Station P042

Questions for Kristine Larson

How did you become a scientist/engineer?

I had originally planned to become an engineer, not a scientist. This was mostly because that is what everyone else in the family did (my father, brother, and sister). There were two big turning points for me. The first was learning about geophysics from my thermodynamics professor (Jim Rice) at Harvard. That ultimately led me to a graduate program in geophysics at UCSD, where I was planning to study seismology. When I arrived at UCSD in 1985 there was no financial support for me to do that, so I ended up working on GPS for my dissertation. I can't think of a better start to my career, so I am big believer in having an open mind about trying new things.

What is your job like?

I have a pretty varied work week. During the academic year I teach aerospace engineering classes. I also need to raise money to pay the salaries for my students, colleagues, computer system managers, etc. So I spend a fair bit of time writing proposals. This year I have been doing a lot of travel. I have been giving seminars for EarthScope at various universities to showcase the work we have been doing with GPS to measure snow depth, etc. In the summer I do research with my students and colleagues.

What are you hoping to learn from your research?

I am a newcomer to climate studies and water cycle research. I have no expectation of becoming an expert in those fields, but I do need to learn enough to make useful water cycle products from GPS data. My goal is to see GPS water cycle products used by climate scientists around the world.

2012 Drought in the Western United States

The P042 GPS site was installed to support measurements of plate boundary deformation. However, it is also providing useful information about the environment. The PBO H₂O group has developed methods to use reflected GPS signals to determine vegetation growth. Figure 1 shows the vegetation growth cycle over the last six years. In 2007 and 2009-2011, vegetation growth generally peaked in June. In 2012 we saw no growth at all. As with most of the western United States that year, temperatures at Wheatland were much higher than average and there was very little precipitation (Figure 2).

Figure 3 shows a close up of an interesting feature from this site. In 2008 there is a "double peak" in vegetation growth. If you look more closely at the precipitation data, there was a little rain in April and May, but not in June. The vegetation began to die. Then there was more rain in August. The vegetation responded by a second growth spurt.

P042 is also being used a soil moisture sensor (Figure 4). These data are used by climate scientists.

Spotlight Questions