Using Synthetic Brightness Temperatures to Address Uncertainties in Cloud-Top-Height Verification

AbstractCloud-top verification is inherently difficult because of large uncertainties in the estimates of observed cloud-top height. Misplacement of cloud top associated with transmittance through optically thin cirrus is one of the most common problems. Forward radiative models permit a direct comparison of predicted and observed radiance, but uncertainties in the vertical position of clouds remain. In this work, synthetic brightness temperatures are compared with forecast cloud-top heights so as to investigate potential errors and develop filters to remove optically thin ice clouds. Results from a statistical analysis reveal that up to 50% of the clouds with brightness temperatures as high as 280 K are actually optically thin cirrus. The filters successfully removed most of the thin ice clouds, allowing for the diagnosis of very specific errors. The results indicate a strong negative bias in midtropospheric cloud cover in the model, as well as a lack of land-based convective cumuliform clouds. The model also predicted an area of persistent stratus over the North Atlantic Ocean that was not apparent in the observations. In contrast, high cloud tops associated with deep convection were well simulated, as were mesoscale areas of enhanced trade cumulus coverage in the Sargasso Sea.

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Dissolved iron in the North Atlantic Ocean and Labrador Sea along the GEOVIDE section (GEOTRACES section GA01)

10.5194/bg-2018-147 ◽

2018 ◽

Cited By ~ 10

Author(s):

Manon Tonnard ◽

Hélène Planquette ◽

Andrew R. Bowie ◽

Pier van der Merwe ◽

Morgane Gallinari ◽

...

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

Sea Water ◽

North Atlantic Ocean ◽

Deep Convection ◽

Labrador Sea ◽

Intermediate Water ◽

The North ◽

Irminger Sea ◽

The North Atlantic

Abstract. Dissolved Fe (DFe) samples from the GEOVIDE voyage (GEOTRACES GA01, May–June 2014) in the North Atlantic Ocean were analysed using a SeaFAST-picoTM coupled to an Element XR HR-ICP-MS and provided interesting insights on the Fe sources in this area. Overall, DFe concentrations ranged from 0.09 ± 0.01 nmol L−1 to 7.8 ± 0.5 nmol L−1. Elevated DFe concentrations were observed above the Iberian, Greenland and Newfoundland Margins likely due to riverine inputs from the Tagus River, meteoric water inputs and sedimentary inputs. Air-sea interactions were suspected to be responsible for the increase in DFe concentrations within subsurface waters of the Irminger Sea due to deep convection occurring the previous winter, that provided iron-to-nitrate ratios sufficient to sustain phytoplankton growth. Increasing DFe concentrations along the flow path of the Labrador Sea Water were attributed to sedimentary inputs from the Newfoundland Margin. Bottom waters from the Irminger Sea displayed high DFe concentrations likely due to the dissolution of Fe-rich particles from the Denmark Strait Overflow Water and the Polar Intermediate Water. Finally, the nepheloid layers were found to act as either a source or a sink of DFe depending on the nature of particles.

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How does the European eel (Anguilla anguilla) retain its population structure during its larval migration across the North Atlantic Ocean?

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-198 ◽

2006 ◽

Vol 63 (1) ◽

pp. 90-106 ◽

Cited By ~ 82

Author(s):

A James Kettle ◽

Keith Haines

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

North Atlantic Ocean ◽

Anguilla Anguilla ◽

European Eel ◽

Sargasso Sea ◽

Larval Migration ◽

The North ◽

The North Atlantic ◽

And Migration

A Lagrangian model is presented of the current-carried migration of the leptocephali (larvae) of the European eel (Anguilla anguilla) across the North Atlantic Ocean from the spawning area in the Sargasso Sea to the adult range in Europe and North Africa. The success of larvae in crossing the Atlantic Ocean and reaching particular latitude bins on the eastern side depended strongly on starting location in the Sargasso Sea and migration depth. In the model domain, silver eel spawners can develop strategies for spawning location and migration depth to preferentially target particular regions in the adult range. This observation may help to explain the presence of gradients in molecular markers in eel samples collected across Europe. Spawning in the period of late winter spring maximizes the average food availability along the 2-year larval trajectory. The fastest transatlantic larval migration in the model is about 2 years, and the route to Europe takes most of the larvae past the east coast of North America in the first year. These model results are consistent with the hypothesis that the European and American eel (Anguilla rostrata) could separate themselves on different sides of the Atlantic Ocean on the basis of the different durations of their larval stages.

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Empirical evidence for deep convection being a major source of stratospheric ice clouds over North America

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-10457-2021 ◽

2021 ◽

Vol 21 (13) ◽

pp. 10457-10475

Author(s):

Ling Zou ◽

Lars Hoffmann ◽

Sabine Griessbach ◽

Reinhold Spang ◽

Lunche Wang

Keyword(s):

North America ◽

Great Plains ◽

Gravity Waves ◽

North Atlantic ◽

Deep Convection ◽

Eastern Pacific ◽

Western Canada ◽

Ice Clouds ◽

The North ◽

North Eastern

Abstract. Ice clouds in the lowermost stratosphere affect stratospheric water vapour and the Earth's radiation budget. The knowledge of its occurrence and driving forces is limited. To assess the distribution and possible formation mechanisms of stratospheric ice clouds (SICs) over North America, we analysed SIC occurrence frequencies observed by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) instrument during the years 2006 to 2018. Possible driving forces such as deep convection are assessed based on Atmospheric Infrared Sounder (AIRS) observations during the same time. Results show that at nighttime, SICs are most frequently observed during the thunderstorm season over the Great Plains from May to August (MJJA) with a maximum occurrence frequency of 6.2 %. During the months from November to February (NDJF), the highest SICs occurrence frequencies are 5.5 % over the north-eastern Pacific and western Canada and 4.4 % over the western North Atlantic. Occurrence frequencies of deep convection from AIRS, which includes storm systems, fronts, mesoscale convective systems, and mesoscale convective complexes at midlatitude and high latitude, show similar hotspots like the SICs, with highest occurrence frequencies being observed over the Great Plains in MJJA (4.4 %) and over the north-eastern Pacific, western Canada, and the western North Atlantic in NDJF (∼ 2.5 %). Both, seasonal patterns and daily time series of SICs and deep convection show a high degree of spatial and temporal relation. Further analysis indicates that the maximum fraction of SICs related to deep convection is 74 % over the Great Plains in MJJA and about 50 % over the western North Atlantic, the north-eastern Pacific, and western Canada in NDJF. We conclude that, locally and regionally, deep convection is the leading factor related to the occurrence of SICs over North America. In this study, we also analysed the impact of gravity waves as another important factor related to the occurrence of SICs, as the Great Plains is a well-known hotspot for stratospheric gravity waves. In the cases where SICs are not directly linked to deep convection, we found that stratospheric gravity wave observations correlate with SICs with as much as 30 % of the cases over the Great Plains in MJJA, about 50 % over the north-eastern Pacific and western Canada, and up to 90 % over eastern Canada and the north-west Atlantic in NDJF. Our results provide a better understanding of the physical processes and climate variability related to SICs and will be of interest for modellers as SIC sources such as deep convection and gravity waves are small-scale processes that are difficult to represent in global general circulation models.

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Underway fCO2 measurements in the North Atlantic Ocean on M/V Atlantic Companion VOS Line during the 2006-2007 cruises

Carbon Dioxide Information Analysis Center ◽

10.3334/cdiac/otg.vos_atlantic_companion_line_2007 ◽

2007 ◽

Author(s):

T. STEINHOFF, ◽

D.W.R. WALLACE, ◽

A. KOERTZINGER,

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

North Atlantic Ocean ◽

The North ◽

The North Atlantic

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Underway fCO2 measurements in the North Atlantic Ocean during the Meteor Cruise 39/2 (15 May- 8 June, 1997)

Carbon Dioxide Information Analysis Center ◽

10.3334/cdiac/otg.met39_2 ◽

1997 ◽

Author(s):

A. KOERTZINGER,

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

North Atlantic Ocean ◽

The North ◽

The North Atlantic

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The airplane icing environment in wintertime storms over the North Atlantic Ocean

10.2514/6.1994-483 ◽

1994 ◽

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

North Atlantic Ocean ◽

The North ◽

The North Atlantic

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Late Quaternary palaeo-oceanography of the Denmark Strait overflow pathway, South-East Greenland margin

Geology of Greenland Survey Bulletin ◽

10.34194/ggu-bulletin.v180.6514 ◽

1998 ◽

Vol 180 ◽

pp. 163-167

Author(s):

Antoon Kuijpers ◽

Jørn Bo Jensen ◽

Simon R . Troelstra ◽

And shipboard scientific party of RV Professor Logachev and RV Dana

Keyword(s):

North Atlantic ◽

Deep Water ◽

Deep Convection ◽

Conveyor Belt ◽

Water Masses ◽

Labrador Sea ◽

Greenland Sea ◽

The North ◽

Denmark Strait ◽

The North Atlantic

Direct interaction between the atmosphere and the deep ocean basins takes place today only in the Southern Ocean near the Antarctic continent and in the northern extremity of the North Atlantic Ocean, notably in the Norwegian–Greenland Sea and Labrador Sea. Cooling and evaporation cause surface waters in the latter region to become dense and sink. At depth, further mixing occurs with Arctic water masses from adjacent polar shelves. Export of these water masses from the Norwegian–Greenland Sea (Norwegian Sea Overflow Water) to the North Atlantic basin occurs via two major gateways, the Denmark Strait system and the Faeroe– Shetland Channel and Faeroe Bank Channel system (e.g. Dickson et al. 1990; Fig.1). Deep convection in the Labrador Sea produces intermediate waters (Labrador Sea Water), which spreads across the North Atlantic. Deep waters thus formed in the North Atlantic (North Atlantic Deep Water) constitute an essential component of a global ‘conveyor’ belt extending from the North Atlantic via the Southern and Indian Oceans to the Pacific. Water masses return as a (warm) surface water flow. In the North Atlantic this is the Gulf Stream and the relatively warm and saline North Atlantic Current. Numerous palaeo-oceanographic studies have indicated that climatic changes in the North Atlantic region are closely related to changes in surface circulation and in the production of North Atlantic Deep Water. Abrupt shut-down of the ocean-overturning and subsequently of the conveyor belt is believed to represent a potential explanation for rapid climate deterioration at high latitudes, such as those that caused the Quaternary ice ages. Here it should be noted, that significant changes in deep convection in Greenland waters have also recently occurred. While in the Greenland Sea deep water formation over the last decade has drastically decreased, a strong increase of deep convection has simultaneously been observed in the Labrador Sea (Sy et al. 1997).

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Zooplankton Biogeochemical Cycles

10.1093/oso/9780199233267.003.0006 ◽

2017 ◽

Author(s):

Deborah Steinberg

Keyword(s):

North Atlantic ◽

North Atlantic Ocean ◽

Significant Proportion ◽

Biogeochemical Cycles ◽

Biological Pump ◽

The North ◽

Particle Export ◽

Chemical Cycling ◽

Cycling Of Nutrients ◽

Planktonic Communities

The structure of planktonic communities profoundly affects particle export and sequestration of organic material (the biological pump) and the chemical cycling of nutrients. This chapter describes the integral and multifaceted role zooplankton (both protozoan and metazoan) play in the export and cycling of elements in the ocean, with an emphasis on the North Atlantic Ocean and adjacent seas. Zooplankton consume a significant proportion of primary production across the world's oceans, and their metabolism plays a key role in recycling carbon, nitrogen, and other elements. The chapter also addresses how human or climate-influenced changes in North Atlantic zooplankton populations may in turn drive changes in zooplankton-mediated biogeochemical cycling.

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