17 results on '"Valero-Delgado, Fernando"'
Number of results to display per page
Search Results
2. The Ross Sea Dipole – temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years
- Author
-
Bertler, Nancy AN, Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B, Winstrup, Mai, Vallelonga, Paul T, Lee, James E, Brook, Ed J, Severinghaus, Jeffrey P, Fudge, Taylor J, Keller, Elizabeth D, Baisden, W Troy, Hindmarsh, Richard CA, Neff, Peter D, Blunier, Thomas, Edwards, Ross, Mayewski, Paul A, Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A, Kurbatov, Andrei, Zhang, Dongqi, Waddington, Edwin D, Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J, Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G, Delmonte, Barbara, Eling, Lukas, Ellis, Aja, Ganesh, Shruthi, Golledge, Nicholas R, Haines, Skylar, Handley, Michael, Hawley, Robert L, Hogan, Chad M, Johnson, Katelyn M, Korotkikh, Elena, Lowry, Daniel P, Mandeno, Darcy, McKay, Robert M, Menking, James A, Naish, Timothy R, Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C, Pyne, Alexander R, Pyne, Rebecca L, Renwick, James, Scherer, Reed P, Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B, Steig, Eric J, Tuohy, Andrea, Venugopal, Abhijith Ulayottil, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A, Winton, V Holly L, Whiteford, Arran, Xiao, Cunde, Yang, Jiao, and Zhang, Xin
- Subjects
Earth Sciences ,Physical Geography and Environmental Geoscience ,Geology ,Climate Action ,Paleontology ,Climate change science - Abstract
Abstract. High-resolution, well-dated climate archives provide anopportunity to investigate the dynamic interactions of climate patternsrelevant for future projections. Here, we present data from a new, annuallydated ice core record from the eastern Ross Sea, named the Roosevelt IslandClimate Evolution (RICE) ice core. Comparison of this record with climatereanalysis data for the 1979–2012 interval shows that RICE reliably capturestemperature and snow precipitation variability in the region. Trends over thepast 2700 years in RICE are shown to be distinct from those in WestAntarctica and the western Ross Sea captured by other ice cores. For most ofthis interval, the eastern Ross Sea was warming (or showing isotopicenrichment for other reasons), with increased snow accumulation and perhapsdecreased sea ice concentration. However, West Antarctica cooled and thewestern Ross Sea showed no significant isotope temperature trend. Thispattern here is referred to as the Ross Sea Dipole. Notably, during theLittle Ice Age, West Antarctica and the western Ross Sea experienced colderthan average temperatures, while the eastern Ross Sea underwent a period ofwarming or increased isotopic enrichment. From the 17th century onwards, thisdipole relationship changed. All three regions show current warming, withsnow accumulation declining in West Antarctica and the eastern Ross Sea butincreasing in the western Ross Sea. We interpret this pattern as reflectingan increase in sea ice in the eastern Ross Sea with perhaps the establishmentof a modern Roosevelt Island polynya as a local moisture source for RICE.
- Published
- 2018
3. The Ross Sea Dipole – Temperature, Snow Accumulation and Sea Ice Variability in the Ross Sea Region, Antarctica, over the Past 2,700 Years
- Author
-
Bertler, Nancy AN, Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B, Winstrup, Mai, Vallelonga, Paul T, Lee, James E, Brook, Ed J, Severinghaus, Jeffrey P, Fudge, Taylor J, Keller, Elizabeth D, Baisden, W Troy, Hindmarsh, Richard CA, Neff, Peter D, Blunier, Thomas, Edwards, Ross, Mayewski, Paul A, Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A, Kurbatov, Andrei, Zhang, Dongqi, Waddington, Ed D, Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J, Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G, Delmonte, Barbara, Eling, Lukas, Ellis, Aja A, Ganesh, Shruthi, Golledge, Nicholas R, Haines, Skylar A, Handley, Michael, Hawley, Robert L, Hogan, Chad M, Johnson, Katelyn M, Korotkikh, Elena, Lowry, Daniel P, Mandeno, Darcy, McKay, Robert M, Menking, James A, Naish, Timothy R, Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C, Pyne, Alexander R, Pyne, Rebecca L, Renwick, James, Scherer, Reed P, Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B, Steig, Eric J, Tuohy, Andrea, Venugopal, Abhijith Ulayottil, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A, Winton, Victoria HL, Whiteford, Arran, Xiao, Cunde, Yang, Jiao, and Zhang, Xin
- Subjects
Climate Action - Abstract
Abstract. High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually-dated ice core record from the eastern Ross Sea. Comparison of the Roosevelt Island Climate Evolution (RICE) ice core records with climate reanalysis data for the 1979–2012 calibration period shows that RICE records reliably capture temperature and snow precipitation variability of the region. RICE is compared with data from West Antarctica (West Antarctic Ice Sheet Divide Ice Core) and the western (Talos Dome) and eastern (Siple Dome) Ross Sea. For most of the past 2,700 years, the eastern Ross Sea was warming with perhaps increased snow accumulation and decreased sea ice extent. However, West Antarctica cooled whereas the western Ross Sea showed no significant temperature trend. From the 17th Century onwards, this relationship changes. All three regions now show signs of warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea, but increasing in the western Ross Sea. Analysis of decadal to centennial-scale climate variability superimposed on the longer term trend reveal that periods characterised by opposing temperature trends between the Eastern and Western Ross Sea have occurred since the 3rd Century but are masked by longer-term trends. This pattern here is referred to as the Ross Sea Dipole, caused by a sensitive response of the region to dynamic interactions of the Southern Annual Mode and tropical forcings.
- Published
- 2017
4. Extending the fabric from the EGRIPice core in space with geophysicalmethods and modelling
- Author
-
Gerber, Tamara Annina, Lilien, David, Rathmann, Nicolas, Franke, Steven, Young, Tun J., Valero-Delgado, Fernando, Ershadi, M. Reza, Drews, Reinhard, Zeising, Ole, Humbert, Angelika, Stoll, Nicolas, Weikusat, Ilka, Grinsted, Aslak, Hvidberg, Christine Schøtt, Jansen, Daniela, Miller, Heinrich, Helm, Veit, Steinhage, Daniel, O'Neill, Charles, Paden, John, Gogineni, Prasad, Dahl-Jensen, Dorthe, and Eisen, Olaf
- Abstract
Anisotropic crystal fabrics in ice sheets develop as a consequence of deformation and hence record information of past ice flow. Simultaneously, the fabric affects the present-day bulk mechanical properties of glacier ice because the susceptibility of ice crystals to deformation is highly anisotropic. This is particularly relevant in dynamic areas such as fast-flowing glaciers and ice streams, where the formation of strong fabrics might play a critical role in facilitating ice flow. Anisotropy is ignored in most state-of-the-art ice sheet models, and while its importance has long been recognized, accounting for fabric evolution and its impact on the ice viscosity has only recently become feasible. Both the application of such models to ice streams and their verification through in-situ observations are still rare. Ice cores provide direct and detailed information on the crystal fabric, but the logistical cost, technical challenges, particularly in fast-flowing ice and shear margins, difficulty in reconstructing the absolute orientation of the core, and their limitation of being a point measurement, make ice cores impractical for a spatially extensive evaluation of the fabric type. Indirect geophysical methods applied from or above the ice surface create the link between the small scale of laboratory experiments and ice–core observations to the large-scale coverage required for ice flow models and the complete understanding of ice stream dynamics. Here, we present a comprehensive analysis of the distribution of the ice fabric in the upstream part of the North-East Greenland Ice Stream (NEGIS). Our results are based on a combination of methods applied to extensive airborne and ground-based radar surveys, ice- and firn-core observations, and numerical ice-flow modelling. They show that in the onset region of NEGIS and around the EGRIP ice core drilling site, the fabric is horizontally strongly anisotropic, forming a horizontal girdle perpendicular to the ice flow, while the horizontal anisotropy reduces quickly over distances of less than five ice thicknesses outside of the ice stream’s shear margins. Downstream of the drill site, the fabric develops into a more vertically symmetric configuration on a time scale of around 2 ka, the first observation of this kind. Our study shows how ice-core based fabric observations, geophysical surveys and ice-flow modelling complement each other to obtain a more comprehensive picture of the spatially strongly varying fabric.
- Published
- 2022
5. Crystal fabric anisotropy causes directional hardening of the Northeast Greenland Ice Stream
- Author
-
Gerber, Tamara, primary, Lilien, David, additional, Rathmann, Nicholas, additional, Franke, Steven, additional, Young, Tun Jan, additional, Valero-Delgado, Fernando, additional, Ershadi, Reza, additional, Drews, Reinhard, additional, Zeising, Ole, additional, Humbert, Angelika, additional, Stoll, Nicolas, additional, Weikusat, Ilka, additional, Grinsted, Aslak, additional, Hvidberg, Christine, additional, Jansen, Daniela, additional, Miller, Heinrich, additional, Helm, Veit, additional, Steinhage, Daniel, additional, O'Neill, Charles, additional, Gogineni, Prasad, additional, Paden, John, additional, Dahl-Jensen, Dorthe, additional, and Eisen, Olaf, additional
- Published
- 2022
- Full Text
- View/download PDF
6. Spatial variation of ice crystal fabric and implications of anisotropic flow on the evolution of the Northeast Greenland Ice Stream
- Author
-
Gerber, Tamara Annina, Lilien, David, Rathmann, Nicolas, Young, Tun J., Valero-Delgado, Fernando, Ershadi, M. Reza, Drews, Reinhard, Jansen, Daniela, Franke, Steven, Hvidberg, Christine Schøtt, Grinsted, Aslak, Zeising, Ole, Humbert, Angelika, Gogineni, Prasad, Miller, Heinrich, Helm, Veit, O'Neill, Charles, Dahl-Jensen, Dorthe, Eisen, Olaf, Gerber, Tamara Annina, Lilien, David, Rathmann, Nicolas, Young, Tun J., Valero-Delgado, Fernando, Ershadi, M. Reza, Drews, Reinhard, Jansen, Daniela, Franke, Steven, Hvidberg, Christine Schøtt, Grinsted, Aslak, Zeising, Ole, Humbert, Angelika, Gogineni, Prasad, Miller, Heinrich, Helm, Veit, O'Neill, Charles, Dahl-Jensen, Dorthe, and Eisen, Olaf
- Abstract
Anisotropic crystal fabrics in ice sheets develop as a consequence of deformation and hence record information of past ice flow. Simultaneously, the fabric affects the present-day bulk mechanical properties of glacier ice because the susceptibility of ice crystals to deformation is highly anisotropic. This is particularly relevant in dynamic areas such as fast-flowing glaciers and ice streams, where the formation of strong fabrics might play a critical role in facilitating ice flow. This fact is ignored in most state-of-the-art ice sheet models, and while their importance has been recognized years ago, accounting for fabrics evolution and their impact on the ice viscosity has only recently become feasible. Both, the application of such models in ice streams as well as their verification through in-situ observations are, however, still rare. We present an extensive dataset of fabric anisotropy derived from radar data recorded in the onset region of the Northeast Greenland Ice Stream by air-borne and ground-based systems. Our methods yield the horizontal anisotropy and are based on travel time anisotropy and splitting as well as birefringence-induced power modulation of radar signals. They complement each other and show good agreement. We compare these in-situ observations with the results obtained from a fabric-evolution model employed along flow tubes in the ice stream onset to discuss the fabric in light of past flow history and its significance for the current flow mechanics of the ice stream.
- Published
- 2022
7. The Ross Sea Dipole-temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years
- Author
-
Bertler, N, Conway, H, Dahl-Jensen, D, Emanuelsson, D, Winstrup, M, Vallelonga, P, Lee, J, Brook, E, Severinghaus, J, Fudge, T, Keller, E, Troy Baisden, W, Hindmarsh, R, Neff, P, Blunier, T, Edwards, R, Mayewski, P, Kipfstuhl, S, Buizert, C, Canessa, S, Dadic, R, Kjær, H, Kurbatov, A, Zhang, D, Waddington, E, Baccolo, G, Beers, T, Brightley, H, Carter, L, Clemens-Sewall, D, Ciobanu, V, Delmonte, B, Eling, L, Ellis, A, Ganesh, S, Golledge, N, Haines, S, Handley, M, Hawley, R, Hogan, C, Johnson, K, Korotkikh, E, Lowry, D, Mandeno, D, Mckay, R, Menking, J, Naish, T, Noerling, C, Ollive, A, Orsi, A, Proemse, B, Pyne, A, Pyne, R, Renwick, J, Scherer, R, Semper, S, Simonsen, M, Sneed, S, Steig, E, Tuohy, A, Ulayottil Venugopal, A, Valero-Delgado, F, Venkatesh, J, Wang, F, Wang, S, Winski, D, Holly, W, Whiteford, A, Xiao, C, Yang, J, Zhang, X, Bertler, Nancy A. N., Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B., Winstrup, Mai, Vallelonga, Paul T., Lee, James E., Brook, Ed J., Severinghaus, Jeffrey P., Fudge, Taylor J., Keller, Elizabeth D., Troy Baisden, W., Hindmarsh, Richard C. A., Neff, Peter D., Blunier, Thomas, Edwards, Ross, Mayewski, Paul A., Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A., Kurbatov, Andrei, Zhang, Dongqi, Waddington, Edwin D., Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J., Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G., Delmonte, Barbara, Eling, Lukas, Ellis, Aja, Ganesh, Shruthi, Golledge, Nicholas R., Haines, Skylar, Handley, Michael, Hawley, Robert L., Hogan, Chad M., Johnson, Katelyn M., Korotkikh, Elena, Lowry, Daniel P., Mandeno, Darcy, McKay, Robert M., Menking, James A., Naish, Timothy R., Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C., Pyne, Alexander R., Pyne, Rebecca L., Renwick, James, Scherer, Reed P., Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B., Steig, Eric J., Tuohy, Andrea, Ulayottil Venugopal, Abhijith, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A., Holly, Winton, Whiteford, Arran, Xiao, Cunde, Yang, Jiao, Zhang, Xin, Bertler, N, Conway, H, Dahl-Jensen, D, Emanuelsson, D, Winstrup, M, Vallelonga, P, Lee, J, Brook, E, Severinghaus, J, Fudge, T, Keller, E, Troy Baisden, W, Hindmarsh, R, Neff, P, Blunier, T, Edwards, R, Mayewski, P, Kipfstuhl, S, Buizert, C, Canessa, S, Dadic, R, Kjær, H, Kurbatov, A, Zhang, D, Waddington, E, Baccolo, G, Beers, T, Brightley, H, Carter, L, Clemens-Sewall, D, Ciobanu, V, Delmonte, B, Eling, L, Ellis, A, Ganesh, S, Golledge, N, Haines, S, Handley, M, Hawley, R, Hogan, C, Johnson, K, Korotkikh, E, Lowry, D, Mandeno, D, Mckay, R, Menking, J, Naish, T, Noerling, C, Ollive, A, Orsi, A, Proemse, B, Pyne, A, Pyne, R, Renwick, J, Scherer, R, Semper, S, Simonsen, M, Sneed, S, Steig, E, Tuohy, A, Ulayottil Venugopal, A, Valero-Delgado, F, Venkatesh, J, Wang, F, Wang, S, Winski, D, Holly, W, Whiteford, A, Xiao, C, Yang, J, Zhang, X, Bertler, Nancy A. N., Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B., Winstrup, Mai, Vallelonga, Paul T., Lee, James E., Brook, Ed J., Severinghaus, Jeffrey P., Fudge, Taylor J., Keller, Elizabeth D., Troy Baisden, W., Hindmarsh, Richard C. A., Neff, Peter D., Blunier, Thomas, Edwards, Ross, Mayewski, Paul A., Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A., Kurbatov, Andrei, Zhang, Dongqi, Waddington, Edwin D., Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J., Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G., Delmonte, Barbara, Eling, Lukas, Ellis, Aja, Ganesh, Shruthi, Golledge, Nicholas R., Haines, Skylar, Handley, Michael, Hawley, Robert L., Hogan, Chad M., Johnson, Katelyn M., Korotkikh, Elena, Lowry, Daniel P., Mandeno, Darcy, McKay, Robert M., Menking, James A., Naish, Timothy R., Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C., Pyne, Alexander R., Pyne, Rebecca L., Renwick, James, Scherer, Reed P., Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B., Steig, Eric J., Tuohy, Andrea, Ulayottil Venugopal, Abhijith, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A., Holly, Winton, Whiteford, Arran, Xiao, Cunde, Yang, Jiao, and Zhang, Xin
- Abstract
High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually dated ice core record from the eastern Ross Sea, named the Roosevelt Island Climate Evolution (RICE) ice core. Comparison of this record with climate reanalysis data for the 1979-2012 interval shows that RICE reliably captures temperature and snow precipitation variability in the region. Trends over the past 2700 years in RICE are shown to be distinct from those in West Antarctica and the western Ross Sea captured by other ice cores. For most of this interval, the eastern Ross Sea was warming (or showing isotopic enrichment for other reasons), with increased snow accumulation and perhaps decreased sea ice concentration. However, West Antarctica cooled and the western Ross Sea showed no significant isotope temperature trend. This pattern here is referred to as the Ross Sea Dipole. Notably, during the Little Ice Age, West Antarctica and the western Ross Sea experienced colder than average temperatures, while the eastern Ross Sea underwent a period of warming or increased isotopic enrichment. From the 17th century onwards, this dipole relationship changed. All three regions show current warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea but increasing in the western Ross Sea. We interpret this pattern as reflecting an increase in sea ice in the eastern Ross Sea with perhaps the establishment of a modern Roosevelt Island polynya as a local moisture source for RICE
- Published
- 2018
8. The Ross Sea Dipole - temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 Years
- Author
-
Bertler, Nancy A.N., Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B., Winstrup, Mai, Vallelonga, Paul T., Lee, James E., Brook, Ed J., Severinghaus, Jeffrey P., Fudge, Taylor J., Keller, Elizabeth D., Baisden, W. Troy, Hindmarsh, Richard C.A., Neff, Peter D., Blunier, Thomas, Edwards, Ross, Mayewski, Paul A., Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A., Kurbatov, Andrei, Zhang, Dongqi, Waddington, Ed D., Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J., Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G., Delmonte, Barbara, Eling, Lukas, Ellis, Aja A., Ganesh, Shruthi, Golledge, Nicholas R., Haines, Skylar A., Handley, Michael, Hawley, Robert L., Hogan, Chad M., Johnson, Katelyn M., Korotkikh, Elena, Lowry, Daniel P., Mandeno, Darcy, McKay, Robert M., Menking, James A., Naish, Timothy R., Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C., Pyne, Alexander R., Pyne, Rebecca L., Renwick, James, Scherer, Reed P., Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B., Steig, Eric J., Tuohy, Andrea, Ulayottil Venugopal, Abhijith, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A., Winton, Victoria H.L., Whiteford, Arran, Xiao, Cunde, Yang, Jiao, Zhang, Xin, Bertler, Nancy A.N., Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B., Winstrup, Mai, Vallelonga, Paul T., Lee, James E., Brook, Ed J., Severinghaus, Jeffrey P., Fudge, Taylor J., Keller, Elizabeth D., Baisden, W. Troy, Hindmarsh, Richard C.A., Neff, Peter D., Blunier, Thomas, Edwards, Ross, Mayewski, Paul A., Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A., Kurbatov, Andrei, Zhang, Dongqi, Waddington, Ed D., Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J., Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G., Delmonte, Barbara, Eling, Lukas, Ellis, Aja A., Ganesh, Shruthi, Golledge, Nicholas R., Haines, Skylar A., Handley, Michael, Hawley, Robert L., Hogan, Chad M., Johnson, Katelyn M., Korotkikh, Elena, Lowry, Daniel P., Mandeno, Darcy, McKay, Robert M., Menking, James A., Naish, Timothy R., Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C., Pyne, Alexander R., Pyne, Rebecca L., Renwick, James, Scherer, Reed P., Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B., Steig, Eric J., Tuohy, Andrea, Ulayottil Venugopal, Abhijith, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A., Winton, Victoria H.L., Whiteford, Arran, Xiao, Cunde, Yang, Jiao, and Zhang, Xin
- Abstract
High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually-dated ice core record from the eastern Ross Sea. Comparison of the Roosevelt Island Climate Evolution (RICE) ice core records with climate reanalysis data for the 1979–2012 calibration period shows that RICE records reliably capture temperature and snow precipitation variability of the region. RICE is compared with data from West Antarctica (West Antarctic Ice Sheet Divide Ice Core) and the western (Talos Dome) and eastern (Siple Dome) Ross Sea. For most of the past 2,700 years, the eastern Ross Sea was warming with perhaps increased snow accumulation and decreased sea ice extent. However, West Antarctica cooled whereas the western Ross Sea showed no significant temperature trend. From the 17th Century onwards, this relationship changes. All three regions now show signs of warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea, but increasing in the western Ross Sea. Analysis of decadal to centennial-scale climate variability superimposed on the longer term trend reveal that periods characterised by opposing temperature trends between the Eastern and Western Ross Sea have occurred since the 3rd Century but are masked by longer-term trends. This pattern here is referred to as the Ross Sea Dipole, caused by a sensitive response of the region to dynamic interactions of the Southern Annual Mode and tropical forcings.
- Published
- 2018
9. The Ross Sea Dipole – Temperature, Snow Accumulation and Sea Ice Variability in the Ross Sea Region, Antarctica, over the Past 2,700 Years
- Author
-
Bertler, Nancy A. N., Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B., Winstrup, Mai, Vallelonga, Paul T., Lee, James E., Brook, Ed J., Severinghaus, Jeffrey P., Fudge, Taylor J., Keller, Elizabeth D., Baisden, W. Troy, Hindmarsh, Richard C. A., Neff, Peter D., Blunier, Thomas, Edwards, Ross, Mayewski, Paul A., Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A., Kurbatov, Andrei, Zhang, Dongqi, Waddington, Ed D., Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J., Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G., Delmonte, Barbara, Eling, Lukas, Ellis, Aja A., Ganesh, Shruthi, Golledge, Nicholas R., Haines, Skylar A., Handley, Michael, Hawley, Robert L., Hogan, Chad M., Johnson, Katelyn M., Korotkikh, Elena, Lowry, Daniel P., Mandeno, Darcy, McKay, Robert M., Menking, James A., Naish, Timothy R., Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C., Pyne, Alexander R., Pyne, Rebecca L., Renwick, James, Scherer, Reed P., Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B., Steig, Eric J., Tuohy, Andrea, Venugopal, Abhijith Ulayottil, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A., Winton, Victoria H. L., Whiteford, Arran, Xiao, Cunde, Yang, Jiao, Zhang, Xin, Bertler, Nancy A. N., Conway, Howard, Dahl-Jensen, Dorthe, Emanuelsson, Daniel B., Winstrup, Mai, Vallelonga, Paul T., Lee, James E., Brook, Ed J., Severinghaus, Jeffrey P., Fudge, Taylor J., Keller, Elizabeth D., Baisden, W. Troy, Hindmarsh, Richard C. A., Neff, Peter D., Blunier, Thomas, Edwards, Ross, Mayewski, Paul A., Kipfstuhl, Sepp, Buizert, Christo, Canessa, Silvia, Dadic, Ruzica, Kjær, Helle A., Kurbatov, Andrei, Zhang, Dongqi, Waddington, Ed D., Baccolo, Giovanni, Beers, Thomas, Brightley, Hannah J., Carter, Lionel, Clemens-Sewall, David, Ciobanu, Viorela G., Delmonte, Barbara, Eling, Lukas, Ellis, Aja A., Ganesh, Shruthi, Golledge, Nicholas R., Haines, Skylar A., Handley, Michael, Hawley, Robert L., Hogan, Chad M., Johnson, Katelyn M., Korotkikh, Elena, Lowry, Daniel P., Mandeno, Darcy, McKay, Robert M., Menking, James A., Naish, Timothy R., Noerling, Caroline, Ollive, Agathe, Orsi, Anaïs, Proemse, Bernadette C., Pyne, Alexander R., Pyne, Rebecca L., Renwick, James, Scherer, Reed P., Semper, Stefanie, Simonsen, Marius, Sneed, Sharon B., Steig, Eric J., Tuohy, Andrea, Venugopal, Abhijith Ulayottil, Valero-Delgado, Fernando, Venkatesh, Janani, Wang, Feitang, Wang, Shimeng, Winski, Dominic A., Winton, Victoria H. L., Whiteford, Arran, Xiao, Cunde, Yang, Jiao, and Zhang, Xin
- Published
- 2017
10. The Ross Sea Dipole – Temperature, Snow Accumulation and Sea Ice Variability in the Ross Sea Region, Antarctica, over the Past 2,700 Years
- Author
-
Bertler, Nancy A. N., primary, Conway, Howard, additional, Dahl-Jensen, Dorthe, additional, Emanuelsson, Daniel B., additional, Winstrup, Mai, additional, Vallelonga, Paul T., additional, Lee, James E., additional, Brook, Ed J., additional, Severinghaus, Jeffrey P., additional, Fudge, Taylor J., additional, Keller, Elizabeth D., additional, Baisden, W. Troy, additional, Hindmarsh, Richard C. A., additional, Neff, Peter D., additional, Blunier, Thomas, additional, Edwards, Ross, additional, Mayewski, Paul A., additional, Kipfstuhl, Sepp, additional, Buizert, Christo, additional, Canessa, Silvia, additional, Dadic, Ruzica, additional, Kjær, Helle A., additional, Kurbatov, Andrei, additional, Zhang, Dongqi, additional, Waddington, Ed D., additional, Baccolo, Giovanni, additional, Beers, Thomas, additional, Brightley, Hannah J., additional, Carter, Lionel, additional, Clemens-Sewall, David, additional, Ciobanu, Viorela G., additional, Delmonte, Barbara, additional, Eling, Lukas, additional, Ellis, Aja A., additional, Ganesh, Shruthi, additional, Golledge, Nicholas R., additional, Haines, Skylar A., additional, Handley, Michael, additional, Hawley, Robert L., additional, Hogan, Chad M., additional, Johnson, Katelyn M., additional, Korotkikh, Elena, additional, Lowry, Daniel P., additional, Mandeno, Darcy, additional, McKay, Robert M., additional, Menking, James A., additional, Naish, Timothy R., additional, Noerling, Caroline, additional, Ollive, Agathe, additional, Orsi, Anaïs, additional, Proemse, Bernadette C., additional, Pyne, Alexander R., additional, Pyne, Rebecca L., additional, Renwick, James, additional, Scherer, Reed P., additional, Semper, Stefanie, additional, Simonsen, Marius, additional, Sneed, Sharon B., additional, Steig, Eric J., additional, Tuohy, Andrea, additional, Ulayottil Venugopal, Abhijith, additional, Valero-Delgado, Fernando, additional, Venkatesh, Janani, additional, Wang, Feitang, additional, Wang, Shimeng, additional, Winski, Dominic A., additional, Winton, Victoria H. L., additional, Whiteford, Arran, additional, Xiao, Cunde, additional, Yang, Jiao, additional, and Zhang, Xin, additional
- Published
- 2017
- Full Text
- View/download PDF
11. Deep drilling at Base Kohnen, Antarctica: results and future development
- Author
-
Wilhelms, Frank, Fritzsche, Diedrich, Hansen, Steffen Bo, Hilmarsson, Sverrir, Grobe, Hannes, Karsten, Achim, Karsten, Lorenz, Jaeschke, Andrea, Takata, Morimasa, Jakobsdottir, Steinunn S., Lawer, Gunther, Gerasimoff, Michael, Hörnby, Kerstin, Jukschat, Paul, Schärmeli, Ivan, Frenzel, Andreas, Lambrecht´, Astrid, Schmitt, Jochen, Kaszmarska, Marzena, Hoffmann, Georg, Sheldon, Simon G., Trenke, Markus, Miller, Heinrich, Lambrecht, Anja, Wilhelms-Dick, Dorothee, Twarloh, Birthe, Valero-Delgado, Fernando, Karlin, Torbjörn, and Kaufmann, Patrik
- Published
- 2012
12. The EPICA Dronning Maud Land deep drilling operation
- Author
-
Wilhelms, Frank, Miller, Heinrich, Gerasimoff, Michael D., Druecker, Cord, Frenzel, Andreas, Fritzsche, Diedrich, Grobe, Hannes, Hansen, Steffen Bo, Hilmarsson, Sverrir A. E., Hoffmann, Georg, Hörnby, Kerstin, Jaeschke, Andrea, Jakobsdottir, Steinunn S., Juckschat, Paul, Karsten, Achim, Karsten, Lorenz, Kaufmann, Patrik R., Karlin, Torbjorn, Kohlberg, Eberhard, Kleffel, Guido, Lambrecht, Anja, Lambrecht, Astrid, Lawer, Gunther, Schaermeli, Ivan, Schmitt, Jochen, Sheldon, Simon G., Takata, Morimasa, Trenke, Marcus, Twarloh, Birthe, Valero-Delgado, Fernando, Wilhelms-Dick, Dorothee, Wilhelms, Frank, Miller, Heinrich, Gerasimoff, Michael D., Druecker, Cord, Frenzel, Andreas, Fritzsche, Diedrich, Grobe, Hannes, Hansen, Steffen Bo, Hilmarsson, Sverrir A. E., Hoffmann, Georg, Hörnby, Kerstin, Jaeschke, Andrea, Jakobsdottir, Steinunn S., Juckschat, Paul, Karsten, Achim, Karsten, Lorenz, Kaufmann, Patrik R., Karlin, Torbjorn, Kohlberg, Eberhard, Kleffel, Guido, Lambrecht, Anja, Lambrecht, Astrid, Lawer, Gunther, Schaermeli, Ivan, Schmitt, Jochen, Sheldon, Simon G., Takata, Morimasa, Trenke, Marcus, Twarloh, Birthe, Valero-Delgado, Fernando, and Wilhelms-Dick, Dorothee
- Abstract
We report on the EPICA Dronning Maud Land (East Antarctica) deep drilling operation. Starting with the scientific questions that led to the outline of the EPICA project, we introduce the setting of sister drillings at NorthGRIP and EPICA Dome C within the European ice-coring community. The progress of the drilling operation is described within the context of three parallel, deep-drilling operations, the problems that occurred and the solutions we developed. Modified procedures are described, such as the monitoring of penetration rate via cable weight rather than motor torque, and modifications to the system (e.g. closing the openings at the lower end of the outer barrel to reduce the risk of immersing the drill in highly concentrated chip suspension). Parameters of the drilling (e.g. corebreak force, cutter pitch, chips balance, liquid level, core production rate and piece number) are discussed. We also review the operational mode, particularly in the context of achieved core length and piece length, which have to be optimized for drilling efficiency and core quality respectively. We conclude with recommendations addressing the design of the chip-collection openings and strictly limiting the cable-load drop with respect to the load at the start of the run., AuthorCount:31
- Published
- 2014
- Full Text
- View/download PDF
13. The EPICA Dronning Maud Land deep drilling operation
- Author
-
Wilhelms, Frank, primary, Miller, Heinrich, additional, Gerasimoff, Michael D., additional, Drücker, Cord, additional, Frenzel, Andreas, additional, Fritzsche, Diedrich, additional, Grobe, Hannes, additional, Hansen, Steffen Bo, additional, Hilmarsson, Sverrir Æ., additional, Hoffmann, Georg, additional, Hörnby, Kerstin, additional, Jaeschke, Andrea, additional, Jakobsdóttir, Steinunn S., additional, Juckschat, Paul, additional, Karsten, Achim, additional, Karsten, Lorenz, additional, Kaufmann, Patrik R., additional, Karlin, Torbjörn, additional, Kohlberg, Eberhard, additional, Kleffel, Guido, additional, Lambrecht, Anja, additional, Lambrecht, Astrid, additional, Lawer, Gunther, additional, Schärmeli, Ivan, additional, Schmitt, Jochen, additional, Sheldon, Simon G., additional, Takata, Morimasa, additional, Trenke, Marcus, additional, Twarloh, Birthe, additional, Valero-Delgado, Fernando, additional, and Wilhelms-Dick, Dorothee, additional
- Published
- 2014
- Full Text
- View/download PDF
14. Transport, storage and processing of the DML-EPICA ice core
- Author
-
Oerter, Hans, Kipfstuhl, J., Fischer, Hubertus, Valero-Delgado, Fernando, and Miller, Heinrich
- Abstract
The poster describes the handling of the EPICA (European Project of Ice Coring in Antarctica) ice core from Dronning Maud Land. After logging and packing the cores are stored in PP-boxes (size 110*35*45 cm) at the drilling site (underground core buffer of the drill and science trench) until the boxes are flown to the German base Neumayer at the coast. There the boxes are stored in freezers, which serve also for ship transport via Cape Town to Bremerhaven, where the voyage of the boxes end in a commercial cold store. The inventory of the boxes as well as the complete store is documented in a database.For EPICA AWI undertook a big effort to reconstruct its cold room facilities. The main storage for ice cores was outsourced to a commercial cold store. The biggest cold room (300 m3) with two levels is now used for ice core processing with a line of horizontal (on loan from University of Bern) and vertical saws, a bench with line-scan camera and optional a bench for DEP and gamma density measurements.In June 2002 the first 450m of the core were processed. For this purpose in addition an ECM bench was provided by University of Bern and devices for CFA (Universities Bern and Heidelberg, AWI) and FIC (University of Firence) were installed. The core was cutted according to the requests of the various labs. The cutting plan was authorized by the EPICAScientific Steering Committee. After the processing campaign the frozen samples were shipped to the various labs. For July and September 2003 it is planned to process the next 1100 m of core drilled in the 2002/03 season. For co-operation within the project data are made available through a data base to which access is only possible for the national representatives of EPICA. Final results of the analyses will be made accessible via the database PANGAEA (www.pangaea.de) as soon as they are published.
- Published
- 2003
15. Dust in Ice Cores High resolution dust concentration and size distribution in the NGRIP ice core
- Author
-
Wolff, Katrin, Miller, Heinrich, Fischer, Hubertus, Ruth, Urs, Schulz, Maximilian, Stuut, J. B., Wegner, Anna, Valero-Delgado, Fernando, Wolff, Katrin, Miller, Heinrich, Fischer, Hubertus, Ruth, Urs, Schulz, Maximilian, Stuut, J. B., Wegner, Anna, and Valero-Delgado, Fernando
- Abstract
Mineral dust in Greenland ice cores exhibit systematic variations of size distribution and particle concentration changes. East Asian deserts are the dominant source area for dust transported to Greenland. The concentration of dust is low during warm periods while cold phases correspond to high particle concentration. Regarding the size distribution, larger particles were found during colder climates and vice versa. The variability of dust concentrations in Greenlandic ice cores is due to changes both during transport and in the dust sources. Dust size spectra provide information on transport time changes in the past with larger particles surviving only during faster transport. Further investigations regarding a seasonal resolution of dust deposition and dust size data are in progress. The aim of the project is to study the dust deposition in seasonal-to-interannual resolution using dust concentration and size measurements on selected time slices in the NorthGRIP ice core covering the period approximately from 50000 yr BP until 2000 yr BP. Analysis of high resolution dust measurements provide detailed information about past abrupt climate fluctuations that occurred within a short period of time. For the dust measurements Multisizer COULTER COUNTER (CC) is used. The CC is a multi-channel analyzer which provides particle sizing and counting within an overall size range of 0.7 µm to 18 µm. Single particle volumes are measured in liquid samples. A new method to achieve a higher temporal resolution from the NGRIP ice core has been developed. This apparatus enables to sample the ice core in mm resolution without contamination and has been already tested on an Antarctic ice core. First measurements in the NGRIP ice cores using this method will be presented here.
- Published
- 2009
16. Both EPICA cores completed: Is the little sister the elder one?
- Author
-
Wilhelms, Frank, Freitag, Johannes, Faria, S. H., Oerter, Hans, Miller, Heinrich, Kipfstuhl, Sepp, Ruth, Urs, Huybrechts, Philippe, Hamman, I., Fritzsche, Diedrich, Lawer, G., Frenzel, Andreas, Dick, Dorothee, Karlin, T., Kaufmann, P., Lambrecht, A., Rybak, Oleg, Twarloh, Birthe, Valero-Delgado, Fernando, Wilhelms, Frank, Freitag, Johannes, Faria, S. H., Oerter, Hans, Miller, Heinrich, Kipfstuhl, Sepp, Ruth, Urs, Huybrechts, Philippe, Hamman, I., Fritzsche, Diedrich, Lawer, G., Frenzel, Andreas, Dick, Dorothee, Karlin, T., Kaufmann, P., Lambrecht, A., Rybak, Oleg, Twarloh, Birthe, and Valero-Delgado, Fernando
- Published
- 2006
17. One-to-one coupling of glacial climate variability in Greenland and Antarctica
- Author
-
EPICA Community Members, The, Barbante, C., Barnola, J.-M., Becagli, S., Beer, J., Bigler, M., Boutron, C., Blunier, T., Castellano, E., Cattani, O., Chappellaz, J., Dahl-Jensen, D., Debret, M., Delmonte, B., Dick, Dorothee, Falourd, S., Faria, S., Federer, U., Fischer, Hubertus, Freitag, Johannes, Frenzel, Andreas, Fritzsche, Diedrich, Fundel, Felix, Gabrielli, P., Gaspari, V., Gersonde, Rainer, Graf, W., Grigoriev, D., Hamann, Ilka, Hansson, M., Hoffmann, G., Hutterli, M. A., Huybrechts, Philippe, Isaksson, E., Johnsen, S., Jouzel, J., Kaczmarska, M., Karlin, T., Kaufmann, P., Kipfstuhl, Sepp, Kohno, Mika, Lambert, F., Lambrecht, Anja, Lambrecht, Astrid, Landais, A., Lawer, G., Leuenberger, M., Littot, G., Loulergue, L., Lüthi, D., Maggi, V., Marino, F., Masson-Delmotte, V., Meyer, Hanno, Miller, Heinrich, Mulvaney, R., Narcisi, B., Oerlemans, J., Oerter, Hans, Parrenin, F., Petit, J.-R., Raisbeck, G., Raynaud, D., Röthlisberger, R., Ruth, Urs, Rybak, Oleg, Severi, M., Schmitt, Jochen, Schwander, J., Siegenthaler, U., Siggaard-Andersen, M.-L., Spahni, R., Steffensen, J. P., Stenni, B., Stocker, T. F., Tison, J.-L., Traversi, R., Udisti, R., Valero-Delgado, Fernando, van den Broeke, M. R., van de Wal, R. S. W., Wagenbach, D., Wegner, Anna, Weiler, K., Wilhelms, Frank, Winther, J.-G., Wolff, E., EPICA Community Members, The, Barbante, C., Barnola, J.-M., Becagli, S., Beer, J., Bigler, M., Boutron, C., Blunier, T., Castellano, E., Cattani, O., Chappellaz, J., Dahl-Jensen, D., Debret, M., Delmonte, B., Dick, Dorothee, Falourd, S., Faria, S., Federer, U., Fischer, Hubertus, Freitag, Johannes, Frenzel, Andreas, Fritzsche, Diedrich, Fundel, Felix, Gabrielli, P., Gaspari, V., Gersonde, Rainer, Graf, W., Grigoriev, D., Hamann, Ilka, Hansson, M., Hoffmann, G., Hutterli, M. A., Huybrechts, Philippe, Isaksson, E., Johnsen, S., Jouzel, J., Kaczmarska, M., Karlin, T., Kaufmann, P., Kipfstuhl, Sepp, Kohno, Mika, Lambert, F., Lambrecht, Anja, Lambrecht, Astrid, Landais, A., Lawer, G., Leuenberger, M., Littot, G., Loulergue, L., Lüthi, D., Maggi, V., Marino, F., Masson-Delmotte, V., Meyer, Hanno, Miller, Heinrich, Mulvaney, R., Narcisi, B., Oerlemans, J., Oerter, Hans, Parrenin, F., Petit, J.-R., Raisbeck, G., Raynaud, D., Röthlisberger, R., Ruth, Urs, Rybak, Oleg, Severi, M., Schmitt, Jochen, Schwander, J., Siegenthaler, U., Siggaard-Andersen, M.-L., Spahni, R., Steffensen, J. P., Stenni, B., Stocker, T. F., Tison, J.-L., Traversi, R., Udisti, R., Valero-Delgado, Fernando, van den Broeke, M. R., van de Wal, R. S. W., Wagenbach, D., Wegner, Anna, Weiler, K., Wilhelms, Frank, Winther, J.-G., and Wolff, E.
- Abstract
Precise knowledge of the phase relationship between climate changes in the two hemispheres is a key for understanding the Earth’s climate dynamics. For the last glacial period, ice core stud- ies1,2 have revealed strong coupling of the largest millennial-scale warm events in Antarctica with the longest Dansgaard–Oeschger events in Greenland3–5 through the Atlantic meridional over- turning circulation6–8. It has been unclear, however, whether the shorter Dansgaard–Oeschger events have counterparts in the shorter and less prominent Antarctic temperature variations, and whether these events are linked by the same mechanism. Here we present a glacial climate record derived from an ice core from Dronning Maud Land, Antarctica, which represents South Atlantic climate at a resolution comparable with the Greenland ice core records. After methane synchronization with an ice core from North Greenland9, the oxygen isotope record from the Dronning Maud Land ice core shows a one-to-one coupling between all Antarctic warm events and Greenland Dansgaard–Oeschger events by the bipolar seesaw6. The amplitude of the Antarctic warm events is found to be linearly dependent on the duration of the concurrent stadial in the North, suggesting that they all result from a similar reduction in the meridional overturning circulation.
- Published
- 2006
Catalog
Books, media, physical & digital resources
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.