Background

Project Statement:

    With growing concern due to climate variation, it is important to create measurement systems to monitor the presence and concentration of elements, molecules and particulates in the atmosphere. This team proposes the design of a low-power solar spectrograph that will measure the relative intensity of H2O Fraunhofer lines (absorption lines) in the atmospheric solar spectrum. Through the design of a durable weather-resistant system, long-term measurements of Fraunhofer lines will be collected at accessible or remote locations to monitor the changes in atmospheric gas concentrations.   


Water vapor Absorption lines (Frounhofer Lines):

    The sun which is often considered a black body radiator emits a broad spectrum of radiation that travels through the earths atmosphere. The plot below shows the total outer atmospheric sunlight (yellow) fits a Blackbody spectrum curve. When the radiation has reached earth's surface, certain wavelength ranges will have been absorbed by atmospheric gases (red). Note that there is a large section missing around 800nm labeled H20.  This system observes this loss in energy due to water vapor content, and may then approximate the humidity in the atmosphere.
File:Solar Spectrum.png
    Below is a Hitran Model of the wavelength dependent absorption by atmospheric gases. Note that at 0.8um there is a defined band corosponding with water vapor absorption. This is the wavelength range that will be monitored.
http://upload.wikimedia.org/wikipedia/commons/6/61/Synthetic_atmosphere_absorption_spectrum.gif

Community Outreach

       One requirement for participation in the spectrograph competition is participation in a community outreach event. The spectrogrpah team participated in the Astronomy Days event at the Museum of the Rockies on April 5th, 2014. The event highlighted current topics of interest related to astronomy and science at Montana State University and worldwide. The spectrograph team spoke with hundreds of children and members of the public about their spectrograph, and lead the construction of paper spectrographs that attendees could take home!