by Andy S. ’22
Last year, Allistair Yu ’20 laid the foundation for my work with the Lakeside Summer Research Institute this summer. In the summer of 2018, sixteen small, inexpensive temperature sensors known as “iButtons” were deployed at various elevations on Mount Baker. Of these sensors, one was exposed to direct sunlight, and the rest were either placed in the shade or buried a few centimeters below the surface. Three more were installed on the Lakeside campus on the old softball field next to Allen-Gates Hall. Allistair developed a program to work with the Lakeside campus sensors in preparation for the ones on Mount Baker, and he demonstrated that temperature differences of sunlight and shade can be used to indirectly estimate the cloudiness, replicating an established technique previously used in the Cascades.
Beginning my research, I felt optimistic and eager to apply his work to Mount Baker, an ecosystem where global warming occurs at an accelerated pace. Understanding more about the mountain’s climate will provide insight on the relationship between warming and glacial melt. There was just one issue though: the one sensor that was exposed to sunlight ran out of battery while deployed in the field. All the data was lost. As an alternative, I repurposed a nearby buried sensor to give me the temperature data I needed. Instead of calculating the sun-shade temperature difference, I sought to determine if buried-shade was a viable alternative. I began with the Lakeside sensors — in short, success! It turns out that the buried-shade temperature difference (see Figure 1) has a strong correlation with solar radiation, which is known to be closely related to cloudiness. The solar radiation data was sourced from a weather station at the University of Washington.
Success did not last for very long. After running the data from the Mount Baker sensors through my adapted program, I got completely opposite results (see Figures 2 and 3). This suggests that the underbrush and moist soil temperatures on Mount Baker perhaps insulated the buried sensors to keep them cooler than the ones in shade, which was not a problem at Lakeside given that the sensor was buried under barren, exposed soil. Despite my progress, there is further work to be done to uncover the poorly known climate of Mount Baker, an alpine environment that can give us early signs of climate change.
Figure 1: Correlation between temperature difference (Tburied - Tshade) at noon and daily solar radiation at noon. Solar radiation is known to be very closely related to cloudiness.
Figure 2: Raw temperature data recorded by two Mount Baker sensors, one in shade and the other buried. The recording period begins in August 2018 and ends one year later. The large gap in the data is due to the buried sensor being unusable for this purpose when there is snow cover.
Figure 3: Distribution of buried-shade temperature differences. Most daytime differences are negative, indicating that the buried sensor remained almost always cooler than the one in shade.