You all are putting out some great - and very valid - hypotheses (what a funny word . . . ).  Ask anyone from a casual beach goer to a professional oceanographer and they will tell you that ocean currents are hard to predict.  Obviously the ocean is a big place and there is a lot going on out there, and everything - from sunlight to water temperature to wind - plays a factor on ocean circulation, or the movement of ocean currents.

Now, before I mentioned there was "a lot going on" in the ocean, and there certainly are a large number of factors that affect ocean circulation.  But it all starts some 93 million miles away . . . with the sun.  Because the earth is round and is tilted on its axis, sunlight does not strike all parts of the earth equally,  especially over the course of a year. Solar radiation - the heat provided by the sun - is fairly constant throughout the year at the equator, but it varies greatly over the course of a year as you move away from the equator. We know this effect as "seasons" and it is more pronounced the closer you get to the poles. Living in Hawaii we aren't as aware of this fact, but people who live further from the equator and closer to the poles are VERY familiar with seasons, as anyone who has been to Minnesota, Canada, or South Africa in Winter time can tell you. The half of the year when a hemisphere receives the most sunlight is broken into Spring and Summer,  while Fall and Winter are the portions of the year when those regions have tilted away from the sun and receive less light.  When comparing the Northern and Southern Hemispheres, you will see they are exactly opposite each other in terms of season: June, July, and August are summer months in the Northern Hemisphere but winter months in the Southern Hemisphere. 

So, how does this affect the ocean? Basically, the ocean waters at the equator are warmer than those at the poles. This is due to more sunlight reaching the equator year round than at the poles. Water holds onto heat very well, and it also moves from areas of "warm" to areas of "cold."  So the difference in temperature of polar water and equatorial water actually fuels the ocean currents, putting the warm water in motion.  As these large masses of water move across the Earth's surface, the rotation of the Earth beneath them causes them to spin.  This is known as the Coriolis Effect, and this is why ocean circulation in the Northern Hempishper is clockwise, and in the Southern Hemisphere it is counter-clockwise. Things get more complicated when landmasses, trade winds, and seasons come into play, but we can make some generalizations and some predictions about where the Niu might go.

 The overall "net" direction of currents at Hawaii's lattitude in the North Pacific is towards the west. If you look down on the ocean from space (if you can't make it to space, try a globe!), the surface currents in the North Pacific circulate clockwise (counter-clockwise in the Southern Hemisphere due to the Coriolis Effect, as we learned). So if you think of the Pacific Ocean in the Northern Hemisphere like a clock face, with the North Pole at approximately "12 o'clock", California at the "3 o'clock" position, the equator midway between the USA and China as the "6 o'clock" position, and China and Japan at the "9 o'clock" position, you can sort of see how we might expect the Niu to follow the currents in a clockwise direction, from Hawaii (somewhere between "3 o'clock" and "6 o'clock") towards Japan. Does this mean the Niu will arrive in Japan? No. Of course it might, in 4-6 months time, but it might get caught in an eddy and return to Hawaii, or be diverted by surface wind, or... ?   This is the exciting part, where you can make your own hypothesis and predictions!

 Here are some things to think about:  Do you think the time of year we launch Niu will have an effect? What about the local weather? Temperature? Even the year we launch it? Keep on forming hypotheses about where you think the Niu will go, because your guess is as good as mine!!

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written by Amy Rapoport , May 09, 2008

Looking forward to watching Niu's jorney.

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