We have defined climate in terms of some statistical properties of long-term weather observations. The purpose of this assignment is to examine some local long-term air temperature records to see how you interpret these records, and if your interpretation changes depending on how you present the data. This will give you practice at summarizing and interpreting large volumes of data.
You are provided two data
at the class web site; click on the station name to get data)
air temperatures for the two stations summarized below (year
Jan-Dec. mean monthly air temperatures all in degrees C):
|Station||Period||Latitude||Longitude||Elevation (m asl)|
|Denver WB City 52225||1872-1972||39 deg 45' N||105 deg 00' W||1591|
|Boulder 50848||1931-1997||40 deg 01'N||105 deg 16' W||1646|
1. The air temperature at a given location often displays a distinct seasonal pattern. To investigate the seasonality of the air temperatures at Denver and Boulder, at each location calculate the mean, standard deviation, minimum, and maximum, for each month for the entire length of records (ignore missing values as indicated by NaN). Construct two tables, (one for Denver and one for Boulder) to show your values. Marks: 10 total, 5 per table.
a) For both stations, plot the mean monthly temperatures and the standard deviation (plot the mean, the mean plus one standard deviation, and the mean minus one standard deviation). Your graph must have a title and have the axes appropriately labeled. Make two separate graphs, one for each station. Marks: 10 total, 5 per graph.
b) With the aid of your graphs, describe the seasonality in the air temperatures (e.g. when is the air temperature most variable?), any differences you observe between the two stations, and anything you think could affect the quality of these measurements. Marks: 5 total.
a)To investigate any long-term trends in the annual air temperature patterns at each station, calculate the mean annual air temperature for both stations (if a month or more of data are missing, you may simply exclude the entire year). Rather than show all your values, what was the mean temperature during 1940-1970 period (inclusive) at both stations (again, just ignore any missing data)? Do get this number, simply calculate the mean annual air temperature for all the years between 1940-1970 (you will get one number for each station). Marks: 5 total, 2.5 for each.
b) Plot the mean annual temperature for all years between 1872-1972 (Denver) and 1931-1997 (Boulder) against year for both stations (make two separate graphs). Connect all the points with a line. Don't use bars please. Appropriately label the axes and give each graph a title. Marks: 10 total, 5 per graph.
c) Describe and try to explain any trends you observe. How do any trends at the two stations compare? If you plot (no need to show) both annual means on the same graph to create on longer-term "regional" picture (both stations are close together), does your interpretation of the "regional" trend change? Marks: 5 total.
a) On separate graphs, plot the mean annual air temperature anomaly against year for both stations using a bar graph. To do this, simply subtract the 1940-1970 mean temperature you calculated in 3a from the mean annual temperature for each year (do this for both stations). To aid interpretation of possible trends, also plot the five-year running mean with a line. Marks: 10 total, 5 per graph.
b) Describe and explain any trends you observe. Does looking at theses new graphs (as compared to those you make in 3a) change your description and explanation of any trends you observe? Marks: 5 total.
Due: February 23
Total Possible Marks: 50
So what has this got to do with the Earth's climate? The Earth's climate it ultimately driven entirely by SF. The objective of this assignment is therefore to quantify how sensitive SF is to fluctuations in changes in photosphere's radiative surface temperature.
1. Plot the Planck (blackbody) curve for the Sun at its current temperature of 5800 K. Use wavelengths between 0.01 and 3.00 um, in increments of at least 0.01 um. Add to this graph Planck curves for the Sun at temperatures 15% and 30% above and below 5800 K. Your final graph will have a total of five plots. As before, your graph must be properly annotated. Marks: 20 total, 3 per plot, 5 for annotation and neatness.
2. Calculate the wavelength of maximum emission for the Sun at each of the five temperatures (the peaks of your five plots). What's happening to the wavelength of maximum emission as the temperature changes? Marks: 10 total, 5 for each maximum wavelength, 5 for description/explanation.
3. Calculate the total energy emitted from the Sun at each of the five temperatures (the area under each plot). What's happening to the energy emitted by the Sun as the temperature changes? Marks: 10 total, 5 for each total energy, 5 for description/explanation.
4. How does SF vary with the Sun's surface
To make this calculation:
a. The solar luminosity (in Watts) = E (from question 3) x area of the Sun (4 "pi" r 2 where r = 6.96 x 108m)
b. SF = solar luminosity / (4 "pi" r 2) where r is the mean Earth-Sun distance of 1.50 x 1011 m
Make a graph (Sun's surface temperature on the x axis, SF on the y axis) to help with your description and explanation. In terms of Earth's climate, should we be worried about a change in SF, or are changes insignificant? Marks: 10 total, 5 for graph, 5 for explanation.
Due: March 8
Total Possible Marks: 55
Use these data for this assignment. The columns of data are the following measured variables:
1. Time: day of year (211 = July 30) before
After decimal is the hour divided by 24 (e.g. noon July 30 =
2. Incident solar radiation (W m-2)
3. Reflected solar radiation (W m-2)
4. Net radiation (W m-2)
5. Latent heat flux (W m-2)
6. Sensible heat flux (W m-2)
7. Air temperature (deg. C)
8. Surface temperature (deg. C)
9. Relative humidity (%)
10. Vapor pressure (kPa)
11. Horizontal wind speed (m s-1)
1. Make a graph of the incident and reflected solar radiation against time. Next, make a new graph of the surface albedo against time. Comment on the nighttime albedo (why is it so crazy? It is reasonable to have negative values?) Describe how and why the albedo of this surface changes with time during the day. Give the albedo around noon for each of the three days. Describe how and why the noontime albedo varies with cloud cover for the three days. Marks: 10 for graphs, 10 for written.
2. Calculate the emitted long-wave radiation from the surface using the measured surface temperature and the Stefan-Boltzmann Law (use emissivity = 0.97). Next, calculate the incident long-wave radiation (emitted from the sky downwards to the surface) as a residual of the radiation balance. Plot the incident short- and long-wave radiation as a function of time (one graph with two lines). Describe and explain any patterns you observe in the incident long-wave, using the incident short-wave to help you. Marks: 10 for graph, 5 for written.
3. Make a graph of the latent heat flux and sensible heat flux
time (one graph with two lines). Which variable(s) do the two
to be responding to and why? Make use of the additional data
to answer this question; make 1:1 graphs of each flux
other variables to help you answer the question. Also, reading
papers cited below will help (both available at the CU Library
site). Marks: 5 for graph, 10 for written.
Blanken, P.D., Rouse, W.R., Culf,
Boudreau, L.D., Jasper, J.N., Kochtubajda B., Schertzer, W.M.,
P., & Verseghy, D. (2000) Eddy covariance measurements of
evaporation from Great Slave Lake, Northwest Territories,
Research, 36 (4), 1069-107.
P.D., Black, T.A., Yang, P.C., Neumann, H.H.,
Nesic, Z., Staebler, R. & den Hartog, G. (2001) The seasonal
and water exchange above and within a boreal aspen forest. Journal
Hydrology, 245 (1-4), 118-136.
4. Using your answers to the questions above, describe the surface (bare soil, short vegetation, forest, wetland, lake, ocean, urban?) that these measurements were taken from and why you think so. Marks: 5.
Due: April 12
Total Possible Marks: 32
The linkage between the global water cycle and climate is evaporation and precipitation. The Earth's surface experiences changes in its vegetation types and coverage due to both natural and anthropogenic disturbances. Therefore is this assignment, you will investigate what changes would occur in the globally averaged precipitation on the land surface and globally averaged runoff from the land to the sea, given a 20% decrease in evaporation from the land surface due to, for example, deforestation or desertification. The illustration of the hydrologic cycle below will help in your answers.
PL = rate of precipitation on the land
PS = rate of precipitation on the sea
R = rate of runoff from the land to the sea
ELL = rate of evapotranspiration from the land that falls as precipitation on the land
ELS = rate of evapotranspiration from the land that falls as precipitation on the sea
ESS = rate of evaporation from the sea that falls as precipitation on the sea
ESL = rate of evaporation from the sea that falls as precipitation on the land
1. Give your immediate rough guess to the answer. Justify your rough estimate stating why you feel it's right or wrong. Marks: 5.
2.Given the illustration above, we can now refine and restate our problem as "How will R and PL change if ELL and ELS both decrease by 20%?" To get us started on the answer, first give three water conservation equations, as water must be conserved in this problem (water inputs = water outputs). With the aid of the illustration above, write the simple equations for the water conservation: 1) in the sea (vertical exchange), 2) on the land (vertical exchange), and 3) rate of water flow from the land to sea equals the rate from the sea to land (horizontal exchange). Write a brief explanation describing each equation. Marks: 6 (2 per equation).
3. Using your three equations above, and given the additional facts: PL = 108 x 103 km3/y, PS = 410 x 103 km3/y, R = 46 x 103 km3/y, and ELL = 3ELS, determine the values in km3/y for ELL, ELS, ESS and ESL. Marks: 8 (2 per value).
4. Now let's decrease evapotranspiration over the land by 20%, while keeping evaporation over the sea the same (as per the original question). Expressing the new rates (after the 20% increase) as primes ('), we can write:
R' = ESL' - ELS'Give the values of R' and PL' using the information given above, and realizing that R + ELS = ESL and PL = ELL + ESL. (Hint: Manipulate the equation to get rid of the unknown prime values, replacing them with your known values). Marks: 8 (4 per value).
PL' = ELL' + ESL'
5. Now let's answer the question as originally stated at the beginning of the assignment. By how much will the total global precipitation rate change? Compare this answer to the rough estimate you give in question 1. (Hints: PGLOBAL = PS + PL, PS + R = ESS + ESL). Marks: 5.
Due: April 26
Total Possible Marks: 30 (20 for content; 5 for references; 5 for style, grammar...)
Write a brief essay on any climatologically-related topic that
you. The minimum length is five single-sided,
must included a minimum of five references (excluding web
references). I strongly suggest you use journal database
engines such as the Web of Science (available to all CU
your research. Your essay must have an introduction, main body,
or conclusions, and references cited. You may summarize the
state of knowledge of
aspect of climatology, or you may prefer to, for example,
pros and cons of global climate change (for example). If you are
if your topic is acceptable, ask the Instructor for approval.
you are clear on how to properly reference (cite) sources to
plagiarisms before you submit this assignment. All essays are
to submission to Turnitin.com to check for plagiarism.