Although a written assignment is not due until Thursday the 19th, we will start working on this in class on Thursday Oct. 12.
For this assignment we are going to look at some satellite images (including animations to show temporal changes), and we will compare them with observations from online weather maps or other sources (such as atmospheric soundings) in order to pinpoint what is going on in areas where cloud cover and precipitation are observed.
Sources of information are provided on the "links" page for chapter 7 on the online syllabus. You are asked to do three things:
1. First, pick a location in the U.S. or North America where precipitation activity seems to be occurring on a current weather map and/or satellite image and see if you can get current or recent weather data showing conditions associated with storm activity. There are multiple sources on the "links" page providing surface weather maps showing temperature, pressure, dewpoint, cumulative rainfall, cloud patterns, fronts, etc. etc. Your job is to look at the large-scale pattern (based on animated satellite loops), pick your location, and start analyzing local conditions. The satellite images of 3-hour rain accumulation (from the Naval Research Lab) can be animated and compared with satellite images of cloud cover. The UNISYS sites have some information that may be of use: maps showing dewpoint, moisture convergence, precipitable water, and lifted index. All of these sound like they have something to do with precipitation but we haven't explained them all in class. Try to figure out what these variables might tell you about local weather conditions (they all have explanations that tell you what to look for) and how they might relate to the occurrence of storm activity. You might also try the upper-air soundings page that we used early in the semester, as it contains information on profiles of dewpoint, temperature and relative humidity vs. height that may turn out to be useful to us. Looking at the vertical profile of dewpoint as compared to actual temperature, and at relative humidity, may tell you something about what is happening in a place where storm activity is occurring as compared with a place where calm weather and clear skies are present.
Using the information at your disposal, write an explanation of both the local variables and the regional conditions affecting the storm activity at your chosen location. Also, based on presence or absence of fronts and the nature of cloud motion and pattern of cloud growth, try to diagnose what kind of precipitation-generating phenomenon is dominant in the area you are looking at.
2. Now let's focus a bit more on global patterns, including tropical weather.
First, look at the following animation and try to interpret in terms of patterns we have discussed in class or that you have seen discussed in the textbook:
Animation of the monthly long-term mean pattern of precipitation
Next, using any of the sites in the "links" list for chapter 7, look up either surface maps or satellite images showing patterns of cloud development and cloud motion. Here are some additional examples that include both midlatitude and tropical weather patterns captured this time two years ago. (But don't rely only on this list; go back and look here for a lot more sites!)
Weather maps from the Weather Channel:
Animated
version, Tuesday Oct. 13 - Monday Oct. 19
Current
version
Satellite images from the Weather Channel:
U.S. enhanced infrared:
Animated
loop (large format), Oct. 17-19, 1998
current
version
UNISYS satellite infrared 12-hour loop from Wednesday, Oct. 11
Tropical Atlantic enhanced infrared (includes eastern N. America, tropics,
Atlantic):
October
17-19, 1998 (animated loop)
current
version
GOES Satellite loop, color IR enhanced, western hemisphere:
Saturday,
Oct. 17, 10:45 a.m. - 7:45 p.m.
current
version
Make sure you have looked at a couple of animations that include both midlatitude and tropical areas.Make careful observations of the details. In particular note the following:
3. This part will not be due as part of this assignment,
but some of the resources provided below are relevant to material in chapter
8 and we will be discussing some of this material later. I have left it
here for later reference, but by the time we get to Oct. 19 we will already
have covered at least the part on tropical weather in class.
a. As a supplement to the material in the textbook, read the
"frequently asked questions"
web site from Colorado State University about tropical cyclones. In
addition to some detailed discussion about the characteristics and behavior
of tropical cyclones and hurricanes, it includes a discussion of the prediction
techniques used by Prof. Bill Gray and his colleagues, including the link
with West African Sahel rainfall and the possible link with El Nino cycles.
You don't need to write anything based on this but I will assume you are
familiar with its contents. A more
detailed discussion of the forecasting methodology is also available.
This is not required; if you do read this, don't worry about the details,
but do note which factors appear to be linked to hurricane activity. This
is an evolving area of research.
Also take a look at the image of Hurricane Georges
striking the Dominican Republic and be prepared to discuss any of the visible
features that tell you something about the dynamics of the storm.
Images/Movies
of Hurricanes and Special Events
Hurricane
Georges approaching Gulf Coast - Sept. 28, 1998 (4.6 mb MPEG)
Hurricane
Georges striking Dominican Republic - good view of eye (September 22)
(excellent picture)
b. Material on El Nino/Southern Oscillation, otherwise known as ENSO. This is an extremely active area of research and there is a wealth of information available on the web. (Actually I need to update this list, which is already out of date!) I suggest you start by reading the first page in the following list. The others listed below it are optional.
El Nino
theme page from NOAA
make sure you look at the
pages on the most
recent El Nino/La Nina cycle and on impacts
of ENSO
NOAA/OGP El Nino-Southern Oscillation
Page
Climatic
Prediction Center El Nino/Southern Oscillation Main Page
Other El Nino sites
Once you have done the reading, take a look at some of the animations of El Nino and La Nina events available here. If you look at the comparison of 2 big El Nino events (1982-83 and 1997-98) you can also see the development of the current La Nina at the tail end of the recent El Nino.
For the written part of this section of the assignment, you are to take one aspect of ENSO - either some aspect of its dynamics, or of its impacts - and prepare a report based on materials you are able to access, which you should be prepared to discuss in class. The first site above has extensive links and there are so many choices that you should have no difficulty finding an interesting topic for your research. (You are welcome to consult library sources if you find references worth pursuing.) Since we will be talking about global climates and the Koppen classification scheme this week in class, it would be useful, as part of your discussion, to try to examine how the impacts or the dynamics you investigate may be linked to our understanding of the typical climatic pattern as revealed by the climograph of at least one climatic region. For example, if you look at the impacts of El Nino on some part of Australia, make sure that you make some reference to the regional climate classification of the area affected and the "typical" pattern of climate that would be expected, as well as the nature of the departure from "typical" conditions that resulted from the El Nino.
c. This is not a required part of the assignment, but we may work it in later on, depending on time availability. A series of web sites on global change and climatic warming are listed below, some of which are particularly useful (see the EPA global warming site, for example). If you find this utterly fascinating and want to concentrate in this next assignment on some aspect of global warming, rather than ENSO, let me know in class.
Global Change and Climatic Warming
