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Papers by Richard Iannuzzi

Research paper thumbnail of Winter and spring controls on the summer food web of the coastal West Antarctic Peninsula

Nature Communications, 2014

Research paper thumbnail of Antarctic Ocean-Ice Interaction: Implications from Ocean Bulk Property Distributions in the Weddell Gyre

Antarctic Research Series, 1998

The sea ice distribution in the Antarctic polar oceans is intimately tied to the underlying ocean... more The sea ice distribution in the Antarctic polar oceans is intimately tied to the underlying ocean structure, which controls the oceans' vertical heat flux and stability. The former determines the rate at which ice grows for a given air-sea heat flux, while the latter limits the amount of sea ice that can grow locally before overturning the water column. These relationships have been described through a set of scalings, allowing us to estimate, through examination of the vertical distributions of ocean temperature and salinity: (1) the maximum amount of in situ ice growth in any one location, (2) the ratio of ice melt to ice growth, (3) the amount of ice that has melted in any particular summer location, (4) the ocean winter-averaged heat flux. Climatological maps of these quantities are presented for the Weddell gyre region and general results described. Results include:

Research paper thumbnail of Bellingshausen and western Antarctic Peninsula region: Pigment biomass and sea-ice spatial/temporal distributions and interannual variabilty

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

Research paper thumbnail of Extreme Anomalous Atmospheric Circulation in the West Antarctic Peninsula Region in Austral Spring and Summer 2001/02, and Its Profound Impact on Sea Ice and Biota*

Journal of Climate, 2006

Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from Septemb... more Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from September 2001 to February 2002, resulting from a strongly positive atmospheric pressure anomaly in the South Atlantic coupled with strong negative anomalies in the Bellingshausen-Amundsen and southwest Weddell Seas. This created a strong and persistent north-northwesterly flow of mild and moist air across the WAP. In situ, satellite, and NCEP-NCAR Reanalysis (NNR) data are used to examine the profound and complex impact on regional sea ice, oceanography, and biota. Extensive sea ice melt, leading to an ocean mixed layer freshening and widespread ice surface flooding, snow-ice formation, and phytoplankton growth, coincided with extreme ice deformation and dynamic thickening. Sea ice dynamics were crucial to the development of an unusually early and rapid (short) retreat season (negative ice extent anomaly). Strong winds with a dominant northerly component created an unusually compact marginal ice zone and a major increase in ice thickness by deformation and over-rafting. This led to the atypical persistence of highly compact coastal ice through summer. Ecological effects were both positive and negative, the latter including an impact on the growth rate of larval Antarctic krill and the largest recorded between-season breeding population decrease and lowest reproductive success in a 30-yr Adélie penguin demographic time series. The unusual sea ice and snow cover conditions also contributed to the formation of a major phytoplankton bloom. Unexpectedly, the initial bloom occurred within compact sea ice and could not be detected in Sea-Viewing Wide Fieldof-View Sensor (SeaWiFS) ocean color data. This analysis demonstrates that sea ice extent alone is an inadequate descriptor of the regional sea ice state/conditions, from both a climatic and ecological perspective; further information is required on thickness and dynamics/deformation. White) for underwater ice photography and krill information; Andy Ross (Oregon State University) for nutrient analysis; Jeff Otten (Raytheon) for collection and processing of TeraScan satellite data; Wendy Kozlowski, Karie Sines, Karen Pelletreau, Irene Garibotti, and Pamela Yeh for biological data collection and sample analysis; Raul Guerrero for CTD data collection; and Enrique Curchister for snow, optics, and sea ice data collection. The MPC Randy Sliester and the Raytheon support staff,

Research paper thumbnail of Western Antarctic Peninsula physical oceanography and spatio–temporal variability

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

This study focuses on 12 years of physical oceanography data, collected during the Palmer, Antarc... more This study focuses on 12 years of physical oceanography data, collected during the Palmer, Antarctica, Long-Term Ecological Research program (PAL LTER) over the continental margin of the western Antarctic Peninsula (WAP). The dataset offers the most long-lived consistent CTD-gridded observations of Antarctic waters collected anywhere in the Southern Ocean. The physical characteristics, water column structure and spatio-temporal variability of the various properties are examined for physically consistent and ecologically important patterns and modes of variability. Unique findings of note include: (1) The average annual ocean heat flux (to the atmosphere) over the continental shelf shows a decreasing trend through time averaging 0.6 W m À2 yr À1 , with an annual average ocean heat flux of 19WmAˋ2.Theoceanheatcontentovertheshelfshowsalinearlyincreasingtrendof2.6A^107JmAˋ2yrAˋ1,duepredominantlytoincreasedupwellingofwarmUpperCircumpolarDeepWater(UCDW)ontotheshelfwithasmallcontributionduetoaslightwarmingofUCDW(butoverlongertimescales(50yr),thewarmingofUCDWdominates),(2)optimalmulti−annualaverageverticalturbulentdiffusivitycoefficient(kz)is19 W m À2 . The ocean heat content over the shelf shows a linearly increasing trend of 2.6 Â 10 7 J m À2 yr À1 , due predominantly to increased upwelling of warm Upper Circumpolar Deep Water (UCDW) onto the shelf with a small contribution due to a slight warming of UCDW (but over longer time scales (50 yr), the warming of UCDW dominates), (2) optimal multi-annual average vertical turbulent diffusivity coefficient (k z ) is 19WmAˋ2.Theoceanheatcontentovertheshelfshowsalinearlyincreasingtrendof2.6A^107JmAˋ2yrAˋ1,duepredominantlytoincreasedupwellingofwarmUpperCircumpolarDeepWater(UCDW)ontotheshelfwithasmallcontributionduetoaslightwarmingofUCDW(butoverlongertimescales(50yr),thewarmingofUCDWdominates),(2)optimalmulti−annualaverageverticalturbulentdiffusivitycoefficient(kz)is8.5 Â 10 À5 m 2 s À1 , determined by inversion considering warming of trapped remnant winter mixed layer water, (3) the water masses in the grid are well separated according to bathymetrically controlled features, dividing the sample domain into 3 sub-regions: slope, shelf and coastal waters; (4) the Antarctic Circumpolar Current (ACC) was always present along the shelf-break (consistent with the Orsi et al. [1995. On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep-Sea Research I 42 (5), 641-673.] climatology) where UCDW shows its farthest southern extent and forms the Southern ACC Front (SACCF). The spatio-temporal variability of the delivery and distribution of ocean heat is dictated by the dynamics that are consistent with changes in the state of ENSO (La Niñ a drives enhanced upwelling in this region) and in the strength of the Southern Annular Mode (SAM; +SAM drives a local response similar to that of La Niñ a). The large 1997-1998 El Niñ o, followed by the transition to the strong La Niñ a of 1998-1999 (amplified by a large +SAM) introduced a regime shift on the shelf, resulting in the elimination of $0.5 m of sea ice melt (presumably from the loss of sea ice being grown). 2002 was an anomalous year coinciding with an extraordinary storm forcing driving a 4.5s increase in the heat content on the shelf. These jumps coincide with considerable changes in sea ice distribution as well. Pure UCDW on the shelf is primarily restricted to the deep canyons, with occasional appearances on the shelf floor near the middle of the grid. Anomalies in summer sea surface temperatures reflect wind strength (stronger winds mixing more cold winter water to the surface, with cooler SST; light winds, the opposite).

Research paper thumbnail of Primary production within the sea-ice zone west of the Antarctic Peninsula: I—Sea ice, summer mixed layer, and irradiance

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

In shelf waters of the western Antarctic Peninsula (wAP), with abundant macro-and micronutrients,... more In shelf waters of the western Antarctic Peninsula (wAP), with abundant macro-and micronutrients, water-column stability has been suggested as the main factor controlling primary production; freshwater input from sea-ice melting stabilizes the upper water column by forming a shallow summer mixed layer. Retreating sea ice in the spring and summer thus defines the area of influence, the sea-ice zone (SIZ) and the marginal ice zone (MIZ). A 12-year time series (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) was analyzed to address two main questions:

Research paper thumbnail of Sea ice in the western Antarctic Peninsula region: Spatio-temporal variability from ecological and climate change perspectives

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

The Antarctic Peninsula region is undergoing rapid change: a warming in winter of almost 6°C sinc... more The Antarctic Peninsula region is undergoing rapid change: a warming in winter of almost 6°C since 1950, the loss of six ice shelves, the retreat of 87% of the marine glaciers, and decreases in winter sea-ice duration. Concurrently, there is evidence of ecosystem change along the western Antarctic Peninsula (wAP). Since the life histories of most polar marine species are

Research paper thumbnail of Palmer LTER: Patterns of distribution of five dominant zooplankton species in the epipelagic zone west of the Antarctic Peninsula, 1993–2004

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

Research paper thumbnail of Winter and spring controls on the summer food web of the coastal West Antarctic Peninsula

Nature Communications, 2014

Research paper thumbnail of Winter and spring controls on the summer food web of the coastal West Antarctic Peninsula

Nature Communications, 2014

Research paper thumbnail of Antarctic Ocean-Ice Interaction: Implications from Ocean Bulk Property Distributions in the Weddell Gyre

Antarctic Research Series, 1998

The sea ice distribution in the Antarctic polar oceans is intimately tied to the underlying ocean... more The sea ice distribution in the Antarctic polar oceans is intimately tied to the underlying ocean structure, which controls the oceans' vertical heat flux and stability. The former determines the rate at which ice grows for a given air-sea heat flux, while the latter limits the amount of sea ice that can grow locally before overturning the water column. These relationships have been described through a set of scalings, allowing us to estimate, through examination of the vertical distributions of ocean temperature and salinity: (1) the maximum amount of in situ ice growth in any one location, (2) the ratio of ice melt to ice growth, (3) the amount of ice that has melted in any particular summer location, (4) the ocean winter-averaged heat flux. Climatological maps of these quantities are presented for the Weddell gyre region and general results described. Results include:

Research paper thumbnail of Bellingshausen and western Antarctic Peninsula region: Pigment biomass and sea-ice spatial/temporal distributions and interannual variabilty

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

Research paper thumbnail of Extreme Anomalous Atmospheric Circulation in the West Antarctic Peninsula Region in Austral Spring and Summer 2001/02, and Its Profound Impact on Sea Ice and Biota*

Journal of Climate, 2006

Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from Septemb... more Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from September 2001 to February 2002, resulting from a strongly positive atmospheric pressure anomaly in the South Atlantic coupled with strong negative anomalies in the Bellingshausen-Amundsen and southwest Weddell Seas. This created a strong and persistent north-northwesterly flow of mild and moist air across the WAP. In situ, satellite, and NCEP-NCAR Reanalysis (NNR) data are used to examine the profound and complex impact on regional sea ice, oceanography, and biota. Extensive sea ice melt, leading to an ocean mixed layer freshening and widespread ice surface flooding, snow-ice formation, and phytoplankton growth, coincided with extreme ice deformation and dynamic thickening. Sea ice dynamics were crucial to the development of an unusually early and rapid (short) retreat season (negative ice extent anomaly). Strong winds with a dominant northerly component created an unusually compact marginal ice zone and a major increase in ice thickness by deformation and over-rafting. This led to the atypical persistence of highly compact coastal ice through summer. Ecological effects were both positive and negative, the latter including an impact on the growth rate of larval Antarctic krill and the largest recorded between-season breeding population decrease and lowest reproductive success in a 30-yr Adélie penguin demographic time series. The unusual sea ice and snow cover conditions also contributed to the formation of a major phytoplankton bloom. Unexpectedly, the initial bloom occurred within compact sea ice and could not be detected in Sea-Viewing Wide Fieldof-View Sensor (SeaWiFS) ocean color data. This analysis demonstrates that sea ice extent alone is an inadequate descriptor of the regional sea ice state/conditions, from both a climatic and ecological perspective; further information is required on thickness and dynamics/deformation. White) for underwater ice photography and krill information; Andy Ross (Oregon State University) for nutrient analysis; Jeff Otten (Raytheon) for collection and processing of TeraScan satellite data; Wendy Kozlowski, Karie Sines, Karen Pelletreau, Irene Garibotti, and Pamela Yeh for biological data collection and sample analysis; Raul Guerrero for CTD data collection; and Enrique Curchister for snow, optics, and sea ice data collection. The MPC Randy Sliester and the Raytheon support staff,

Research paper thumbnail of Western Antarctic Peninsula physical oceanography and spatio–temporal variability

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

This study focuses on 12 years of physical oceanography data, collected during the Palmer, Antarc... more This study focuses on 12 years of physical oceanography data, collected during the Palmer, Antarctica, Long-Term Ecological Research program (PAL LTER) over the continental margin of the western Antarctic Peninsula (WAP). The dataset offers the most long-lived consistent CTD-gridded observations of Antarctic waters collected anywhere in the Southern Ocean. The physical characteristics, water column structure and spatio-temporal variability of the various properties are examined for physically consistent and ecologically important patterns and modes of variability. Unique findings of note include: (1) The average annual ocean heat flux (to the atmosphere) over the continental shelf shows a decreasing trend through time averaging 0.6 W m À2 yr À1 , with an annual average ocean heat flux of 19WmAˋ2.Theoceanheatcontentovertheshelfshowsalinearlyincreasingtrendof2.6A^107JmAˋ2yrAˋ1,duepredominantlytoincreasedupwellingofwarmUpperCircumpolarDeepWater(UCDW)ontotheshelfwithasmallcontributionduetoaslightwarmingofUCDW(butoverlongertimescales(50yr),thewarmingofUCDWdominates),(2)optimalmulti−annualaverageverticalturbulentdiffusivitycoefficient(kz)is19 W m À2 . The ocean heat content over the shelf shows a linearly increasing trend of 2.6 Â 10 7 J m À2 yr À1 , due predominantly to increased upwelling of warm Upper Circumpolar Deep Water (UCDW) onto the shelf with a small contribution due to a slight warming of UCDW (but over longer time scales (50 yr), the warming of UCDW dominates), (2) optimal multi-annual average vertical turbulent diffusivity coefficient (k z ) is 19WmAˋ2.Theoceanheatcontentovertheshelfshowsalinearlyincreasingtrendof2.6A^107JmAˋ2yrAˋ1,duepredominantlytoincreasedupwellingofwarmUpperCircumpolarDeepWater(UCDW)ontotheshelfwithasmallcontributionduetoaslightwarmingofUCDW(butoverlongertimescales(50yr),thewarmingofUCDWdominates),(2)optimalmulti−annualaverageverticalturbulentdiffusivitycoefficient(kz)is8.5 Â 10 À5 m 2 s À1 , determined by inversion considering warming of trapped remnant winter mixed layer water, (3) the water masses in the grid are well separated according to bathymetrically controlled features, dividing the sample domain into 3 sub-regions: slope, shelf and coastal waters; (4) the Antarctic Circumpolar Current (ACC) was always present along the shelf-break (consistent with the Orsi et al. [1995. On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep-Sea Research I 42 (5), 641-673.] climatology) where UCDW shows its farthest southern extent and forms the Southern ACC Front (SACCF). The spatio-temporal variability of the delivery and distribution of ocean heat is dictated by the dynamics that are consistent with changes in the state of ENSO (La Niñ a drives enhanced upwelling in this region) and in the strength of the Southern Annular Mode (SAM; +SAM drives a local response similar to that of La Niñ a). The large 1997-1998 El Niñ o, followed by the transition to the strong La Niñ a of 1998-1999 (amplified by a large +SAM) introduced a regime shift on the shelf, resulting in the elimination of $0.5 m of sea ice melt (presumably from the loss of sea ice being grown). 2002 was an anomalous year coinciding with an extraordinary storm forcing driving a 4.5s increase in the heat content on the shelf. These jumps coincide with considerable changes in sea ice distribution as well. Pure UCDW on the shelf is primarily restricted to the deep canyons, with occasional appearances on the shelf floor near the middle of the grid. Anomalies in summer sea surface temperatures reflect wind strength (stronger winds mixing more cold winter water to the surface, with cooler SST; light winds, the opposite).

Research paper thumbnail of Primary production within the sea-ice zone west of the Antarctic Peninsula: I—Sea ice, summer mixed layer, and irradiance

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

In shelf waters of the western Antarctic Peninsula (wAP), with abundant macro-and micronutrients,... more In shelf waters of the western Antarctic Peninsula (wAP), with abundant macro-and micronutrients, water-column stability has been suggested as the main factor controlling primary production; freshwater input from sea-ice melting stabilizes the upper water column by forming a shallow summer mixed layer. Retreating sea ice in the spring and summer thus defines the area of influence, the sea-ice zone (SIZ) and the marginal ice zone (MIZ). A 12-year time series (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) was analyzed to address two main questions:

Research paper thumbnail of Sea ice in the western Antarctic Peninsula region: Spatio-temporal variability from ecological and climate change perspectives

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

The Antarctic Peninsula region is undergoing rapid change: a warming in winter of almost 6°C sinc... more The Antarctic Peninsula region is undergoing rapid change: a warming in winter of almost 6°C since 1950, the loss of six ice shelves, the retreat of 87% of the marine glaciers, and decreases in winter sea-ice duration. Concurrently, there is evidence of ecosystem change along the western Antarctic Peninsula (wAP). Since the life histories of most polar marine species are

Research paper thumbnail of Palmer LTER: Patterns of distribution of five dominant zooplankton species in the epipelagic zone west of the Antarctic Peninsula, 1993–2004

Deep Sea Research Part II: Topical Studies in Oceanography, 2008

Research paper thumbnail of Winter and spring controls on the summer food web of the coastal West Antarctic Peninsula

Nature Communications, 2014