scholarly journals Human-caused Indo-Pacific warm pool expansion

2016 ◽  
Vol 2 (7) ◽  
pp. e1501719 ◽  
Author(s):  
Evan Weller ◽  
Seung-Ki Min ◽  
Wenju Cai ◽  
Francis W. Zwiers ◽  
Yeon-Hee Kim ◽  
...  
Keyword(s):  
Climate Model ◽  
Hydrological Cycle ◽  
Heat Content ◽  
Warm Pool ◽  
Small Island ◽  
Past Century ◽  
The Pacific ◽  
Pacific Warm Pool ◽  
Basin Scale ◽  
Climate Model Simulations

The Indo-Pacific warm pool (IPWP) has warmed and grown substantially during the past century. The IPWP is Earth’s largest region of warm sea surface temperatures (SSTs), has the highest rainfall, and is fundamental to global atmospheric circulation and hydrological cycle. The region has also experienced the world’s highest rates of sea-level rise in recent decades, indicating large increases in ocean heat content and leading to substantial impacts on small island states in the region. Previous studies have considered mechanisms for the basin-scale ocean warming, but not the causes of the observed IPWP expansion, where expansion in the Indian Ocean has far exceeded that in the Pacific Ocean. We identify human and natural contributions to the observed IPWP changes since the 1950s by comparing observations with climate model simulations using an optimal fingerprinting technique. Greenhouse gas forcing is found to be the dominant cause of the observed increases in IPWP intensity and size, whereas natural fluctuations associated with the Pacific Decadal Oscillation have played a smaller yet significant role. Further, we show that the shape and impact of human-induced IPWP growth could be asymmetric between the Indian and Pacific basins, the causes of which remain uncertain. Human-induced changes in the IPWP have important implications for understanding and projecting related changes in monsoonal rainfall, and frequency or intensity of tropical storms, which have profound socioeconomic consequences.

Effects of Central American Mountains on the Eastern Pacific Winter ITCZ and Moisture Transport*

2005 ◽  
Vol 18 (18) ◽  
pp. 3856-3873 ◽  
Author(s):  
Haiming Xu ◽  
Shang-Ping Xie ◽  
Yuqing Wang ◽  
R. Justin Small
Keyword(s):  
Central America ◽  
Climate Model ◽  
Warm Pool ◽  
Central American ◽  
Eastern Pacific ◽  
Global Ocean ◽  
Boreal Winter ◽  
The Pacific ◽  
Pacific Warm Pool ◽  
Eastern Pacific Warm Pool

Abstract The intertropical convergence zone (ITCZ) is displaced to the south edge of the eastern Pacific warm pool in boreal winter, instead of being collocated. A high-resolution regional climate model is used to investigate the mechanism for this displaced ITCZ. Under the observed sea surface temperature (SST) and lateral boundary forcing, the model reproduces the salient features of eastern Pacific climate in winter, including the southward displaced ITCZ and gap wind jets off the Central American coast. As the northeast trades impinge on the mountains of Central America, subsidence prevails off the Pacific coast, pushing the ITCZ southward. Cold SST patches induced by three gap wind jets have additional effects of keeping the ITCZ away from the coast. In an experiment in which both the Central American mountains and their effect on SST are removed, the ITCZ shifts considerably northward to cover much of the eastern Pacific warm pool. The Central American mountains are considered important to freshwater transport from the Atlantic to the Pacific Ocean, which in turn plays a key role in global ocean thermohaline circulation. The results of this study show that this transport across Central America is not very sensitive to the fine structure of the orography because the increased flow in the mountain gaps in a detailed topography run tends to be compensated for by broader flow in a smoothed topography run. Implications for global climate modeling are discussed.

scholarly journals Effect of the Indo-Pacific Warm Pool on Lower-Stratospheric Water Vapor and Comparison with the Effect of ENSO

2018 ◽  
Vol 31 (3) ◽  
pp. 929-943 ◽  
Author(s):  
Fei Xie ◽  
Xin Zhou ◽  
Jianping Li ◽  
Quanliang Chen ◽  
Jiankai Zhang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Climate Model ◽  
Southern Oscillation ◽  
Deep Convection ◽  
Warm Pool ◽  
Latent Heat Release ◽  
Stratospheric Water Vapor ◽  
Asymmetric Effects ◽  
Pacific Warm Pool ◽  
Tropopause Temperature

Abstract Time-slice experiments with the Whole Atmosphere Community Climate Model, version 4 (WACCM4), and composite analysis with satellite observations are used to demonstrate that the Indo-Pacific warm pool (IPWP) can significantly affect lower-stratospheric water vapor. It is found that a warmer IPWP significantly dries the stratospheric water vapor by causing a broad cooling of the tropopause, and vice versa for a colder IPWP. Such imprints in tropopause temperature are driven by a combination of variations in the Brewer–Dobson circulation in the stratosphere and deep convection in the troposphere. Changes in deep convection associated with El Niño–Southern Oscillation (ENSO) reportedly have a small zonal mean effect on lower-stratospheric water vapor for strong zonally asymmetric effects on tropopause temperature. In contrast, IPWP events have zonally uniform imprints on tropopause temperature. This is because equatorial planetary waves forced by latent heat release from deep convection project strongly onto ENSO but weakly onto IPWP events.

scholarly journals Decadal Variability of the Indian and Pacific Walker Cells since the 1960s: Do They Covary on Decadal Time Scales?

2017 ◽  
Vol 30 (21) ◽  
pp. 8447-8468 ◽  
Author(s):  
Weiqing Han ◽  
Gerald A. Meehl ◽  
Aixue Hu ◽  
Jian Zheng ◽  
Jessica Kenigson ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Decadal Variability ◽  
Tropical Indian Ocean ◽  
Warm Pool ◽  
Past Century ◽  
The Pacific ◽  
Decadal Variations ◽  
Long Term Trends ◽  
The Indian Ocean ◽  
The 1960S

Previous studies have investigated the centennial and multidecadal trends of the Pacific and Indian Ocean Walker cells (WCs) during the past century, but have obtained no consensus owing to data uncertainties and weak signals of the long-term trends. This paper focuses on decadal variability (periods of one to few decades) by first documenting the variability of the WCs and warm-pool convection, and their covariability since the 1960s, using in situ and satellite observations and reanalysis products. The causes for the variability and covariability are then explored using a Bayesian dynamic linear model, which can extract nonstationary effects of climate modes. The warm-pool convection exhibits apparent decadal variability, generally covarying with the Indian and Pacific Ocean WCs during winter (November–April) with enhanced convection corresponding to intensified WCs, and the Indian–Pacific WCs covary. During summer (May–October), the warm-pool convection still highly covaries with the Pacific WC but does not covary with the Indian Ocean WC, and the Indian–Pacific WCs are uncorrelated. The wintertime coherent variability results from the vital influence of ENSO decadal variation, which reduces warm-pool convection and weakens the WCs during El Niño–like conditions. During summer, while ENSO decadal variability still dominates the Pacific WC, decadal variations of ENSO, the Indian Ocean dipole, Indian summer monsoon convection, and tropical Indian Ocean SST have comparable effects on the Indian Ocean WC overall, with monsoon convection having the largest effect since the 1990s. The complex causes for the Indian Ocean WC during summer result in its poor covariability with the Pacific WC and warm-pool convection.

A 12-Million-Year Temperature History of the Tropical Pacific Ocean

Science ◽  
2014 ◽  
Vol 344 (6179) ◽  
pp. 84-87 ◽  
Author(s):  
Yi Ge Zhang ◽  
Mark Pagani ◽  
Zhonghui Liu
Keyword(s):  
El Niño ◽  
El Nino ◽  
Warm Pool ◽  
Sea Surface ◽  
Temperature History ◽  
Seawater Chemistry ◽  
The Pacific ◽  
Pacific Warm Pool ◽  
History Of ◽  
The Tropical Pacific

The appearance of permanent El Niño–like conditions prior to 3 million years ago is founded on sea-surface temperature (SST) reconstructions that show invariant Pacific warm pool temperatures and negligible equatorial zonal temperature gradients. However, only a few SST records are available, and these are potentially compromised by changes in seawater chemistry, diagenesis, and calibration limitations. For this study, we establish new biomarker-SST records and show that the Pacific warm pool was ~4°C warmer 12 million years ago. Both the warm pool and cold tongue slowly cooled toward modern conditions while maintaining a zonal temperature gradient of ~3°C in the late Miocene, which increased during the Plio-Pleistocene. Our results contrast with previous temperature reconstructions that support the supposition of a permanent El Niño–like state.

scholarly journals Evaluating Climate Model Simulations of the Radiative Forcing and Radiative Response at Earth’s Surface

2019 ◽  
Vol 32 (13) ◽  
pp. 4089-4102 ◽  
Author(s):  
Ryan J. Kramer ◽  
Brian J. Soden ◽  
Angeline G. Pendergrass
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Models ◽  
Lapse Rate ◽  
Radiation Budget ◽  
Model Simulations ◽  
Climate Model Simulations

Abstract We analyze the radiative forcing and radiative response at Earth’s surface, where perturbations in the radiation budget regulate the atmospheric hydrological cycle. By applying a radiative kernel-regression technique to CMIP5 climate model simulations where CO2 is instantaneously quadrupled, we evaluate the intermodel spread in surface instantaneous radiative forcing, radiative adjustments to this forcing, and radiative responses to surface warming. The cloud radiative adjustment to CO2 forcing and the temperature-mediated cloud radiative response exhibit significant intermodel spread. In contrast to its counterpart at the top of the atmosphere, the temperature-mediated cloud radiative response at the surface is found to be positive in some models and negative in others. Also, the compensation between the temperature-mediated lapse rate and water vapor radiative responses found in top-of-atmosphere calculations is not present for surface radiative flux changes. Instantaneous radiative forcing at the surface is rarely reported for model simulations; as a result, intermodel differences have not previously been evaluated in global climate models. We demonstrate that the instantaneous radiative forcing is the largest contributor to intermodel spread in effective radiative forcing at the surface. We also find evidence of differences in radiative parameterizations in current models and argue that this is a significant, but largely overlooked, source of bias in climate change simulations.

Intraseasonal Variability of the Zonal-Mean Tropical Tropopause Height

2007 ◽  
Vol 64 (7) ◽  
pp. 2695-2706 ◽  
Author(s):  
Seok-Woo Son ◽  
Sukyoung Lee
Keyword(s):  
Large Scale ◽  
Intraseasonal Variability ◽  
Warm Pool ◽  
Temperature Fields ◽  
Convective Heating ◽  
Tropopause Height ◽  
Tropical Tropopause ◽  
The Pacific ◽  
Pacific Warm Pool ◽  
Tropical Troposphere

Abstract Intraseasonal variability of the zonal-mean tropical tropopause height is shown to be modulated by localized tropical convection. Most of this convective activity is identified as being part of the Madden–Julian oscillation. While the convection is highly localized over the Pacific warm pool, a large-scale circulation response to the convective heating rapidly warms most of the tropical troposphere and cools most of the lowest few kilometers of the tropical stratosphere. These changes in temperature fields raise the tropical tropopause at most longitudes within 10 days of the convective heating maximum.

scholarly journals Modulation of Atmospheric Response to North Pacific SST Anomalies under Global Warming: A Statistical Assessment

2012 ◽  
Vol 25 (19) ◽  
pp. 6554-6566 ◽  
Author(s):  
Bolan Gan ◽  
Lixin Wu
Keyword(s):  
Global Warming ◽  
North Pacific ◽  
Climate Model ◽  
Storm Track ◽  
Early Winter ◽  
The North ◽  
Basin Scale ◽  
Climate Model Simulations ◽  
The North Pacific ◽  
Sst Anomalies

Abstract In this study the modulation of ocean-to-atmosphere feedback over the North Pacific in early winter from global warming is investigated based on both the observations and multiple climate model simulations from a statistical perspective. It is demonstrated that the basin-scale atmospheric circulation displays an equivalent barotropic ridge in response to warm SST anomalies in the Kuroshio–Oyashio Extension (KOE) region. This warm SST–ridge response in early winter can be enhanced significantly by global warming, indicating a strengthening of air–sea coupling over the North Pacific. This enhancement is likely associated with the intensification of storm tracks and, in turn, the amplification of atmospheric transient eddy feedback in a warm climate, although the secular trend of enhanced storm-track activity over the North Pacific is suggested to be biased in reanalysis product.

scholarly journals Decadal Western Pacific Warm Pool Variability: A Centroid and Heat Content Study

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Autumn Kidwell ◽  
Lu Han ◽  
Young-Heon Jo ◽  
Xiao-Hai Yan
Keyword(s):  
Heat Content ◽  
Warm Pool ◽  
Western Pacific ◽  
Western Pacific Warm Pool ◽  
Pacific Warm Pool
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