scholarly journals Krill motion in the Southern Ocean: quantifying in situ krill movement behaviors and distributions during the late austral autumn and spring

2018 ◽  
Vol 63 (6) ◽  
pp. 2839-2857 ◽  
Author(s):  
Mary K. Kane ◽  
Regina Yopak ◽  
Christopher Roman ◽  
Susanne Menden‐Deuer
Keyword(s):  
Southern Ocean ◽  
Quantifying In ◽  
Austral Autumn

scholarly journals A Modeling Case Study of Mixed-Phase Clouds over the Southern Ocean and Tasmania

2010 ◽  
Vol 138 (3) ◽  
pp. 839-862 ◽  
Author(s):  
Anthony E. Morrison ◽  
Steven T. Siems ◽  
Michael J. Manton ◽  
Alex Nazarov
Keyword(s):  
Southern Ocean ◽  
Supercooled Liquid ◽  
Mixed Phase ◽  
Weather Research And Forecasting ◽  
Marine Stratocumulus ◽  
Cloud Structure ◽  
In Situ Observations ◽  
Cloud Tops ◽  
Mixed Phase Clouds

Abstract The cloud structure associated with two frontal passages over the Southern Ocean and Tasmania is investigated. The first event, during August 2006, is characterized by large quantities of supercooled liquid water and little ice. The second case, during October 2007, is more mixed phase. The Weather Research and Forecasting model (WRFV2.2.1) is evaluated using remote sensed and in situ observations within the post frontal air mass. The Thompson microphysics module is used to describe in-cloud processes, where ice is initiated using the Cooper parameterization at temperatures lower than −8°C or at ice supersaturations greater than 8%. The evaluated cases are then used to numerically investigate the prevalence of supercooled and mixed-phase clouds over Tasmania and the ocean to the west. The simulations produce marine stratocumulus-like clouds with maximum heights of between 3 and 5 km. These are capped by weak temperature and strong moisture inversions. When the inversion is at temperatures warmer than −10°C, WRF produces widespread supercooled cloud fields with little glaciation. This is consistent with the limited in situ observations. When the inversion is at higher altitudes, allowing cooler cloud tops, glaciated (and to a lesser extent mixed phase) clouds are more common. The simulations are further explored to evaluate any orographic signature within the cloud structure over Tasmania. No consistent signature is found between the two cases.

scholarly journals Neural network-based estimates of Southern Ocean net community production from in situ O<sub>2</sub> / Ar and satellite observation: a methodological study

2014 ◽  
Vol 11 (12) ◽  
pp. 3279-3297 ◽  
Author(s):  
C.-H. Chang ◽  
N. C. Johnson ◽  
N. Cassar
Keyword(s):  
Neural Network ◽  
Organic Carbon ◽  
Southern Ocean ◽  
Mixed Layer ◽  
Sea Surface ◽  
Carbon Export ◽  
Net Community Production ◽  
Basin Scale ◽  
Community Production

Abstract. Southern Ocean organic carbon export plays an important role in the global carbon cycle, yet its basin-scale climatology and variability are uncertain due to limited coverage of in situ observations. In this study, a neural network approach based on the self-organizing map (SOM) is adopted to construct weekly gridded (1° × 1°) maps of organic carbon export for the Southern Ocean from 1998 to 2009. The SOM is trained with in situ measurements of O2 / Ar-derived net community production (NCP) that are tightly linked to the carbon export in the mixed layer on timescales of one to two weeks and with six potential NCP predictors: photosynthetically available radiation (PAR), particulate organic carbon (POC), chlorophyll (Chl), sea surface temperature (SST), sea surface height (SSH), and mixed layer depth (MLD). This nonparametric approach is based entirely on the observed statistical relationships between NCP and the predictors and, therefore, is strongly constrained by observations. A thorough cross-validation yields three retained NCP predictors, Chl, PAR, and MLD. Our constructed NCP is further validated by good agreement with previously published, independent in situ derived NCP of weekly or longer temporal resolution through real-time and climatological comparisons at various sampling sites. The resulting November–March NCP climatology reveals a pronounced zonal band of high NCP roughly following the Subtropical Front in the Atlantic, Indian, and western Pacific sectors, and turns southeastward shortly after the dateline. Other regions of elevated NCP include the upwelling zones off Chile and Namibia, the Patagonian Shelf, the Antarctic coast, and areas surrounding the Islands of Kerguelen, South Georgia, and Crozet. This basin-scale NCP climatology closely resembles that of the satellite POC field and observed air–sea CO2 flux. The long-term mean area-integrated NCP south of 50° S from our dataset, 17.9 mmol C m−2 d−1, falls within the range of 8.3 to 24 mmol C m−2 d−1 from other model estimates. A broad agreement is found in the basin-wide NCP climatology among various models but with significant spatial variations, particularly in the Patagonian Shelf. Our approach provides a comprehensive view of the Southern Ocean NCP climatology and a potential opportunity to further investigate interannual and intraseasonal variability.

Quantifying in situ and modeling net nitrogen mineralization from soil organic matter in arable cropping systems

2017 ◽  
Vol 111 ◽  
pp. 44-59 ◽  
Author(s):  
Hugues Clivot ◽  
Bruno Mary ◽  
Matthieu Valé ◽  
Jean-Pierre Cohan ◽  
Luc Champolivier ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Nitrogen Mineralization ◽  
Cropping Systems ◽  
Net Nitrogen Mineralization ◽  
Quantifying In

scholarly journals Assessing Surface Heat Flux Products with In Situ Observations over the Australian Sector of the Southern Ocean

2019 ◽  
Vol 36 (9) ◽  
pp. 1849-1861
Author(s):  
Vidhi Bharti ◽  
Eric Schulz ◽  
Christopher W. Fairall ◽  
Byron W. Blomquist ◽  
Yi Huang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Southern Ocean ◽  
Sensible Heat Flux ◽  
Surface Heat ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Atmospheric Composition ◽  
Systematic Bias ◽  
Positive Bias

Given the large uncertainties in surface heat fluxes over the Southern Ocean, an assessment of fluxes obtained by European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim) product, the Australian Integrated Marine Observing System (IMOS) routine observations, and the Objectively Analyzed Air–Sea Heat Fluxes (OAFlux) project hybrid dataset is performed. The surface fluxes are calculated using the COARE 3.5 bulk algorithm with in situ data obtained from the NOAA Physical Sciences Division flux system during the Clouds, Aerosols, Precipitation, Radiation, and Atmospheric Composition over the Southern Ocean (CAPRICORN) experiment on board the R/V Investigator during a voyage (March–April 2016) in the Australian sector of the Southern Ocean (43°–53°S). ERA-Interim and OAFlux data are further compared with the Southern Ocean Flux Station (SOFS) air–sea flux moored surface float deployed for a year (March 2015–April 2016) at ~46.7°S, 142°E. The results indicate that ERA-Interim (3 hourly at 0.25°) and OAFlux (daily at 1°) estimate sensible heat flux H s accurately to within ±5 W m−2 and latent heat flux H l to within ±10 W m−2. ERA-Interim gives a positive bias in H s at low latitudes (<47°S) and in H l at high latitudes (>47°S), and OAFlux displays consistently positive bias in H l at all latitudes. No systematic bias with respect to wind or rain conditions was observed. Although some differences in the bulk flux algorithms are noted, these biases can be largely attributed to the uncertainties in the observations used to derive the flux products.

scholarly journals Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe

PLoS ONE ◽  
2018 ◽  
Vol 13 (5) ◽  
pp. e0196075 ◽  
Author(s):  
N. González-Muñoz ◽  
F. Sterck ◽  
J. M. Torres-Ruiz ◽  
G. Petit ◽  
H. Cochard ◽  
...  
Keyword(s):  
Tree Species ◽  
Hydraulic Properties ◽  
Phenotypic Variability ◽  
Distribution Range ◽  
Quantifying In
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