global warming - national oceanic and atmospheric ... · this presentation covers the following...
TRANSCRIPT
![Page 1: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/1.jpg)
© Crown copyright Met Office
Isolating the signal of ocean global warmingMatt Palmer CLIMAR 3 meeting, Gydnia, Poland, 8th May 2008
![Page 2: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/2.jpg)
© Crown copyright Met Office
Collaborators
• Keith Haines
• Simon Tett
• Tara Ansell
![Page 3: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/3.jpg)
© Crown copyright Met Office
Contents
This presentation covers the following areas
• Introduction
• Data & methods
• Time series
• Spatial maps
• Conclusions
![Page 4: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/4.jpg)
© Crown copyright Met Office
Data
• Temperature profiles from ENACT/ENSEMBLES
• Version 2 (1956-2004) and version 3 (1950-2006)
• Based on WOD01/WOD05 with updates from Argo GDACs and GTSSP (1990 onwards)
• Available from:
http://www.metoffice.gov.uk/hadobs/en3
![Page 5: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/5.jpg)
© Crown copyright Met Office
Method
• Create 2°×2° gridded fields for each month:
1. Mean temperature > 14°C
2. Mean depth of 14°C
3. Mean temperature > 220m
• Create monthly climatology for 1956-2004
• Compute the volume-weighted mean anomaly for each month for each ocean basin.
• No in-filling. Assumption that missing grid boxes = mean value of observed grid boxes.
![Page 6: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/6.jpg)
© Crown copyright Met Office
Why isotherms?
Fixed-depth level
thermocline
Sea surface
WindWind
Zone of Ekmanconvergence
T1
T2
z
x
Short time-scales: waves, eddies
Long time-scales: mean winds, ocean advection
Walin [1982], Stevenson and Niiler [1983], Toole et al. [2004]
![Page 7: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/7.jpg)
© Crown copyright Met Office
Time series
Palmer et al. [2007]
![Page 8: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/8.jpg)
© Crown copyright Met Office
Sampling errors
See Palmer and Brohan Poster
![Page 9: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/9.jpg)
© Crown copyright Met Office
XBT corrections
No XBT corrections XBT corrections*
*Following Wijffels et al. [2008]
![Page 10: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/10.jpg)
© Crown copyright Met Office
Spatial maps
Palmer et al. [2007]
Trend in T > 14°CMean depth of 14°C
Trend in T > 220m Trend in depth of 14°C
![Page 11: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/11.jpg)
© Crown copyright Met Office
ConclusionsFor isotherm analyses:
• Reduction in high-freq and multi-annual variability
• More consistent warming trends among basins
• More uniform pattern of global warming
• Removal of fall-rate XBT bias
• More information to suggest possible mechanisms
![Page 12: global warming - National Oceanic and Atmospheric ... · This presentation covers the following areas • Introduction • Data & methods • Time series ... • More consistent warming](https://reader035.vdocuments.us/reader035/viewer/2022071211/602366fa9f8ffc64c74ff5d1/html5/thumbnails/12.jpg)
© Crown copyright Met Office
Questions and answers