July 3, 2009

Look at what I did. I shrunk the Figures. Why did it take a whole day to get it right?

CRAP! Now how do I get the pictures in my blog????



3.3.1.2 Analysis of Temperature and Pressure Variation at the Launch Site

The document of the U.S. Standard Atmosphere Model of 1962 was not available for review. To determine the variability of temperature and pressure data for this mission, the team decided to collect NOAA data from the National Weather Service site at Ft Worth, Texas [12]. This location is the closest the site of the mission launch at Palestine, Texas. Since the launch will occur during the last week in July 2009, sounding balloon data was collected during the last week in July from 2005 through 2008.

Composite graphs of temperature and pressure vs. altitude constructed from the data are shown in Figures 2 and 3. The figures show variability in both temperature and pressure. A regression analysis was done on the composite data to examine the curve fit and the variation in the data in more detail. A piecewise linear regression analysis was done on the temperature graph to focus on the troposphere, tropopause, and the stratosphere separately. However, the exponential trend of the pressure data required a regression analysis on the natural log of pressure versus altitude.

Figure 4 shows the results of the regression analysis for the temperature data. The equation representing the troposphere indicates a -6.73 deg C/km trend. This is in agreement with the standard model. The equation representing the tropopause has an intercept on the temperature axis of -72 deg C, which is in agreement with temperatures of the tropopause. The equation representing the stratosphere indicates a 1.8 deg C/km trend.

Figure 5 shows the results of the regression analysis for the pressure data. The equation reasonably fits the data. The Standard Model uses 4 piecewise equations to fit the data in this range. Even though the fit in Figure 5 could be improved by sectioning the data, using one equation for all of the data still will show that pressure is not the critical factor in the collection process with respect to data variation.

Figures 6 through 8 show the residual plots of the data corresponding to the troposphere, tropopause, and the stratosphere. Figure 6 shows a temperature variation of 3 C for the troposphere. Figure 7 shows a temperature variation of 6 C for the tropopause. Figure 8 shows a temperature variation of 4 C for the stratosphere. Figure 9 shows a 0.1 cyclic variation in the natural log of pressure throughout the data. That is equivalent to a 1 mbar variation in the pressure. Inconsistency of the regression model with the data as seen in Figure 5 is due primarily to the increasing percent error as pressure values fall toward zero.

Results from the regression analysis indicate a variation in temperature and pressure specific for Ft Worth, Texas during the last week in July. Any measurement of temperature must be accurate to within 3 C and any measurement of pressure must be accurate to within 1 mbar to compare against the regression models.


















3.3.1.3 Albedo Factors and Measurement

Albedo encountered during flight can effect changes in the heat budget affecting atmospheric temperature. Photographs of the earth give a good representation of how terrain, clouds, and precipitation affect albedo. Photographs taken from the payload will be erratic due to the pendulous motion during the flight, and all pictures taken will not capture the albedo factors. Enough photographs need to be taken during flight to account for this motion. Photographs need not be taken more often than sampled temperature.