispheric snow ”anomaly” trackers for SE & SWE The Snow Watch Group stimulated the development of new daily “trackers” for Northern Hemisphere snow extent (SE) and snow water equivalent (SWE). Snow trackers have been developed for GCW by the Finnish Meteorological Institute and Environment Canada. The FMI SWE tracker used SWE algorithms developed by GlobSnow, was initially developed shortly after the meeting. These products are available in near real-time on the GCW and Globsnow websites. Satellite, in-situ and operational NWP analyses contribute to the development of these snow products. These products are relevant to CryoNet, since in-situ snow depth data are used in the algorithm to generate SWE. Hence standards, guidelines and exchange of data in real-time for snow depth measurements are very important for development and validation of products. Team: K. Luojus, R. Brown, C. Derksen, D. Robinson, S. Wunderle

12. CMC - SE CMC - SWE FMI - SWE These 3 trackers are currently on-line. Daily graphs distrivuted via GCW-website

13. An inventory of snow datasets The development of a baseline inventory of snow-related datasets was considered an important priority for GCW A draft inventory is being prepared for discussion at a GCW- related meeting in conjunction with this year’s Eastern Snow Conference (ESC), to be organized in Boone, North Carolina, USA 3-5 June 2014 Team: R. Brown (Ouranos) & Julie Friddell (U. Waterloo)

14. Initiate activity to standardize snow-related nomenclature, and promote standards and best practices as a contribution to CryoNet Standardization of observing practices and snow-related nomenclature was considered a high priority activity in the questionnaire particularly for snowfall and solid precipitation where practices vary widely between countries. Jeff Key has led the compilation of standards and best practices for cryospheric measurements for GCW, including snow measurements. GCW is drawing on existing measurement methods where possible and where a scientific consensus has been or can be reached. An initial inventory of existing documents describing measurement practices is given on the GCW website, under CryoNet A glossary has also being initiated for GCW by Jeff Key and currently has over 2000 entries from several sources Action is a contribution to CryoNet development and will also contribute to the work of the Infrastructure and Practices Team.

15. Additional items Identify/confirm interested experts for the different actions? Upcoming meetings – 2 alternative approaches: Low budget: “smaller” side meetings combined with conferences & workshops (ESC, IGARSS, SnowPEX, …) WMO funded: a dedicated snow watch meeting… 2-3 day meeting in 2014? Hosted by? …Budget?