NOAA Teacher at Sea
Onboard NOAA Ship Ronald H. Brown
September 5 – October 6, 2001
Mission: Eastern Pacific Investigation of Climate Processes
Geographical Area: Eastern Pacific
Date: September 8, 2001
Latitude: 19º 57.1N
Longitude: 108º 21.4W
Seas: Sea wave height: 2-3 feet
Swell wave height: 3-4 feet
Visibility: 10-12 miles
Cloud cover: 4/8
Water Temp: 29.4ºC
Today I met with the radar scientists from Colorado State University (Ft. Collins, Colorado). These guys are meteorologists who are studying the internal structure of storms over tropical oceans. As radar scientists, they rely primarily on radar systems for obtaining data. They are using pretty sophisticated equipment and software for their research, and have been spending the last several days just getting everything set up.
Although all four members of this group – Dr. Rob Cifelli, Dr. Walt Peterson, Mr. Bob Bowie and Dr. Dennis Boccippio – are very nice guys with a great sense of humor, from my perspective, they are somewhat the villains on the ship. These guys are hoping we will encounter storms- lots of them- the bigger, the better. Have any of you seen the movie “The Perfect Storm?”
Here’s some background information that will help you understand the research this group is working on. Storms on land and storms on the ocean tend to be about the same size vertically, but the way they function internally is quite different. On land, storms can be generated over pretty short periods of time, and can run themselves out pretty quickly. A lot of people in the mid-west are familiar with the daily rain storms that hit during summer afternoons- suddenly coming out of nowhere, and then disappearing as fast as they arrived. This is because land is full of heat pockets. You could have rivers, farms, asphalt and concrete highways, homes, and forests, and they all heat and cool at different rates. The differences in the rate of heating cause pressure gradients, which can lead to volatile weather conditions.
The ocean does not contain heat pockets the way the land does, and therefore, the air above the ocean heats more slowly. Pressure gradients in the air above the ocean are not as steep, so when storms are generated over the ocean, they grow slowly over long periods of time, and can become quite large. Do you remember hearing in the news about hurricanes? The weathermen will track hurricanes for many days to see where it is moving and how large it is getting. This is an example of an ocean storm growing slowly to a very large size.
If we can understand how storms form and behave in a certain area, it will help us understand the climate in that area. If you want to learn about the climate of San Diego, California, for example, it’s not very hard. You can visit the library and find all sorts of documents about the climate and typical weather conditions. There have been weather stations in San Diego for at least a hundred years, and there is plenty of data that has been collected. There aren’t too many surprises.
But what do we really know about climate over the oceans? Not a whole lot. Storms heat the atmosphere and affect the climate. NASA and NASDA (the Japanese Space Agency) have a satellite called TRMM (Tropical Rainfall Measuring Mission) provides data about storms from very far away, but we don’t have oceans full of weather stations to show us exactly what’s going on at the surface and in the troposphere. Plus, TRMM can only measure what it sees from the sky- the tops of storms. You have to be on the ocean to see the rest of the storm. And since the satellite passes over each location on earth only twice a day, the data can be up to 12 hours old. When’s the last time you heard of a storm that hadn’t changed in 12 hours?
How do the atmosphere and the ocean interact? How are storms in the tropics different from storms in the mid-latitude regions? What impact does the tropical ocean water have on the air above it? What impact does it have on storms that form over it? That’s where this group from Colorado State University comes into the picture. The R/V RONALD H. BROWN is equipped with a Doppler Radar system that uses microwaves to echo off of condensed water, ice crystals, and hail. It can create 3D profiles of storms within 150 km of the ship. A satellite can only see the top of the storm, but the radar system on the ship can see the internal structure of it. And if we happen to be in the middle of a big storm, the radar can see everything going on around us for the duration of the storm (not just once every 12 hours, like the TRMM satellite). Unfortunately, hurricane Henrietta was too far away to effectively measure with the radar. These guys will also be launching weather balloons from the ship to gather additional atmospheric data in the sky above us.
What can the world hope to learn from the research being done by this group? Well, if we have a better understanding of how storms are behaving in the tropics, we will have a better understanding of the factors affecting ocean climate. Since events such as El Niño originate in the tropical area of the Pacific Ocean, this research may help us better understand what causes seasonal climate changes and El Niño and provide better forecasting of such events.
Travel Log: The air temperature is getting much warmer each day, and you can definitely tell we’re in the tropics. One of my students, Kalen, asked if I had seen any wildlife? Excellent question. I forgot to mention earlier that I saw a bunch of flying fish! They were really cool- almost looked like birds jumping out of the ocean, flying 10 or 20 feet, then diving back in. You could see them just about any time you looked for them during the last couple days. We also passed a huge school of at least a hundred porpoises, about a mile away. I’m hoping we’ll see some more a little closer so I can get some pictures for you.
Have you ever heard of sailors seeing a green flash at sunset? Captain Dreves announced last night that the conditions were good to see it, so I ran out on deck. After staring at the horizon a couple minutes I saw what looked like neon green flashes of lightening, only for a second. I waited and waited and finally the sun dipped below the horizon, but I’m not sure if I saw it. I’m not sure if what I saw was THE green flash, or if my eyes were getting strained from staring at the sunset too long. I told Captain Dreves “well, I guess I have 3 and a half more weeks to see it again” and he said “I was at sea 30 years before I saw my first one.” Oh, well.
Question of the day: What causes the green flash that sailors sometimes see at sunset?
Photo Descriptions: Today’s photos show some of the equipment that the group from the Colorado State University are using for their research. Dr. Rob Cifelli and Dr. Walt Peterson are working on the computer to establish the radar settings they will be using to collect data. Bob Bowie is standing at the radar station that controls the Doppler Radar unit on the ship. Dr. Dennis Boccippio inflates a weather balloon, which you see aloft in a separate picture. Finally, all four members of the CSU team pause for a picture.
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