Download Observed climatic changes in the Nordic Seas 1900-2009

Alexander Korablev
Observed climatic changes in the Nordic
Seas
1900-2009
OUTLINE
Oceanographic database for the Nordic Seas
Regional variability of thermohaline characteristics in selected
regions from in situ observations
Climatological horizontal fields for the Nordic Seas
Summary
Status October 2010
Oceanographic database for the Nordic Seas
60˚N — 82˚N
45˚W — 70˚E
1870 — 2010
456645 stations
45 sources
16000
AARI [13]
AARIOD [24336]
AARI_TGM [41207]
AARIcr [565]
ARGO [7711]
14000
AWI [137]
AWI_CD [642]
Cearex [2776]
IGY
1957-58
ESIMO [557]
ESOP [215]
GSP [142]
ICES2010 [14550]
ICES_0207 [10255]
ICES_0209 [3374]
IMR [262]
IMR9002 [32720]
10000
IOPAS_2008 [771]
IOPAS [281]
IORAS [272]
IPY 3
2007-2009
IPY [309]
8000
6000
IPY 2
1932-33
Global Oceanographic Data
Archeology and Rescue Project
(GODAR)
> 40000 stations
added/corrected against original
cruise reports
Number of stations by source
12000
4000
ITP [163]
LOGS [27]
MAIA [9]
Mike [11536]
MMBI [386]
NABOS [19]
NANSEN [8]
NOAA [516]
NNDCD [2260]
NPI [315]
OCL [10826]
Obninsk [24076]
ODB_CA [140047]
ODB_ICES [15920]
Overflow [303]
PNSEC [734]
Report [7]
2000
RSHU [55]
Tractor [311]
VEINS [113]
VEINS_H [14485]
WHOI [215]
0
1900
WOD2001 [80190]
1910
1920
1930
1940
1950
1960
Years
1970
1980
1990
2000
2010
WOD2005 [11755]
WOD2009 [1274]
Time-depth diagrams for selected areas 1896 - 2009
‘the
strong
of
the event
late
1960s
and vertical exchange intensification’
‘the
late
1950searly
1960s
warming
event’
‘The
‘The
early
1920-1930s’
20thcooling
century
warming
low-salinity
anomaly’
Negative
Present
salinity
warm,
anomaly
salty
andof
low
the
density
mid-1990s
regime
The Great
Salinity
Anomaly
Example of estimated and mean fields (nearest neighborhood)
(Intrinsic Kriging approach: details after ‘Thank You’ slide)
Kriging Standard Deviations (KSD) provides
estimation of interpolation quality for each field
(depends on samples density)
Standard Error of the mean provides quality
of the climatological fields
(depends on a variable variance and samples
amount in a grid point)
Example of estimated and mean fields (smoothing)
MZ
MIZ
BZ
FZ
FZ
It is dangerous to evaluate anomalies between estimated field and highly smoothed climatology field especially
when they have been produced by different objective analysis methods with unknown errors of interpolation
Temperature and salinity anomalies example
(June 1976 at 50m relative to 1900-2009)
Unsmoothed temperature anomalies
Unsmoothed salinity anomalies
Smoothed temperature anomalies
Smoothed salinity anomalies
GSA Propogation
Now anomality of each monthly gridded field with data can be estimated relative to climatological field for selected period
Climatological fields for 1900-2009 period in June at standard levels
?
?
GS Gyre
AW
GS Gyre
IS Gyre
FZ
AW
EIC
Reliable climatalogical fields may not be computed due to lack of observation over Greenland shelf
LB Gyre
Variability from in situ data and gridded fields. Comparison (June_d15)
Spatial pattern of anomalies during stable regimes in the NS
(June_d15 50m)
Warm period
around 1960
Strong atmospheric
cooling
The GSA propagation
Low salinity anomaly Warm period since
of the mid-1990s
The late-1990s
[1900-2009] climatological fields are generally warmer and saltier than [1957-1990] climatalogical fields at 50 m
[1900-2009] - [1957-1990]
(June_d15 50m)
Strongest deviations, more than 1oC located in the Northern part of the NS, in BSO and Fram Strait regions
Upper layer regimes and vertical exchange in the Nordic Seas
T/S properties on
28.0 isopycnal
surface (25-1000m)
Strong atmospheric
The GSA propagation
cooling
Low salinity anomaly
of the mid-1990s
1.5
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
-0.9
-1
-1.5
75
70
65
60
-10
0
10
20
30
4
0.15
0.125
0.1
0.075
0.05
0.025
70
0
-0.025
-0.05
65
-0.075
-0.1
Convection
intensification in
the Nordic Seas
2
1
0
-1
-2
-3
-4
-0.125
60
-0.15
-10
0
10
20
30
40
cluster_1 (Polar Domain)
cluster_4 (Arctic Domain)
cluster_9 (Atlantic Domain)
3
40
75
Warm/salty period
since
the late-1990s
5
SAT_Anomalies_DJFM
Warm period
around 1960
-5
Mean SAT over
the NS: Polar,
Arctic and Atlantic
Domains
1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
YEARS
Due to the upper layer salinity increase the NS are now potentially preconditioned for vertical exchange
intensification if strong atmospheric cooling will occur. Similar to the late 1960s event.
Mixed Layer temperature and salinity 2000-2010 (OWS ‘Mike’)
Mean 1948-2009
AW low boundary ~380 m
Winter convection ~170 m
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
12
35.2
35.16
Salinity [psu]
Temperature [°C]
11
10
9
8
6
2
3
4
5
6
7
month
8
9
10
4
6
8
10
12
2
4
Month
01dtd
02dtd
03dtd
05dtd
08dtd
1
35.08
35
2
Criterion
35.12
35.04
7
6
8
Month
35.2
4
35.16
Salinity [psu]
MLD [m]
Mixed Layer mean seasonal cycle (OWS ‘Mike’)
11
12
1
12
5
6
11 12
35.12
35.08
10
35.04
35
2 3
10
7
9
8
8
centered on winter
Smirnov, A. Korablev, G. Alekseev and I. Esau Temporal and spatial changes in mixed layer
properties and atmospheric net heat flux in the Nordic Seas. IOP Conf. Series: Earth and
Environmental Science 13 (2010), doi:10/1088/1755-1315/13/1/012006
Simulated (MGO report, fig1 temperature/salinity anomalies versus observations )
Canadian Global Climate model Version 3
Ocean resolution 0.3o -> 1o
Observed
Temperature
anomalies
[oC]
Observed
Salinity
anomalies
[psu]
Summary
Oceanographic database for the Nordic Seas (including NA and Arctic) and time
series were updated up to the beginning of 2010
Time series reveal
variability is shaped by thermochaline anomalies propagation with different
intensity, duration and spatial extent
different stable upper layer regimes define intensity of the vertical exchange
Monthly climatological fields based on non–stationary Intrinsic Kriging approach
were computed for June 1900 – 2009
Reproduce spatial pattern and temporal variability reasonably well
Show wide spread warming of the NS with acceleration in the northern parts
Climatology for 1900-2009 period is generally warmer than for 1957-1990
Enhanced advection of sea ice and Polar water from Arctic affects heat fluxes over
the NS and vertical mixing
Quick comparison of simulated (CMIP3 models MGO report) and observed
variability in the Norwegian Sea show substantial differences especially in the
upper layer salinity regimes and deep water temperatures
Thank you!
Flowchart for horizontal fields gridding by Intrinsic Kriging
Monthly or monthly
centered samples at
standard depth levels
ODB
Data
Observed field:
Data\in
[irregular locations]
Estimated field(internal):
Estimated field(out):
Data\grid
Data\out
[10x10 km]
[0.25x0.25 deg]
1. Estimation
Inversion problems are
NSM
disabled (selection duplicates
Input: data\in
within 1km)
Drift trials: “no drift”
“1 x y”
“1 x y x2 xy y2”
Covariance: Exp 250
NH: 250x250km; 3,16,3,3
Output model: t_mod;
variable values with
ksd at grid points
ODB
Climate
2. Interpolation into required grid
(Linear Model Kriging)
Input: grid\t_est
grid\t_ksd
Output: out\t_est
out\t_ksd
Filtering (optional)
Kriging
Input: data\in
model: t_mod Extrapolation outside
Output: grid\t_est
data area is disabled
grid\t_ksd
(selection from Convex Hull)
Filtering(optional)
Notations
ODB
IK
NSM
NH
KSD
-Oceanographic DataBase
- Intrinsic Kriging
- non-stationary modeling
-Neighborhood (ex: 50x50km 4,16,2,3)
-ellipsoid distances: 50x50
-min number of samples: 4
-number of angular sectors: 16
-optimum number samples per sector: 2
-max number of consecutive empty sectors: 3
-Kriging Standard Deviation
Grid for 60-82N, 45W-70E
Observed
Field
ISATIS www.geovariances.com
Mean (climatological) horizontal fields computing
Output (ODBClimate application):
ODB
Climate
Monthly ( or centered)
gridded (0.25 deg) fields
1900-2009 at standard
depth levels
Mean at the grid points: arithmetic averaging
for certain period (e.g. 1900-2009)
Standard Error of the Mean: σ/N-2
Thresholds:
ODB
Climate
KSD_SD: standard deviation of the KSD
computed for all estimated fields
QF: Quality flags were set at estimated values
according to variable standard deviations
computed for time series at grid nodes (>=3)
Threshold values definition problem
Output
Expert control for each estimated field (-)
From KSD total variance (3,4,5 σ)
Time series consistency at grid nodes (1..5..9
SD)
Time series at grid points (areas)
Time/depth diagrams
mean (climatological) fields for different
periods
anomality assessment for monthly or mean
fields
Additional quality control on observed data