Youyu Lu - Academia.edu (original) (raw)

Papers by Youyu Lu

Estuarine Coastal and Shelf Science, Nov 1, 2022

Marine Pollution Bulletin, Nov 1, 2022

Journal Of Geophysical Research: Oceans, May 1, 2019

Key points: 1. Two new indices are defined to quantify the influence of Galápagos Islands on SST ... more Key points: 1. Two new indices are defined to quantify the influence of Galápagos Islands on SST in Eastern Tropic Pacific. 2. New indices show stronger (weaker) Islands' influence in boreal fall (spring) and during La Niña (El Niño) years. 3. Variations of Islands' influence are related to distributions of background temperature, upwelling and surface currents.

2015 AGU Fall Meeting, Dec 16, 2015

Continental Shelf Research, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of Marine Science and Engineering, Feb 28, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Geophysical Research Letters, Mar 20, 2023

This paper describes the Coastal Ice Ocean Prediction System for the East Coast of Canada (CIOPS-... more This paper describes the Coastal Ice Ocean Prediction System for the East Coast of Canada (CIOPS-E) running operationally at Environment and Climate Change Canada (ECCC). CIOPS-E uses a one-way downscaling technique on a 1/36 o horizontal grid (~2 km) to simulate high-resolution ice and ocean conditions over the northwest Atlantic Ocean and the Gulf of St. Lawrence (GSL). CIOPS-E is forced at its lateral boundaries with ECCC's Regional Ice-Ocean Prediction System (RIOPS) and tidal conditions from the Oregon State University TPXO model. The three-dimensional temperature and salinity fields are spectrally nudged towards the RIOPS solution offshore of the 1500 m isobath to, effectively constrain mesoscale features in the Gulf Stream area. Over the continental shelf and the GSL, the CIOPS-E solution is free to develop fully according to model dynamics. CIOPS-E is evaluated over one year from March 2019 to February 2020. Overall, the CIOPS-E improves the representation of tides compared to ECCC's lower resolution systems: RIOPS (1/12 o) and the Regional Marine Prediction System-Gulf of St. Lawrence (RMPS-GSL, 5 km). The accuracy of the tides are comparable to the TPXO at most coastal tide gauges. Subtidal water levels from CIOPS-E agree well with the observed seasonal variability and show improved errors statistics at all stations compared to RIOPS and RMPS-GSL. Improvements are especially noted for the GSL. Sea surface temperatures (SSTs) from CIOPS-E are lower (higher) in spring (fall) over most of the GSL compared to satellitederived analyses and RIOPS. Comparison with in-situ observations of SST show significant improvement in CIOPS-E with

Journal of Atmospheric and Oceanic Technology

A series of laboratory experiments are carried out to demonstrate the impacts of instrumented bot... more A series of laboratory experiments are carried out to demonstrate the impacts of instrumented bottom frame legs on flow and turbulence. The magnitudes of vertical velocity, turbulent kinetic energy, dissipation, and shear stress induced by the frame legs depend on several factors, including the diameter and number of the frame legs, distances between the legs and the observational location, and the magnitude of the incoming flow and its direction with respect to the layout of the frame. In situ observations were carried out near the mouth of the Yellow River using two acoustic Doppler velocimeters mounted on a bottom frame. The estimated vertical velocity and turbulent kinetic energy dissipation rate show a significant asymmetry with flood and ebb tidal flows. This asymmetry can be partly explained by the influences of the bottom frame legs. Finally, the design and deployment principles of bottom frames are discussed for the purpose of reducing the impacts of the frame legs. Signifi...

Arctic Technology Conference, 2016

EGU General Assembly Conference Abstracts, Apr 1, 2015

How does storage of carbon in sea ice impacts the partial pressure of CO 2 ? To answer this quest... more How does storage of carbon in sea ice impacts the partial pressure of CO 2 ? To answer this question, one can consider the upper layer of the ocean, partially covered by sea ice forming and melting. The atmospheric pCO 2 and wind speed at 10m height are known, as are the ice concentration and meltingfreezing rate and the ocean surface temperature and salinity. The surface ocean pCO 2 (in µatm) would vary along the seasonal cycle due to changes in temperature, salinity, air-sea gas exchange, dilution and concentration related to surface freshwater fluxes (either from precipitation-evaporation, or from ice melt and formation). Biology would also impact carbonate properties due to production and respiration. Finally, advection and mixing could also modify surface properties. Two scenarios emerge, with for sole difference the storage and release of alkalinity and dissolved inorganic carbon (DIC) by sea ice.

Advances in Atmospheric Sciences, 2018

Variations in the high-frequency oscillations of tropical cyclones (TCs) over the western North P... more Variations in the high-frequency oscillations of tropical cyclones (TCs) over the western North Pacific (WNP) are studied in numerical model simulations. Power spectrum analysis of maximum wind speeds at 10 m (MWS 10) from an ensemble of 15 simulated TCs shows that oscillations are significant for all TCs. The magnitudes of oscillations in MWS 10 are similar in the WNP and South China Sea (SCS); however, the mean of the averaged significant periods in the SCS (1.93 h) is shorter than that in the open water of the WNP (2.83 h). The shorter period in the SCS is examined through an ensemble of simulations, and a case simulation as well as a sensitivity experiment in which the continent is replaced by ocean for Typhoon Hagupit (2008). The analysis of the convergence efficiency within the boundary layer suggests that the shorter periods in the SCS are possibly due to the stronger terrain effect, which intensifies convergence through greater friction. The enhanced convergence strengthens the disturbance of the gradient and thermal wind balances, and then contributes to the shorter oscillation periods in the SCS.

Atmospheric and Oceanic Science Letters

Frontiers in Marine Science

The freshwater transport (FWT) by the Labrador Current (LC) around the Grand Banks of Newfoundlan... more The freshwater transport (FWT) by the Labrador Current (LC) around the Grand Banks of Newfoundland (GBN) is diagnosed with the 26-year Global Ocean Physical Reanalysis 1/12° data (GLORYS12v1) during 1993 - 2018. The time-mean FWT of the LC above the 1027.25 kg/m3 isopycnal surface is 83.6 mSv (1 mSv = 103m3/s) southward through the Flemish Pass. Among this 83.6 mSv, 42% (35.2 mSv) is exported into the interior of the North Atlantic along the whole pathway of the LC from the Flemish Pass to the Tail of the GBN, with 25.5 mSv by the mean advection and 7.2 mSv by the mesoscale eddy transport. The seasonal and inter-annual variations of the FWT in the east of the GBN are mainly caused by the variation of the horizontal velocity of the LC, and the variation of salinity makes a nontrivial contribution to the variation of the FWT to the north of 45°N. Around the Tail of the GBN, the mesoscale eddies make significant contributions to the time-mean FWT and the seasonal and inter-annual varia...

. The Arctic Ocean is generally undersaturated in CO2 and acts as a net sink of atmospheric CO2. ... more . The Arctic Ocean is generally undersaturated in CO2 and acts as a net sink of atmospheric CO2. This oceanic uptake is strongly modulated by sea ice, which can prevent air-sea gas exchange and has major impacts on stratification and primary production. Moreover, carbon is stored in sea ice with a ratio of alkalinity to dissolved inorganic carbon that is larger than in seawater. It has been suggested that this storage amplifies the seasonal cycle of seawater pCO2 and leads to an increase in oceanic carbon uptake in seasonally ice-covered regions compared to those that are ice-free. Given the rapidly changing ice-scape in the Arctic Ocean, a better understanding of the link between the seasonal cycle of sea ice and oceanic uptake of CO2 is needed. Here, we investigate how the storage of carbon in sea ice affects the air-sea CO2 flux and quantify its dependence on the ratio of alkalinity to inorganic carbon in ice. To this end, we present two independent approaches: a theoretical framework that provides an analytical expression of the amplification of carbon uptake in seasonally ice-covered oceans, and a simple parameterization of carbon storage in sea ice implemented in a 1D physical-biogeochemical ocean model. Sensitivity simulations show a linear relation between ice melt and the amplification of seasonal carbon uptake. A 30 % increase in carbon uptake in the Arctic Ocean is estimated compared to ice melt without amplification. Applying this relationship to different future scenarios from an Earth System Model that does not account for the effect of carbon storage in sea ice suggests that Arctic Ocean carbon uptake is underestimated by 5 to 15 % in these simulations.