The Center for Atmospheric Sciences | » John J. Blalock

    • B.S., Physics, Longwood University, 2013

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      Recent News:

      June 10, 2016 : APS Scientists Observe Mercury Transit with the Public

      On May 9th, 2016, a special celestial event occurred when the planet Mercury lined up exactly with the Sun in the sky as viewed from the Earth. In Hampton, Mercury began to cross the disk of the Sun shortly after sunrise at 7:20am and spent a leisurely seven hours making a sharp, round shadow on […]

      October 23, 2015 : APS Professor Moore Hosts Astronomy Night Event

      The White House announced earlier this year that October 19th of this year was going to be the National Astronomy Night, and invited professional scientists and amateur astronomers to host events around the country.  The goal is to expand access to STEM experiences for the next generation of scientists, engineers, and inventors.  The White House […]

      August 6, 2015 : Grad Student John Blalock wins NASA Fellowship

      BIG Congratulations to Planetary Science PhD student John Blalock, who has won a prestigious NASA Earth and Space Science Fellowship to support his doctoral dissertation research! John’s winning research proposal was titled “Measurement of Seasonal Changes in Saturn’s Zonal Wind Profile using Cassini ISS images,” in which he proposed to examine images of Saturn collected […]

      June 1, 2015 : APS Exhibit lights up CNU STEM Day
      Fire tornado demonstration.

      The Hampton University Atmospheric and Planetary Science Department took its show on the road on Saturday, May 30, to Christopher Newport University’s annual STEM Day celebration.  Faculty members John McNabb and William Moore were joined by graduate students John Blalock, Liqiao Lei, and Earnest Nyaku inside and outside the CNU Field House to demonstrate atmospheric […]

  • John J. Blalock

    I am currently a second-year PhD student studying planetary science at Hampton University. I earned my B.S. from Longwood University in 2013, majoring in physics and minoring in mathematics.

    My research interests focus on using various cloud-tracking techniques to gather information about the dynamics of planetary atmospheres. In planetary atmospheres, wind speeds can be measured by analyzing the motions of clouds. The clouds act as tracers of the wind movements and thus by measuring their movements one can interpret what the wind field is. A useful diagnosis of a planet’s global atmospheric dynamics is the zonal (east-west) mean wind profile, i.e., mean of the zonal component of the wind vectors. Two of the common cloud tracking techniques are a one-dimensional correlation method and a two-dimensional Correlation Imaging Velocimetry (CIV) technique. The 1D method measures the wind speed by calculating the correlation between a single-pixel latitude strips extracted from two latitude-longitude projected cloud maps as they are are shifted in the east-west direction. The two-dimensional method works in a similar way, except that the correlation is calculated
    between two-dimensional subwindows within the two images and the subwindows are shifted in
    the north-south directions as well as in the east-west (creating a search window). I utilize both the 1D and 2D techniques (in addition to manual tracking techniques) for my research projects.

    Beyond simply using the cloud-tracking techniques, I also do some more theoretical work to better understand the limitations of current techniques and where they can be improved. In particular, trying to determine how to characterize the uncertainties associated with tracking measurements is a very important part of my work. Furthermore, trying to develop techniques that are more flexible and can work with various levels of data is also important and can prove to be very powerful for particular cloud-tracking applications. Current techniques require that data be of the same resolution and be mapped onto a common grid. Not only is information lost during this process, but it severely limits the kinds of motions that can be tracked. Rotations, for example, can not be explicitly tracked with current techniques. If you can eliminate the need for this kind of data processing for tracking to work, you not only preserve data but also open the door for every interesting kinds of tracking to be performed.

    While at Longwood for my undergraduate career, I completed a Senior Honors Thesis project entitled “Effects of Electric and Magnetic Fields on Moving Liquid Paint on a Glass Surface.” If you are interested in reading it, a PDF version is available here: Blalock_Senior_Honors_Thesis.pdf

    Project: Seasonl Analysis of Zonal Winds and Vertical Wind Shear on Saturn from Cassini ISS Images

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    We are working on a project to calculate global mean zonal wind profiles for different altitudes in Saturn’s lower atmosphere using Cassini ISS images captured using the continuum band (CB) and methane absorption (MT) filters between 2004 and 2013. Specifically, I utilize the CB2 (750 nm), MT2 (727 nm), and MT3 (889 nm) filters for […]

    Project: Analysis of Venusian Zonal Winds Using Venus Express Data

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    We measure the zonal mean wind structure of Venus between 2006 and 2013 in the ultraviolet images captured by the Venus Monitoring Camera (VMC) onboard the ESA Venus Express (VEx) spacecraft which observed Venus’s southern hemisphere. Our wind measurements employ a digital two-dimensional Correlation Imaging Velocimetry (CIV) method to track cloud motions. Our current focus is on understanding […]