RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 9, ES3003, doi:10.2205/2007ES000283, 2007
Interannual trends in the Southern Ocean sea surface temperature and sea level from remote sensing dataS. A. Lebedev1, 2 1Geophysical Center, Russian Academy of Sciences, Moscow, Russia2State Oceanographic Institute, Moscow, Russia ContentsAbstract
[1] As it was shown recently, climate changes in Antarctica resulted in interannual
trends of some climatic parameters like sea level atmospheric pressure, surface air
temperature, ice thickness and others. These tendencies have effect on the Southern
Ocean meteorological and hydrological regime. The following remote sensing data:
AVHRR MCSST data, satellite altimetry data (merged data of mission ERS-2,
TOPEX/Poseidon, Jason-1, ENVISAT, GFO-1) are used to analyze the interannual
and/or climatic tendency of sea surface temperature (SST) and sea level anomaly
(SLA). According to the obtained results, SST has positive
trend 0.01 1. Introduction
[2] The Southern Ocean plays a key role in the climatic system on the Earth. According
to recent investigations sea level atmospheric pressure, simulated from NCEP-NCAR
reanalysis, has the following climatic tendency at 65oS
-0.166 [3] It means that some of basic climatic parameters have different trends. This shows that Earth's climatic system changes very largely. [4] These climatic variations have an effect on the position of the Subantarctic and Polar Fronts [Kostianoy et al., 2003, 2004; Lebedev and Sirota, 2004, 2007; Moore et al., 1999; Sirota et al., 2004; etc.] and consequently on the Antarctic Circumpolar Current (ACC) and its intensity [Fu and Chelton, 1984]. In the Drake Passage and near the Kerguelen Plateau, position of the ACC axis shifts to the south with a rate of about 0.016 deg yr-1 or 1.8 km yr-1 [Lebedev, 2006]. [5] The Antarctic Circumpolar Current plays a key role in the Earth's climate system. Water mass transformations in the Southern Ocean "close'' the overturning circulation by converting deep water. The ACC connects the ocean basins, allowing a global overturning circulation to exist, and allowing anomalies to propagate between basins. Observations have been sufficient to establish the influence of the Southern Ocean on the mean state of the World Ocean and Earth's climate. [6] All changes in the ACC can be seen in sea surface temperature (SST) and sea level anomaly (SLA) interannual trends based on remote sensing data (IR-radiometry and satellite altimetry). 2. Data and Methodology[7] Analysis of interannual trends of SST was based on weekly mean MCSST (AVHRR, 1998; http://podaac.jpl.nasa.gov:2031/DATASET_DOCS/avhrr_wkly_mcsst.html) data with spatial and temporal resolution of 1/6o and one week. The SST data were derived from the AVHRR (Advanced Very High Resolution Radiometers) mounted on the NOAA satellites. These data are produced in the Physical Oceanography Distributed Active Archive Center of Jet Propulsion Laboratory since 1981 with the temperature resolution of about 0.3oC [McClain et al., 1985].
[9] Analysis of interannual trends of SLA was based on the merged sea level anomaly products (data of ERS-2, TOPEX/Poseidon, Jason-1, ENVISAT, GFO-1 missions) of the Collecte Localisation Satellites CNES as part of the Environment and Climate European Commission Projects (ENACT - EVK2-CT2001-00117, AGORA - ENV4-CT956-0113 and DUACS - ENV44-T96-0357) [Le Traon et al., 1998, 2001]; (AVISO, 2002: SSALTO/DUACS User Handbook. CLS. AVI-NT-011-312-CN).
[11] Interannual or climatic trends of SST and SLA were calculated as linear regression for each grid point with spatial resolution of 0.5o. Results of these computations are shown in Figure 3. 3. Results
[12] According to the obtained results SST has positive trend higher than 0.01
[13] In the area between the Southwest Pacific Basin and Pacific-Antarctic Ridge, and
southward of the Argentine Basin and Mid-Atlantic Ridge SST trend is more than
-0.065
[14] Sea level anomalies or absolute sea level increases in all area of the Southern Ocean
(Figure 3b) and has an average rate of about 0.24
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