Matthew Weston Lab Partners: Sam Jacobs, Mackenzie Hoult 09/06/18-09/07/18 Land Use/Cover Change 1
Over the past 80 years our community in Portland Oregon has changed dramatically. Through urbanization and expanding neighborhoods the city has grown. Specifically our community on Palatine Hill has grown as well. Our lab was designed to inspect land use in the Lewis and Clark College community. Looking into how overall land cover has changed within the parameters of Lewis & Clark College and the surrounding neighborhood and natural areas in the last eighty years allowed us to inspect the effects cover change has had on temperature and humidity. Using aerial photography dating back to 1939, we were able to compare the current land cover to today's taken by satellite. To put this into perspective we used Google’s Earth Engine that provided a timelapse of urbanization around the world.These historical aerials helped us decide on applicable areas to study, presenting a wide range of possible readouts from high population zones on campus, relatively populated zones in Collins View, and less populated zones in Riverview Natural Area. Our group was sent to the neighborhood of Collins View. According to the historical aerial photography from 1939, this area used to be a mixture of larger residential properties as well as possible commercial land use. Our exact property sat on the border of an expanding neighborhood with very few houses around but large agricultural area surrounding the land to the South. The yard has been slightly landscaped and hedges were grown on the borders of the property. Through the Google Earth Engine, we found that the area was moderately populated in the mid 1980’s and 1990’s, but a large expansion of the now suburban neighborhood began in the 2000’s, and the area has now become tightly packed residential properties. In order to receive the most accurate data possible our group used Garmin GPS device (as well as double checking the coordinates on google), which is able to mark coordinates for the testing location. Additionally my group used the compass feature which allows us to set up our measuring device at precisely North to be as unaffected by the daily sunlight. The measuring device we used was a Kestrel Drop. This device is used to take readouts of multiple data points in the atmosphere. The device is also set to refresh the readouts every 5 seconds. Through the Kestrel Link, we were able to measure accurate data on temperature and humidity in 10 minute intervals during our testing period of 5pm September 6th to 5pm September 7th. Additionally, averages were assessed concerning average temperature and average humidity during that period to increase accuracy. After the 24 hour period had passed, we returned to the site to analyze the data. According to the Kestrel Drop, this particular property at the coordinates (45.45665, -122.67726) had an average temperature of 19.8 degrees Celsius throughout the 24 hour period. The Kestrel Drop recorded a maximum temperature of 29.8 and a minimum temperature of 12.3.
Time Temperature (degrees Celsius) Average 5:00pm 9/6/18 - 5:00pm 9/7/18 19.8 3:30 pm September 7th 29.8 6:50-7:00 am September 7th 12.3
Based on this table, it appears that the height of the temperature coincides with the period just after the sun is highest in the sky, while the lowest temperature occurs directly before sunrise warms the day. The temperature follows a clear curve of sunlight, as the property itself was relatively open, allowing sunlight to enter relatively unfiltered by minimal trees and building in the yard inside of the bushes on the border. The average relative humidity of the property was 56.9%, with a maximum humidity of 86.8% and a minimum of 22.2%.
Time Relative Humidity (%) Average 5:00pm 9/6/18 - 5:00pm 9/7/18 56.9 6:10 am September 7th 86.8 3:40 pm September 7th 22.2
Based on this table, there is an obvious juxtaposition between the correlation of temperature and humidity. At the maximum humidity for the day, the temperature corresponds to the minimum temperature. This is also true the other way,, the minimum humidity aligns with the maximum temperature on September 7th. Our group did not find this too surprising, as the physical observations of the property and weather on September 7th was of a dry and sunny day. The cloud cover that we assumed to change humidity readouts did not appear until the night of the 6th to 7th, so little moisture was present until then. After clearing up during the day the humidity can then be seen dropping throughout the 7th. To properly assess the larger implications of cover change in the Lewis & Clark College area, it will be useful to crosscheck the Riverview Natural Area as well as the Lewis and Clark Campus. From an aerial perspective, Riverview still remains relatively unchanged compared to Collins View. A comparison between temperature/humidity within the same testing period would provide possible explanations to the effects of urbanization had on the area. Overall, the data taken within our testing period represents a valuable insight into the climate of suburban Pacific Northwest properties, as Collins View’s expansion over time is typical of many suburban communities throughout the region.