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Chen J.,Ocean University of China | Cui T.,First Institute of Oceanography
Journal of Geophysical Research C: Oceans | Year: 2015

In this study, a neural network-based four-band model (NNFM) for the global oceanic and coastal waters has been developed in order to retrieve the total absorption coefficients a(λ). The applicability of the quasi-analytical algorithm (QAA) and NNFM models is evaluated by five independent data sets. Based on the comparison of a(λ) predicted by these two models with the field measurements taken from the global oceanic and coastal waters, it was found that both the QAA and NNFM models had good performances in deriving a(λ), but that the NNFM model works better than the QAA model. The results of the QAA model-derived a(λ), especially in highly turbid waters with strong backscattering properties of optical activity, was found to be lower than the field measurements. The QAA and NNFM models-derived a(λ) could be obtained from the MODIS data after atmospheric corrections. When compared with the field measurements, the NNFM model decreased by a 0.86-24.15% uncertainty (root-mean-square relative error) of the estimation from the QAA model in deriving a(λ) from the Bohai, Yellow, and East China seas. Finally, the NNFM model was applied to map the global climatological seasonal mean a(443) for the time range of July 2002 to May 2014. As expected, the a(443) value around the coastal regions was always larger than the open ocean around the equator. Viewed on a global scale, the oceans at a high latitude exhibited higher a(443) values than those at a low latitude. © 2014. American Geophysical Union. All Rights Reserved.

Lu C.-H.,Fuzhou University | Zhu C.-L.,First Institute of Oceanography | Li J.,Fuzhou University | Liu J.-J.,Fuzhou University | And 3 more authors.
Chemical Communications | Year: 2010

We have proved that functionalized nanoscale graphene oxide can protect oligonucleotides from enzymatic cleavage and efficiently deliver oligonucleotides into cells. © The Royal Society of Chemistry 2010.

Zheng X.-T.,Ocean University of China | Xie S.-P.,Ocean University of China | Xie S.-P.,University of Hawaii at Manoa | Xie S.-P.,University of California at San Diego | And 4 more authors.
Journal of Climate | Year: 2013

The response of the Indian Ocean dipole (IOD) mode to global warming is investigated based on simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5). In response to increased greenhouse gases, an IOD-like warming pattern appears in the equatorial Indian Ocean, with reduced (enhanced) warming in the east (west), an easterly wind trend, and thermocline shoaling in the east. Despite a shoaling thermocline and strengthened thermocline feedback in the eastern equatorial Indian Ocean, the interannual variance of the IOD mode remains largely unchanged in sea surface temperature (SST) as atmospheric feedback and zonal wind variance weaken under global warming. The negative skewness in eastern Indian Ocean SST is reduced as a result of the shoaling thermocline. The change in interannual IOD variance exhibits some variability among models, and this intermodel variability is correlated with the change in thermocline feedback. The results herein illustrate that mean state changes modulate interannual modes, and suggest that recent changes in the IOD mode are likely due to natural variations. © 2013 American Meteorological Society.

Chiang J.C.H.,University of California at Berkeley | Fang Y.,University of California at Berkeley | Fang Y.,First Institute of Oceanography
Journal of Climate | Year: 2010

Model evidence is presented to make the case that the midlatitude North Pacific wintertime transient eddy activity may have been significantly weaker during the mid-Holocene (~6000 yr BP). A simulation of the midHolocene climate in an atmospheric general circulation model coupled to a reduced gravity ocean model showed significant reduction to transient eddy activity, up to 30% in the main storm-track region. The reduced baroclinic eddy activity is associated with basinwide climate changes over the northern and tropical Pacific, including a deepening of the Aleutian low, colder SSTs in the western and central North Pacific, a strengthening and southward shift of the subtropical jet, and a strengthened South Pacific convergence zone. These associated climate changes are consistently simulated across a range of Paleoclimate Modeling Inter comparison Project Phase II (PMIP2) coupled models forced with mid-Holocene climate forcings, suggesting they are a robust response to mid-Holocene orbital forcing. The authors link the mid-Holocene climate changes to two related modern-day analogs: (i) interannual variations in wintertime North Pacific storminess and (ii) the phenomenon of midwinter suppression whereby North Pacific transient eddy activity in today's climate is reduced in midwinter. In both instances, the associated North Pacific climate conditions resemble those seen in the mid-Holocene simulations. While it remains to be seen which analog is dynamically more appropriate, the latter link-midwinter suppression-offers the simple physical interpretation that the mid Holocene reduction in storminess is a consequence of a "more winterlike" climate resulting from the mid Holocene precessional forcing. © 2010 American Meteorological Society.

Li Z.,First Institute of Oceanography | Yu W.,First Institute of Oceanography | Li T.,University of Hawaii at Manoa | Murty V.S.N.,National Institute of Oceanography of India | Tangang F.,National University of Malaysia
Journal of Climate | Year: 2013

The annual cycle of tropical cyclone (TC) frequency over the Bay of Bengal (BoB) exhibits a notable bimodal character, different from a single peak in other basins. The causes of this peculiar feature were investigated through the diagnosis of a genesis potential index (GPI) with the use of the NCEP Reanalysis I dataset during the period 1981-2009. A methodology was developed to quantitatively assess the relative contributions of four environmental parameters. Different from a conventional view that the seasonal change of vertical shear causes the bimodal feature, it was found that the strengthened vertical shear alone from boreal spring to summer cannot overcome the relative humidity effect. It is the combined effect of vertical shear, vorticity, and SST that leads to the GPI minimum in boreal summer. It is noted that TC frequency in October-November is higher than that in April-May, which is primarily attributed to the difference of mean relative humidity between the two periods. In contrast, more supercyclones (category 4 or above) occur in April-May than in October-November. It is argued that greater ocean heat content, the first branch of northward-propagating intraseasonal oscillations (ISOs) associated with the monsoon onset over the BoB, and stronger ISO intensity in April-May are favorable environmental conditions for cyclone intensification. © 2013 American Meteorological Society.

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