CASE #3: Floating Away The Situation: While entering New York Harbor, several boxes of rubber ducks fell off their cargo ship. Using the data provided, direct the rescuers on where they should look first. What factors do you think influence ocean currents? Answers for Evidence A: Why are currents easier to predict in harbors than in the open ocean? Answers for Evidence B: Answers for Evidence C: Are ocean currents always the same?

Search & Rescue (SAR) When ships are in distress or people fall overboard, the United States Coast Guard gets the call. Using the best available information they have, like the last known location, they then spring in to Search & Rescue mode. Unfortunately, a lot of time can elapse from when an event happens to the time the Coast Guard gets called. Likewise, it is not easy for helicopters or ships to reach the rescue location. For these reasons, the Coast Guard has to be able to predict where a ship or a person might drift. In order to conduct a systematic search, the Coast Guard must figure out where the distressed person will most likely be. To do this they use a variety of datasets to predict the ocean currents and define a search area. More accurate predictions mean more lives saved and more money saved (by limiting the fuel and people time spent searching large areas). The SAR Mission Search and Rescue (SAR) is one of the Coast Guard's oldest missions. Minimizing the loss of life, injury, property damage or loss by rendering aid to persons in distress and property in the maritime environment has always been a Coast Guard priority. Coast Guard SAR response involves multi-mission stations, cutters, aircraft and boats linked by communications networks. The National SAR Plan divides the U.S. area of SAR responsibility into internationally recognized inland and maritime SAR regions. The Coast Guard is the Maritime SAR Coordinator. To meet this responsibility, the Coast Guard maintains SAR facilities on the East, West and Gulf coasts; in Alaska, Hawaii, Guam, and Puerto Rico, as well as on the Great Lakes and inland U.S. waterways. The Coast Guard is recognized worldwide as a leader in the field of search and rescue.

Datasets that are used in SAR HF Radar Surface Currents The CODAR (Coastal Ocean RADAR) system is a series of antennas (shown here) along the New Jersey Coast that measure the surface currents of the ocean using radio waves. Codar data is generally shown using maps of colored arrows. The size of the arrows represents the speed of the current, as does the color (red=fast, blue=slow), and the direction the arrow is pointing is the direction of the surface current. Navigating your course with surface currents obtained from CODAR is easy. Simply use the plots to gauge the velocity of the surface currents for the waters that you are in. The arrows on the plots show the direction of the current flow, and the size and color of the arrows both depict the speed of the currents. If you need a rough estimate of the magnitude of the speed, use the attached color bar to find the value. The flow of a particular parcel of water in the ocean is called a current. Tidal Observations Maritime activities throughout the world depend on accurate tidal and current information for safe operation. Tidal measuring systems measure the height of the water a specific points in coastal areas. They can collect information every 6 minutes and transmit their data back to NOAA using satellites. Knowing where you are in the tidal cycle is helpful in predicting currents in harbors. Rising tidal levels indicate times when water is flowing into the harbor while decreasing tide levels generally denote times when currents flow out of the harbor. A predicted path of a drifter (shown in black) using tide data (red) and surface current data (blue)

Tides in New York Harbor The chart below shows the tidal height at the Battery over the course of 2 days. The blue line is the predicted height based on astronomical models while the red height is the measured height at the Battery. 1.If the box of rubber ducks fell overboard near Governor's Island at Midnight on November 4th, should rescuers look north (upstream) or south (downstream) of the island? 2.What if the spill occurred at 4pm (16:00) on the 4th? 3.What would you tell rescuers if it took them longer than 2-3 hours to find the ducks? Evidence A

Currents along the New Jersey Coast HF Radars can also provide information on near-shore currents. The chart below depicts the along-shore current (that is parallel to the coast) from Loveladies, NJ. Positive values indicate times when the currents were heading to the north, while negative values depict times when the currents were towards the south. 1.If a box of ducks washed up on the Loveladies beach around midnight on November 3rd, from which direction (north or south) would it have come from? Evidence B

HF Radar Surface Currents The following map shows the surface currents off the coast of New Jersey. The arrow designates the direction of the current while the current speed is represented by color. Note: 10 cm/s is about the same speed as 5.4 miles per day. 1.If the box of ducks fell overboard at 40°15” North 73°45” West what direction will it head? 2.If the box of ducks fell overboard at 39°15” North 74°0” West what direction will it head? 3.How far would this box travel in one day? 4.If the box fell over 1° East of the location in #2, how much farther would it have traveled in one day? Evidence C

HF Radar Surface Currents (take 2) Evidence D The following map shows the surface currents off the coast of New Jersey. The arrow designates the direction of the current while the current speed is represented by color. Note: 10 cm/s is about the same speed as 5.4 miles per day. 1.Would you change any of your answers to “Evidence C” based on the following map taken several days later?