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Author
Dukhovskoy, D.S. ; Yashayaev, I. ; Proshutinsky, A. ; Bamber, J.L. ; Bashmachnikov, I.L. ; Chassignet, E.P. ; Lee, C.M. ; Tedstone, A.J.
Title
Role of Greenland Freshwater Anomaly in the Recent Freshening of the Subpolar North Atlantic
Type
$loc['typeJournal Article']
Year
2019
Publication
Journal of Geophysical Research: Oceans
Abbreviated Journal
J. Geophys. Res. Oceans
Volume
124
Issue
5
Pages
3333-3360
Keywords
Greenland ice sheet melting ; freshwater anomaly ; subpolar North Atlantic ; subpolar gyre ; passive tracer numerical experiment ; freshwater budget
Abstract
The cumulative Greenland freshwater flux anomaly has exceeded 5000 km3 since the 1990s. The volume of this surplus fresh water is expected to cause substantial freshening in the North Atlantic. Analysis of hydrographic observations in the subpolar seas reveal freshening signals in the 2010s. The sources of this freshening are yet to be determined. In this study, the relationship between the surplus Greenland freshwater flux and this freshening is tested by analyzing the propagation of the Greenland freshwater anomaly and its impact on salinity in the subpolar North Atlantic based on observational data and numerical experiments with and without the Greenland runoff. A passive tracer is continuously released during the simulations at freshwater sources along the coast of Greenland to track the Greenland freshwater anomaly. Tracer budget analysis shows that 44% of the volume of the Greenland freshwater anomaly is retained in the subpolar North Atlantic by the end of the simulation. This volume is sufficient to cause strong freshening in the subpolar seas if it stays in the upper 50�100 m. However, in the model the anomaly is mixed down to several hundred meters of the water column resulting in smaller magnitudes of freshening compared to the observations. Therefore, the simulations suggest that the accelerated Greenland melting would not be sufficient to cause the observed freshening in the subpolar seas and other sources of fresh water have contributed to the freshening. Impacts on salinity in the subpolar seas of the freshwater transport through Fram Strait and precipitation are discussed.
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Summary Language
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Series Editor
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Series Volume
Series Issue
Edition
ISSN
2169-9275
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1029
Permanent link to this record
Author
Fender, C.K. ; Kelly, T.B. ; Guidi, L. ; Ohman, M.D. ; Smith, M.C. ; Stukel, M.R.
Title
Investigating Particle Size-Flux Relationships and the Biological Pump Across a Range of Plankton Ecosystem States From Coastal to Oligotrophic
Type
$loc['typeJournal Article']
Year
2019
Publication
Frontiers in Marine Science
Abbreviated Journal
Front. Mar. Sci.
Volume
6
Issue
Pages
Keywords
Abstract
Address
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
2296-7745
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1074
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Author
Fox-Kemper, B. ; Adcroft, A. ; Böning, C.W. ; Chassignet, E.P. ; Curchitser, E. ; Danabasoglu, G. ; Eden, C. ; England, M.H. ; Gerdes, R. ; Greatbatch, R.J. ; Griffies, S.M. ; Hallberg, R.W. ; Hanert, E. ; Heimbach, P. ; Hewitt, H.T. ; Hill, C.N. ; Komuro, Y. ; Legg, S. ; Le Sommer, J. ; Masina, S. ; Marsland, S.J. ; Penny, S.G. ; Qiao, F. ; Ringler, T.D. ; Treguier, A.M. ; Tsujino, H. ; Uotila, P. ; Yeager, S.G.
Title
Challenges and Prospects in Ocean Circulation Models
Type
$loc['typeJournal Article']
Year
2019
Publication
Frontiers in Marine Science
Abbreviated Journal
Front. Mar. Sci.
Volume
6
Issue
Pages
Keywords
Southern Ocean ; Overturning Circulation: Regional sea level ; submesoscale ; ice shelves ; turbulence
Abstract
We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become important are beginning to be resolved in regional and process models. Coupling to sea ice, ice shelves, and high-resolution atmospheric models has stimulated new ideas and driven improvements in numerics. Observations have provided insight into turbulence and mixing around the globe and its consequences are assessed through perturbed physics models. Relatedly, parameterizations of the mixing and overturning processes in boundary layers and the ocean interior have improved. New diagnostics being used for evaluating models alongside present and novel observations are briefly referenced. The overall goal is summarizing new developments in ocean modeling, including how new and existing observations can be used, what modeling challenges remain, and how simulations can be used to support observations.
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Summary Language
Original Title
Series Editor
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Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
2296-7745
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1011
Permanent link to this record
Author
Freeman, E. ; Kent, E.C. ; Brohan, P. ; Cram, T. ; Gates, L. ; Huang, B. ; Liu, C. ; Smith, S.R. ; Worley, S.J. ; Zhang, H.-M.
Title
The International Comprehensive Ocean-Atmosphere Data Set – Meeting Users Needs and Future Priorities
Type
$loc['typeJournal Article']
Year
2019
Publication
Frontiers in Marine Science
Abbreviated Journal
Front. Mar. Sci.
Volume
6
Issue
Pages
435
Keywords
Abstract
The International Comprehensive Ocean-Atmosphere Data Set (ICOADS) is a collection and archive of in situ marine observations, which has been developed over several decades as an international project and recently guided by formal international partnerships and the ICOADS Steering Committee. ICOADS contains observations from many different observing systems encompassing the evolution of measurement technology since the 18th century. ICOADS provides an integrated source of observations for a range of applications including research and climate monitoring, and forms the main marine in situ surface data source, e.g., near-surface ocean observations and lower atmospheric marine-meteorological observations from buoys, ships, coastal stations, and oceanographic sensors, for oceanic and atmospheric research and reanalysis. ICOADS has developed ways to incorporate user and reanalyses feedback information associated with permanent unique identifiers and is also the main repository for data that have been rescued from ships’ logbooks and other marine data digitization activities. ICOADS has been adopted widely because it provides convenient access to a range of observation types, globally, and through the entire marine instrumental record. ICOADS has provided a secure home for such observations for decades. Because of the increased volume of observations, particularly those available in near-real-time, and an expansion of their diversity, the ICOADS processing system now requires extensive modernization. Based on user feedback, we will outline the improvements that are required, the challenges to their implementation, and the benefits of upgrading this important and diverse marine archive and distribution activity.
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Publisher
Place of Publication
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Summary Language
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Series Editor
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Series Volume
Series Issue
Edition
ISSN
2296-7745
ISBN
Medium
Area
Expedition
Conference
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Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1041
Permanent link to this record
Author
Gentemann, C.L. ; Clayson, C.A. ; Brown, S. ; Lee, T. ; Parfitt, R. ; Farrar, J.T. ; Bourassa, M. ; Minnett, P.J. ; Seo, H. ; Gille, S.T. ; Zlotnicki, V.
Title
FluxSat: Measuring the Ocean-Atmosphere Turbulent Exchange of Heat and Moisture from Space
Type
$loc['typeJournal Article']
Year
2020
Publication
Remote Sensing
Abbreviated Journal
Remote Sensing
Volume
12
Issue
11
Pages
1796
Keywords
air-sea interactions ; mesoscale ; fluxes
Abstract
Recent results using wind and sea surface temperature data from satellites and high-resolution coupled models suggest that mesoscale ocean-atmosphere interactions affect the locations and evolution of storms and seasonal precipitation over continental regions such as the western US and Europe. The processes responsible for this coupling are difficult to verify due to the paucity of accurate air-sea turbulent heat and moisture flux data. These fluxes are currently derived by combining satellite measurements that are not coincident and have differing and relatively low spatial resolutions, introducing sampling errors that are largest in regions with high spatial and temporal variability. Observational errors related to sensor design also contribute to increased uncertainty. Leveraging recent advances in sensor technology, we here describe a satellite mission concept, FluxSat, that aims to simultaneously measure all variables necessary for accurate estimation of ocean-atmosphere turbulent heat and moisture fluxes and capture the effect of oceanic mesoscale forcing. Sensor design is expected to reduce observational errors of the latent and sensible heat fluxes by almost 50%. FluxSat will improve the accuracy of the fluxes at spatial scales critical to understanding the coupled ocean-atmosphere boundary layer system, providing measurements needed to improve weather forecasts and climate model simulations.
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Summary Language
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Series Editor
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Series Issue
Edition
ISSN
2072-4292
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1111
Permanent link to this record
Author
Groenen, Danielle Elizabeth
Title
Diagnosing the Atmospheric Phenomena Associated with the Onset and Demise of the Rainy Season in Mesoamerica
Type
$loc['typeJournal Article']
Year
2019
Publication
Abbreviated Journal
Volume
Issue
Pages
Keywords
Abstract
Mexico and Central America (Mesoamerica) are situated in a complex and unique geographical position with the Caribbean Sea to the East and the tropical Eastern Pacific Ocean to the West. The weather patterns of this region are driven by winds, temperatures, moisture, and orography of several mountain ranges. This study finds the dates of the onset and demise of rainfall regimes on a specific day using NASA’s Tropical Rainfall Measuring Mission (TRMM) rainfall for years 1998–2012, area-averaged over land. Using NASA’s MERRA-2 Reanalysis data, we also look at the phenomenology of the triggers of the rainy season onset and demise on the daily time-scale instead of the monthly scales used by previous studies. We find that the Mesoamerican Rainy Season can be distinguished into two parts: the Early Spring Rainfall (ESR) associated with light rains and the Late Spring Rainfall (LSR) associated with heavy rains. Two algorithms are used to obtain these rainy season distinctions. A new algorithm was developed during this study, called the SLOPE algorithm, to calculate when the rain rates first start to increase. In the second method, the daily cumulative anomalies of rainfall are compared to the climatological rainfall to find the time of onset of the heavy rains, called the MINCA algorithm. To better understand the phenomenology associated with the timing of the rainfall, we look at the monsoon trough, moisture flux convergence, moist static energy anomalies, and the weakening/strengthening of the winds associated with the Caribbean Low-Level Jet and Panama Jet. The light rain rates begin, on average, in mid-March, approximately one month after the peak of the winter Caribbean Low-Level Jet and the Panama Jet. The ramp-up between the light rains and heavy rains is associated with a significant weakening of both jets and the northward progression of a monsoon trough off the western coast of Central America. The heavy rain rates begin, on average, in mid-May, and are associated with the timing when the Panama Jet goes to near zero magnitude and a strong monsoon trough in the eastern Pacific. At the demise of the rainfall, approximately in mid-November, the Panama Jet strengthens again, the total moisture flux convergence decreases significantly, and the monsoon trough retreats southward and eastward. The results of this study have positive implications in agriculture and water resources for Mesoamerica, as this information may help resource managers better plan and adapt to climate variability.
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$loc['no']
Call Number
COAPS @ user @
Serial
1085
Permanent link to this record
Author
Guerra, L.A.A. ; Paiva, A.M. ; Chassignet, E.P.
Title
On the translation of Agulhas rings to the western South Atlantic Ocean
Type
$loc['typeJournal Article']
Year
2018
Publication
Deep Sea Research Part I: Oceanographic Research Papers
Abbreviated Journal
Deep Sea Research Part I: Oceanographic Research Papers
Volume
139
Issue
Pages
104-113
Keywords
Abstract
The shedding of Agulhas rings is the primary process connecting the Indian and Atlantic oceans. The rings transport warm and salty waters that feed the surface limb of the Atlantic Meridional Overturning Circulation. Early studies suggest that Agulhas rings decay and diffuse their contents within the South Atlantic subtropical gyre. In this paper, we update the ring census using an automated algorithm to detect and track eddies over more than 23 years of satellite altimetry data (1993-2016) and calculate their main characteristics. While 140 rings spawned from the Agulhas Retroflection, their following splitting and merging resulted in 74 long-lived rings that crossed the Walvis Ridge and translated towards the west. Eventually, three rings reached the western boundary. For one of them, we use in situ measurements to document its interaction with the Brazil Current and two cyclonic eddies, which resulted in a current velocity increase by three times. Although already hypothesized, this interaction had not been demonstrated with in situ evidence until now.
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Thesis
Publisher
Place of Publication
Editor
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Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
0967-0637
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
994
Permanent link to this record
Author
Hoffman, R.N. ; Privé, N. ; Bourassa, M.
Title
Comments on “Reanalyses and Observations: What's the Difference?”
Type
$loc['typeJournal Article']
Year
2017
Publication
Bulletin of the American Meteorological Society
Abbreviated Journal
Bull. Amer. Meteor. Soc.
Volume
98
Issue
11
Pages
2455-2459
Keywords
GEOPHYSICAL DATA ; marine surface winds ; energy and water cycles
Abstract
Are there important differences between reanalysis data and familiar observations and measurements? If so, what are they? This essay evaluates four possible answers that relate to: the role of inference, reliance on forecasts, the need to solve an ill-posed inverse problem, and understanding of errors and uncertainties. The last of these is argued to be most significant. The importance of characterizing uncertainties associated with results—whether those results are observations or measurements, analyses or reanalyses, or forecasts—is emphasized.
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Series Editor
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Series Issue
Edition
ISSN
0003-0007
ISBN
Medium
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Approved
$loc['no']
Call Number
COAPS @ rl18 @
Serial
990
Permanent link to this record
Author
Holbach, H.M. ; Uhlhorn, E.W. ; Bourassa, M.A.
Title
Off-Nadir SFMR Brightness Temperature Measurements in High-Wind Conditions
Type
$loc['typeJournal Article']
Year
2018
Publication
Journal of Atmospheric and Oceanic Technology
Abbreviated Journal
J. Atmos. Oceanic Technol.
Volume
35
Issue
9
Pages
1865-1879
Keywords
Tropical cyclones ; Wind ; Air-sea interaction ; Microwave observations ; Remote sensing ; Surface observations
Abstract
Wind and wave-breaking directions are investigated as potential sources of an asymmetry identified in off-nadir remotely sensed measurements of ocean surface brightness temperatures obtained by the Stepped Frequency Microwave Radiometer (SFMR) in high-wind conditions, including in tropical cyclones. Surface wind speed, which dynamically couples the atmosphere and ocean, can be inferred from SFMR ocean surface brightness temperature measurements using a radiative transfer model and an inversion algorithm. The accuracy of the ocean surface brightness temperature to wind speed calibration relies on accurate knowledge of the surface variables that are influencing the ocean surface brightness temperature. Previous studies have identified wind direction signals in horizontally polarized radiometer measurements in low to moderate (0�20 m s−1) wind conditions over a wide range of incidence angles. This study finds that the azimuthal asymmetry in the off-nadir SFMR brightness temperature measurements is also likely a function of wind direction and extends the results of these previous studies to high-wind conditions. The off-nadir measurements from the SFMR provide critical data for improving the understanding of the relationships between brightness temperature, surface wave�breaking direction, and surface wind vectors at various incidence angles, which is extremely useful for the development of geophysical model functions for instruments like the Hurricane Imaging Radiometer (HIRAD).
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Series Editor
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Series Issue
Edition
ISSN
0739-0572
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ rl18 @
Serial
980
Permanent link to this record
Author
Hu, X. ; Cai, M. ; Yang, S. ; Wu, Z.
Title
Delineation of thermodynamic and dynamic responses to sea surface temperature forcing associated with El Niño
Type
$loc['typeJournal Article']
Year
2018
Publication
Climate Dynamics
Abbreviated Journal
Clim Dyn
Volume
51
Issue
11-12
Pages
4329-4344
Keywords
El Niño ; SST anomalies ; Thermodynamic and dynamic responses ; Gill-type response
Abstract
A new framework is proposed to gain a better understanding of the response of the atmosphere over the tropical Pacific to the radiative heating anomaly associated with the sea surface temperature (SST) anomaly in canonical El Niño winters. The new framework is based on the equilibrium balance between thermal radiative cooling anomalies associated with air temperature response to SST anomalies and other thermodynamic and dynamic processes. The air temperature anomalies in the lower troposphere are mainly in response to radiative heating anomalies associated with SST, atmospheric water vapor, and cloud anomalies that all exhibit similar spatial patterns. As a result, air temperature induced thermal radiative cooling anomalies would balance out most of the radiative heating anomalies in the lower troposphere. The remaining part of the radiative heating anomalies is then taken away by an enhancement (a reduction) of upward energy transport in the central-eastern (western) Pacific basin, a secondary contribution to the air temperature anomalies in the lower troposphere. Above the middle troposphere, radiative effect due to water vapor feedback is weak. Thermal radiative cooling anomalies are mainly in balance with the sum of latent heating anomalies, vertical and horizontal energy transport anomalies associated with atmospheric dynamic response and the radiative heating anomalies due to changes in cloud. The pattern of Gill-type response is attributed mainly to the non-radiative heating anomalies associated with convective and large-scale energy transport. The radiative heating anomalies associated with the anomalies of high clouds also contribute positively to the Gill-type response. This sheds some light on why the Gill-type atmospheric response can be easily identifiable in the upper atmosphere.
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Publisher
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Summary Language
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Series Editor
Series Title
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Series Volume
Series Issue
Edition
ISSN
0930-7575
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
997
Permanent link to this record