Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Janet Machol

Research Interests

  • Improved ultraviolet and X-ray solar irradiance measurements
  • Impacts of solar variability on the Earth's upper atmosphere
  • Methods to retrieve exospheric density from solar observations
  • Development of real-time auroral forecasts

Current Research

I lead our solar irradiance team which works on both the development, calibration and validation of solar irradiance data products for operational space weather and scientific uses as well as space weather research. In particular, our group focuses on measurements from the Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS) aboard the NOAA GOES-R satellites as well as instruments aboard earlier GOES satellites. Scientific GOES data products are available here

Upper atmospheric density has major impacts on satellite operations due to satellite drag, but is not well measured. To help improve these measurements and understanding of this region, I lead a project to investigate a new method to determine exospheric hydrogen (H) density measurements from solar extreme ultraviolet observations and to examine the relationship between space weather and the H density distribution.

Prior to joining CIRES/NOAA NCEI, I worked in the CIRES/NOAA CSD atmospheric lidar group where I developed an automated tropospheric water vapor lidar. I also participated in the development and field deployments of other atmospheric lidars. My PhD work involved the development of femtosecond lasers and time-resolved studies of semiconductor nanocrystals. 

Honors and Awards

  • 2020 CIRES/ NOAA Administrator Award for GOES-R team (team award)
  • 2019 GOES-R Program 'Unsung Hero' Award
  • 2017 CIRES Gold Medal to match NASA Group Achievement Award (team award)
  • 2016 NOAA/NCEI CCOG Team Member of the Year Award (team award)
  • 2014 NOAA NGDC Customer Service Excellence Award (team award)
  • 2013 US Department of Commerce Certificate of Appreciation (team award)
  • 1995 National Research Council Postdoctoral Fellowship

View Publications

  • Lean JL; Coddington O; Marchenko S; Machol J; DeLand MT; Kopp G. (Aug 2020). Solar Irradiance Variability: Modeling the Measurements. Earth and Space Science , 7(8). 10.1029/2019EA000645
  • Machol, J., M. Snow, D. Woodraska, T. Woods, R. Viereck, and O. Coddington. (2019). An Improved Lyman-alpha Composite. Earth and Space Science, 6.
  • Snow, M; Machol, J; Viereck, R; Woods, T; Weber, M; Woodraska, D; Elliott, J. (NOV 2019). A Revised Magnesium II Core-to-Wing Ratio From SORCE SOLSTICE. EARTH AND SPACE SCIENCE, 6(11), 2106-2114. 10.1029/2019EA000652
  • Thiemann, EMB; Eparvier, FG; Woodraska, D; Chamberlin, PC; Machol, J; Eden, T; Jones, AR; Meisner, R; Mueller, S; Snow, M; Viereck, R; Woods, TN. (10-Dec 2019). The GOES-R EUVS model for EUV irradiance variability. JOURNAL OF SPACE WEATHER AND SPACE CLIMATE, 9. 10.1051/swsc/2019041
  • Chamberlin, PC, TN Woods, L Didkovsky, FG Eparvier, AR Jones, JL Machol, JP Mason, M Snow, EMB Thiemann, RA Viereck and DL Woodraska. (OCT 2018). Solar Ultraviolet Irradiance Observations of the Solar Flares During the intense September 2017 Storm Period. SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, 16(10), 1470-1487. 10.1029/2018SW001866
  • Dominique, M, AN Zhukov, P Heinzel, IE Dammasch, L Wauters, L Dona, S Shestov, M Kretzschmar, J Machol, G Lapenta and W Schmutz. (10-Nov 2018). First Detection of Solar Flare Emission in Mid-ultraviolet Balmer Continuum. ASTROPHYSICAL JOURNAL LETTERS, 867(2). 10.3847/2041-8213/aaeace
  • Woods, TN, A Caspi, PC Chamberlin, A Jones, R Kohnert, JP Mason, CS Moore, S Palo, C Rouleau, SC Solomon, J Machol and R Viereck. (1-Feb 2017). New Solar Irradiance Measurements from the Miniature X-Ray Solar Spectrometer Cubesat. ASTROPHYSICAL JOURNAL, 835(2). 10.3847/1538-4357/835/2/122
  • Suess, K, M Snow, R Viereck and J Machol. (16-Feb 2016). Solar Spectral Proxy Irradiance from GOES (SSPRING): a model for solar EUV irradiance. JOURNAL OF SPACE WEATHER AND SPACE CLIMATE, 6. 10.1051/swsc/2016003
  • Snow, M, M Weber, J Machol, R Viereck and E Richard. (21-Jan 2014). Comparison of Magnesium II core-to-wing ratio observations during solar minimum 23/24. JOURNAL OF SPACE WEATHER AND SPACE CLIMATE, 4. 10.1051/swsc/2014001
  • Machol, JL, AA Reinard, RA Viereck and DA Biesecker. (JUL 2013). Identification and replacement of proton-contaminated real-time ACE solar wind measurements. SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, 11(7), 434-440. 10.1002/swe.20070
  • Machol, JL, JC Green, RJ Redmon, RA Viereck and PT Newell. (9-Mar 2012). Evaluation of OVATION Prime as a forecast model for visible aurorae. SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, 10. 10.1029/2011SW000746
  • Alvarez, RJ, CJ Senff, AO Langford, AM Weickmann, DC Law, JL Machol, DA Merritt, RD Marchbanks, SP Sandberg, WA Brewer, RM Hardesty and RM Banta. (OCT 2011). Development and Application of a Compact, Tunable, Solid-State Airborne Ozone Lidar System for Boundary Layer Profiling. JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY, 28(10), 1258-1272. 10.1175/JTECH-D-10-05044.1
  • Machol, JL, RD Marchbanks, CJ Senff, BJ McCarty, WL Eberhard, WA Brewer, RA Richter, RJ Alvarez, DC Law, AM Weickmann and SP Sandberg. (20-Jan 2009). Scanning tropospheric ozone and aerosol lidar with double-gated photomultipliers. APPLIED OPTICS, 48(3), 512-524. 10.1364/AO.48.000512
  • Machol, J.L., T. Ayers, K.T. Schwenz, K.W. Koenig, R.M. Hardesty, C.J. Senff, M.A. Krainak, J.B. Abshire, H.E. Bravo, and S.P. Sandberg. (20-May 2004). Preliminary measurements with an automated compact differential absorption lidar for the profiling of water vapor. , 43(15), 3110-3121. 10.1364/AO.43.003110
  • Machol, JL. (20-Aug 1997). Comparison of the pseudorandom noise code and pulsed direct-detection lidars for atmospheric probing. APPLIED OPTICS, 36(24), 6021-6023. 10.1364/AO.36.006021