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Title: Process-oriented Diagnosis Of Tropical Cyclones In High-resolution Gcms.
Creator: Kim, Daehyun, Moon, Yumin, Camargo, Suzana J., Wing, Allison A., Sobel, Adam H., Murakami, Hiroyuki, Vecchi, Gabriel A., Zhao, Ming, Page, Eric
Abstract/Description: This study proposes a set of process-oriented diagnostics with the aim of understanding how model physics and numerics control the representation of tropical cyclones (TCs), especially their intensity distribution, in GCMs. Three simulations are made using two 50-km GCMs developed at NOAA's Geophysical Fluid Dynamics Laboratory. The two models are forced with the observed sea surface temperature [Atmospheric Model version 2.5 (AM2.5) and High Resolution Atmospheric Model (HiRAM)], and in the...
Show moreThis study proposes a set of process-oriented diagnostics with the aim of understanding how model physics and numerics control the representation of tropical cyclones (TCs), especially their intensity distribution, in GCMs. Three simulations are made using two 50-km GCMs developed at NOAA's Geophysical Fluid Dynamics Laboratory. The two models are forced with the observed sea surface temperature [Atmospheric Model version 2.5 (AM2.5) and High Resolution Atmospheric Model (HiRAM)], and in the third simulation, the AM2.5 model is coupled to an ocean GCM [Forecast-Oriented Low Ocean Resolution (FLOR)]. The frequency distributions of maximum near-surface wind near TC centers show that HiRAM tends to develop stronger TCs than the other models do. Large-scale environmental parameters, such as potential intensity, do not explain the differences between HiRAM and the other models. It is found that HiRAM produces a greater amount of precipitation near the TC center, suggesting that associated greater diabatic heating enables TCs to become stronger in HiRAM. HiRAM also shows a greater contrast in relative humidity and surface latent heat flux between the inner and outer regions of TCs. Various fields are composited on precipitation percentiles to reveal the essential character of the interaction among convection, moisture, and surface heat flux. Results show that the moisture sensitivity of convection is higher in HiRAM than in the other model simulations. HiRAM also exhibits a stronger feedback from surface latent heat flux to convection via near-surface wind speed in heavy rain-rate regimes. The results emphasize that the moisture-convection coupling and the surface heat flux feedback are critical processes that affect the intensity of TCs in GCMs.
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Date Issued: 2018-03
Identifier: FSU_libsubv1_wos_000427438100001, 10.1175/JCLI-D-17-0269.1
Format: Citation

Title: Influence Of Global Warming On Western North Pacific Tropical Cyclone Intensities During 2015.
Creator: Yang, Se-Hwan, Kang, Nam-Young, Elsner, James B., Chun, Youngsin
Abstract/Description: The climate of 2015 was characterized by a strong El Nino, global warmth, and record-setting tropical cyclone (TC) intensity for western North Pacific typhoons. In this study, the highest TC intensity in 32 years (1984-2015) is shown to be a consequence of above normal TC activity-following natural internal variation-and greater efficiency of intensity. The efficiency of intensity (EINT) is termed the ''blasting'' effect and refers to typhoon intensification at the expense of occurrence....
Show moreThe climate of 2015 was characterized by a strong El Nino, global warmth, and record-setting tropical cyclone (TC) intensity for western North Pacific typhoons. In this study, the highest TC intensity in 32 years (1984-2015) is shown to be a consequence of above normal TC activity-following natural internal variation-and greater efficiency of intensity. The efficiency of intensity (EINT) is termed the ''blasting'' effect and refers to typhoon intensification at the expense of occurrence. Statistical models show that the EINT is mostly due to the anomalous warmth in the environment indicated by global mean sea surface temperature. In comparison, the EINT due to El Nino is negligible. This implies that the record-setting intensity of 2015 might not have occurred without environmental warming and suggests that a year with even greater TC intensity is possible in the near future when above normal activity coincides with another record EINT due to continued multidecadal warming.
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Date Issued: 2018-01
Identifier: FSU_libsubv1_wos_000425164800025, 10.1175/JCLI-D-17-0143.1
Format: Citation

Title: Understanding The Variations Of The Length And The Seasonal Rainfall Anomalies Of The Indian Summer Monsoon.
Creator: Misra, Vasubandhu, Bhardwaj, Amit, Noska, Ryne
Abstract/Description: The canonical relationship between the length and the total seasonal rainfall anomalies of the Indian summer monsoon (ISM) is the association of the longer (shorter) season with wetter (drier) seasonal rainfall anomalies. This study shows that such canonical behavior is clearly associated with relatively strong ENSO SST anomalies in the eastern equatorial Pacific Ocean that appear in the boreal summer and fall seasons. The noncanonical relationship is caused by a longer (shorter) season...
Show moreThe canonical relationship between the length and the total seasonal rainfall anomalies of the Indian summer monsoon (ISM) is the association of the longer (shorter) season with wetter (drier) seasonal rainfall anomalies. This study shows that such canonical behavior is clearly associated with relatively strong ENSO SST anomalies in the eastern equatorial Pacific Ocean that appear in the boreal summer and fall seasons. The noncanonical relationship is caused by a longer (shorter) season associated with drier (wetter) ISM seasonal rainfall anomalies. A majority of these noncanonical seasons, with anomalously short season length but anomalously high seasonal mean rain, tend to occur under relatively weak La Nina forcing during the boreal summer season. Although the onset of such seasons occurs through canonical ENSO forcing of a large- scale meridional temperature gradient, the demise is dictated by the depletion of moist static energy from the underlying cooling of the upper ocean in the northern Indian Ocean. This is due to stronger meridional Ekman ocean heat transport forced by the stronger low- level atmospheric southwesterlies than those in the corresponding canonical wet ISM season.
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Date Issued: 2017-03
Identifier: FSU_libsubv1_wos_000395539100012, 10.1175/JCLI-D-16-0501.1
Format: Citation

Title: Decadal Variability Of The Meridional Geostrophic Transport In The Upper Tropical North Pacific Ocean.
Creator: Zhou, Hui, Yuan, Dongliang, Yang, Lina, Li, Xiang, Dewar, William
Abstract/Description: The meridional geostrophic transport (MGT) in the interior tropical North Pacific Ocean is estimated based on global ocean heat and salt content data. The decadal variations of the zonally and vertically integrated MGT in the tropical North Pacific Ocean are found to precede the Pacific decadal oscillation (PDO) by 1-3 years. The dynamics of the MGT are analyzed based on Sverdrup theory. It is found that the total meridional transport variability (MGT plus Ekman) is dominated by the MGT...
Show moreThe meridional geostrophic transport (MGT) in the interior tropical North Pacific Ocean is estimated based on global ocean heat and salt content data. The decadal variations of the zonally and vertically integrated MGT in the tropical North Pacific Ocean are found to precede the Pacific decadal oscillation (PDO) by 1-3 years. The dynamics of the MGT are analyzed based on Sverdrup theory. It is found that the total meridional transport variability (MGT plus Ekman) is dominated by the MGT variability having positive correlations with the PDO index. The Sverdrup transports differ from the total meridional transport significantly and have insignificant correlations with PDO index, suggesting that the MGT variability is not controlled by the Sverdrup dynamics. In comparison, the simulated meridional transport variability in the models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) and the Ocean General Circulation Model for the Earth Simulator are dominated by the Sverdrup transports, having insignificant correlations with the simulated PDO indices. The comparison suggests that the non-Sverdrup component in the MGT is important for the predictability of PDO and that significant deficiencies exist in these models in simulating a realistic structure of the tropical ocean gyre variability and predicting the decadal climate variations associated with it.
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Date Issued: 2018-08-01
Identifier: FSU_libsubv1_wos_000438848800007, 10.1175/JCLI-D-17-0639.1
Format: Citation

Title: Dynamic downscaling of the North American Monsoon with the NCEP-Scripps Regional Spectral Model from the NCEP CFS global model.
Creator: Chan, Steven, Misra, Vasubandhu
Abstract/Description: The June-September (JJAS) 2000-2007 NCEP coupled Climate Forecasting System (CFS) global hindcasts are downscaled over the North and South American continents with the NCEP-Scripps Regional Spectral Model (RSM) with anomaly nesting (AN) and without bias correction (control). A diagnosis of the North American Monsoon (NAM) in CFS and RSM hindcasts is presented here. RSM reduces errors caused by coarse resolution, but is unable to address larger scale CFS errors even with bias correction. CFS...
Show moreThe June-September (JJAS) 2000-2007 NCEP coupled Climate Forecasting System (CFS) global hindcasts are downscaled over the North and South American continents with the NCEP-Scripps Regional Spectral Model (RSM) with anomaly nesting (AN) and without bias correction (control). A diagnosis of the North American Monsoon (NAM) in CFS and RSM hindcasts is presented here. RSM reduces errors caused by coarse resolution, but is unable to address larger scale CFS errors even with bias correction. CFS has relatively weak Great Plains and Gulf of California low-level jets. Low-level jets are strengthened from downscaling, especially after AN bias correction. The RSM NAM hydroclimate shares similar flaws with CFS with problematic diurnal and seasonal variability. Flaws in both diurnal and monthly variability are forced by erroneous convection-forced divergence outside the monsoon core region in eastern and southern Mexico. NCEP Reanalysis shows significant seasonal variability errors, and AN shows little improvement in regional scale flow errors. Our results suggest extreme caution must be taken when the correction is applied relative to reanalyses. Analysis also shows North American Regional Reanalysis NAM seasonal variability has benefited from precipitation data assimilation, but many questions remain concerning NARR's representation of NAM.
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Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0030, 10.1175/2010JCLI3593.1
Format: Citation

Title: Temperature-Salinity Structure of the North Atlantic Circulation and Associated Heat and Freshwater Transports.
Creator: Xu, Xiaobiao, Rhines, Peter B., Chassignet, Eric P.
Abstract/Description: This study investigates the circulation structure and relative contribution of circulation components to the time-mean meridional heat and freshwater transports in the North Atlantic, using numerical results of a high-resolution ocean model that are shown to be in excellent agreement with the observations. The North Atlantic circulation can be separated into the large-scale Atlantic meridional overturning circulation (AMOC) that is diapycnal and the subtropical and subpolar gyres that largely...
Show moreThis study investigates the circulation structure and relative contribution of circulation components to the time-mean meridional heat and freshwater transports in the North Atlantic, using numerical results of a high-resolution ocean model that are shown to be in excellent agreement with the observations. The North Atlantic circulation can be separated into the large-scale Atlantic meridional overturning circulation (AMOC) that is diapycnal and the subtropical and subpolar gyres that largely flow along isopycnal surfaces but also include prominent gyre-scale diapycnal overturning in the Subtropical Mode Water and Labrador Sea Water. Integrals of the meridional volume transport as a function of potential temperature theta and salinity S yield streamfunctions with respect to theta and to S, and heat functions. These argue for a significant contribution to the heat transport by the southward circulation of North Atlantic Deep Water. At 26.5 degrees N, the isopycnic component of the subtropical gyre is colder and fresher in the northward-flowing western boundary currents than the southward return flows, and it carries heat southward and freshwater northward, opposite of that of the diapycnal component. When combined, the subtropical gyre contributes virtually zero to the heat transport and the AMOC is responsible for all the heat transport across this latitude. The subtropical gyre however significantly contributes to the freshwater transport, reducing the 0.5-Sv (1 Sv =10(6) m(3) s(-1)) southward AMOC freshwater transport by 0.13 Sv. In the subpolar North Atlantic near 58 degrees N, the diapycnal component of the circulation, or the transformation of warm saline upper Atlantic water into colder fresher deep waters, is responsible for essentially all of the heat and freshwater transports.
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Date Issued: 2016-11
Identifier: FSU_libsubv1_wos_000386205900009, 10.1175/JCLI-D-15-0798.1
Format: Citation

Title: An Assessment of Multimodel Simulations for the Variability of Western North Pacific Tropical Cyclones and Its Association with ENSO.
Creator: Han, Rongqing, Wang, Hui, Hu, Zeng-Zhen, Kumar, Arun, Li, Weijing, Long, Lindsey N., Schemm, Jae-Kyung E., Peng, Peitao, Wang, Wanqiu, Si, Dong, Jia, Xiaolong, Zhao, Ming,...
Show moreHan, Rongqing, Wang, Hui, Hu, Zeng-Zhen, Kumar, Arun, Li, Weijing, Long, Lindsey N., Schemm, Jae-Kyung E., Peng, Peitao, Wang, Wanqiu, Si, Dong, Jia, Xiaolong, Zhao, Ming, Vecchi, Gabriel A., Larow, Timothy E., Lim, Young-Kwon, Schubert, Siegfried D., Camargo, Suzana J., Henderson, Naomi, Jonas, Jeffrey A., Walsh, Kevin J. E.
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Abstract/Description: An assessment of simulations of the interannual variability of tropical cyclones (TCs) over the western North Pacific (WNP) and its association with El Nino-Southern Oscillation (ENSO), as well as a subsequent diagnosis for possible causes of model biases generated from simulated large-scale climate conditions, are documented in the paper. The model experiments are carried out by the Hurricane Work Group under the U.S. Climate Variability and Predictability Research Program (CLIVAR) using...
Show moreAn assessment of simulations of the interannual variability of tropical cyclones (TCs) over the western North Pacific (WNP) and its association with El Nino-Southern Oscillation (ENSO), as well as a subsequent diagnosis for possible causes of model biases generated from simulated large-scale climate conditions, are documented in the paper. The model experiments are carried out by the Hurricane Work Group under the U.S. Climate Variability and Predictability Research Program (CLIVAR) using five global climate models (GCMs) with a total of 16 ensemble members forced by the observed sea surface temperature and spanning the 28-yr period from 1982 to 2009. The results show GISS and GFDL model ensemble means best simulate the interannual variability of TCs, and the multimodel ensemble mean (MME) follows. Also, the MME has the closest climate mean annual number of WNP TCs and the smallest root-mean-square error to the observation. Most GCMs can simulate the interannual variability of WNP TCs well, with stronger TC activities during two types of El Nino-namely, eastern Pacific (EP) and central Pacific (CP) El Nino-and weaker activity during La Nina. However, none of the models capture the differences in TC activity between EP and CP El Nino as are shown in observations. The inability of models to distinguish the differences in TC activities between the two types of El Nino events may be due to the bias of the models in response to the shift of tropical heating associated with CP El Nino.
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Date Issued: 2016-09-15
Identifier: FSU_libsubv1_wos_000383828300001, 10.1175/JCLI-D-15-0720.1
Format: Citation

Title: Impact of the Madden-Julian Oscillation on the Indonesian Throughflow in the Makassar Strait during the CINDY/DYNAMO Field Campaign.
Creator: Shinoda, Toshiaki, Han, Weiqing, Jensen, Tommy G., Zamudio, Luis, Metzger, E. Joseph, Lien, Ren-Chieh
Abstract/Description: Previous studies indicate that equatorial zonal winds in the Indian Ocean can significantly influence the Indonesian Throughflow (ITF). During the Cooperative Indian Ocean Experiment on Intraseasonal Variability (CINDY)/Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign, two strong MJO events were observed within a month without a clear suppressed phase between them, and these events generated exceptionally strong ocean responses. Strong eastward currents along the equator in...
Show morePrevious studies indicate that equatorial zonal winds in the Indian Ocean can significantly influence the Indonesian Throughflow (ITF). During the Cooperative Indian Ocean Experiment on Intraseasonal Variability (CINDY)/Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign, two strong MJO events were observed within a month without a clear suppressed phase between them, and these events generated exceptionally strong ocean responses. Strong eastward currents along the equator in the Indian Ocean lasted more than one month from late November 2011 to early January 2012. The influence of these unique MJO events during the field campaign on ITF variability is investigated using a high-resolution (1/25 degrees) global ocean general circulation model, the Hybrid Coordinate Ocean Model (HYCOM). The strong westerlies associated with these MJO events, which exceed 10 m s(-1), generate strong equatorial eastward jets and downwelling near the eastern boundary. The equatorial jets are realistically simulated by the global HYCOM based on the comparison with the data collected during the field campaign. The analysis demonstrates that sea surface height (SSH) and alongshore velocity anomalies at the eastern boundary propagate along the coast of Sumatra and Java as coastal Kelvin waves, significantly reducing the ITF transport at the Makassar Strait during January-early February. The alongshore velocity anomalies associated with the Kelvin wave significantly leads SSH anomalies. The magnitude of the anomalous currents at the Makassar Strait is exceptionally large because of the unique feature of the MJO events, and thus the typical seasonal cycle of ITF could be significantly altered by strong MJO events such as those observed during the CINDY/DYNAMO field campaign.
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Date Issued: 2016-09-01
Identifier: FSU_libsubv1_wos_000382801400003, 10.1175/JCLI-D-15-0711.1
Format: Citation

Title: Assessing the Radiative Effects of Global Ice Clouds Based on CloudSat and CALIPSO Measurements.
Creator: Hong, Yulan, Liu, Guosheng, Li, J.-L. F.
Abstract/Description: Although it is well established that cirrus warms Earth, the radiative effect of the entire spectrum of ice clouds is not well understood. In this study, the role of all ice clouds in Earth's radiation budget is investigated by performing radiative transfer modeling using ice cloud properties retrieved from CloudSat and CALIPSO measurements as inputs. Results show that, for the 2008 period, the warming effect (similar to 21.8 +/- 5.4 W m(-2)) induced by ice clouds trapping longwave radiation...
Show moreAlthough it is well established that cirrus warms Earth, the radiative effect of the entire spectrum of ice clouds is not well understood. In this study, the role of all ice clouds in Earth's radiation budget is investigated by performing radiative transfer modeling using ice cloud properties retrieved from CloudSat and CALIPSO measurements as inputs. Results show that, for the 2008 period, the warming effect (similar to 21.8 +/- 5.4 W m(-2)) induced by ice clouds trapping longwave radiation exceeds their cooling effect (similar to-16.7 +/- 1.7 W m(-2)) caused by shortwave reflection, resulting in a net warming effect (similar to 5.1 +/- 3.8 W m(-2)) globally on the earthatmosphere system. The net warming is over 15 W m(-2) in the tropical deep convective regions, whereas cooling occurs in the midlatitudes, which is less than 10 W m(-2) in magnitude. Seasonal variations of ice cloud radiative effects are evident in the midlatitudes where the net effect changes from warming during winter to cooling during summer, whereas warming occurs all year-round in the tropics. Ice cloud optical depth t is shown to be an important factor in determining the sign and magnitude of the net radiative effect. Ice clouds with tau < 4.6 display a warming effect with the largest contributions from those with tau approximate to 1.0. In addition, ice clouds cause vertically differential heating and cooling of the atmosphere, particularly with strong heating in the upper troposphere over the tropics. At Earth's surface, ice clouds produce a cooling effect no matter how small the tau value is.
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Date Issued: 2016-11
Identifier: FSU_libsubv1_wos_000386205900006, 10.1175/JCLI-D-15-0799.1
Format: Citation

Title: Climate Mechanism for Stronger Typhoons in a Warmer World.
Creator: Kang, Nam-Young, Elsner, James B.
Abstract/Description: Violent typhoons continue to have catastrophic impacts on economies and welfare, but how they are responding to global warming has yet to be fully understood. Here, an empirical framework is used to explain physically why observations support a tight connection between increasing ocean warmth and the increasing intensity of supertyphoons in the western North Pacific. It is shown that the energy needed for deep convection is on the rise with greater heat and moisture in the lower tropical...
Show moreViolent typhoons continue to have catastrophic impacts on economies and welfare, but how they are responding to global warming has yet to be fully understood. Here, an empirical framework is used to explain physically why observations support a tight connection between increasing ocean warmth and the increasing intensity of supertyphoons in the western North Pacific. It is shown that the energy needed for deep convection is on the rise with greater heat and moisture in the lower tropical troposphere but that this energy remains untapped when air pressure is high. Accordingly, tropical cyclone formation is becoming less common, but those that do form are likely to reach extreme intensities from the discharge of stored energy. These thermodynamic changes to the environment most significantly influence the upper portion of extreme typhoon intensities, indicating that supertyphoons are likely to be stronger at the expense of overall tropical cyclone occurrences in the western North Pacific.
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Date Issued: 2016-02
Identifier: FSU_libsubv1_wos_000369285500001, 10.1175/JCLI-D-15-0585.1
Format: Citation

Department of Earth, Ocean and Atmospheric Science (4)	+ -
Center for Ocean-Atmospheric Prediction Studies (3)	+ -
Department of Geography (2)	+ -
Department of Physics (1)	+ -
Geophysical Fluid Dynamics Institute (1)	+ -

Atmospheric sciences (1)	+ -
Meteorology (1)	+ -
Oceanography (1)	+ -

text (10)	+ -
journal article (4)	+ -

Camargo, Suzana J. (2)	+ -
Elsner, James B. (2)	+ -
Kang, Nam-Young (2)	+ -
Misra, Vasubandhu (2)	+ -
Vecchi, Gabriel A. (2)	+ -

Zhao, Ming (2)	+ -
Bhardwaj, Amit (1)	+ -
Chan, Steven (1)	+ -
Chassignet, Eric P. (1)	+ -
Chun, Youngsin (1)	+ -
Dewar, William (1)	+ -
Han, Rongqing (1)	+ -
Han, Weiqing (1)	+ -
Henderson, Naomi (1)	+ -
Hong, Yulan (1)	+ -
Hu, Zeng-Zhen (1)	+ -
Jensen, Tommy G. (1)	+ -
Jia, Xiaolong (1)	+ -
Jonas, Jeffrey A. (1)	+ -
Kim, Daehyun (1)	+ -
Kumar, Arun (1)	+ -
Larow, Timothy E. (1)	+ -
Li, J.-L. F. (1)	+ -
Li, Weijing (1)	+ -
Li, Xiang (1)	+ -
Lien, Ren-Chieh (1)	+ -
Lim, Young-Kwon (1)	+ -
Liu, Guosheng (1)	+ -
Long, Lindsey N. (1)	+ -
Metzger, E. Joseph (1)	+ -

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