Peter Thejll
Encyclopedia
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
researcher. His research in solar variation
Solar variation
Solar variation is the change in the amount of radiation emitted by the Sun and in its spectral distribution over years to millennia. These variations have periodic components, the main one being the approximately 11-year solar cycle . The changes also have aperiodic fluctuations...
helped provide conclusive evidence of the greenhouse effect
Greenhouse effect
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...
on the Earth's climate in the late 20th century. In particular, his landmark study with Knud Lassen on Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
land air temperature showed that the rise of 0.4 degrees Celsius since 1980 could not be accounted for by the solar cycle
Solar cycle
The solar cycle, or the solar magnetic activity cycle, is a periodic change in the amount of irradiation from the Sun that is experienced on Earth. It has a period of about 11 years, and is one component of solar variation, the other being aperiodic fluctuations. Solar variation causes changes in...
. Climatologists have pointed to this finding as an "actual piece of evidence for greenhouse warming".
Thejll received his undergraduate education at the University of Copenhagen
University of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...
. He received an M.S. in physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
and a Ph.D. in astrophysics
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
from the University of Delaware
University of Delaware
The university is organized into seven colleges:* College of Agriculture and Natural Resources* College of Arts and Sciences* Alfred Lerner College of Business and Economics* College of Earth, Ocean and Environment* College of Education and Human Development...
.
Thejll was a Carlsberg Fellow at the Niels Bohr Institute
Niels Bohr Institute
The Niels Bohr Institute is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics....
and worked at the Nordic Institute for Theoretical Physics. Thejll currently is a senior scientist at the Danish Meteorological Institute
Danish Meteorological Institute
The Danish Meteorological Institute is the official Danish meteorological institute, administrated by the Ministry of Transport and Energy. The institute makes weather forecasts and observations for Denmark, Greenland, and the Faroe Islands....
in Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
. He is currently involved in the creation of a global automatic system to observe the Earth's reflectivity - albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
- using observations of the earthshine on the Moon. Such data can be used for climate change studies and calibration of satellite data as the measurements deliver independent data on the albedo. The Swedish research agency VINNOVA is funding this project.