ARCTIC CLIMATE CHARACTERISTICS AND RECENT TRENDS FROM SPACE
Xuanji Wang 1, Jeffrey R. Key 2, Taneil Uttal 3, and Shelby Frisch 4
1Cooperative
Institute for Meteorological Satellite Studies (CIMSS)/Space Science and Engineering Center (SSEC), UW-Madison, Madison, Wisconsin;
2Office of Research and Applications (ORA), NOAA/NESDIS, Madison, Wisconsin; 3NOAA Environmental Technology Laboratory (ETL), Boulder, Colorado;
4Cooperative Institute for Research of the Atmosphere (CIRA), Colorado State University, Fort Collins, Colorado.
Introduction
With broad spectral coverage and high spatial and
temporal resolutions, satellite sensors can provide the
data needed for the analysis of spatial and temporal
variations of climate parameters in data-sparse regions
such as the Arctic and Antarctic. The newly available
Advanced Very High Resolution Radiometer AVHRR
Polar Pathfinder (APP) data set was extended to
include cloud fraction, cloud optical depth, cloud
particle phase and size, cloud-top pressure and
temperature, surface skin temperature, surface
broadband albedo, radiative fluxes, and cloud forcing
(hereafter APP-x dataset) for the polar regions over the
19-yr period from 1982 to 2000. The APP-x data set
has been compared with the surface data collected
during the Surface Heat Balance of the Arctic Ocean
(SHEBA) field experiment in the western Arctic, with
the data from Arctic and Antarctic meteorological
stations and cloud radar measurements collected in
Barrow, Alaska. Numerous modeling studies have
shown that the Arctic is one of the most sensitive
regions on Earth to global climate change due to the
positive feedback between surface temperature, surface
albedo, and ice extent, known as the ice-albedo
feedback. The purpose of this work is to draw a more
complete picture of the Arctic climate by describing
the temporal and spatial characteristics of the climate
components. First and second order statistics will be
given for surface, cloud, and radiation properties as a
whole and for 18 sub-areas, by season and in the
annual mean. Recent Arctic climate trends in surface,
cloud, and radiation properties over the period 19822000 based on the APP-x data set are presented and
discussed. Possible linkages to global climate change
are investigated preliminarily.
APP-x Data Set Validation
Fig.2. Comparisons between APP-x and SHEBA in surface skin temperature (above left)
and in surface broadband albedo (above right) in a 25 x 25 km2 box with SHEBA ship
centered. Cloud fraction is also shown at the bottom.
Fig.8. Annual cycles of the surface skin temperature,
Fig.7. Spatial distribution of the annual mean
surface skin temperatures in Celsius degree
averaged over the period 1982–2000 on 14:00
LST for the Arctic ocean and surrounding
landmasses.
surface broadband albedo, cloud temperature and
atmospheric precipitable water averaged over the
period 1982–2000 on 14:00 LST for the Arctic ocean
and surrounding landmasses north of 60oN.
Fig.3. Comparisons between APP-x and SHEBA in surface downwelling shortwave
radiation (above left) and in surface downwelling longwave radiation (above right) over a
25 x 25 km2 box with SHEBA ship centered. Cloud fraction is also shown at the bottom.
Fig.10. Annual cycles of cloud fraction, cloud optical
depth, cloud particle effective radius and phase
averaged over the period 1982–2000 on 14:00 LST
for the Arctic ocean and surrounding landmasses
north of 60oN.
Fig.9. Spatial distribution of the annual mean cloud
fraction on a scale of 0 to 1 averaged over the period
1982–2000 on 14:00 LST for the Arctic ocean and
surrounding landmasses.
Fig.4. Cloud fraction from APP-x
data, radar measurements, and
monthly average CERES-TEAM
retrievals based on MODIS data.
Note that APP-x data calculated from
1998-2000, and CERES TEAM data
calculated from 2000-2003.
Fig.14. Correlation coefficient images between monthly Arctic Oscillation (AO) indices and the
surface temperature anomalies on 14:00 LST (Left) and 04:00 LST (Right) over the period 1982–
2000. The color scale indicates the correlation coefficient values; the contours give the statistical
confidence levels in percent (%) based on the Student’s T test.
APPX
RADAR
CERES-TEAM
Conclusions
Fig.5. Cloud visible optical depth
from APP-x data, radar measurements,
and monthly mean CERES-TEAM
retrievals based on MODIS data. Note
that APP-x data calculated from 19982000, and CERES TEAM data
calculated from 2000-2003. Note that
“*” indicates that radar had less than
15 days of data due to outages in that
month.
Retrieval Algorithm
Appx_T14= 0.179639614 * year - 108.0156521
Appx_T4= 0.1689407018 * year- 88.99823825
Appx_t14 = 0.1515994211 * year - 64.14159363
Insiut_T= 0.1758484561 * year - 101.5492425
Appx_T_Insitu = 0.1482589298 * year - 58.40344823
Appx14:00
Appx4:00
Appx14:00
Appx4:00
Spring
Eureka
In-Situ
In-Situ
254
244
The Cloud and Surface Parameter Retrieval (CASPR)
system, a toolkit for the analysis of the AVHRR data
from
NOAA
satellites,
(available
at
http://stratus.ssec.wisc.edu/caspr/caspr.html) is used
to retrieve surface, cloud, and radiative properties with
standard APP data set to create a extended APP-x data
set.
Satellite retrieved surface and cloud properties over the Arctic region were validated
with surface-based measurements and radar data, and used to investigate Arctic climate
characteristics and its recent trends. This study indicates that the Arctic has been
warming in spring, summer, and autumn at decadal rates of 1.16oC degree , 0.72oC
degree and 0.74oC degree, respectively. In winter the Arctic has been cooling at the
decadal rate of -0.35oC degree, which is mainly attributed to the central Arctic Ocean
north of 80oN where the surface temperature has decreased at -2.2oC degree per decade
at the confidence level of as high as 99.7%. The surface broadband albedo also signals
warming trend at the decadal rate of -3.1% at the confidence level of 98.8% in autumn.
The Arctic Ocean has experienced warming much stronger than the surrounding
landmasses, resulting in the decrease of sea ice extent and sea ice thinning as other
researchers have reported recently. Cloud cover over the Arctic tends to be larger in
spring and summer due to more water vapour available from melting sea ice or water
vapour transfer from large scale circulations, which needs to be investigated in the
future. The interactions between Arctic climate change and global climate system need
to be investigated further in both of modeling study and continuous observations.
APPX
RADAR
CERES-TEAM
Appx_T4= 0.186832614 * year - 135.080354
Winter
Eureka
242
252
Temperature(0K)
Temperature(0K)
240
238
250
248
236
246
234
1980
1984
1988
1992
1996
1980
2000
1988
1992
1996
2000
Insitu_T= 0.2311762807 * year - 206.690358
Appx14:00
Appx4:00
Appx14:00
Appx4:00
Summer
Eureka
1984
Appx_T14 = 0.2081042105 * year - Year
161.9157205
Appx_T4= 0.2008404912 * year - 148.5385933
Appx_T14= 0.04924449123
* year + 174.7480327
Year
Fall
Eureka
In-Situ
Fig.11. Time series and trends of the surface skin temperature,
broadband albedo, and cloud fraction in winter (DJF), spring
(MAM), summer (JJA), autumn (SON), and annual mean
(ANNUAL) over 1982-2000 on 14:00 LST for the Arctic region
north of 60oN. Numbers in parentheses are the trend slope per year
(“S”) with its standard deviation and the F test confidence level
(“P”). The first pair of S and P denotes the surface temperature trend
(green line), the second pair stands for the surface albedo (red line),
and the third pair represents the cloud fraction (blue line).
In-Situ
264
280
260
Temperature(0K)
276
Temperature(0K)
References
244
232
Appx_T4 = 0.05284945614 * year + 165.5239976
Insitu_T= 0.017766 * year + 241.6711361
272
256
252
268
248
264
1980
1980
1984
1988
1992
1996
2000
1984
1988
1992
1996
2000
Year
Year
1
Fig.1. Study area and the division of the entire Arctic region.
Fig.13. Spatial distribution of the surface skin temperature (Left) and cloud fraction (Right) trends
for the Arctic in winter over the period 1982-2000 from APP-x 14:00 LST data set. The contours in
the image stand for the confidence levels, and the colors represent the trend values as indicated by
right-side color bars for the surface temperature in degree per year and cloud fraction on a scale of 0
to 1 per year. Areas with cooling trends are marked with dashes.
Linkage to the Global Climate System
Data Sets
• APP-x data set, a extended data set from the AVHRR
Polar Pathfinder (APP) project, covering the period
1982 - 2000 at a spatial resolution of 25 km for the
Arctic/Antarctic regions on local solar times (LST) of
14:00 and 04:00.
• NCEP/NCAR reanalysis data set from National
Center for the Environmental Prediction (NCEP) /
National Center for Atmospheric Research (NCAR)
for the atmospheric profile data.
• ISCCP D2 data set from the International Satellite
Cloud Climatology Project (ISCCP) for the ozone data.
Arctic Climate Characteristics and Recent Trends
Fig.6. Comparisons in surface temperature between APP-x data and in-situ measurements
in Eureka (88.05ºN, 86.42ºW) for Winter (Dec, Jan, Feb), Spring (Mar, Apr, May),
Summer (Jun, Jul, Aug) and Fall (Sept, Oct, Nov).
2
3
4
4
Fig.12. Arctic sub-areal trends in surface temperature
averaged over 1982–2000 on 14:00 LST for winter (DJF),
spring (MAM), summer (JJA), autumn (SON), and annual
mean (ANN) from the top to bottom panels in order. The
number on the top of each bar represents the statistical
confidence level in percent (%). The Area IDs representing
the Arctic sub-areas from 1 to 18 labeled on the horizontal
coordinate, i.e. X axis, are given in Fig.1, and the Area IDs
from 19 to 21 stand for the Arctic Ocean north of 60oN, the
Arctic Landmasses north of 60oN, and the Arctic region north
of 60oN, respectively.
5
3
6
Key, J., 2002: The Cloud and Surface Parameter Retrieval (CASPR) System for Polar
AVHRR User’s Guide. NOAA/NESDIS/ORA/ASPT, University of Wisconsin,
1225 West Dayton St., Madison, WI 53562, 68 pp.
Wang, X.J., and J.R. Key, 2003: Recent Trends in Arctic Surface, Cloud, and Radiation
Properties from Space, SCIENCE, 299, 1725-1728, 14 March.
*Note:
*
Some of photos were taken by people not associated with this work. See the copyright
information below. None of the photos can be used commercially.
1: K. Claffey; 2: J. Key; 3: Feenicks Polarbear Image Gallery; 4: Photographer
unknown; 5: Thomas D. Mangelsen, from "Images of Nature" (a calendar); 6: Copyright
Corel Corporation, From "The Arctic", a Corel Professional Photos CDROM.