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Aiden Robert Max JönssonPhD student

About me

I was born and raised in Los Angeles, California, but now call Stockholm, Sweden my home. My undergraduate studies were in mechanical and marine engineering to begin with, and during the beginning to my bachelor-level studies at California Maritime Academy, I took courses in introductory oceanography, where I learned that the physical laws in engineering fundamentals could be applied to study the world's oceans. I moved to Europe and finished my bachelor's degree in mechanical engineering at Denmark's Technical University. After some consideration, I felt much more interested in natural sciences than in engineering, and began studies in atmospheric sciences and oceanography at Stockholm University. This was the right choice; the workings of the climate system and its many components are an incredibly interesting and exciting topic to work with.

Outside of the university, I am interested in many kinds of crafts, like wood- and metalworking, textiles, gardening, cooking, and fermenting foods and beverages. I really enjoy trying to engage in and practice arts, including different types of visual arts, writing, and making music — now mostly with analog synthesizers, which I have a lot of fun building myself.

Prior to the Ph.D. research

Previously, I have worked on a project together with social scientists to calculate the physical severity of natural hazards (floods, droughts, storms, and temperature extremes) for geopolitical states to test whether hazard severity effectively plays a part in determining humanitarian relief/aid allocation where it is needed. I remain interested in learning about and studying meteorological extremes.

My master's degree project focused on the role of moisture transport into the Antarctic sea ice zone, and the connection between moisture transport and states of low sea ice extent in its various sectors. In it, we used satellite observations and reanalysis products to study atmospheric conditions during states of low sea ice cover and looked at links to moisture inflow to the Antarctic polar region as well as the Southern Annular Mode.

Research

I research a feature of Earth's climate system that is as of yet not well understood: the fact that both the northern and southern hemispheres (NH and SH) have very similar albedo, despite the NH having more aerosols and land surface cover that increase the NH clear-sky albedo. This is because the distribution of clouds compensates the hemispheric difference in clear-sky albedo, through greater cloud amount and albedo in the SH. This feature remains persistent throughout the past two decades of satellite observations, and we want to investigate the questions: is there a physical mechanism in the climate system that serves to reduce the difference in albedo between (and thereby the input of solar radiative energy into) the hemispheres, and could this tell us something about how clouds and albedo will respond to a warming climate?

To study this, I am  using satellite observations of Earth's radiation balance, and compare output from climate models with these observations as well as investigate the response and evolution of hemispheric albedo differences and cloud distributions to different experimental forcings.

Publications

A selection from Stockholm University publication database

  • Persistence and Variability of Earth's Interhemispheric Albedo Symmetry in 19 Years of CERES EBAF Observations

    2022. Aiden R. Jönsson, Frida A.-M. Bender. Journal of Climate 35 (1), 249-268

    Article

    Despite the unequal partitioning of land and aerosol sources between the hemispheres, Earth’s albedo is observed to be persistently symmetric about the equator. This symmetry is determined by the compensation of clouds to the clear-sky albedo. Here, the variability of this interhemispheric albedo symmetry is explored by decomposing observed radiative fluxes in the CERES EBAF satellite data record into components reflected by the atmosphere, clouds, and the surface. We find that the degree of interhemispheric albedo symmetry has not changed significantly throughout the observational record. The variability of the interhemispheric difference in reflected solar radiation (asymmetry) is strongly determined by tropical and subtropical cloud cover, particularly those related to nonneutral phases of El Niño–Southern Oscillation (ENSO). As ENSO is the most significant source of interannual variability in reflected radiation on a global scale, this underscores the interhemispheric albedo symmetry as a robust feature of Earth’s current annual mean climate. Comparing this feature in observations with simulations from coupled models reveals that the degree of modeled albedo symmetry is mostly dependent on biases in reflected radiation in the midlatitudes, and that models that overestimate its variability the most have larger biases in reflected radiation in the tropics. The degree of model albedo symmetry is improved when driven with historical sea surface temperatures, indicating that the degree of symmetry in Earth’s albedo is dependent on the representation of cloud responses to coupled ocean–atmosphere processes.

    Read more about Persistence and Variability of Earth's Interhemispheric Albedo Symmetry in 19 Years of CERES EBAF Observations

  • Humanitarian need drives multilateral disaster aid

    2021. Lisa Maria Dellmuth (et al.). Proceedings of the National Academy of Sciences of the United States of America 118 (4)

    Article

    As the climate changes, human livelihoods will increasingly be threatened by extreme weather events. To provide adequate disaster relief, states extensively rely on multilateral institutions, in particular the United Nations (UN). However, the determinants of this multilateral disaster aid channeled through the UN are poorly understood. To fill this gap, we examine the determinants of UN disaster aid using a dataset on UN aid covering almost 2,000 climate-related disasters occurring between 2006 and 2017. We make two principal contributions. First, we add to research on disaster impacts by linking existing disaster data from the Emergency Events Database (EM-DAT) to a meteorological reanalysis. We generate a uniquely global hazard severity measure that is comparable across different climate-related disaster types, and assess and bolster measurement validity of EM-DAT climate-related disasters. Second, by combining these data with social data on aid and its correlates, we contribute to the literature on aid disbursements. We show that UN disaster aid is primarily shaped by humanitarian considerations, rather than by strategic donor interests. These results are supported by a series of regression and out-of-sample prediction analyses and appear consistent with the view that multilateral institutions are able to shield aid allocation decisions from particular state interests to ensure that aid is motivated by need.

    Read more about Humanitarian need drives multilateral disaster aid

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