scholarly journals Initialized Decadal Predictions by LASG/IAP Climate System Model FGOALS-s2: Evaluations of Strengths and Weaknesses

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Bo Wu ◽  
Xiaolong Chen ◽  
Fengfei Song ◽  
Yong Sun ◽  
Tianjun Zhou
Keyword(s):  
Indian Ocean ◽  
Radiative Forcing ◽  
Climate Model ◽  
Initial Conditions ◽  
Global Climate Model ◽  
Western Pacific ◽  
Decadal Prediction ◽  
Climate System Model ◽  
Tropical Western Pacific ◽  
The Indian Ocean

Decadal prediction experiments are conducted by using the coupled global climate model FGOALS-s2, following the CMIP 5 protocol. The paper documents the initialization procedures for the decadal prediction experiments and summarizes the predictive skills of the experiments, which are assessed through indicators adopted by the IPCC AR5. The observational anomalies of surface and subsurface ocean temperature and salinity are assimilated through a modified incremental analysis update (IAU) scheme. Three sets of 10-year-long hindcast and forecast runs were started every five years in the period of 1960–2005, with the initial conditions taken from the assimilation runs. The decadal prediction experiment by FGOALS-s2 shows significant high predictive skills in the Indian Ocean, tropical western Pacific, and Atlantic, similar to the results of the CMIP5 multimodel ensemble. The predictive skills in the Indian Ocean and tropical western Pacific are primarily attributed to the model response to the external radiative forcing associated with the change of atmospheric compositions. In contrast, the high skills in the Atlantic are attributed, at least partly, to the improvements in the prediction of the Atlantic multidecadal variability coming from the initialization.

Some new data on tropical western Pacific Ascidians

Zootaxa ◽  
2010 ◽  
Vol 2561 (1) ◽  
pp. 1 ◽  
Author(s):  
FRANÇOISE MONNIOT
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
New Records ◽  
Western Pacific ◽  
Additional Species ◽  
Tropical Western Pacific ◽  
The Pacific ◽  
The Indian Ocean ◽  
Made In

Numerous collections of ascidians have been made in the Pacific and Indian Oceans but the inventory is far from complete. Each sampling provides new species. Two new didemnids are described here from Palau and Vanuatu. New records are given for 22 additional species with complementary descriptions and underwater photographs. The tropical ascidian fauna is highly diverse and successive new collections show that many of the species are not only widely distributed from the central to western Pacific but also common to the Indian Ocean.

scholarly journals Sea Level controls on Agulhas Leakage Salinity and the Atlantic Overturning Circulation

2021 ◽  
Author(s):  
Sophie Nuber ◽  
James Rae ◽  
Morten Andersen ◽  
Xu Zhang ◽  
Bas de Boer ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Sea Level ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Salt Content ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Land Bridge ◽  
The Indian Ocean

Abstract The Indian Ocean has been proposed as an important source of salt for North Atlantic deep-water convection sites, via the Agulhas Leakage, and may thus drive changes in the ocean’s overturning circulation. However, while past changes in Agulhas leakage volume have been explored, little is known about this water’s salt content, representing a major gap in our understanding of Agulhas salinity supply. Here, we present new planktonic foraminiferal Mg/Ca-derived sea surface temperatures (SST) and stable isotope-derived salinity reconstructions for the last 1.2Ma from the western Indian Ocean source waters of the Agulhas Leakage to investigate glacial-interglacial changes in surface water properties. We find that SST and relative salinity both increase during glaciation, leading to high salinity and SST during glacial maxima. We show that the onset of surface salinification and warming in the Indian Ocean occurs during a phase of rapid land-bridge exposure in the Indonesian archipelago induced by sea level lowering. We link these findings to new global climate model results which show that the export of salt from the Indian Ocean via the Agulhas Leakage can directly impact the deglacial Atlantic meridional overturning circulation and therefore global climate.

Ciallusiidae (Ascidiacea, Tunicata), a monotypic family from deeper waters of the tropical Indo-West Pacific

Zootaxa ◽  
2008 ◽  
Vol 1742 (1) ◽  
pp. 47 ◽  
Author(s):  
PATRICIA KOTT
Keyword(s):  
Indian Ocean ◽  
Western Australia ◽  
Type Species ◽  
Geographic Range ◽  
Western Pacific ◽  
Ciliated Epithelium ◽  
West Pacific ◽  
Tropical Western Pacific ◽  
The Family ◽  
The Indian Ocean

Ciallusia longa Van Name, 1918, the type species of the family Ciallusiidae is confirmed as a junior synonym of Pterygascidia mirabilis Sluiter, 1904. Although relationships with Ciona and Perophora have successively been proposed, examination of 12 newly recorded specimens from the northwestern coast of Western Australia, together with a review of documented specimens, demonstrate a relationship with the Phlebobranchia. As in many Phlebobranchia, the taxon has a large, flat branchial sac, simple branchial tentacles, translucent gelatinous test, specialisation of muscles into long rows of bundles of short parallel bands and a straight gut. However, rather than Corellidae (as Sluiter had proposed on the basis of the lack of ciliated epithelium lining the pharyngeal perforations) the family most closely related appears to be the family Agneziidae (see Huus 1936 and Kott 1985) which has dorsal languets. The newly recorded specimens extend the known geographic range of this species from the tropical western Pacific to the Indian Ocean.

scholarly journals An Improved Parameterization for Simulating Arctic Cloud Amount in the CCSM3 Climate Model

2008 ◽  
Vol 21 (21) ◽  
pp. 5673-5687 ◽  
Author(s):  
Steve Vavrus ◽  
Duane Waliser
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Cloud Amount ◽  
The Arctic ◽  
Climate Simulation ◽  
Polar Regions ◽  
Climate System Model ◽  
Model Version

Abstract A simple alternative parameterization for predicting cloud fraction in the Community Climate System Model, version 3 (CCSM3) global climate model is presented. This formula, dubbed “freeezedry,” is designed to alleviate the bias of excessive low clouds during polar winter by reducing the cloud amount under very dry conditions. During winter, freezedry decreases the low cloud amount over the coldest regions in high latitudes by over 50% locally and more than 30% averaged across the Arctic. The cloud reduction causes an Arctic-wide drop of 15 W m−2 in surface cloud radiative forcing (CRF) during winter and about a 50% decrease in mean annual Arctic CRF. Consequently, wintertime surface temperatures fall by up to 4 K on land and 2–8 K over the Arctic Ocean, thus significantly reducing the model’s pronounced warm bias. Freezedry also affects CCSM3’s sensitivity to greenhouse forcing. In a transient-CO2 experiment, the model version with freezedry warms up to 20% less in the North Polar and South Polar regions (1.5- and 0.5-K-smaller warming, respectively). Paradoxically, the muted high-latitude response occurs despite a much larger increase in cloud amount with freezedry during nonsummer months (when clouds warm the surface), apparently because of the colder modern reference climate. While improving the polar climate simulation in CCSM3, freezedry has virtually no influence outside of very cold regions and has already been implemented in another climate model, the Global Environmental and Ecological Simulation of Ecological Systems, version 1 (GENESIS1). Furthermore, the simplicity of this parameterization allows it to be readily incorporated into other GCMs, many of which also suffer from excessive wintertime polar cloudiness.

Decadal Prediction of Indian Ocean Dipole

2020 ◽  
Author(s):  
Feba Francis ◽  
Ashok Karumuri ◽  
Matthew Collins
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Initial Conditions ◽  
Southern Oscillation ◽  
Global Climate ◽  
Climate Science ◽  
Decadal Prediction ◽  
Science And Society ◽  
The Indian Ocean ◽  
The Tropics

<p> </p><p>Decadal Prediction is the prediction of climate for the next 5–20 years. Decadal Prediction has gained great importance as it tries to bridge the gap between seasonal and Centennial (50-100 year) predictions creating a balance between initial conditions and boundary conditions. We analysed the model output from CMIP5 decadal runs of nine models. Our results show that two of the decadal hindcasts show prediction skills of significance for the <strong>Indian Ocean Dipole</strong> for up to a decade. The Indian Ocean Dipole is one of the leading modes of climate variability in the tropics, which affects global climate. As already established, the models also show year-long lead predictability of the El Niño Southern Oscillation. We found no significant skills for the Indian Summer Monsoon. We are presently looking for the source of the lead predictability of Indian Ocean Dipole which appears to be due to links from <strong>the Southern Ocean</strong>. These decadal prediction skills and predictability for a climate driver like the Indian Ocean Dipole have immense helpfulness for climate science and society in general. <strong><br></strong></p>

scholarly journals Indian Ocean impact on ENSO evolution 2014–2016 in a set of seasonal forecasting experiments

2021 ◽  
Author(s):  
Michael Mayer ◽  
Magdalena Alonso Balmaseda
Keyword(s):  
Pacific Ocean ◽  
Indian Ocean ◽  
El Niño ◽  
Initial Conditions ◽  
El Nino ◽  
Southern Oscillation ◽  
Heat Content ◽  
Tropical Pacific ◽  
Decadal Variations ◽  
The Indian Ocean

AbstractThis study investigates the influence of the anomalously warm Indian Ocean state on the unprecedentedly weak Indonesian Throughflow (ITF) and the unexpected evolution of El Niño-Southern Oscillation (ENSO) during 2014–2016. It uses 25-month-long coupled twin forecast experiments with modified Indian Ocean initial conditions sampling observed decadal variations. An unperturbed experiment initialized in Feb 2014 forecasts moderately warm ENSO conditions in year 1 and year 2 and an anomalously weak ITF throughout, which acts to keep tropical Pacific ocean heat content (OHC) anomalously high. Changing only the Indian Ocean to cooler 1997 conditions substantially alters the 2-year forecast of Tropical Pacific conditions. Differences include (i) increased probability of strong El Niño in 2014 and La Niña in 2015, (ii) significantly increased ITF transports and (iii), as a consequence, stronger Pacific ocean heat divergence and thus a reduction of Pacific OHC over the two years. The Indian Ocean’s impact in year 1 is via the atmospheric bridge arising from altered Indian Ocean Dipole conditions. Effects of altered ITF and associated ocean heat divergence (oceanic tunnel) become apparent by year 2, including modified ENSO probabilities and Tropical Pacific OHC. A mirrored twin experiment starting from unperturbed 1997 conditions and several sensitivity experiments corroborate these findings. This work demonstrates the importance of the Indian Ocean’s decadal variations on ENSO and highlights the previously underappreciated role of the oceanic tunnel. Results also indicate that, given the physical links between year-to-year ENSO variations, 2-year-long forecasts can provide additional guidance for interpretation of forecasted year-1 ENSO probabilities.

scholarly journals Projected Changes in Extreme Temperature and Precipitation Indices Over CORDEX-MENA Domain

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 622
Author(s):  
Tugba Ozturk ◽  
F. Sibel Saygili-Araci ◽  
M. Levent Kurnaz
Keyword(s):  
Regional Climate Model ◽  
Radiative Forcing ◽  
Climate Model ◽  
Global Climate Model ◽  
Regional Climate ◽  
Climate Extreme ◽  
Pronounced Increase ◽  
Temperature And Precipitation ◽  
Projected Changes ◽  
Extreme Indices

In this study, projected changes in climate extreme indices defined by the Expert Team on Climate Change Detection and Indices were investigated over Middle East and North Africa. Changes in the daily maximum and minimum temperature- and precipitation- based extreme indices were analyzed for the end of the 21st century compared to the reference period 1971–2000 using regional climate model simulations. Regional climate model, RegCM4.4 was used to downscale two different global climate model outputs to 50 km resolution under RCP4.5 and RCP8.5 scenarios. Results generally indicate an intensification of temperature- and precipitation- based extreme indices with increasing radiative forcing. In particular, an increase in annual minimum of daily minimum temperatures is more pronounced over the northern part of Mediterranean Basin and tropics. High increase in warm nights and warm spell duration all over the region with a pronounced increase in tropics are projected for the period of 2071–2100 together with decrease or no change in cold extremes. According to the results, a decrease in total wet-day precipitation and increase in dry spells are expected for the end of the century.

scholarly journals Comparison of ice particle characteristics simulated by the Community Atmosphere Model (CAM5) with in-situ observations

2014 ◽  
Vol 14 (6) ◽  
pp. 7637-7681 ◽  
Author(s):  
T. Eidhammer ◽  
H. Morrison ◽  
A. Bansemer ◽  
A. Gettelman ◽  
A. J. Heymsfield
Keyword(s):  
Size Distribution ◽  
Radiative Forcing ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Atmospheric Model ◽  
Slope Parameter ◽  
Cloud Radiative Forcing ◽  
Threshold Size ◽  
Cloud Ice

Abstract. Detailed measurements of ice crystals in cirrus clouds were used to compare with results from the Community Atmospheric Model Version 5 (CAM5) global climate model. The observations are from two different field campaigns with contrasting conditions: Atmospheric Radiation Measurements Spring Cloud Intensive Operational Period in 2000 (ARM-IOP), which was characterized primarily by midlatitude frontal clouds and cirrus, and Tropical Composition, Cloud and Climate Coupling (TC4), which was dominated by anvil cirrus. Results show that the model typically overestimates the slope parameter of the exponential size distributions of cloud ice and snow, while the variation with temperature (height) is comparable. The model also overestimates the ice/snow number concentration (0th moment of the size distribution) and underestimates higher moments (2nd through 5th), but compares well with observations for the 1st moment. Overall the model shows better agreement with observations for TC4 than for ARM-IOP in regards to the moments. The mass-weighted terminal fallspeed is lower in the model compared to observations for both ARM-IOP and TC4, which is partly due to the overestimation of the size distribution slope parameter. Sensitivity tests with modification of the threshold size for cloud ice to snow autoconversion (Dcs) do not show noticeable improvement in modeled moments, slope parameter and mass weighed fallspeed compared to observations. Further, there is considerable sensitivity of the cloud radiative forcing to Dcs, consistent with previous studies, but no value of Dcs improves modeled cloud radiative forcing compared to measurements. Since the autoconversion of cloud ice to snow using the threshold size Dcs has little physical basis, future improvement to combine cloud ice and snow into a single category, eliminating the need for autoconversion, is suggested.

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