Lab-5-Oakland-Upper-Air-Soundings-2023

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Feb 20, 2024

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EPS/Chem 182, Spring 2023 Last revised, 3/21/23 1 Lab 5: Field Trip and Data Analysis for Oakland Upper Air Radiosonde Launches _________________________________________________________ Part 1: Field Trip Write-up [Spring 2020, 2021, and 2023: Part 1 is eliminated.] Describe in approximately 2 to 3 written pages both a brief overview and some specific details about the instrumentation and launch and data retrieval procedures for the weather balloon launches at the Oakland Airport site you observed. Describe this in a way that another upper division student at your equivalent level of technical expertise would appreciate. To do so, you will need to bring your notebook to the launch, ask questions, take notes on various details and equipment information, and then do some research on the web with information gleaned during the trip. Also include a description of how the data are used and by whom. Part 2: Predicting where a radiosonde may land ( start prior to your field trip 5 April 2023 or, if the “astra” planner is online again, up to 6 days after that) Where do radiosondes land? All over the place, from farm land in the Central Valley to the remote Sierras and maybe others, given the wind speeds and directions from the surface all the way into the stratosphere as the balloon ascends. Use one of the following websites to predict where the balloons we observe will land. [For the Astra site, which is currently offline, the simulated trajectories can be run from two weeks before to one week ahead of the current date – that’s how long they keep previous weather conditions or future forecasts used in the simulation. For the alternate site below, you can only predict for the current day or for up to 6 days ahead]. [Note that the location may change as the weather predictions change.] ASTRA High Altitude Balloon Flight Planner: http://astra-planner.soton.ac.uk/ Use the following parameters (for a typical LMS-6 Lockheed Martin Sippican radiosonde launch at OAK = Oakland International Airport and other simulation choices): FLIGHT INFO: Helium, parachute = TA200, Totex parachute = 0.94 m; payload weight (0.4 kg = 235 g radiosonde plus associated line, train regulator, and parachute); Nozzle lift = 1.5 kg (amount of helium in the balloon minus the weight of the balloon); Train equivalent sphere = 0.2. LAUNCH SITE: Select on a map or input coordinates where the Oakland Upper Air Launch Site is (see maps in lecture slides). WEATHER DATA: use online forecasts, standard resolution SIMULATION SETTINGS: use the default Input the above then select “RUN THE SIMULATION.”

EPS/Chem 182, Spring 2023 Last revised, 3/21/23 2 An alternate trajectory calculator: https://www.stratoflights.com/en/tutorial/weather-balloon-tools/predicting-the-flight-path/ [Note that the time you input should be Universal Time; our launches at OAK are typically at 23:00 on the date of the launch (even though you will look up the data on the web to do your analysis for Part 3 below as “00Z” on the next calendar date).] Part 3: Radiosonde Data Analysis Of the launch we ( expected to have ) observed, and one for which you can do a trajectory prediction above in Part 2 : 2023-03-16-00Z (4 pm PDT launch 3/15/23 California time) 2023-04-06-00Z (4 pm PDT launch 4/05/23 California time) compare the temperature profiles from each launch. How similar are they? How different? [If we find that the new autonomous launcher has more failures than we’re accustomed to from human launchers, then choose another flight nearby in date that successfully returns data far into the stratosphere.] In some semesters, there have been large differences in the profiles for the different launches observed; in others, the differences between profiles are more subtle and may not be evident until you've compared them to the US standard atmosphere, as you will do below). For the following data analysis, choose the two flights above flight you observed plus another that was characteristically different from the two listed above. 3.1 Variation of Temperature and Relative Humidity with Altitude * Go to the following website and find the text data for the selected flights as follows: http://weather.uwyo.edu/upperair/sounding.html First, select "region=north america", "type of plot=text:list", "year=2023", "month=mar", and then, for example, "from=16/00Z" and "to=16/00Z" if you want to retrieve the sounding data for March 16 th (i.e., the one with local launch date = March 15 th ). Next, click on "OAK" on the map (alternatively you can specify OAK as site # 72493). A separate window with a table of the data should pop up. * Copy the data to the clipboard and import into a data analysis and plotting program such as Excel or Matlab. For Excel, after placing the column headers and data in your clipboard, you can then go to "edit" and "paste special"; select "text" and then "OK." You should then see a clipboard icon pop up, so click on the arrow on the icon and select "use text import wizard." From here, select "delimited" then "next." Then be sure that the "space" and "treat consecutive delimiters as one" boxes are marked and then click "next." Next, click "finish." There are many other ways to do this in Excel (including

EPS/Chem 182, Spring 2023 Last revised, 3/21/23 3 making a text file with the data on your pc and then importing this under "Data", etc.). This should be NOT be a difficult step, but I've found each Excel program may have different defaults, so if you are having trouble, e-mail an instructor. * Plot altitude on the y-axis and temperature and relative humidity on the x-axis (The given units work out such that these 2 variables can easily be plotted using the x-axis without having to specify separate axes if desired). Make 2 separate plots for the 2 different flights, then answer or do the following : a . Comment on the general trends in temperature and relative humidity as a function of altitude for the two flights and their likely causes. b. If there are large fluctuations in relative humidity in either of the flights, what might be the reason? c . Use the US Standard Atmosphere 1976 temperature profile data for midlatitudes from the excel file on bCourses and include these data on each of the 2 plots for the 2 flights. These data represent an annually-averaged "typical" temperature profile for midlatitudes. Compare and contrast the US Standard Atmosphere Profile with the actual profiles. Speculate (as a "non-meteorologist") on what might cause differences between the profiles we observed and a "typical" one. d . Determine the altitude of the WMO-defined tropopause (given below) for each of the two flights you are analyzing (Note: there might be more than one tropopause for a given flight!) and mark it on your plots. It will be helpful for you to plot up the definitions given below along with the flight data in order to compare slopes (i.e., the lapse rates, − dT/dz). WMO Tropopause Definition From A Temperature Lapse Rate Definition of the Tropopause Based on Ozone , J. M. Roe and W. H. Jasperson, 1981. In the following discussion the lapse rate is defined as − dT/dz. The main features of the WMO tropopause definition are as follows: • The first tropopause (i.e., the conventional tropopause) is defined as the lowest level at which the lapse rate decreases to 2 K/km or less, and the average lapse rate from this level to any level within the next higher 2 km does not exceed 2 K/km. • If above the first tropopause the average lapse rate between any level and all higher levels within 1 km exceed 3 K/km, then a second tropopause is defined by the same criterion as under the statement above. This tropopause may be either within or above the 1 km layer. • A level otherwise satisfying the definition of tropopause, but occurring at an altitude below that of the 500 mbar level will not be designated a tropopause unless it is the only level satisfying the definition and the average lapse rate fails to exceed 3 K/km over at least 1 km in any higher layer.

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