A (left) shows the simple case where under one atmospheric cell one has four ocean cells. B (right) on the other hand shows a bit more complicated situations with nine ocean cells influencing one atmospheric cell
This snack is hopefully the first in a series discussing the uncertainties and errors in climate simulations. I feel this important topic is often misunderstood by public and even by scientists, but it is of great importance when trying to understand the results.
There are plenty of sources of model uncertainties and errors, such as initial conditions1, sub grid scale parameterizations2, underlying physics, uncertainties in forcing and many others. I will discuss one of the smallest ones which is often neglected, but which is interesting at least in terms of model development: coupling between different components of earth system models.
Heavy rain? It must be the monsoon. Or is it? (photo: Mathew Reeve)
Before we can investigate the presence or absence of some attribute…. or before we can rank objects or measure them in terms of some variable, we must form the concept of the variable (Lazarfeld and Barton, 1951)
Scientific research is based around definitions. We use definable concepts in our scientific questions, our project proposals, and our research design. We need definitions so that scientists can communicate together and with society. Without robust definitions, research can easily ramble off in irrelevant directions. Continue reading
Picture 1: View of New York City from Rockefeller Center. Upper part looking to the south, Empire State Building in the foreground. Lower part looking to the north, Central Park in the middle. (Picture: Hella Wittmeier)
Nobody moves to New York City because of the climate. Bitterly cold winters and burning hot summers leave only the transition seasons of spring and autumn comfortable. But the weather certainly isn’t the first thing that springs to mind when we think of the city that never sleeps, is it??
More than 1.5 million people live in Manhattan (Picture 1) on less than 60 km2, no matter how hot, cold, wet or windy. It is one of the most densely populated areas worldwide. Taking a walk through the streets of Manhattan with its tall buildings that shield the ground from direct sunlight gives you an intense, but colorful feeling of smallness. And yet when you climb a little higher and glimpse the overwhelming city from above, you feel like you can reach the sky. The distant horizon swims in the ocean, emphasizing the majestic skyline of Manhattan in front, solid as a rock. Continue reading
Figure 1: Doppler LiDAR measurement principle
If you think that wind directions are still estimated by holding your index finger into sky, you are not up to date. Star Wars technologies have entered the real scientific world of experimental atmospheric researchers. Traditional meteorological wind measurements (e.g. cup anemometers) are limited to near-ground levels. What if we are interested in winds at higher altitudes? Building up higher masts is challenging in terms of construction and cost efficiency. Wind measurements with newest laser technologies enable not only wind profiles up to several kilometres but also 2D pictures of the ambient flow field.
Figure 1: The global distribution of warming at the time of 2oC above pre-industrial levels using the Norwegian Earth System Model (NorESM). Temperatures are shown relative to the mean for the period 1850-1900 (from Medhaug and Drange, in preparation).
The globe is warming, glaciers are melting, sea level is rising and ice caps are starting to disappear. This is predominantly due to the increasing amount of greenhouse gases, like for example CO2 and methane, in the atmosphere through fossil fuel burning, deforestation etc., causing the global temperatures to rise because of the “greenhouse effect”.
Joseph Fourier first discovered the “greenhouse effect” in 1824. He calculated the temperature of the earth based on its size and position relative to the sun. He showed that the earth should have been much colder than it was. He wondered why, and concluded that the atmosphere must have an insulating effect on the earth. This insulating effect is because certain gasses that exist in our atmosphere trap heat. The gases let the energy from the sun pass through the atmosphere but trap the energy emitted from the Earth’s surface.
Alexander Korablev and his colleagues have been developing a new climatological atlas for the Nordic Seas and Northern North Atlantic based on more than 500 000 in-situ oceanographic stations (black dots in the figure).
Variability in our oceans influences the variability in our atmosphere through complex air-sea interactions. We need to fully understand variability in both the ocean and the atmosphere to fully understand our climate. This sounds obvious, but has previously been fraught with difficulty. If we want to say something robust about variability then we need observations, preferably at a high spatial resolution and over a long period of time. Continue reading
Figure 1: Taken at 9 am on 16/01/2013 at the University of Hawai’i at Manoa campus.
Most people would think of Hawai’i as a place where you find perfect blue skies everyday of the year. In reality however, this is quite rarely the case. Usually the sky above Hawai’i is filled with scattered cumulus clouds moving with the trade winds and sometimes high-altitude cirrus clouds associated with the subtropical jet. Furthermore, we occasionally encounter frontal passages or heavy rain events associated with upper-troposphere disturbances called “Kona Lows”. Continue reading
This post is co-authored by Hella and Aleksi both PhD students at UiB. Hella is currently visiting at Lamont-Doherty Earth Observatory (LDEO) for the whole spring while Aleksi just got a glimpse of the work and life around the NYC.
Travelling to a different country always broadens your mind. Meeting new people from different cultural backgrounds, experiencing new surroundings, tasting exotic food – all our senses are challenged to help us see our world through different eyes.