Port Aransas South Jetty

ISLAND OBSERVER

TONY AMOS The University of Texas Marine Science Institute received a 25-year Honored Institution Award from the National Weather Service at the recent meeting of UTMSI’s Marine Advisory Council.

The award recognizes our maintenance of a Cooperative Weather Observer station at UTMSI since July 1985. The Weather Service provides a temperature sensor and recorder and a rain gauge for our station (No. 7170), one of 11,000 throughout the U.S., and we submit daily high and low air temperature and rainfall data to a central database. Some families have provided data to the NWS for 100 years, with four or five generations continuing on the work. Most stations check the results for each day at some reasonable hour of the day, say 5 or 6 p.m. When we got the station, I had been collecting data aboard research ships at sea for years. For ships at sea to the nearest minute, the day begins at 12 a.m. and ends at 11:59 p.m., or to put it in less confusing military time, the day starts at 0000 hours and ends at 2359 hours. (Maybe that’s just as confusing!)

Height and heat PHOTO AND ILLUSTRATION BY TONY AMOS At left, a Cooper’s hawk perches on a rooftop in the East Street neighborhood of Port Aransas on a recent day. At right, a chart explores just how hot it’s been in town since 1986. So I thought that we should record the data for the day here in Port Aransas at midnight rather than a more convenient 5 p.m. After all, a calendar day stretches from midnight to midnight, and on some occasions, either the high or the low for the day occurs at midnight. So, for about 10 years, I marked the chart at midnight but eventually elicited the help of UTMSI security personnel, who work at midnight anyway. I am particularly indebted to Jim Moreno, who does the lion’s share of midnight data gathering.

Class, turn your attention to the Weather Watch in this issue of the South Jetty! Most of this data comes from the co-op weather station No. 7170. I wrote a program to produce this weekly table, to store the overall data and also to search for record highs and lows and rainfalls as the daily numbers are entered. Record highs and lows are shown for each day as well as the year they occurred. Symbols show when new records occur. Times of sunrise and sunset are calculated for Port Aransas and listed from the coming newspaper week of Thursday through Wednesday. (Note how at this time of year, the sun rises perceptibly earlier and sets later each day with the day lengthening by nearly 10 minutes per week now). The sea water temperature comes from measurements I make in the surf off Mustang Island Gulf beach on alternate days about an hour after daybreak, when the sea temperature is about at its low for the day and before it gets warmed by direct solar heating, hence it’s listed as SEA TEMP (LOW). Sometimes, I cannot do the measurement, so unless there are three measurements for the week, I do not calculate the mean.

Now we have a 26-year offi cial record for Port Aransas weather. It will be continued when I quit overseeing it, and I hope that in 2085, there will be a 100-year record for people to peruse.

What have we learned already? It’s getting warmer and wetter, with big swings in between. One illustration of the trend is shown in the chart. I had marveled when I first looked at the data that there were far fewer days each year when the temperature reached 90 degrees or more, especially when compared to Corpus Christi’s record. From 1994 to around 2000, there was a sharp rise, followed by a much lesser increase with time to the present with two extraordinarily warm years, 1998 and 2005. To predict trends is a tricky business. A simple straight-line prediction (the purple in the chart with this column) would predict that by 2132, every day of the year would be 90 degrees or more, obviously nonsense. What is called a polynomial prediction (black) would be more reasonable, reaching a plateau. There are many other ways of looking at the data, some of which can be found on UTMSI’s Web site at http://nearshore.utmsi. utexas.edu/yearly.htm. Food for thought: There have been only two days in 26 years here when the temperature reached 100 degrees or more, Sept. 5, 2000 (101.4) and Sept. 3, 2011 (100.0).

In case you’re bored with all these numbers and charts, two interesting birds recently showed up in my back yard: A green-tailed towhee and a Cooper’s hawk that was not one released by the Animal Rehabilitation Keep (ARK).

Tony Amos is a research fellow at UTMSI and director of the ARK.