Twin Otter and windy conditions return to McMurdo

A tired Twin Otter crew returned to McMurdo on Monday night. While weather conditions prevented them from sampling at AGO4, they still made it to the TAMS site and collected lots of data between Pole and McMurdo. Actually, the weather was quite nice at AGO4, winds were only 5 kts, but because AGO4 is about 12,000 ft, our Twin Otter (weighted down by all the scientific instruments) is too heavy to take off from AGO4 without some stronger headwinds to help us out. That and the fact that there really isn't much of a runway, so the drifts over the old runway make it difficult to get up to the required speed. Luckily, the guys were thinking a head and collected snow cores from Seismic Center, TAMSEIS Camp, and AGO4 on the way to the pole. Tuesday was a rest day for the pilots and gave us a chance to work on the instruments. I was lucky that the spectroradiometer calibrations had not changed very much over the 3 long days of sampling and we have beautiful weather for calibrations on Tuesday. For Wednesday we planned two flights. A short 1.5 hour flight to investigate the NO levels near the NCAR OH inlet. We are still trying to figure out why the OH instrument sometimes has problems when we are flying at higher altitudes. Since the winds were not cooperating (i.e, conditions not favorable to measure outflow from the glaciers) we decided to try and sample the Mt. Erebus plume in the afternoon. So we all went out early on Wednesday morning and got instruments warmed up and ready to go. Unfortunately, the winds started to pick up and 30 minutes before takeoff the airport was shut down as it became Condition 2 visibility. By the time we got back from Willy Field to McMurdo we had condition 1 visibility. We kept hanging around the Crary Lab hoping for the winds to die down, but no luck. I went over to the McMurdo machine shop to get a core extractor fabricated. We are really lucky to have such top notch facilities here in town. These guys are really good at what the do and it makes it so much easier to do our science. For tomorrow, we have rescheduled a morning OH test flight, and as forecast has changed we are hoping to have an afternoon flight to Midpoint Charlie up on the plateau. This is part 2 of a "day/night" sampling strategy. As Sun is up 24 hours a day, this is really a "higher Sun vs. lower Sun" comparison. All the instruments are going to be sampling on the way to Midpoint C and then they will land there and Doug will get a long sampling tube and sample NO coming out of the snow. While this is going on, Ed and Sae Wung will collect a bunch of snow cores. Forecast says that conditions should be better in the morning. We will keep our fingers crossed.