scholarly journals Seasonal and Secular Variations of Atmospheric 14Co2 Over the Western Pacific Since 1994

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 901-910 ◽  
Author(s):  
H Kitagawa ◽  
Hitoshi Mukai ◽  
Yukihiro Nojiri ◽  
Yasuyuki Shibata ◽  
Toshiyuki Kobayashi ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Southern Oscillation ◽  
Monitoring Program ◽  
Western Pacific ◽  
Environmental Research ◽  
Enso Events ◽  
Global Environmental ◽  
Secular Variations ◽  
The Western Pacific

Air sample collections over the western Pacific have continued since 1992 as a part of Center for Global Environmental Research, National Institute for Environmental Studies (CGER-NIES) global environmental monitoring program. The air samples collected on the Japan-Australia transect made it possible to trace the seasonal and secular 14CO2 variations, as well as an increasing trend of greenhouse gases over the western Pacific. A subset of CO2 samples from latitudes of 10–15°N and 23–28°S were chosen for accelerator mass spectrometry (AMS) 14C analysis using a NIES-TERRA AMS with a 0.3–0.4% precision. These 14CO2 records in maritime air show seasonal variations superimposed on normal exponential decreasing trends with a time constant of about 16 yr. The Δ14C values in the Northern Hemisphere are lower those in the Southern Hemisphere by 3–4 during 1994–2002. The Northern Hemisphere record shows relatively high seasonality (2.3 ± 1.5) as compared with the Southern Hemisphere (1.3 ± 1.2). The maximum values of seasonal cycles appear in late autumn and early winter in the Northern and Southern Hemispheres, respectively. Oscillations of 1–10 yr over the western Pacific are found to correlate possibly with the El Niño/Southern Oscillation (ENSO) events.

scholarly journals Ship-borne FTIR measurements of CO and O<sub>3</sub> in the Western Pacific from 43° N to 35° S: an evaluation of the sources

2012 ◽  
Vol 12 (2) ◽  
pp. 815-828 ◽  
Author(s):  
T. Ridder ◽  
C. Gerbig ◽  
J. Notholt ◽  
M. Rex ◽  
O. Schrems ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Western Pacific ◽  
Fossil Fuel Combustion ◽  
Source Regions ◽  
The Western Pacific

Abstract. Carbon monoxide (CO) and ozone (O3) have been measured in the Western Pacific (43° N to 35° S) during a ship campaign with Research Vessel Sonne in fall 2009. Observations have been performed using ship-based solar absorption Fourier Transform infrared spectrometry, flask sampling, balloon sounding, and in-situ Fourier Transform infrared analysis. The results obtained are compared to the GEOS-Chem global 3-D chemistry transport model for atmospheric composition. In general, a very good agreement is found between the GEOS-Chem model and all instruments. The CO and O3 distributions show a comparable variability suggesting an impact from the same source regions. Tagged-CO simulations implemented in the GEOS-Chem model make it possible to differentiate between different source processes and source regions. The source regions are verified with HYSPLIT backward trajectory calculations. In the Northern Hemisphere fossil fuel combustion in Asia is the dominant source. European and North American fossil fuel combustion also contribute to Northern Hemispheric CO pollution. In the Southern Hemisphere contributions from biomass burning and fossil fuel combustion are dominant; African biomass burning has a significant impact on Western Pacific CO pollution. Furthermore, in the tropical Western Pacific enhanced upper tropospheric CO within the tropical tropopause layer mainly originates from Indonesian fossil fuel combustion and can be transported into the stratosphere. The source regions of the measured O3 pollution are simulated with a tagged-O3 simulation implemented in the GEOS-Chem model. Similar source regions compared to the tagged-CO simulations are identified by the model. In the Northern Hemisphere contributions from Asia, Europe, and North America are significant. In the Southern Hemisphere emissions from South America, south-east Africa, and Oceania significantly contribute to the measured O3 pollution.

The Influence of Atmospheric Convection on the Interaction between the Indian Ocean and ENSO

2017 ◽  
Vol 30 (24) ◽  
pp. 10155-10178 ◽  
Author(s):  
Claudia E. Wieners ◽  
Henk A. Dijkstra ◽  
Will P. M. de Ruijter
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Western Pacific ◽  
Water Volume ◽  
Maritime Continent ◽  
Enso Events ◽  
The Indian Ocean ◽  
The Western Pacific

In recent years it has been proposed that a negative (positive) Indian Ocean dipole (IOD) in boreal autumn favors an El Niño (La Niña) at a lead time of 15 months. Observational analysis suggests that a negative IOD might be accompanied by easterly anomalies over the western Pacific. Such easterlies can enhance the western Pacific warm water volume, thus favoring El Niño development from the following boreal spring onward. However, a Gill-model response to a negative IOD forcing would lead to nearly zero winds over the western Pacific. The authors hypothesize that a negative IOD—or even a cool western Indian Ocean alone—leads to low-level air convergence and hence enhanced convectional heating over the Maritime Continent, which in turn amplifies the wind convergence so as to cause easterly winds over the western Pacific. This hypothesis is tested by coupling an idealized Indian Ocean model and a convective feedback model over the Maritime Continent to the Zebiak–Cane model. It is found that, for a sufficiently strong convection feedback, a negative (positive) IOD indeed forces easterlies (westerlies) over the western Pacific. The contribution from the eastern IOD pole dominates. IOD variability is found to destabilize the El Niño–Southern Oscillation (ENSO) mode, whereas Indian Ocean basinwide warming (IOB) variability dampens ENSO, even in the presence of convection. The influence of the Indian Ocean on the spectral properties of ENSO is dominated by the IOB, while the IOD is a better predictor for individual ENSO events.

scholarly journals Ship-borne FTIR measurements of CO and O<sub>3</sub> in the Western Pacific from 43° N to 35° S: an evaluation of the sources

2011 ◽  
Vol 11 (8) ◽  
pp. 22951-22985 ◽  
Author(s):  
T. Ridder ◽  
C. Gerbig ◽  
J. Notholt ◽  
M. Rex ◽  
O. Schrems ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Western Pacific ◽  
Fossil Fuel Combustion ◽  
Source Regions ◽  
The Western Pacific

Abstract. Carbon monoxide (CO) and ozone (O3) have been measured in the Western Pacific (43° N to 35° S) during a ship campaign with Research Vessel Sonne in fall 2009. Observations have been performed using ship-based solar absorption Fourier Transform infrared spectrometry, flask sampling, balloon sounding, and in-situ Fourier Transform infrared analysis. The obtained results are compared to the GEOS-Chem global 3-D chemistry transport model for atmospheric composition. In general, a very good agreement is found between the GEOS-Chem model and all instruments. The CO and O3 distributions show a comparable variability suggesting an impact from the same source regions. Tagged-CO simulations implemented in the GEOS-Chem model allow to differentiate between different sources and source regions. The sources are verified with HYSPLIT backward trajectory calculations. In the Northern Hemisphere fossil fuel combustion in Asia is the dominant source. European and North American fossil fuel combustion also contribute to Northern Hemispheric CO pollution. In the Southern Hemisphere contributions from biomass burning and fossil fuel combustion are dominant; African biomass burning has a significant impact on Western Pacific CO pollution. Furthermore, in the tropical Western Pacific enhanced upper tropospheric CO within the tropical tropopause layer mainly originates from Indonesian fossil fuel combustion and can be transported into the stratosphere. The sources and source regions of the measured O3 pollution are simulated with a tagged-O3 simulation implemented in the GEOS-Chem model. Similar source regions compared to the tagged-CO simulations are identified by the model. In the Northern Hemisphere contributions from Asia, Europe, and North America are significant. In the Southern Hemisphere the impact of emissions from South America, South-East Africa, and Oceania is important.

scholarly journals Analysis of GPS water vapor variability during the 2011 La Niña event over the western Pacific Ocean

2013 ◽  
Vol 56 (3) ◽  
Author(s):  
Wayan Suparta ◽  
Ahmad Iskandar ◽  
Mandeep Singh Jit Singh ◽  
Mohd. Alauddin Mohd. Ali ◽  
Baharudin Yatim ◽  
...  
Keyword(s):  
Water Vapor ◽  
Pacific Ocean ◽  
Southern Oscillation ◽  
Correlation Coefficients ◽  
Precipitable Water ◽  
La Niña ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
La Nina ◽  
The Western Pacific

<p>We analyzed the variability of global positioning system (GPS) water vapor during the 2011 La Niña events over the western Pacific Ocean. The precipitable water vapor (PWV) derived from the UMSK (Malaysia) GPS station was investigated and compared with four other selected GPS stations: NTUS (Singapore), PIMO (Philippines), BAKO (Indonesia) and TOW2 (Australia). Analysis of the correlation between PWV and the sea-surface temperature anomaly (SSTa) on a weekly basis for the three La Niña cases of January–February–March, August–September–October, and October–November–December was used as an indicator of the influence of the El Niño Southern Oscillation. A good relationship between GPS PWV and SSTa for the Niño 4 region, with correlation coefficients between -0.91 and -0.94, was observed for the August–September–October and October–November–December cases. During the 2011 La Niña events, the water vapor was seen to increase to about 8.39 mm for the October–November–December case, with decreases of about 4.20 mm for the remaining months, compared to the mean 2011 value. This implies that during these events, the precipitation in the western Pacific is increased, due to stronger easterly trade winds blowing along the eastern Pacific Ocean than along the western Pacific, and a mass of warm water moving westwards, thereby increasing the evaporation.</p>

scholarly journals On the dynamical mechanisms explaining the western Pacific subsurface temperature buildup leading to ENSO events

2015 ◽  
Vol 42 (8) ◽  
pp. 2961-2967 ◽  
Author(s):  
Joan Ballester ◽  
Simona Bordoni ◽  
Desislava Petrova ◽  
Xavier Rodó
Keyword(s):  
Western Pacific ◽  
Subsurface Temperature ◽  
Enso Events ◽  
The Western Pacific

The Hadley Circulation Regime Change: Combined Effect of the Western Pacific Warming and Increased ENSO Amplitude

2018 ◽  
Vol 31 (23) ◽  
pp. 9739-9751 ◽  
Author(s):  
Yi-Peng Guo ◽  
Zhe-Min Tan
Keyword(s):  
Regime Change ◽  
Southern Oscillation ◽  
Hadley Circulation ◽  
Warming Trend ◽  
Combined Effect ◽  
Western Pacific ◽  
South Pacific Convergence Zone ◽  
Boreal Winter ◽  
Enso Events

The variation in the interannual relationship between the boreal winter Hadley circulation (HC) and El Niño–Southern Oscillation (ENSO) during 1948–2014 is investigated. The interannual variability of the HC is dominated by two principal modes: the equatorial asymmetric mode (AM) and the equatorial symmetric mode (SM). The AM of the HC during ENSO events mainly results from a combined effect of the ENSO sea surface temperature (SST) anomalies and the climatological background SST over the South Pacific convergence zone. Comparatively, the SM shows a steady and statistically significant relationship with ENSO; however, the interannual relationship between the AM and ENSO is strengthened during the mid-1970s, which leads to a HC regime change—that is, the interannual pulse of the HC intensity and its response to ENSO are stronger after the mid-1970s than before. The long-term warming trend of the tropical western Pacific since the 1950s and the increased ENSO amplitude play vital roles in the HC regime change. Although the tropical eastern Pacific also experienced a long-term warming trend, it has little influence on the HC regime change due to the climatologically cold background SST over the cold tongue region.

Assessing the Skill and Value of Seasonal Thermal Stress Forecasts for Coral Bleaching Risk in the Western Pacific

2016 ◽  
Vol 55 (7) ◽  
pp. 1565-1578 ◽  
Author(s):  
A. G. Griesser ◽  
C. M. Spillman
Keyword(s):  
Thermal Stress ◽  
Pacific Ocean ◽  
Coral Bleaching ◽  
Southern Oscillation ◽  
Hot Spot ◽  
Western Pacific ◽  
Equatorial Pacific Ocean ◽  
Anthropogenic Pressures ◽  
Skill Scores ◽  
The Western Pacific

AbstractOver the last 30 years, coral reefs around the world have been under considerable stress because of increasing anthropogenic pressures, overfishing, pollution, and climate change. A primary stress factor is anomalously warm water events, which can cause mass coral bleaching and widespread reef damage. Forecasts of sea surface temperature (SST) and the associated risk of coral bleaching can assist managers, researchers, and other stakeholders in monitoring and managing coral reef resources. At the Australian Bureau of Meteorology, monthly forecasts of SST and thermal stress metrics have been developed that are based on a dynamical seasonal prediction system known as the Predictive Ocean Atmosphere Model for Australia (POAMA). To support the effective use of these forecasts in risk-based decision-making frameworks in the western and central tropical Pacific Ocean, the skill of these forecast tools in this region was assessed using several categorical forecast skill scores. It was found that the model provides SST forecasts with statistically significant skill up to 8 months in advance (correlation coefficient > 0.4; p = 0.05) across the region. The highest skill (r > 0.9) was achieved over the central equatorial Pacific Ocean, likely as a result of this region’s strong relationship with the El Niño–Southern Oscillation (ENSO). Potential forecast value was assessed using a simplified cost–loss ratio decision model, which indicated that POAMA’s seasonal hot-spot thermal stress forecasts can provide valuable information to reef management and policy makers in the western Pacific region.

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