Mapping the Mid-Atlantic Cold Pool Evolution and Variability with Ocean Gliders and Numerical Models W. Brown, W. Boicourt, C. Flagg, A. Gangopadhyay, O. Schofield, S. Glenn, and J. Kohut Cold Pool Context MAB Glider Measurements Cold Pool Glider Measurements MTS OCEANS’12 Presentation 17 October 2012

The Mid Atlantic Bight (MAB) COLD POOL Ou & Houghton 1982 NOAA/NMFS 1979 Survey Bottom Temperatures Remnant Winter Water Isolated by spring stratification Fed by Cold Water from upshelf

The COLD POOL is extensive & elusive …. is always evolving in TIME-SPACE ….from cradle to grave Eroded by cross-shelf exchanges Advected by downshelf flow Destroyed by autumn storms

Modeling suggests & Observations show an INFLOW Total temperature transport of water with T< 10 o C - Cold Pool water - (in 10 5 m 3 - o C) normal to the 1979 Nantucket Shoals Flux Experiment (NSFE) mooring array. Positive is toward the MAB. (adapted from Ramp et al., 1988)

2010 MODEL SIMULATIONS “…illustrate the idea, …but have a ways to go”

The Conceptual Bottom-Trapped MAB COLD POOL

How Do We Define and Forecast COLD POOL? …with the power of MARACOOS! Mid Atlantic Regional Association Coastal Ocean Observing System

Opportunistic “slices of the COLD POOL”..with gliders MARACOOS Glider Trajectory Composite present repeat cross-shelf red /orange/yel zig-zag along-shelf cyan zig-zag inner-shelf dark blue (Schofield et al., 2010). Gliders operations -virtually independent of weather …..can be maintained at sea essentially indefinitely

Glider Cost Effectiveness Ocean Gliders - a robust tool for monitoring coastal ocean dynamics in the Middle Atlantic region - Endurance transect time series glider surveys covering over 18,000 kilometers of the NJ shelf in 826 days. Cost estimate basis: a full-time dedicated glider technician for glider prep and monitoring coastal vessels for glider deployment and recovery expenses for batteries-Iridium-insurance-nominal maintenance-repair $6 per vertical profile $47 per kilometer traversed Cost ~ 1/4 to 1/10 of a typical coastal ocean boat/ship survey.

OCEAN GLIDERs can measure the COLD POOL …. hidden from a satellite’s eye 2-8 August 2011 southeast of NJ

Composite Seasonal Picture 11 Sep-14 Oct 2008  2008 Cold Pool loses distinctiveness NE CP Temp ~ 9.5 o C 23 May-13 Jun 2007  2007 Cold Pool established NE CP Temp ~ 5.0 o C 14 Apr-09 May2011  2011 Cold Pool established off NJ NE ww Temp ~ 4.9 o C 19 Mar-12 Apr 2010  2010 winter waters NE ww Temp ~ 4.5 o C

Eastern MAB Warmest Year in many! 2012 Glider Temperature Transects south of Massachusetts and Rhode Island April June May April 2011 T ~ 5.0 o C T ~ 4.9 o C T ~ 8.5 o C T ~ 7.5 o C Historical Temperature Transects

A Plan for Sustained Measurements with Data Assimilation Modeling

Summary MAB COLD POOL a challenging observational/modeling objective Ocean Gliders are a cost-effective observational technology for measuring the Cold Pool Data-assmilation modeling: … an essential integrator of information (inc. glider) … Cold Pool forecasting tool