Climate Science News

Daily sea ice extent updates resume with provisional data

NSIDC Artic Sea Ice News - Fri, 2016-05-06 08:00

NSIDC has obtained data from the DMSP F-18 satellite and is in the process of intercalibrating the F-18 data with F-17 data. Intercalibration addresses differences between the series of sensors, in order to provide a long-term, consistent sea ice record. While this work continues, we are displaying the uncalibrated F-18 data in the daily extent image. The daily time series graph shows F-17 data through March 31, and F-18 data from April 1 forward. Initial evaluation of the uncalibrated F-18 data indicates reasonable agreement with F-17, but the data should be considered provisional and quantitative comparisons with other data should not be done at this time.

Because these are provisional data, the Sea Ice Index has not been updated and continues to display only F-17 data through March 31. We expect to make the F-18 data available in Charctic soon.

For general information on the intercalibration of sensors, see the documentation for Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data. This documentation will be updated when the intercalibration to F-18 is complete.

For more information on the F-17 satellite sensor issues, see our previous post.

Categories: Climate Science News

Extended outage of NSIDC’s sea ice data source; April sea ice extent very low

NSIDC Artic Sea Ice News - Tue, 2016-05-03 13:05

The Defense Meteorological Satellite Program (DMSP) F17 satellite is experiencing continuing issues with its passive microwave sensor. Data from the 37V channel, used to observe sea ice, have been unusable since early April, although the 37H channel used for the Greenland Ice Sheet Today melt area mapping is unaffected. NSIDC is working to bring the DMSP F18 satellite online for its near-real-time source of data for sea ice monitoring. Based on other data sources, sea ice extent remains far below average for the satellite record period, and likely setting record daily lows. The April sea ice decline rate appears to have been slightly faster than average.

Overview of conditions sea ice concentration map

Figure 1a. Arctic sea ice concentration, in percent concentration, for May 1, 2016 from the Japan Aerospace Exploration Agency (JAXA) satellite Shizuku (GCOM-W1) AMSR2 instrument. Areas of ocean with at least 15% ice concentration are considered ice-covered, when calculating sea ice extent.

Credit: Japan Aerospace Exploration Agency, courtesy University of Bremen
High-resolution image

sea ice extent graphs

Figure 1b. The graphs show Arctic sea ice extent as of April 29, 2016, along with ice extent data for previous years. Top, sea ice extent for 2016 from the Japan Aerospace Exploration Agency (JAXA) satellite Shizuku (GCOM-W1) AMSR2 instrument. Bottom, similar plot using the same sensor but a different method and channel, from University of Bremen.

Credit: National Snow and Ice Data Center/JAXA/University of Bremen
High-resolution image

The Arctic Sea Ice News and Analysis reference sea ice product, the Sea Ice Index, will be suspended until a new calibration can be completed for the F18 satellite, which is underway. The Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument flying on Shizuku (GCOM-W1), a satellite operated by the Japan Aerospace Exploration Agency (JAXA), provides data on sea ice extent and rates of change, but because it uses a different sensor and processing algorithm, the extent numbers cannot be directly compared with those from the SMMR-SSM/I-SSMIS instruments record; the AMSR2 algorithm gives extents that differ by several tens of thousands of square kilometers, or a fraction of a percent to a few percent of total sea ice extent.

A look at the Arctic Data archive system at the National Institute of Polar Research in Japan reveals that sea ice since mid-April has remained at record low daily levels as assessed over their archive of sea ice extent, and is approximately 400,000 square kilometers (154,400 square miles) below the previous daily record extents at this time. This is supported by another analysis of sea ice extent produced by the University of Bremen using the same satellite but a different sensor channel. Both assessments of sea ice extent indicate that the April rate of decline for 2016 is slightly faster than the long-term average of their respective archives. Another sea ice monitoring site, The Cryosphere Today, continues to use the DMSP F17 data, and their graphics show evidence of the sensor issues. This site reports sea ice area in its graphical trend, not extent (area of ocean with at least 15% sea ice coverage) as do the other sites and NSIDC. However, the trend and record low daily extents for the second half of April may be interpreted from these data as well.

Conditions in context temperature and pressure anomaly plots

Figure 2. Left, sea level pressure for April 2016 relative to average conditions for the same month, 1981 to 2010. Right, air temperature departure from average for April 2016 at the 925 hPa level (approximately 2,500 feet altitude) relative to the same reference period.

Credit: National Snow and Ice Data Center/NOAA ESRL Physical Sciences Division
High-resolution image

April 2016 was quite warm over nearly all of the Arctic Ocean. Air temperatures at the 925 hPa level (about 2,500 feet above the surface) were typically 3 to 5 degrees Celsius (6 to 9 degrees Fahrenheit) above average over the central Arctic Ocean, with larger positive departures compared to average over central Siberia (6 to 8 degrees Celsius, or 11 to 18 degrees Fahrenheit). The sea level pressure pattern featured above average pressures over the Beaufort Sea north of Alaska, and below average pressures over the Aleutians, western Baffin Bay, and Scandinavia. The April 2016 Arctic Oscillation Index transitioned from positive to negative through the month, consistent with the varied patterns of pressure over the Arctic. See our previous discussion of the Arctic Oscillation.

Twist and shout MODIS animation

Figure 3. This series of images from April 1 to 24, 2016 shows recent fracturing and rotation of sea ice near Alaska and the western Canadian Arctic archipelago. Click on the image to see the animation. Images are from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument via NASA Worldview.

Credit: National Snow and Ice Data Center/NASA Worldview
Play the animation

Using a series of images from the Moderate Resolution Imaging Spectrometer (MODIS) from NASA Worldview, we created a short video showing sea ice drift north of Alaska in the Beaufort Sea. The strong anti-cyclonic (high air pressure) pattern produced surface winds that fractured the ice, twisting it in a clockwise direction and opening the pack ice significantly. Dramatic, similar fracturing of sea ice in the Beaufort Sea has been noted in earlier posts (see March 6, 2013).

 

Motion in the ocean ice age maps

Figure 4a. Sea ice age mappings for 2015, Week 36 (at the summer sea ice minimum extent) showing the differences between the old (left) and new (right) processing. The improvements in the new processing have resulted in changes in the ice age mapping.

Credit: National Snow and Ice Data Center, courtesy M. Tschudi, C. Fowler, J. Maslanik, R. Stewart/University of Colorado Boulder; W. Meier/NASA Cryospheric Sciences
High-resolution image
View comparison images for 2011 to 2015

age extent plot

Figure 4b. The graph compares the extent of ice in each age category (in years) for 2015 Week 36, at the time of the sea ice minima, from versions 2 (Old NRT) and 3 (New NRT) of the near-real-time ice age algorithm.

Credit: National Snow and Ice Data Center, courtesy W. Meier/NASA Cryospheric Sciences
High-resolution image

The NSIDC sea ice motion and sea ice age products have recently been updated via a release of Version 3. This version was created by re-running the previous algorithms, and incorporating a few improvements. First, a number of unrealistic AVHRR and buoy velocities that had been noted were removed. Also, a more accurate sea ice mask, based on the same sea ice concentration product used in our sea ice extent analysis, was implemented. Finally, the Version 3 updates include buoy-derived motions in the Arctic through the entire time series (1979 to 2015). Near-real-time processing of provisional ice age data, which are frequently shown here as a first look at ice conditions, has also been updated to include some of the improvements of Version 3, including the incorporation of near-real-time buoy data and NSIDC’s near-real-time sea ice concentration product as the basis for the sea ice mask. As with any near-real-time product, the fields should be considered provisional and are subject to change. Full details of the product changes and the new processing methods are included in the product documentation for Polar Pathfinder Daily 25 km EASE-Grid Sea Ice Motion Vectors, Version 3 and EASE-Grid Sea Ice Age, Version 3.

Categories: Climate Science News

Sensor on F-17 experiencing difficulties, sea ice time series temporarily suspended

NSIDC Artic Sea Ice News - Tue, 2016-04-12 15:27

NSIDC has suspended daily sea ice extent updates until further notice, due to issues with the satellite data used to produce these images. The vertically polarized 37 GHz channel (37V) of the Special Sensor Microwave Imager and Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) F-17 satellite that provides passive microwave brightness temperatures is providing spurious data. The 37V channel is one of the inputs to the sea ice retrieval algorithms, so this is resulting in erroneous estimates of sea ice concentration and extent. The problem was initially seen in data for April 5 and all data since then are unreliable, so we have chosen to remove all of April from NSIDC’s archive.

It is unknown at this time if or when the problem with F-17 can be fixed. In the event that the sensor problem has not been resolved, NSIDC is working to transition to another satellite in the DMSP series. Transitioning to a different satellite will require a careful calibration against the F-17 data to ensure consistency over the long-term time series. While this transition is of high priority, NSIDC has no firm timeline on when it will be able to resume providing the sea ice time series. For background information on the challenges of using data in near-real-time, see the ASINA FAQ, “Do your data undergo quality control?

Categories: Climate Science News

Daily images showing spurious data

NSIDC Artic Sea Ice News - Mon, 2016-04-11 09:50

The daily sea ice extent images are sporadically displaying erroneous data. NSIDC is investigating with our satellite data providers.

Categories: Climate Science News

March ends a most interesting winter

NSIDC Artic Sea Ice News - Wed, 2016-04-06 09:20

Low Arctic sea ice extent for March caps a highly unusual winter in the Arctic, characterized by persistent warmth in the atmosphere that helped to limit ice growth. Above-average influx of ocean heat from the Atlantic and southerly winds helped to keep ice extent especially low in the Barents and Kara seas. Northern Hemisphere snow cover for both February and March was also unusually low

Overview of conditions Figure 1. Arctic sea ice extent for March 2016 was 14.43 million square kilometers (5.57 million square miles). The magenta line shows the 1981 to 2010 median extent for that month.

Figure 1. Arctic sea ice extent for March 2016 was 14.43 million square kilometers (5.57 million square miles). The magenta line shows the 1981 to 2010 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Sea ice extent reached its seasonal maximum on March 24 of 14.52 million square kilometers (5.607 million square miles), barely beating out February 25, 2015 for the lowest seasonal maximum in the satellite record. Arctic sea ice extent averaged for the entire month of March 2016 was 14.43 million square kilometers (5.57 million square miles), the second lowest in the satellite record. This is 1.09 million square kilometers (421,000 square miles) below the 1981 to 2010 average extent, and 40,000 square kilometers (15,000 square miles) above the record low monthly average for March that occurred in 2015. At the end of the month, extent remained well below average everywhere except in the Labrador Sea, Baffin Bay, and Hudson Bay. Ice extent was especially low in the Barents and Kara seas.

Conditions in context Figure 2. The graph above shows Arctic sea ice extent as of April 3, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2013 in brown, and 2011 to 2012 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data.

Figure 2. The graph above shows Arctic sea ice extent as of April 3, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2013 in brown, and 2011 to 2012 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Because ice extent typically climbs through the first part of March until it reaches its seasonal maximum and then declines, the daily average ice growth rate for the month is typically quite small and is not a particularly meaningful number. This year’s seasonal maximum, while quite low, also occurred rather late in the month. Very early in the month, extent declined, raising anticipation that an early maximum had been reached. However, after a period of little change, extent slowly rose again, reaching the seasonal maximum on March 24.

March of 2016 saw unusually warm conditions over nearly all of the Arctic Ocean. Air temperatures at the 925 hPa level (about 3,000 feet above the surface) were typically 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) above average over the Arctic coastal seas, with larger positive departures compared to average nearer the Pole (4 to 8 degrees Celsius or 7 to 14 degrees Fahrenheit). This was associated with a pattern of above-average sea level pressures centered over the northern Beaufort Sea north of Alaska, and below-average pressures over the Atlantic side of the Arctic, especially pronounced over Baffin Bay and Davis Strait. Through March, the Arctic Oscillation Index bounced between moderate positive and negative values.

March 2016 compared to previous years  National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly March ice extent for 1979 to 2016 shows a decline of 2.7 percent per decade.

Credit: National Snow and Ice Data Center
High-resolution image

Arctic sea ice extent averaged for March 2016 was the second lowest in the satellite record. Through 2016, the linear rate of decline for March extent is 2.7 percent per decade, or a decline of 42,100 square kilometers (16,200 square miles) per year.

The winter in review Figure 4. This graph shows differences in Arctic sea ice from December 28, 2015 to January 4, 2016, estimated from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS).

Figure 4. This graph shows differences in Arctic sea ice thickness from December 28, 2015 to January 4, 2016, estimated from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS).

Credit: National Snow and Ice Data Center, courtesy PIOMAS
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Figure 5. This figure shows observed (blue columns) and predicted (cyan) winter sea ice area in the Barents Sea. The prediction is based on observed Atlantic heat entering the Barents Sea and the sea ice area the previous year. The predicted sea ice area for this winter (2016) is well below average, and less than that observed for 2015. Anomalously strong southerly winds have also contributed to the very small sea ice area this winter (not shown).

Figure 5. This figure shows observed (blue columns) and predicted (cyan) winter sea ice area in the Barents Sea. The prediction is based on observed Atlantic heat entering the Barents Sea and the sea ice area the previous year. The predicted sea ice area for this winter (2016) is well below average, and less than that observed for 2015. Anomalously strong southerly winds have also contributed to the very small sea ice area this winter (not shown).

Credit: Ingrid Onarheim/Bjerknes Centre for Climate Research
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 National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab| High-resolution image

Figure 6. This snow cover anomaly map shows the percent difference between snow cover for March 2016, compared with average snow cover for March from 1981 to 2010. Areas in orange and red indicate lower than usual snow cover, while regions in blue had more snow than average.

Credit: National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab
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Figure 7. This graph shows snow cover extent anomalies in the Northern Hemisphere for March from 1967 to 2016. The anomaly is relative to the 1981 to 2010 average.

Figure 7. This graph shows snow cover extent anomalies in the Northern Hemisphere for March from 1967 to 2016. The anomaly is relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab
High-resolution image

The unusual warmth for March of 2016 continues a pattern of above-average temperatures for most of the Arctic and much of the Northern Hemisphere that has characterized the entire winter. As an exclamation point on the unusual warmth, there was a brief weather event at the very end of December 2015 when air temperatures near the Pole nearly reached the melting point. As we noted in our January post, the event was related to a pulse of warm air moving almost due south to north from the sub-tropical Atlantic to the regions north of Svalbard, an atmospheric river set between broad high and low pressure areas in Europe and the north Atlantic.

The December event also led to higher than average air temperatures over the Kara and Barents seas, reducing the sea ice concentration and causing thinning of the ice that was there. While sea ice normally grows and thickens over winter, the difference in thickness estimated from Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) shows that between December 28, 2015 and January 4, 2016, sea ice within the Kara and Barents seas thinned by more than 30 centimeters (Figure 4). Thinning also occurred north of Greenland and off the coast of Siberia, while the ice thickened over most of the Arctic Ocean. Higher than average temperatures remained in the region after the weather event had passed, which may have further prevented the ice from growing back. The reasons for the persistent warmth over the entire Arctic this past winter are currently under investigation; a link with the strong El Niño pattern of this winter may be involved.

While the warm atmospheric conditions played a role in the low ice extent for March 2016, the especially low extent that has persisted in the Barents and Kara seas appears to be linked with another heat source—an influx of warm Atlantic waters, entering between Bear Island and Norway (the Barents Sea opening). Ingrid Onarheim from the Bjerknes Centre for Climate Research in Bergen, Norway has been studying this issue and predicted a small sea ice cover in the Barents Sea this winter based on observed Atlantic heat transport to the Barents Sea through April 2015 (Figure 5). In addition to the above-average ocean heat transport, prevailing southerly winds have pushed the sea ice northward since November 2015, bringing in warm air that damps the normally high ocean-air heat loss and favoring ice formation. This likely contributed to the below-average ice conditions in the Arctic this winter. Atlantic heat transport due to near-surface ocean currents reached a long-term maximum in the mid-2000s. Several studies have suggested a more moderate inflow of Atlantic waters may characterize the years ahead, leading to increases in the Barents Sea ice cover in the coming years.

Along with low sea ice extent and above-average temperatures, March of 2016 also saw a very low monthly snow cover extent for the Northern Hemisphere (Figures 6 and 7). Snow cover was low across northern Eurasia, with only minor areas of above-average snow cover in western Turkey, northern Kazakhstan and Mongolia, and easternmost High-Mountain Asia. In North America, snow cover was low across nearly all of the coterminous 48 states in the U.S., despite a series of storms late in the month in the central Rockies and Great Plains. Overall, March 2016 had 37.16 million square kilometers (14.35 million square miles) of snow cover extent, 2.97 million square kilometers (1.15 million square miles) below the 1981 to 2010 average of 40.13 million square kilometers (15.50 million square miles). This makes March 2016 the 49th lowest out of 50 years on record in snow cover extent for the Northern Hemisphere. While April and May could still bring snow to the higher latitudes, we note that low snow cover, similar to low sea ice cover, leads to greater heat absorption by the surface in the Arctic and further warming as we move toward summer.

A younger ice cover  NSIDC courtesy University of Colorado Boulder, M. Tschudi, C. Fowler, J. Maslanik, R. Stewart, W. Meier.

Figure 8. These graphs show Arctic sea ice age from March 4 to 10, 2016. The top graph shows ice age distribution for that week alone and the bottom graph shows ice age distribution for that week from 1985 to 2016.

Credit: NSIDC courtesy University of Colorado Boulder, M. Tschudi, C. Fowler, J. Maslanik, R. Stewart, W. Meier.
High-resolution image

Ice age data for mid-March shows that 70 percent of the sea ice within the Arctic basin consists of first-year ice and only 30 percent is multiyear ice. First-year ice is generally only 1.5 to 2 meters (5 to 6.5 feet) thick. This implies a thinner ice pack as the melt season gets underway. In addition, the oldest ice, or ice at least 5 years or older, is at its smallest level in the satellite record, representing only 3 percent of the total ice cover. Some of this very old ice is found in the western Beaufort Sea and extending towards the Chukchi Sea regions where we have seen large summer ice losses in recent years. Typically this old ice is concentrated north of Greenland and within the Canadian Arctic Archipelago.

Not only is the oldest ice at record low levels, but it it is not recovering. Beginning 2007, we see a strong decline that lasts until 2012 and has not changed much since. If anything it has gone down. In that time we have seen some recovery in younger multiyear ice types: e.g., 2-year ice jumped back up after a one-year minimum, 3-year ice recovered to a lesser degree, and 4-year ice to an even lesser degree. It is not surprising to see some recovery and that first-year ice recovery propagates through time. However, that recovery happens less as the ice gets older, and for 5-year ice and older there is essentially no recovery. The bottom line is that ice no longer survives in the Arctic for very long. It is lasting three to four years tops before melting or advecting out through Fram Strait. This is a big change from the past when much of the ice cover would survive upwards of a decade.

Southern view

Antarctic sea ice grew rapidly in March, rising from below-average daily extents to above-average extents during the month, and increasing by nearly 90,000 square kilometers (35,000 square miles) per day. Sea ice growth was particularly fast in the eastern Ross Sea. Winter temperatures on the continent through the month were near-average overall, but 4 to 6 degrees Celsius (7 to 11 degrees Fahrenheit) below average over the eastern Ross Sea and West Antarctic Ice Sheet.

 

Categories: Climate Science News

Another record low for Arctic sea ice maximum winter extent

NSIDC Artic Sea Ice News - Mon, 2016-03-28 12:00

Arctic sea ice appears to have reached its annual maximum extent on March 24, and is now the lowest maximum in the satellite record, replacing last year’s record low. This year’s maximum extent occurred later than average. A late season surge in ice growth is still possible. NSIDC will post a detailed analysis of the 2015 to 2016 winter sea ice conditions in early April.

Overview of conditions

Figure 1. Arctic sea ice extent for March 24, 2016 was 14.52 million square kilometers (5.607 million square miles). The orange line shows the 1981 to 2010 median extent for that day. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

On March 24, 2016, Arctic sea ice likely reached its maximum extent for the year, at 14.52 million square kilometers (5.607 million square miles). This year’s maximum ice extent was the lowest in the satellite record, with below-average ice conditions everywhere except in the Labrador Sea, Baffin Bay, and Hudson Bay. The maximum extent is 1.12 million square kilometers (431,000 square miles) below the 1981 to 2010 average of 15.64 million square kilometers (6.04 million square miles) and 13,000 square kilometers (5,000 square miles) below the previous lowest maximum that occurred last year. This year’s maximum occurred twelve days later than the 1981 to 2010 average date of March 12. The date of the maximum has varied considerably over the years, occurring as early as February 24 in 1996 and as late as April 2 in 2010.

Conditions in context Figure 2. The graph above shows Arctic sea ice extent as of March 27, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2013 in brown, and 2011 to 2012 in purple. The 1981 to 2010 average is in dark gray.

Figure 2. The graph above shows Arctic sea ice extent as of March 27, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2013 in brown, and 2011 to 2012 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

Sea ice extent was below average throughout the Arctic, except in the Labrador Sea, Baffin Bay, and Hudson Bay. However, it was especially low in the Barents Sea. Below average winter ice conditions in the Kara and Barents seas have been a persistent feature in the last several years, while the Bering Sea has overall seen slightly positive trends towards more sea ice during winter.

Below average sea ice extent is in part a result of higher than average temperatures that have plagued the Arctic all winter. Air temperatures at the 925 hPa level from December 2015 through February 2016 were above average everywhere in the Arctic, with hotspots near the Pole and from the Kara Sea towards Svalbard exceeding 6 Celsius degrees (11 degrees Fahrenheit) above average. These higher than average temperatures continued into March, with air temperatures during the first two weeks reaching 6 degrees Celsius (11 degrees Fahrenheit) above average in a region stretching across the North Pole toward northern Greenland, and up to 12 degrees Celsius (22 degrees Fahrenheit) above average north of Svalbard.

These unusually warm conditions have no doubt played a role in the record low ice extent this winter. Another contributing factor has been a predominance of southerly winds in the Kara and Barents seas that have helped to keep the ice edge northward of its typical position. This area has also seen an influx of warm Atlantic waters from the Norwegian Sea.

There is little correlation between the maximum winter extent and the minimum summer extent—this low maximum does not ensure that this summer will see record low ice conditions. A key factor is the timing of widespread surface melting in the high Arctic. An earlier melt onset is important to the amount of energy absorbed by the ice cover during the summer. If surface melting starts earlier than average, the snow darkens and exposes the ice below earlier, which in turn increases the solar heat input, allowing more ice to melt. With the likelihood that much of the Arctic cover is somewhat thinner due to the warm winter, early surface melting would favor reduced summer ice cover.

Final analysis pending

At the beginning of April, NSIDC scientists will release a full analysis of winter conditions, along with monthly data for March. For more information about the maximum extent and what it means, see the NSIDC Icelights post, the Arctic sea ice maximum.

 

Categories: Climate Science News

February continues streak of record low Arctic sea ice extent

NSIDC Artic Sea Ice News - Wed, 2016-03-02 11:00

Arctic sea ice was at a satellite-record low for the second month in a row. The first three weeks of February saw little ice growth, but extent rose during the last week of the month. Arctic sea ice typically reaches its maximum extent for the year in mid to late March.

Overview of conditions  National Snow and Ice Data Center|High-resolution image

Figure 1. Arctic sea ice extent for February 2016 was 14.22 million square kilometers (5.48 million square miles). The magenta line shows the 1981 to 2010 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Arctic sea ice extent for February averaged 14.22 million square kilometers (5.48 million square miles), the lowest February extent in the satellite record. It is 1.16 million square kilometers (448,000 square miles) below the 1981 to 2010 long-term average of 15.4 million square kilometers (5.94 million square miles) and is 200,000 square kilometers (77,000 square miles) below the previous record low for the month recorded in 2005.

The first three weeks of February saw little ice growth, but extent rose during the last week of the month primarily due to growth in the Sea of Okhotsk (180,000 square kilometers or 70,000 square miles) and to a lesser extent in Baffin Bay (35,000 square kilometers or 13,500 square miles). Extent is presently below average in the Barents and Kara seas, as well as the Bering Sea and the East Greenland Sea. Extent decreased in the Barents and East Greenland seas during the month of February. In other regions, such as the Sea of Okhotsk, Baffin Bay, and the Labrador Sea, ice conditions are near average to slightly above average for this time of year. An exception is the Gulf of St. Lawrence, which remains largely ice free.

In the Antarctic, sea ice reached its minimum extent for the year on February 19, averaging 2.6 million square kilometers (1 million square miles). It is the ninth lowest Antarctic sea ice minimum extent in the satellite record.

Conditions in context Figure 2a. The graph above shows Arctic sea ice extent as of March 1, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2013 in brown, and 2011 to 2012 in purple.

Figure 2a. The graph above shows Arctic sea ice extent as of March 1, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2013 in brown, and 2011 to 2012 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

Figure 2b. These three images show two-week average Arctic sea ice drift data from January through mid-February derived from the Advanced Microwave Scanning Radiometer 2 (AMSR-2). The image on the left shows the period January 1 to 15, the middle image shows January 14 to 31, and the image on the right shows February 1 to 16. ||Images courtesy Alek Petty/NASA Goddard Space Flight Center/University of Maryland, data from Centre ERS d'Archivage et de Traitement (CERSAT)/French Institute for Exploration (Ifremer)| High-resolution image

Figure 2b. These three images show two-week average Arctic sea ice drift data from January through mid-February derived from the Advanced Microwave Scanning Radiometer 2 (AMSR-2). The image on the left shows the period January 1 to 15, the middle image shows January 14 to 31, and the image on the right shows February 1 to 16.

Credit: Alek Petty/NASA Goddard Space Flight Center/University of Maryland, data from Centre ERS d’Archivage et de Traitement (CERSAT)/French Institute for Exploration (Ifremer)
High-resolution image

NASA and NOAA announced that January 2016 was the ninth straight month of record-breaking high surface temperatures for the globe. In terms of regional patterns, the Arctic stands out, with surface temperatures more than 4 degrees Celsius (7.2 degrees Fahrenheit) above the 1951 to 1980 average. These high temperatures were in part responsible for the record low sea ice extent observed for January. Persistent warmth has continued into February; air temperatures at the 925 hPa level were 6 to 8 degrees Celsius (11 to 14 degrees Fahrenheit) above the 1981 to 2010 average over the central Arctic Ocean near the pole. The rate of ice growth for February was near average at 19,700 square kilometers (7,600 square miles) per day, compared to 20,200 square kilometers (7,800 square miles) per day for the 1981 to 2010 average.

Atmospheric circulation patterns have also favored low sea ice extent, particularly in the Barents and Kara seas. Ice motion drift data derived from the Advanced Microwave Scanning Radiometer 2 (AMSR2) satellite and provided by the Centre ERS d’Archivage et de Traitement (CERSAT) show that since January 1, there has been cyclonic, or counterclockwise, sea ice motion in the Barents Sea helping to keep sea ice from advancing south. During the second half of January, an anti-cyclonic, or clockwise, circulation pattern developed in the Beaufort Sea, which subsequently strengthened and expanded to include most of the Arctic Ocean. This, combined with high pressure over Greenland and low pressure over Spitsbergen, has favored enhanced ice export out of Fram Strait, helping to flush old, thick ice out of the Arctic Ocean, leaving behind thinner ice that is more apt to melt away in summer. Whether this circulation pattern will continue and set the stage for very low September sea ice extent remains to be seen.

February 2016 compared to previous years  National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly February sea ice extent for 1979 to 2016 shows a decline of 3.0 percent per decade.

Credit: National Snow and Ice Data Center
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February 2016 sea ice extent was the lowest in the satellite record at 14.22 million square kilometers (5.48 million square miles). The linear rate of decline for February is now 3.0 percent per decade.

Record warmth revealed by the AIRS instrument Figure 4. These two images show February 2016 departures from the 2003 to 2015 average for 925 hPa air temperature (left) and precipitable water (right) as derived from the NASA AIRS instrument.||Images courtesy Linette Boisvert/NASA Goddard Space Flight Center.| High-resolution image

Figure 4. These two images show February 2016 departures from the 2003 to 2015 average for 925 hPa air temperature (left) and precipitable water (right) as derived from the NASA AIRS instrument.

Credit: Linette Boisvert/NASA Goddard Space Flight Center
High-resolution image

Since 2003, the Atmospheric Infrared Sounder (AIRS) onboard the NASA Aqua satellite has collected daily temperature and humidity profiles globally. Although the record is fairly short, AIRS data can provide insight into recent changes in Arctic climate. February average air temperatures, measured by AIRS at 925 hPa, are around 5 degrees Celsius (9 degrees Fahrenheit) above the 2003 to 2015 average over the Beaufort and Chukchi seas and the central Arctic Ocean. Above-average temperatures are also the rule over the Kara Sea and Northern Siberia (6 degrees Celsius or 11 degrees Fahrenheit above average). Regions with especially higher than average temperatures correspond to regions of low sea ice, demonstrating the role played by heat fluxes from open water areas. For example, the Sea of Okhotsk experienced below-average air temperatures, and also had above-average sea ice extents, whereas the Kara, Barents, and Bering seas and the Gulf of St. Lawrence had higher air temperatures compared to average, which coincides with lower than average sea ice extent.

A similar relationship is seen in the total precipitable water for February 2016. Precipitable water is the amount of water vapor in the atmospheric column totaled from the surface to the top of the troposphere, expressed as kilograms of water per square meter (one kilogram per square meter equals 1 millimeter of water depth). In February, areas with precipitable water between 12 percent (Bering Sea) to 70 percent (Kara Sea) above the 2003 to 2015 February average corresponded to regions with below-average sea ice extent. Water vapor is a greenhouse gas, and with more water vapor in the air, there is a stronger emission of longwave radiation to the surface. Conversely, the observation that above-average amounts of water vapor are found over areas of reduced sea ice extent points to a role of local evaporation, and evaporation is a cooling process that by itself will favor ice growth.

A late freeze-up  National Snow and Ice Data Center, data provided by J. Miller/T. Markus, NASA Goddard Space Flight Center I High-resolution image

Figure 5. This images shows freeze-up anomalies in the Arctic for 2015. Reds indicate areas where freeze-up began later than average and blues indicate freeze-up beginning earlier than average.

Credit: National Snow and Ice Data Center, data provided by J. Miller/T. Markus, NASA Goddard Space Flight Center
High-resolution image

Sea ice reformed or refroze later than average throughout most of the Arctic, especially in the Kara and Barents seas where the freeze-up happened about two months later than average. Ice was also late to form in the Beaufort, Chukchi, East Siberian, and Laptev seas, between ten and forty days later than average. In contrast, the timing of freeze-up over the central Arctic Ocean near the pole was near average, as was also the case in Baffin Bay and parts of Hudson Bay. When freeze-up happens late, the ice has less time to thicken before the melt season starts, leading to a thinner ice cover that is more prone to melting out in summer.

References

NASA Goddard Institute for Space Studies. Global Land-Ocean Temperature Index in 0.01 degrees Celsius. http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt.

NASA Goddard Institute for Space Studies. NASA, NOAA Analyses Reveal Record-Shattering Global Warm Temperatures in 2015. http://www.giss.nasa.gov/research/news/20160120.

National Oceanic and Atmospheric Administration. Global Analysis – January 2016. https://www.ncdc.noaa.gov/sotc/global/201601.

 

Categories: Climate Science News

January hits new record low in the Arctic

NSIDC Artic Sea Ice News - Thu, 2016-02-04 13:20

January Arctic sea ice extent was the lowest in the satellite record, attended by unusually high air temperatures over the Arctic Ocean and a strong negative phase of the Arctic Oscillation (AO) for the first three weeks of the month. Meanwhile in the Antarctic, this year’s extent was lower than average for January, in contrast to the record high extents in January 2015.

Overview of conditions sea ice extent map

Figure 1. Arctic sea ice extent for January 2016 was 13.53 million square kilometers (5.2 million square miles). The magenta line shows the 1981 to 2010 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Arctic sea ice extent during January averaged 13.53 million square kilometers (5.2 million square miles), which is 1.04 million square kilometers (402,000 square miles) below the 1981 to 2010 average. This was the lowest January extent in the satellite record, 90,000 square kilometers (35,000 square miles) below the previous record January low that occurred in 2011. This was largely driven by unusually low ice coverage in the Barents Sea, Kara Sea, and the East Greenland Sea on the Atlantic side, and below average conditions in the Bering Sea and Sea of Okhotsk. Ice conditions were near average in Baffin Bay, the Labrador Sea and Hudson Bay. There was also less ice than usual in the Gulf of St. Lawrence, an important habitat for harp seals.

Conditions in context Figure 2a. The graph above shows Arctic sea ice extent as of February 3, 2016

Figure 2a. The graph above shows Arctic sea ice extent as of February 3, 2016, along with daily ice extent data for four previous years. 2015 to 2016 is shown in blue, 2014 to 2015 in green, 2013 to 2014 in orange, 2012 to 2011 in brown, and 2011 to 2012 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

 National Snow and Ice Data Center, courtesy NOAA Earth System Research Laboratory Physical Sciences Division| High-resolution image

Figure 2b. These graphs show average sea level pressure and air temperature anomalies at 925 millibars (about 3,000 feet above sea level) for January 2016.

Credit: National Snow and Ice Data Center, courtesy NOAA Earth System Research Laboratory Physical Sciences Division
High-resolution image

January 2016 was a remarkably warm month. Air temperatures at the 925 hPa level were more than 6 degrees Celsius (13 degrees Fahrenheit) above average across most of the Arctic Ocean. These unusually high air temperatures are likely related to the behavior of the AO. While the AO was in a positive phase for most of the autumn and early winter, it turned strongly negative beginning in January. By mid-January, the index reached nearly -5 sigma or five standard deviations below average. The AO then shifted back to positive during the last week of January. (See the graph at the NOAA Climate Prediction Web site.)

The sea level pressure pattern during January, which featured higher than average pressure over northern central Siberia into the Barents and Kara sea regions, and lower than average pressure in the northern North Pacific and northern North Atlantic regions, is fairly typical of the negative phase of the AO. Much of the focus by climate scientists this winter has been on the strong El Niño. However, in the Arctic, the AO is a bigger player and its influence often spills out into the mid-latitudes during winter by allowing cold air outbreaks. How the AO and El Niño may be linked remains an active area of research.

January 2016 compared to previous years extent trend graph

Figure 3. Monthly January ice extent for 1979 to 2016 shows a decline of 3.2% per decade.

Credit: National Snow and Ice Data Center
High-resolution image

The monthly average January 2016 sea ice extent was the lowest in the satellite record, 90,000 square kilometers (35,000 square miles) below the previous record low in 2011. The next lowest extent was in 2006. Interestingly, while 2006 and 2011 did not reach record summer lows, they both preceded years that did, though this may well be simply coincidence.

The trend for January is now -3.2% per decade. January 2016 continues a streak that began in 2005 where every January monthly extent has been less than 14.25 million square kilometers (5.50 million square miles). In contrast, before 2005 (1979 through 2004), every January extent was above 14.25 million square kilometers.

Predicting decadal trends in Arctic winter sea ice cover sea ice change graphic

Figure 4. The map shows areas of the Arctic where sea ice models predicted ice gain and loss for 2007 to 2017

Credit: S. Yeager et al.
High-resolution image

Observations show an increase in the rate of winter sea ice loss in the North Atlantic sector of the Arctic up until the late 1990s followed by a slowdown in more recent years. The observed trend over the period 2005 to 2015 is actually positive (a tendency for more ice). In a paper recently published in Geophysical Research Letters, scientists at the National Center for Atmospheric Research (NCAR) show that the Community Earth System Model (CESM) was able to predict this period of winter ice growth in the North Atlantic. The study further suggests that in the near future, sea ice extent in this part of the Arctic is likely to remain steady or even increase (Figure 4). The ability to predict the winter sea ice extent in this region is related to the ability of the model to capture the observed variability in the Atlantic Meridional Overturning Circulation (MOC), an ocean circulation pattern that brings warm surface waters from the tropics towards the Arctic. When the MOC is strong, more warm water is brought towards the North Atlantic sector of the Arctic, helping to reduce the winter ice cover. When it is weak, less warm water enters the region and the ice extends further south. However, while there is an indication that the MOC may be weakening, this winter so far has seen considerably less ice than average in the North Atlantic sector.

References

Yeager, S. G., A. R. Karspeck, and G. Danabasoglu. 2015. Predicted slowdown in the rate of Atlantic sea ice loss. Geophysical Research Letters, 42, 10,704–10,713, doi:10.1002/2015GL065364.

Correction

On February 8, 2016, a reader called our attention to contradictory sentences in our post. We have corrected the erroneous sentence in the section January 2016 compared to previous years. The sentence used to read “The monthly average January 2016 sea ice extent was the lowest in the satellite record, 110,000 square kilometers (42,500 square miles) less than the previous record low in 2011.” We’ve corrected it to “The monthly average January 2016 sea ice extent was the lowest in the satellite record, 90,000 square kilometers (35,000 square miles) below the previous record low in 2011.” as stated in the section Overview of conditions.

Categories: Climate Science News

A strong El Niño this year ?

AVISO Climate Change News - Tue, 2015-09-01 05:00
Satellite altimetry, which measures  sea surface height (which rises with higher temperatures during El Niño or falls with colder temperatures during La Niña), is vital for the early detection, analysis and close monitoring of these phenomena. Altimetry contributes to their forecasts. It is also an important asset to be able to better understand them, and thus better forecast them, including their intensity. With the continuity of altimetry since 1992, an unprecedented time series has been collected. Next satellites will help by ensuring continuity of observations, and improving data quality. An El Niño was announced early in May 2015. At this time, maps of Sea Level Anomalies showed large areas across the equatorial Pacific with above average. Sea Surface Temperature were also above-average on May 2015 and strengthenes across the east-central Pacific during summer. Those conditions were as high as observed during 1987 El-Niño, and thus forecasts are close to that episode. By keeping in mind, the last years when El Niño aborted, the 2015 event is examined in detail and particularly the atmospheric features. During July easterly winds were weaker than normal. The ocean-atmosphere coupling was in place: El Niño conditions are present. On August, anomalies of sea surface temperatures in the equatorial Pacific Ocean are above average of +2°C. If this anomaly persists during the next three months, a strong event would be reached. Models currently predict a strong event at its peak in late fall/early winter (2015).

Monthly mean of Sea Level Anomalies (annual and seasonal cycles removed)measured by altimetry over the Pacific for August 1997 (left) and August 2015 (right). Credits CNES/CLS.

Further information:
  • Indicators: ENSO
  • Applications: Climate, ENSO
  • Image of the month, July 2015 "El Niño's return, west side story".
  • ENSO current conditions on CPC/NCEP website
  • Météo France (2015/08/28): Vers un épisode El Niño de forte intensité (in french)
Categories: Climate Science News

Feeling the heat

NASA Climate News - Fri, 2012-09-14 00:09
A former intern tells why she?s returned to JPL
Categories: Climate Science News

Grace mission offers a novel view of Earth?s water supplies

NASA Climate News - Thu, 2012-09-13 02:09
The Grace mission offers a novel and much needed view of Earth?s water supplies.
Categories: Climate Science News

'Earth Now' available for Android

NASA Climate News - Mon, 2012-09-10 02:09
Follow the vital signs of our planet
Categories: Climate Science News

NASA's Global Hawk mission begins with flight to Hurricane Leslie

NASA Climate News - Fri, 2012-09-07 01:09
NASA has begun its latest hurricane science field campaign.
Categories: Climate Science News

NASA voyage set to explore link between sea saltiness and climate

NASA Climate News - Tue, 2012-09-04 22:09
A NASA-sponsored expedition is set to sail to the North Atlantic's saltiest spot.
Categories: Climate Science News

No surprise

NASA Climate News - Wed, 2012-08-29 05:08
JPL ice expert reflects on record Arctic low
Categories: Climate Science News

New Arctic minimum

NASA Climate News - Mon, 2012-08-27 22:08
Sea ice breaks lowest extent on record
Categories: Climate Science News

Tracking shuttle exhaust reveals more information about atmospheric winds

NASA Climate News - Mon, 2012-08-27 22:08
On July 8, 2011 the Space Shuttle Atlantis launched for the very last time. As the shuttle reached a height of about 70 miles over the east coast of the U.S., it released ? as it always did shortly after launch ? 350 tons of water vapor exhaust.
Categories: Climate Science News

Tropical storm Isaac brings heavy rains to eastern Caribbean

NASA Climate News - Wed, 2012-08-22 23:08
NASA's Tropical Rainfall Measuring Mission satellite captured rainfall data from Tropical Storm Isaac as it continues moving through the Caribbean Sea.
Categories: Climate Science News

NASA expands network for measurement of tiny airborne particles

NASA Climate News - Thu, 2012-08-16 01:08
Scientists at NASA have added yet another instrument to an expanding climate research hub at NASA's Langley Research Center, putting Hampton, Va., on the map in a worldwide network of atmospheric measurements.
Categories: Climate Science News

Summer storm spins over Arctic

NASA Climate News - Mon, 2012-08-13 22:08
An unusually strong storm formed off the coast of Alaska on August 5 and tracked into the center of the Arctic Ocean, where it slowly dissipated over the next several days.
Categories: Climate Science News
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