2013 NABOS Summer School students and instructors
With the expedition coming to an end, we also got to see the results of all the stunning and complex work of the NABOS Summer School students, who have been working throughout the expedition on projects presented by Summer School instructors (described in the “Project Time!” post from 9/18). NABOS Summer School Director Vladimir Alexeev, of the International Arctic Research Center at the University of Alaska-Fairbanks, shared some overall successes of the Summer School – successfully incorporating students into science observations onboard… hosting 55 lectures from students as well as scientists onboard (remember the collaborative nature of science?)… the building of new friendships and professional relationships… and the students producing some publish-worthy project results. As you are looking at these detailed figures, remember the BIG picture. Students are trying to understand the Great Arctic Cyclone of 2012… Hurricane Katrina… global permafrost… sea ice forecasting… the planetary boundary layer between the atmosphere and ocean… Arctic silica… Enjoy the beautiful results of what they created, along with captions that they included for you. None of these pictures tell the whole story, but you can see how there are so many parts of the picture!
Weather Research and Forecasting (WRF) Project: Modeling the Great Arctic Cyclone of 2012
(Tobias, Antoine, jake, Eric, Marie, Ioana)
Project: The goal was to use the WRF meteorological model (which is on the regional scale) along with an ocean/sea ice model (on the global scale) to simulate the great Arctic cyclone of 2012 – and the subsequent record minimum of sea ice that year.
We simulated the “Great Polar Cyclone” of 2012 in a meso-scale meteorological model and used the information on the winds and temperatures to force a coupled ocean-sea ice model. The figure shows the wind speeds during 2012-08-06 (00:00 UTC) that we used for forcing the sea ice model. The maximum resolved wind speeds were around 15 m/s. You can easily recognize the cyclone by the location of the highest wind speeds. The cyclone was located on the west side of the Arctic (the top of the picture), where you also can recognize the Bering Strait.
Changes in sea ice extent and in sea ice volume due to different storm strengths. The “ctrl winds” horizontal lines correspond to the reference storm strength, the “winds / 2” curves correspond to a weaker storm (winds speeds divided by two) and the “winds * 2” curves correspond to a stronger storm (winds speeds multiplied by two). The time interval during which winds are adjusted in the model is indicated by the vertical lines. The three rows correspond to different states of the sea ice before the storm.
The Minimum Sea Level Pressure between Aug 2 (midnight, UTC) and Aug 15 (6pm, UTC) for 3 WRF cases with differing sea ice boundary conditions. Red lines indicate the respective entry and exit points of the cyclone into and out of the physical region in which the model is simulated.
Here is a simulation of the ‘great’ Arctic cyclone of 2012 with WRF, driven with atmospheric data derived from observation (known as ERA-Interim reanalysis) and a spatial resolution of 47.5°. Color contours indicate the mean sea-level pressure on August 6, 2012 at 6pm UTC. The black dots mark the track of the cyclone, starting on August 4, 12pm, until August 14, 12pm. The cyclone track is obtained by the detection of the minimum of the mean-sea level pressure within the region.
Weather Research and Forecasting (WRF) – Modeling Hurricane Katrina
Project: Using the WRF model, the goal was to simulate extreme weather events like Hurricane Katrina and a strong wind event near Novorossiisk, Russia, called bora. Another goal was to learn which parameters of the simulation to use (like spatial and time resolution and region size) in order to represent Hurricane Katrina most accurately; and for bora, to analyze the hydrometeorological conditions before and during the event.
This figure shows the results of our 4 models, each run at a different spatial resolution. The image shows that our model run at a resolution of 20kilometers most accurately follows the path of the actual hurricane (the colored dots connected by the white path), although all of the modeled hurricanes showed late landfall times. For reference, the actual atmospheric pressure was 902mb.
Developing a Permafrost Model
(Florence, Mathieu, Marika, Meri)
Project: This group developed a computer model to determine the potential presence or absence of permafrost in locations throughout the northern hemisphere. (Permafrost is anything – ice, soil, rock – that stays below at below-freezing temperatures for at least two years.) By inputting factors like soil temperature, air temperature, snow depth and density, and a given year and month, they could determine how their model compares to existing permafrost models.
The model produced images of the type of permafrost is present in the northern hemisphere. We adjusted model parameters to determine what changes would occur in permafrost extent, given different conditions. This is the surface frost index (F+) 10-year average from 2000 to 2009 for the Northern Hemisphere. Using the colored scale in the image, it can be seen that continuous permafrost occurs where F+ ≥ 0.67, extensive discontinuous permafrost occurs where 0.67 > F+ > 0.6, and sporadic permafrost is present where F+ > 0.5.
Evaluating Sea Ice Forecast Model
Project: The goal of this project was to assess the results of a computer model which applies probability and trends in sea ice conditions, as opposed to current weather data, in forecasting those conditions. To do this, model results were compared with direct observations.
Sea ice extent observed and modeled from March-October 2010. There is significant negative error (i.e. the observed values are bigger than the modeled values) in July-August, caused by rapid changes in sea ice concentration but small changes in sea ice extent.
Investigating the Planetary Boundary Layer
(Ekaterina, Elena K., Irina L., Maria P., Anna G., Svetlana L.)
Project: This group made visual observations of clouds, and evaluating the performance of the MTP instrument (Meteorological Temperature Profiler) in different cloud conditions versus data from the radiosondes (weather balloons) launched from the ship. They learned about turbulent heat and air flow at the “boundary layer” between the atmosphere and the ocean, and how sea ice affects that layer.
This is a comparison of the MTP-5 (meteorological temperature profile) data versus radiosonde (weather balloon) data, in order to evaluate the capabilities of the MTP-5 in clear versus cloudy conditions. On the right, in clear weather, the data show a 90% correlation coefficient between the two methods. In cloudy/humid weather, the MTP-5 data does not correlate well with the radiosonde data (the cloud level begins at about 150meters). The next step is to create a data processing algorithm to account for using the MTP-5 in cloudy conditions.
This shows that we have an atmospheric surface layer to a height of 300m, and an atmospheric boundary layer between 300m and 1700m in height (where you can see the curve do a “switchback”). The behavior of the temperature curve is good indicator of when the boundary layer begins. The boundary layer is very important for climate modeling, because it helps define the layers of stability in the atmosphere.
Hydrochemistry: Measuring Silica in the Arctic
The goal was to assist in the HydroChem lab onboard, and to measure silica content from water samples from all of the CTD stations (we have had about 100 stations so far). They will now analyze the results to learn about differences in water at different depths and different locations throughout the Arctic. This study will tell them about marine life conditions, which help suggest ideal fishing practices.
The picture shows all CTD stations made during the cruise. Comparing transects (the circled areas), we found striking differences in silica content between the seas (influenced by Atlantic waters) to the west of the Lomonosov Ridge (the shallow ridge in the top right part of the image) and the East Siberian Sea, which is influenced by waters from the North Pacific.
To be continued with my own results from the expedition…!