Morningside Atgmospheric Particulates Data

General Problem: Measuring atmospheric particulate levels and relating them to weather.

Tip 3: ALL DATA CONTAINS NOISE!

You probably have noticed that when you leave the window of your room open for several days that a lot of black particles accumulate on your floor and window sill. Constantly there is a flux of particles raining down from the atmosphere. Some of these particles are washed out of the atmosphere by precipitation (wet deposition), some are deposited simply by gravitational settling in the atmosphere (dry deposition). Your task in this experiment is to determine the dry deposition flux in New York City using the provided Scotch tape.

Things To Do:

Session 1: Collecting the data

  1. Familarize yourself with Atmospheric Particulates
  2. Peel off one (only one!) layer of the provided tape and put it on something flat and heavy with the sticky side pointing upward as demonstrated in class. Put it somewhere outside where you think you will get a representative particle flux. Collect particles for about 24 hours. Then take the scotch tape and fix it (sticky side down) on the provided Sampling Sheet, so that the 5 squares are covered. We intentionally do not want to give you a detailed list of instructions. We want you to spend some time thinking for yourself how to best conduct the experiment.
  3. The instructor will assign you a time during which you should collect the samples.
  4. Think carefully about where to collect your data!
  5. Which parameters may have an influence on the experiment? Please take notes of all the circumstances during the experiment.
  6. Count the number of particles in each of the 5 squares of your sample with the provided magnifying lens and write down the results on a separate sheet. label the individual counts as XY1...XY5 (XY stands for your initials, two letters only!). Repeat counting particles of the 5 squares without looking at your previous results and write down the results, labeling them XY6...XY10. Bring the Samp0ling sheet and your counts to the next class.

Session 2: Data Analysis

  1. Enter your own data into a single column of a spreadsheet, with the first set of 5 counts in the first five rows, the second set in the next five rows.
  2. Determine the mean, standard error of the mean, median and standard deviation of the first 5 counts, the second 5 counts and of all 10 counts. Is there a difference between the two sets of counts? What could be the cause?
  3. Write you 10-count mean and standard error of the mean in the proper time slot in the table your instructor has provided on the classroom blackboard. When the table is complete, you will use it to examine the time variability of particulates.
  4. Make a histogram of the 10 counts of your sample and mark mean, standard error of the mean, median and standard deviation on it.
  5. Take the histogram from above and overlay the normal adistribution (Excel function: NORMDIST). Use the bar/line combination plot for this. Are your data normal distributed?
  6. Swap your sampling sheet with another student. Count the 5 squares of this other sheet twice. Calculate again mean, standard error of the mean, median, and standard deviation. Compare your results to the other student's.
  7. Enter the data from the blackboard into a spreadsheet, and save it for the next session.

Session 3: Interpretation and Summarization

  1. Examine the particulate time series that you saved from the last session. Plot both the mean measurement and the standard error of the mean (as error bars). Is there a statistically significant variation of atmospheric particulates over the course of the experiment?
  2. It you find a trend, do you have an explanation? Look at the weather data and air trajectories for the particular days from the COLA/IGES current weather conditions maps.
  3. What conclusions can we draw regarding the particle deposition rates in NYC?
  4. Use the remaining class time to work on your lab reports.

In the lab report discuss the question what you could learn about the dry deposition flux of particulate matter in NYC from the experiments that were done by you and other students on "your" day. In your lab report discuss: