Publication list

"And if my poor talents, my little experience of the present and insufficient study of the past, should make the result of my labors defective and of little utility, I shall at least have shown the way to others, who will carry out my views with greater ability, eloquence, and judgment, so that if I do not merit praise, I ought at least not to incur censure."

— Niccolo Machiavelli, Discourses on Livy, 1531.

Peer reviewed articles

· A. Marshak, A. Delgado-Bonal, and Y. Knyazikhin, Effect of Scattering Angle on Earth Reflectance, Frontiers in Remote Sensing, 2:719610, (2021) doi:10.3389/frsen.2021.719610

· A. Delgado-Bonal, A. Marshak, Y. Yang, and L. Oreopoulos, Global daytime variability of clouds from DSCOVR/EPIC observations, Geophysical Research Letters, 48, e2020GL091511, (2021) doi:10.1029/2020GL091511

· A. Delgado-Bonal, A. García López, Quantifying the randomness of the forex markets, Physica A: Statistical Mechanics and its Applications, 569, 125770 (2021) doi:10.1016/j.physa.2021.125770 - PDF

· A. Delgado-Bonal, A. Marshak, Y. Yang, and L. Oreopoulos, Daytime variability of cloud fraction from DSCOVR/EPIC observations, Journal of Geophysical Research: Atmospheres, 125, e2019JD031488, (2020) doi:10.1029/2019JD031488 - PDF

· A. Delgado-Bonal, On the use of complexity algorithms: a cautionary lesson from climate research, Scientific Reports, 10, 5092, (2020) - PDF

· A. Delgado-Bonal, A. Marshak, Y. Yang and D. Holdaway, Analyzing changes in the complexity of climate in the last four decades using MERRA-2 radiation data, Scientific Reports, 10, 922, (2020) doi:10.1038/s41598-020-57917-8 - PDF

· A. Delgado-Bonal, Quantifying the randomness of the stock markets, Scientific Reports, 9, 12761, (2019) doi:10.1038/s41598-019-49320-9 - PDF

· A. Delgado-Bonal and A. Marshak, Approximate Entropy and Sample Entropy: A Comprehensive Tutorial, Entropy, 21(6), 541, (2019) doi:10.3390/e21060541 - PDF

· A. Delgado-Bonal, Entropy of radiation: the unseen side of light, Scientific Reports, 7, 1642, (2017) doi:10.1038/s41598-017-01622-6 - PDF

· A. Delgado-Bonal and F.J. Martín-Torres, Human vision is determined based on information theory, Scientific Reports, 6, 36038, (2016) doi:10.1038/srep36038 - PDF

· A. Delgado-Bonal, M.-P. Zorzano and F.J. Martín-Torres, Martian Top of the Atmosphere 10-to 420 nm spectral irradiance database and forecast for solar cycle 24, Solar Energy, Vol. 134, pp. 228-325, (2016) doi:10.1016/j.solener.2016.05.004 - PDF

· A. Delgado-Bonal, F.J. Martín-Torres, S. Vázquez-Martín, M.-P. Zorzano, Solar and wind exergy potentials for Mars, Energy, Vol. 102, pp. 550-558, (2016) doi:10.1016/ - PDF

· A. Delgado-Bonal and F.J. Martín-Torres, Solar Cell Temperature on Mars, Solar Energy, Vol. 118, pp. 74-79, (2015) doi:10.1016/j.solener.2015.04.035 - PDF

· A. Delgado-Bonal and F.J. Martín-Torres, Evaluation of the Mars atmospheric chemical entropy production, Entropy, Vol. 17, pp. 5047-5062, (2015) doi:10.3390/e17075047 - PDF

Books, Book chapters, and articles

· A. Delgado-Bonal, Space Debris: a complex solution for a changing legal problem (in Spanish). Instituto Iberoamericano de Derecho Aeronáutico y del Espacio (in support of the United Nations) . ISBN 978-84-09-25420-0. Madrid, Spain (2020).

· A. Delgado-Bonal and F.J. Martín-Torres, A Mathematic Approach to Nitrogen Fixation Through Earth History, in: The Early Evolution of the Atmospheres of Terrestrial Planets, Springer, Vol. 35, pp. 23-31, (2013) doi:10.1007/978-1-4614-5191-4_3 - PDF

Recent Papers

Cloud fraction
April 2020

Daytime variability of cloud fraction from DSCOVR/EPIC observations

Journal of Geophysical Research: Atmospheres

The location of the Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) offers a global view of the Earth and captures its atmosphere at different locations and time of the day. In this paper, we take advantage of that unique feature to study the daytime variability of cloud fraction in a seasonal and zonal context. We observe that the ensemble behavior over ocean has a distinctive convex shape, with higher cloud fractions at early morning and late afternoon, while no such pattern is seen over land. Unique perspectives are obtained by analyzing the cloud fraction of the globe as a whole and separately for each hemisphere, and by studying the effect of the viewing zenith angle on cloud fraction retrievals. PDF

Mar 2020

On the use of complexity algorithms: a cautionary lesson from climate research

Scientific Reports

Complexity algorithms provide information about datasets which is radically different from classical moment statistics. Instead of focusing on the divergences from central values, they quantify other characteristics such as order, pattern repetitions, or the existence of attractors. However, those analyses must be done with the proper statistical treatment, which is, unfortunately, not always the case. In this contribution, I provide an example of the hazards of applying complexity measures without sufficient care by correcting a previously published analysis that aimed to quantify the complexity of climate. I clarify some misconceptions about the use of Sample Entropy and revise the incorrect assessments and conclusions drawn from the previous misapplication of the methods. PDF

Featured article

Sep 2019

Quantifying the randomness of the stock markets

· Scientific Reports

entropy ratio

Randomness has been mathematically defined and quantified in time series using algorithms such as Approximate Entropy (ApEn). Even though ApEn is independent of any model and can be used with any time series, as the markets have different statistical values, it cannot be applied directly to make comparisons between series of financial data. In this paper, we develop further the use of Approximate Entropy to quantify the existence of patterns in evolving data series, defining a measure to allow comparisons between time series and epochs using a maximum entropy approach. We apply the methodology to the stock markets as an example of its application, showing that the number of patterns changed for the six analyzed markets depending on the economic situation, in agreement with the Adaptive Markets Hypothesis.
doi:10.1038/s41598-019-49320-9 PDF