1. Climatological-scale science from sparse data Michael Steele & Wendy Ermold Polar Science Center / Applied Physics Laboratory / University of Washington, Seattle WA USA Kara Sea # of profiles

2. Michael Steele Polar Science Center / APL University of Washington http://psc.apl.washington.edu September sea ice cover 1979 2003 N. Pole N. America RussiaRussia RussiaRussia Example: A study of Arctic Ocean surface warming over the past 100 years How much ocean warming?

3. WOD’05 data distribution, colored by: Temperature (ºC) YearsTemperature Earliest Year 50  N – 90  N 0-10 m July, Aug, Sept

4. Temperature (ºC)Temperature Data Handling details: 1. ACQUIRE THE DATA The data were downloaded off the web as “wrapped” ascii files: World Ocean Database, 2005 http://www.nodc.noaa.gov/OC5/WOD05/pr_wod05.html 2. REFORMATING Data were reformatted into the following ascii columns: Profile_ID# latitude longitude depth temperature salinity month year

5. Instrument Counts for some Arctic shelves Drifting Buoy Data mechanical bathythermograph data ocean station data: bottle, low res CTD eXpendable bathythermograph data

6. Raw data histograms Temporal Bias

7. SPATIAL BIAS Mean SST = 2.2 CMean SST = 1.9 C Example: East Siberian + eastern Laptev Seas Temperature (ºC) Raw Data 50km bin averaged dense WARM profiles sparse COLD profiles

8. Fake trends cold warmer hot Year 1 Year 2 Year 3 datadata Steady state ocean + spatially biased sampling  fake warming trend!

9. The solution: Multiple Regression T = a + b  x + c  y + d  PHC(x,y) + e  year spatial field Anomalies are defined relative to the mean spatial field over a given time period. …no “intra-year” predictor ^

10. Long-term N/AO trends Are these trends reflected in the SST data?

11. °C per decade (a)SST : 1930-1965 (b) SST : 1965-1995 (c) SST : 1930-1995 (d) OHC : 1965-1995 MJ/m 2 per decade -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 -100 -80 -60 -40 -20 0 20 40 60 80 100 SST trend OHC trend No M.R. here : just smoothed, 300 km binned trends

12. (a) Beaufort-E (b) Beaufort-W (c) Bering (d) ESS+Laptev (e) Kara (f) Barents SST anomalies using M.R. Ice thickness (m)