1. NOAA Satellite Snow Cover Extent Climate Data Record at the Half Century Mark
David A. Robinson
Rutgers, The State University of New Jersey
Piscataway, NJ
WMO Global Cryosphere Watch: Snow Watch Team – 2nd Session
Columbus, Ohio | June 13, 2016
Research supported by
Global Science and Technology, Inc.
at NOAA NCEI

2. NOAA Visible Weekly SCE Climate Data Record
Weekly charts
Digitization
Daily IMS
Nov 1966
Oct 1972
May 1975
1990s May 1999
ESSA, NOAA, GOES Series
Weekly 190 km
Digitized
METEOSAT
& GMS added
Reanalysis of
Feb
1997
2004
IMS 24 km
IMS 4 km
Interactive Multisensor Snow & Ice Mapping System
Dec
2014
IMS 1 km

3. NW Arizona

4. Quebec/Labrador

5. 10 March 2015
Mauna Kea,
Hawaii
22 February 2015

6. NOAA Visible Weekly SCE Climate Data Record
Specifications
Binary (snow / no snow) over NH land surface
88 × 88 Cartesian grid on polar stereographic projection
190.6 km resolution at 60°N
Weekly temporal resolution
October 4, 1966–present
Inputs to CDR
October 1966–May 1999: primarily visible satellite imagery from multiple instruments
After May 1999: Interactive Multisensor Snow and Ice Mapping System (IMS)
SCE derived from multiple sources by trained analysts
NH SCE CDR simplified processing flow diagram

7. Interactive Multisensor Snow and Ice Mapping System (IMS)
1 km, 4 km & 24 km Northern Hemisphere Analysis
Snow & Ice Cover
Produced daily at U.S. National Ice Center
Pre-Processing
Indirect Sources
Analyst Derived Output
Satellites
GOES (E & W)
MeteoSat (MSG & 7)
MTSAT
NOAA Automated Snow & Ice
AVHRR (Channels 1 & 3)
MODIS (Channel 8)
ASCAT
AMSU (Derived snow, ice, rain)
Other Sources
Radar
Models
Surface Observations
Webcams
Buoys
Charts

8. Northern Hemisphere Continental Snow Cover 10 January 2012
Extent
Departure
(blue: positive; red: negative)

9. Northern Hemisphere Continental Snow Cover January 2012
Extent
Departure
(blue: positive; tan: negative)

10. Swings from most to least extensive SCEs occurring within months
Departures
Feb 2010
May 2010
3rd most extensive
1st least extensive

11. NH Snow Cover Extent:
Departures derived from mean, plotted on 7th month

12. NH Spring (MAM) SCE Departures
2016 is lowest on record at mil. sq. km (-2.65 anomaly), mean is 29.79
2nd and 3rd lowest are 1968 (27.34) and 1990 (27.43) respectively
Departures derived from mean

13. May NH Snow Extent Anomalies: 1967-2016
4th lowest May on record
May 2016 Departure from Mean

14. NOAA SCE compared with station observations
fractional coverage of snow
North America: Compare one degree cells from 53°W – 168°W longitude and 20°N – 71°N, not including
any coastline and with at least 5 stations.
Extent adjustment to “reach” IMS era: +5.23% , +2.75% (NOAA maps underreporting
in the pre-IMS era)

15. Time to start generating an IMS CDR:
17 years of operational IMS output and growing
Operational since November 1998
24 km resolution at 60°N
Daily temporal resolution
Bring IMS SCE output up to CDR standards

16. Mean IMS SCE January Percent of days snow covered
Total 526 days, lowest value 1 day (0.19%)

17. Mean IMS SCE April Percent of days snow covered
Total 508 days, lowest value 1 day (0.197%)

18. Mean IMS SCE May Percent of days snow covered
Total 526 days, lowest value 1 day (0.19%)

19. Mean IMS SCE
Percent of days
snow covered
April
May

20. Mean IMS SCE
Percent of days
snow covered
January
April

21. Mean IMS SCE
Percent of days
snow covered
January
May

22. 2006
2008
2010
2012
Columbia Basin SCE
April 1
Source:
4 km IMS daily

23. Columbia Basin: IMS SCE vs. Discharge
April-July streamflow volume in the Yakima basin as a function of percent snow cover for each month [right], including only the 5 key 24 km grid points in the basin [above].
We determined that by looking at certain regions within a subbasin that experience more variability in snow cover than others, that a SCE – discharge signal emerged. These were mainly grid points at moderate elevations where greater variability in snow extent is seen within a season and more notably, inter-annually. Five such 24 km cells were identified (out of 33) in the Yakima basin.
By looking at certain regions within a subbasin that experience more variability in snow cover than others, a SCE – discharge signal emerged.
These were mainly grid points at moderate elevations where greater variability in SCE is seen within a season and more notably, inter-annually.

24. Columbia Basin: IMS SCE vs. SNOTEL SWE
Green Lake SNOTEL station within the Yakima basin.
SWE (blue line) (inches) at the SNOTEL station and the days when the 4 km cell was mapped as snow covered in the IMS product (grey vertical bars) from
Within the Yakima subbasin a preliminary study examined whether there was a relationship between SCE depicted within IMS 4 km grid cells and the snow water equivalent (SWE) measured at SNOTEL stations within the cells. The graph [above right] shows a strong relationship between SWE and IMS melt out. In other cases, at more heavily forested sites the IMS depicted melt out prior to the loss of SNOTEL SWE.
The graph shows a strong relationship between SWE and IMS melt out.
In other cases, at more heavily forested sites the IMS depicted melt out prior to the loss of SNOTEL SWE.

25. Issues warranting consideration
Local, regional, hemispheric:
Timing of season
Length of season
Average and extreme depth
Average and extreme snow water equivalent
Associated impacts
physical
societal

26. Pursuing answers Ongoing/improved monitoring in situ satellite
integrated
Change detection/attribution investigations
Ongoing assessments of snow cover within the system
data and model driven
Cooperation with social scientists

27. Thanks Dave Robinson david.robinson@rutgers.edu snowcover.org
Somerset, NJ, 21 March 2015
NASA/GSFC/Suomi NPP
White Marble – 26 May 2012