International Pacific Research Center

Honolulu, HI, United States

International Pacific Research Center

Honolulu, HI, United States

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News Article | May 4, 2017
Site: www.eurekalert.org

Daydreams of the tropical paradise of Hawai'i rarely include snow in the imagery, but nearly every year, a beautiful white blanket covers the highest peaks in the state for at least a few days. However, systematic observations of snowfall and the snow cover dimensions on Mauna Kea and Mauna Loa are practically nonexistent. A group of climate modelers led by Chunxi Zhang from the International Pacific Research Center (IPRC) at the University of Hawai'i at Manoa used satellite images to quantify recent snow cover distributions patterns. They developed a regional climate model to simulate the present-day snowfalls and then to project future Hawaiian snowfalls. Their results indicate that the two volcano summits are typically snow-covered at least 20 days each winter, on average, but that the snow cover will nearly disappear by the end of the century. To evaluate the current situation, Zhang and his colleagues examined surface composition data retrieved from satellite imagery of Hawai'i Island from 2000 to 2015 to construct a daily index of snow cover. They used this data compilation to evaluate the quality of their regional atmospheric climate model, based on global climate projections that included several scenarios of anticipated climate change. Zhang then ran simulations representative of the end of the 21st century, assuming a moderate business-as-usual scenario for greenhouse gas emissions projections, to establish how long Hawai'i might enjoy its occasional glimpses of white-topped mountains. "We recognized that Hawaiian snow has an aesthetic and recreational value, as well as a cultural significance, for residents and visitors," explained Zhang. "So, we decided to examine just what the implications of future climate change would be for future snowfall in Hawai'i." Unfortunately, the projections suggest that future average winter snowfall will be ten times less than present day amounts, virtually erasing all snow cover. The findings were not a total surprise, with future projections showing that even with moderate climate warming, air temperatures over the higher altitudes increase even more than at sea level, and that, on average, fewer winter storm systems will impact the state. However, the group's new method for establishing the current snow cover on these Hawaiian mountains provides another avenue for monitoring the progression of climate change in the region. Ultimately, this study also illustrates the benefits of the recent trend in model downscaling, highlighting the regional and local effects of global climate change.


Yu J.,Nanjing University of Information Science and Technology | Wang Y.,International Pacific Research Center | Hamilton K.,International Pacific Research Center
Journal of Climate | Year: 2010

This paper reports on an analysis of the tropical cyclone (TC) potential intensity (PI) and its control parameters in transient global warming simulations. Specifically, the TC PI is calculated for phase 3 of the Coupled Model Intercomparison Project (CMIP3) integrations during the first 70 yr of a transient run forced by a 1% yr -1 CO 2 increase. The linear trend over the period is used to project a 70-yr change in relevant model parameters. The results for a 15-model ensemble-mean climate projection show that the thermodynamic potential intensity (THPI) increases on average by 1.0% to~3.1% over various TC basins, which is mainly attributed to changes in the disequilibrium in enthalpy between the ocean and atmosphere in the transient response to increasing CO 2 concentrations. This modest projected increase in THPI is consistent with that found in other recent studies. In this paper the effects of evolving large-scale dynamical factors on the projected TC PI are also quantified, using an empirical formation that takes into account the effects of vertical shear and translational speed based on a statistical analysis of present-day observations. Including the dynamical efficiency in the formulation of PI leads to larger projected changes in PI relative to that obtained using just THPI in some basins and smaller projected changes in others. The inclusion of the dynamical efficiency has the largest relative effect in the main development region (MDR) of the North Atlantic, where it leads to a 50% reduction in the projected PI change. Results are also presented for the basin-averaged changes in PI for the climate projections from each of the 15 individual models. There is considerable variation among the results for individual model pro- jections, and for some models the projected increase in PI in the eastern Pacific and south Indian Ocean regions exceeds 10%. © 2010 American Meteorological Society.


News Article | November 10, 2016
Site: www.eurekalert.org

It is well-established in the scientific community that increases in atmospheric CO2 levels result in global warming, but the magnitude of the effect may vary depending on average global temperature. A new study, published this week in Science Advances and led by Tobias Friedrich from the International Pacific Research Center (IPRC) at the University of Hawai?i at Mānoa (UHM), concludes that warm climates are more sensitive to changes in CO2 levels than cold climates. Increasing atmospheric CO2 concentrations cause an imbalance in the Earth's heat budget: more heat is retained than expelled, which in turn generates global surface warming. Climate sensitivity is a term used to describe the amount of warming expected to result after an increase in the concentration of CO2. This number is traditionally calculated using complex computer models of the climate system, but despite decades of progress, the number is still subject to uncertainty. The new study, which included scientists from the University of Washington, the University at Albany, and the Potsdam Institute for Climate Impact Research, took a different approach in calculating climate sensitivity: using data from the history of Earth. The researchers examined various reconstructions of past temperatures and CO2 levels to determine how the climate system has responded to previous changes in its energy balance. "The first step was to reconstruct the history of global mean temperatures for the last 784,000 years, using combined data from marine sediment cores, ice cores, and computer simulations covering the last eight glacial cycles," said Friedrich, a post-doctoral researcher at IPRC. The second step involved calculating the Earth's energy balance for this time period, using estimates of greenhouse gas concentrations extracted from air bubbles in ice cores, and incorporating astronomical factors, known as Milankovitch Cycles, that effect the planetary heat budget. "Our results imply that the Earth's sensitivity to variations in atmospheric CO2 increases as the climate warms," explained Friedrich. "Currently, our planet is in a warm phase -- an interglacial period -- and the associated increased climate sensitivity needs to be taken into account for future projections of warming induced by human activities." Using these estimates based on Earth's paleoclimate sensitivity, the authors computed the warming over the next 85 years that could result from a human-induced, business-as-usual greenhouse gas emission scenario. The researchers project that by the year 2100, global temperatures will rise 5.9°C (~10.5°F) above pre-industrial values. This magnitude of warming overlaps with the upper range of estimates presented by the Intergovernmental Panel on Climate Change (IPCC). "Our study also allows us to put our 21st century temperatures into the context of Earth's history. Paleoclimate data can actually teach us a lot about our future," said Axel Timmermann, co-author of the study and professor at UHM. The results of the study demonstrate that unabated human-induced greenhouse gas emissions are likely to push Earth's climate out of the envelope of temperature conditions that have prevailed for the last 784,000 years. "The only way out is to reduce greenhouse gas emissions as soon as possible," concluded Friedrich.


News Article | November 11, 2016
Site: www.sciencedaily.com

It is well-established in the scientific community that increases in atmospheric CO levels result in global warming, but the magnitude of the effect may vary depending on average global temperature. A new study, published this week in Science Advances and led by Tobias Friedrich from the International Pacific Research Center (IPRC) at the University of Hawai?i at Mānoa (UHM), concludes that warm climates are more sensitive to changes in CO levels than cold climates. Increasing atmospheric CO concentrations cause an imbalance in Earth's heat budget: more heat is retained than expelled, which in turn generates global surface warming. Climate sensitivity is a term used to describe the amount of warming expected to result after an increase in the concentration of CO . This number is traditionally calculated using complex computer models of the climate system, but despite decades of progress, the number is still subject to uncertainty. The new study, which included scientists from the University of Washington, the University at Albany, and the Potsdam Institute for Climate Impact Research, took a different approach in calculating climate sensitivity: using data from the history of Earth. The researchers examined various reconstructions of past temperatures and CO levels to determine how the climate system has responded to previous changes in its energy balance. "The first step was to reconstruct the history of global mean temperatures for the last 784,000 years, using combined data from marine sediment cores, ice cores, and computer simulations covering the last eight glacial cycles," said Friedrich, a post-doctoral researcher at IPRC. The second step involved calculating Earth's energy balance for this time period, using estimates of greenhouse gas concentrations extracted from air bubbles in ice cores, and incorporating astronomical factors, known as Milankovitch Cycles, that effect the planetary heat budget. "Our results imply that Earth's sensitivity to variations in atmospheric CO increases as the climate warms," explained Friedrich. "Currently, our planet is in a warm phase -- an interglacial period -- and the associated increased climate sensitivity needs to be taken into account for future projections of warming induced by human activities." Using these estimates based on Earth's paleoclimate sensitivity, the authors computed the warming over the next 85 years that could result from a human-induced, business-as-usual greenhouse gas emission scenario. The researchers project that by the year 2100, global temperatures will rise 5.9°C (~10.5°F) above pre-industrial values. This magnitude of warming overlaps with the upper range of estimates presented by the Intergovernmental Panel on Climate Change (IPCC). "Our study also allows us to put our 21st century temperatures into the context of Earth's history. Paleoclimate data can actually teach us a lot about our future," said Axel Timmermann, co-author of the study and professor at UHM. The results of the study demonstrate that unabated human-induced greenhouse gas emissions are likely to push Earth's climate out of the envelope of temperature conditions that have prevailed for the last 784,000 years. "The only way out is to reduce greenhouse gas emissions as soon as possible," concluded Friedrich.


Rhee J.,Climate Center | Cai W.,CSIRO | Plummer N.,Bureau of Meteorology | Sivakumar M.,World Meteorological Organization | And 3 more authors.
Bulletin of the American Meteorological Society | Year: 2015

The Asia-Pacific Economic Cooperation (APEC) Climate Symposium 2013 was held with the theme of regional cooperation on drought prediction science for disaster preparedness and management. Gusti Muhammad Hatta, the Indonesian minister for research and technology, opened the symposium, noting the importance of the event in strengthening drought preparedness in order to contribute to the APEC mission of sustainable economic growth and prosperity in the Asia-Pacific region. In his keynote address, Donald Wilhite, professor at the University of Nebraska-Lincoln and founder of the National Drought Mitigation Center, presented a state-of-the-art system for monitoring drought conditions in the United States. The second keynote address, by Andi Eka Sakya of the Indonesia Agency for Meteorology, Climatology, and Geophysics (BMKG), focused on a potential drought monitoring information system for Indonesia. He introduced the geographical and climatological conditions of Indonesia and explained other existing information systems produced by BMKG. The conference presentations described the extent of existing research and scientific understanding of the processes and mechanisms that control rainfall and other variables relevant to drought in different areas.


Xiang B.,University of Hawaii at Manoa | Xiang B.,First Institute of Oceanography | Yu W.,First Institute of Oceanography | Li T.,University of Hawaii at Manoa | And 3 more authors.
Geophysical Research Letters | Year: 2011

Boreal summer is a critical season for the rapid development of the Indian Ocean Dipole (IOD). In this study, three factors related to the boreal summer mean state are proposed to be important for the rapid development of the IOD, by strengthening the equatorial zonal wind anomaly and thus the dynamic Bjerknes feedback. Firstly, as part of the Indo-Pacific warm pool, the high mean SST in the southeastern tropical Indian Ocean (SEIO) acts as an essential prerequisite for the development of anomalous convection. Secondly, the maximum of the suppressed precipitation in response to a cold SST anomaly (SSTA) in the SEIO, shifts northward towards the equator because the mean precipitation is equatorially trapped in boreal summer. Thirdly, the monsoonal easterly shear in boreal summer promotes an enhanced, more equatorially symmetric low-level Rossby wave response to a prescribed equatorially asymmetric heating over the SEIO. The above three processes promote a greater equatorial zonal wind response and thus a greater Bjerknes feedback, as well as a greater IOD development during boreal summer. Copyright © 2011 by the American Geophysical Union.


Ogata T.,International Pacific Research Center | Ogata T.,University of Tsukuba | Xie S.-P.,University of Hawaii at Manoa | Xie S.-P.,University of California at San Diego | And 2 more authors.
Journal of Climate | Year: 2013

The amplitude of El Niño-Southern Oscillation (ENSO) displays pronounced interdecadal modulations in observations. The mechanisms for the amplitude modulation are investigated using a 2000-yr preindustrial control integration from the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). ENSO amplitude modulation is highly correlated with the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV), which features equatorial zonal dipoles in sea surface temperature (SST) and subsurface temperature along the thermocline. Experiments with an ocean general circulation model indicate that both interannual and decadal-scale wind variability are required to generate decadal-scale tropical Pacific temperature anomalies at the sea surface and along the thermocline. Even a purely interannual and sinusoidal wind forcing can produce substantial decadal-scale effects in the equatorial Pacific, with SST cooling in the west, subsurface warming along the thermocline, and enhanced upper-ocean stratification in the east. A mechanism is proposed by which residual effects of ENSO could serve to alter subsequent ENSO stability, possibly contributing to long-lasting epochs of extreme ENSO behavior via a coupled feedback with TPDV. © 2013 American Meteorological Society.


Ogata T.,International Pacific Research Center | Xie S.-P.,Pacific University in Oregon | Xie S.-P.,Ocean University of China | Lan J.,Ocean University of China | Zheng X.,Ocean University of China
Journal of Climate | Year: 2013

Interannual anomalies of sea surface temperature (SST), wind, and cloudiness in the southeastern tropical Indian Ocean (SE-TIO) show negative skewness. In this research, asymmetry between warm and cold episodes in the SE-TIO and the importance of ocean dynamics are investigated.Acoupled model simulation and observations show an asymmetric relationship between SST and the thermocline depth in the SE-TIO where SST is more sensitive to an anomalous shoaling than to deepening of the thermocline. This asymmetric thermocline feedback on SST is a result of a deep mean thermocline. Sensitivity experiments with an ocean general circulation model (OGCM) show that a negative SST skewness arises in response to sinusoidal zonal wind variations that are symmetric between the westerly and easterly phases. Heat budget analysis with an OGCM hindcast also supports the importance of ocean dynamics for SST skewness off Sumatra and Java. © 2013 American Meteorological Society.


Xu J.,Chinese Academy of Meteorological Sciences | Wang Y.,International Pacific Research Center | Wang Y.,University of Hawaii at Manoa
Weather and Forecasting | Year: 2015

The dependence of tropical cyclone (TC) intensification rate IR on storm intensity and size was statistically analyzed for North Atlantic TCs during 1988-2012. The results show that IR is positively (negatively) correlated with storm intensity (the maximum sustained near-surface wind speed Vmax) when Vmax is below (above) 70-80 knots (kt; 1 kt = 0.51 m s-1), and negatively correlated with storm size in terms of the radius of maximum wind (RMW), the average radius of gale-force wind (AR34), and the outer-core wind skirt parameter DR34 (=AR34 - RMW). The turning point for Vmax of 70-80 kt is explained as a balance between the potential intensification and the maximum potential intensity (MPI). The highest IR occurs for Vmax = 80 kt, RMW ≤ 40 km, and AR34 = DR34 = 150 km. The high frequency of occurrence of intensifying TCs occurs for Vmax ≤ 80 kt and RMW between 20 and 60 km, AR34 ≤ 200 km, and DR34 ≤ 150 km. Rapid intensification (RI) often occurs in a relatively narrow parameter space in storm intensity and both inner- and outer-core sizes. In addition, a theoretical basis for the intensity dependency has also been provided based on a previously constructed simplified dynamical system for TC intensity prediction. © 2015 American Meteorological Society.


Li T.,International Pacific Research Center
Geophysical Monograph Series | Year: 2010

The Asian monsoon consists of three subcomponents, Indian monsoon (IM), East Asian monsoon (EAM), and western North Pacific monsoon (WNPM). All these submonsoon systems exhibit remarkable intraseasonal and interannual variabilities. In this chapter, we will review recent progress in understanding the monsoon annual cycle and some of major issues related to the monsoon intraseasonal and interannual variabilities; describe the spatial-temporal structure of the northward propagating intraseasonal oscillation in the monsoon region; and discuss what physical processes lead to quasi-biennial and lower-frequency variabilities of the India monsoon, how El Niño (La Niña) events have a delayed impact on East Asian climate, and how the atmosphere-ocean interaction in the monsoon-warm ocean leads to the tropospheric biennial oscillation. Specific emphases are placed on the discussion of the physical processes that are responsible for the described phenomena. Copyright © 2010 by the American Geophysical Union.

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