Data show that Arctic ice is melting at an increasing rate, a rate that NASA wants to more clearly define through airborne observation. ESSIC Assistant Research Scientist Sinead Farrell has worked with NASA to help accomplish that goal.
Farrell is a member of NASA’s Operation IceBridge science team – she is one of 5 or 6 sea ice scientists on a science team of more than 15 people – that surveyed land and sea ice in the Arctic Ocean from aircraft equipped with a range of instruments, including radars, lasers, digital cameras, surface temperature instruments and a gravimeter, in order to measure changes in ice thickness.
Farrell’s individual role in the project is that of a sea ice observer, providing advice when determining which areas of the sea ice are most critical to survey and when designing flight plans over those areas.
While in the field, she also provided guidance when last-minute decisions – such as adjusting when ice moved from its prior location or to change direction based on the location of field teams – needed to be made while on the 8-hour flight campaigns, and she created a booklet of directions for particular areas prior to each flight campaign.
The team would periodically fly over field teams taking direct, manual measurements on the ice in order to calibrate and validate (calval) the airborne instruments’ measurements.
Farrell said that the mission focused on the Arctic Ocean because that’s where many of the changes are happening right now. However, the project also includes Antarctica; the team will conduct essentially the same project from their base in southern Chile starting Tuesday.
Although she will not be a part of this campaign in person as she has been, Farrell will still assist the team from afar.
The IceBridge mission was created, Farrell said, in order to fill a gap in data collection in between the 2009 retirement of the ICESat (Ice, Cloud, and Land Elevation Satellite) ice-measuring satellite and the 2016 launch of ICESat-2.
“The disadvantage of this is we can’t survey the whole region all the time,” Farrell said. “But we can go to specific areas.”
Now that there are four years of IceBridge data, Farrell said the data can be linked to ICESat time series.
This year, the data analysis phase of the project went much faster because of the adoption of a different processing approach, Farrell said. In past years, the data-crunching process took about six months, whereas this year it took only six weeks to release a preliminary version of the sea ice thickness measurements.
Farrell said the process was accelerated by using temperature measurements to identify breaks (or “leads”) in the sea ice based on spikes in the temperature data. This cuts down on processing time because it involves analysis of a subset of the data, as opposed to the full data set.
“It’s not the final answer, but it’s close,” Farrell said, adding that the advantage of the new approach is that they can use this data in March and April to predict sea ice conditions in September.
NASA made headlines when it released a report in July illustrating that the extent of ice surface melt in Greenland increased from about 40 percent to 97 percent in the span of four days in July.
Regarding the question of whether this increase in surface melting is indicative of climate change, Farrell believes that much more data is needed to be able to make such an attribution.
“One year is not an indicator of climate change. if we see this happening year to year, then that is a trend and may indicate climate change,” she said. “We can’t really say anything about climate from just one year.”
However, Farrell did say that there is data available (see image at right, courtesy of nsidc.org) from 1979 to 2011 that illustrates a clear decline in sea ice extent in the Arctic; she said that this data has been collected for long enough that it is “totally” indicative of a long-term trend of sea ice loss in the Arctic Ocean.
In addition to her duties on the IceBridge team, Farrell was selected in February to serve on the ICESat-2 Science Definition Team.