page_title: Forrest Mims
section_title: 30 years of Atmospheric Measurements
hierarchical_section_title: Forrest Mims / 30 years of Atmospheric Measurements
caption_attribution_description: English: The various sun photometers, radiometers and cameras on the table are used every day at solar noon when the sun is not blocked by clouds. See Wikimedia and www.forrestmims.org for 25-year charts of total ozone, total water vapor and optical depth (haze). Mims' original LED sun photometer (placed in service during fall 1989) is in his left hand. Two Microtops II are in his right hand. One is among the very first (1997) and the other is the only MicroTOPS II with LEDs as photodetectors. The photo was made by Minnie C. Mims on 4 Feb 2016 with a Sony a6000.
context_page_description: Forrest M. Mims III is an American amateur scientist, magazine columnist, and author of Getting Started in Electronics and Engineer's Mini-Notebook series of instructional books that were originally sold in Radio Shack electronics stores. Mims graduated from Texas A&M University in 1966 with a major in government and minors in English and history. He became a commissioned officer in the United States Air Force.
  Mims has no formal academic training in science, but still went on to have a successful career as a science author, researcher, lecturer and syndicated columnist. His series of electronics books sold over 7 million copies and he is widely regarded as one of the world's most prolific citizen scientists. Mims does scientific studies in many fields using instruments he designs and makes and he has been published in a number of peer-reviewed journals, often with professional scientists as co-authors. Much of his research deals with ecology and environmental science. A simple instrument he developed to measure the ozone layer earned him a Rolex Award for Enterprise in 1993. In December 2008 Discover named Mims one of the "50 Best Brains in Science."
context_section_description: For more than thirty years, Mims has made accurate and detailed atmospheric measurements.  These include measuring the ozone layer, haze (aerosol optical depth), and the total column water vapor.
  The project began in May 1988, when Mims started experimenting with making UV-B measurements with homemade equipment.  In 1989, Mims designed and built the first Total Ozone Portable Spectrometer (TOPS) to monitor ozone, and instruments to measure haze and water vapor. The first TOPS (Total Ozone Portable Spectrometer) ozone instrument earned a 1993 Rolex Award.
  On February 4, 1990, these instruments were first used at solar noon to measure the ozone layer, haze (aerosol optical depth) and total column water vapor.  The photograph at left by Mims wife Minnie was made February 4, 2016, the 26th anniversary date.
  The various sun photometers, radiometers and cameras on the table are used every day at solar noon when the sun is not blocked by clouds.  See Wikimedia and www.forrestmims.org for 25-year charts of total ozone, total water vapor and optical depth (haze). Mims' original LED sun photometer (placed in service during fall 1989) is in his left hand. Two Microtops II are in his right hand. One is among the very first (1997) and the other is the only MicroTOPS II with LED’s as photodetectors. 
  Mims first LED sun photometer is still in use (he is shown holding it in the 26th anniversary photo above).  It has dual LED’s acting as narrow band sensors, one at 830 nm and another at 940 nm (near-IR).  The 830 nm LED is for optical depth.  The ratio of the photocurrents from the 830 nm and 940 nm LEDs provides total water vapor. 
   The chart at right shows the total ozone measured from 1990 through 2016.  
  Total ozone (Dobson units) measured at solar noon at Geronimo Creek Observatory since February 4, 1990. Measurements conducted only when sun is open and free of clouds. Mims has compared his measurements against Dobson 76 and Brewers 009 and 119 at the Mauna Loa Observatory each year since 1992.
   In addition to measuring total ozone, Mims has measured the aerosol optical depth (AOD) at 830 nm with his original instrument since 1990. The chart at left shows the data.  
  Measurements made at or near solar noon when the sun is not obstructed by clouds. Peaks indicate smoke, dust and smog. Saharan dust events are measured each summer. 
    The chart at right shows the total column water vapor measured since 1990. Total column water vapor is measured at 940 nm and 830 nm (reference wavelength) using the same sun photometer first used on February 4, 1990. 
  The ratio of these two wavelengths provides the total water vapor.  The trend is slightly down (approx. -1.5 mm/decade). Calibration: NOAA GPS data from Galveston, TX, and Mauna Loa Observatory, HI. Measurements are made at or near solar noon when clouds are not before the sun.  
  Water vapor is the key global warming gas. The 1997-98 peak in Mims's data occurred during a major El Nino. No such peak occurred during the 2015-16 El Nino. The general shape of the data resembles the global water vapor plot in NASA's ongoing NVAP study.
  In addition to Mims' measurements in his home state of Texas, he made atmospheric measurements in Brazil during two three-week campaigns for NASA’s Goddard Space Flight Center.  In August 1995, Mims led a 2-man team to measure the ozone layer during the SCAR-B campaign at Cuiaba in central Brazil since the ozone instrument aboard the Nimbus-7 satellite had ceased working.        
  In August 1997, Mims led a 2-man team that measured ozone layer, smoke optical depth, UV-B and water vapor near Alta Floresta in Amazonia.          
  During the fall of 1996, NASA’s Goddard Space Flight Center assigned Mims to fly at a moment's notice to a series of 7 major forest fires in Utah, California, Wyoming and Montana.  A GSFC scientist had discovered that a new satellite ozone instrument could also detect smoke, and Mims was assigned to measure total ozone and the optical depth of smoke during satellite overpasses.
caption: Forrest M. Mims III on the 25th anniversary of his atmospheric measurements (1990 to 2016)
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