How sensitive is the sub-seasonal prediction to the choice of dynamical cores in the atmospheric model?

2020 ◽  
Author(s):  
Ha-Rim Kim ◽  
Baek-Min Kim ◽  
Sang-Yoon Jun ◽  
Yong-Sang Choi
Keyword(s):  
North America ◽  
Prediction Model ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
The Arctic ◽  
Late Winter ◽  
Grid System ◽  
Early Winter ◽  
Dynamical Core ◽  
The One

<p>This study investigates the prediction skill of the sub-seasonal prediction model that can depend on the choice of dynamical cores: the finite volume (FV) dynamical core on a latitude-longitude grid system versus spectral element (SE) dynamical core on a cubed-sphere grid system. Recent researches showed that the SE dynamical core on a uniform grid system increases parallel scalability and removes the need for polar filters mitigating uncertainty in climate prediction, particularly for the Arctic region. However, it remains unclear whether the choice of dynamical cores can actually yield significant skill changes or not. To tackle this issue, we implemented a sub-seasonal prediction model based on the Community Atmospheric Model version 5 (CAM5) by incorporating the above two dynamical cores with virtually the same physics schemes. Sub-seasonal prediction skills of the SE dynamical core and FV dynamical core are verified with ERA-interim reanalysis during the early winter (November – December) and the late winter (January – February) from 2001/2002 to 2017/2018. The prediction skills of the two different dynamical cores were significantly different regardless of the virtually same physics schemes. In the ocean, the predictability of the SE dynamical core is similar to the FV dynamical core, mostly because of our simulation configuration imposing the same boundary and initial conditions at the surface. Notable differences in the one-month predictability between the two cores are found for the wintertime Arctic and mid-latitudes, particularly over North America and Eurasia continents. With the one-month lead, SE dynamical core exhibited higher predictability over North America in late winter, whereas the FV dynamical core showed relatively higher predictability in East Asia and Eurasia in early winter. One of the reasons for these differences may be the different manifestations of Arctic-midlatitudes linkage in the two dynamical cores; the SE dynamical core captures warmer Arctic and colder mid-latitudes relatively well than the FV dynamical core. Therefore, we conclude that the careful choice of dynamical cores of sub-seasonal prediction models is needed.</p>

scholarly journals Altered sub-seasonal predictability of Community Atmosphere Model 5 (CAM5) in CESM 1.2.1 by the choices of dynamical core

2020 ◽  
Author(s):  
Ha-Rim Kim ◽  
Baek-Min Kim ◽  
Sang-Yoon Jun ◽  
Yong-Sang Choi
Keyword(s):  
North America ◽  
Prediction Models ◽  
Initial Conditions ◽  
Seasonal Prediction ◽  
Prediction Skill ◽  
The Arctic ◽  
Late Winter ◽  
Grid System ◽  
Early Winter ◽  
Dynamical Core

Abstract. This study investigates the prediction skill of sub-seasonal prediction models that vary based on the choice of two dynamical cores: the finite volume (FV) dynamical core on a latitude-longitude grid system and the spectral element (SE) dynamical core on a cubed-sphere grid system. Recent research showed that the SE dynamical core on a uniform grid system increases parallel scalability and removes the need for polar filters for mitigating uncertainty in climate prediction, particularly for the Arctic region. However, it still remains questionable whether the choice of dynamical cores can actually yield significant changes in prediction skill. To tackle this issue, we implemented a sub-seasonal prediction model based on the Community Atmospheric Model version 5 by incorporating the above two dynamical cores with virtually the same physics schemes. Sub-seasonal prediction skills of the SE dynamical core and FV dynamical core are verified with ERA-Interim reanalysis during the early winter (November–December) and the late winter (January–February) from 2001/2002 to 2017/2018. The prediction skills of two different dynamical cores were significantly different regardless of the similar physics scheme. In the ocean, the predictability of the SE dynamical core is similar to that of the FV dynamical core, mostly because our simulation configuration imposes the same boundary and initial conditions at the surface. Notable differences in the one-month predictability between the two cores are observed for the wintertime Arctic and mid-latitudes, particularly over North America and Eurasia continents. With a one-month lead, the SE dynamical core exhibited higher predictability over North America in late winter (r ≈ 0.45 in SE, r ≈ 0.10 in FV) whereas the FV dynamical core showed relatively higher predictability in East Asia and Eurasia in early winter (r ≈ 0.15 in SE, r ≈ 0.43 in FV). Therefore, we conclude that caution is needed when selecting the dynamical cores of sub-seasonal prediction models. Partially, these differences can be ascribed to the different manifestations of Arctic-mid-latitude linkage in the two dynamical cores; the SE dynamical core captures warmer Arctic and colder mid-latitudes relatively better than the FV dynamical core.

Abundance, social organization, and population trend of the arctic wolf in north and east Greenland during 1978–1998

2009 ◽  
Vol 87 (10) ◽  
pp. 895-901 ◽  
Author(s):  
Ulf Marquard-Petersen
Keyword(s):  
North America ◽  
Social Organization ◽  
Prey Availability ◽  
Population Trend ◽  
Population Characteristics ◽  
The Arctic ◽  
Late Winter ◽  
Early Winter ◽  
North Central ◽  
East Greenland

Abundance, social organization, and population trend of the arctic wolf ( Canis lupus arctos Pocock, 1935) in north and east Greenland, 1978–1998, were determined from 353 sightings of 552 wolves by the Danish military, by expeditions, and from 8 consecutive years (1991–1998) of fieldwork. Available evidence suggested that this wolf population consisted of up to 55 wolves in favorable times. Six core packs were identified. Maximum wolf density was estimated at 1 wolf/3745 km2, which appears to be the lowest wolf density reported, representing 3.5% of maximum late winter wolf density in Denali Park, Alaska, and <1% of that in north-central Minnesota. Social organization was characterized by a preponderance of pairs and lone wolves. Mean early winter pack size was 2.6 wolves/pack; the lowest reported for wolves in North America. Packs >4 wolves were rare, constituting 3.8% of early winter sightings. The population increased, on average, 8% per year during the period 1978–1991 and appeared to reach a peak in 1991–1992. These depressed population characteristics are likely the consequence of the lowest ungulate prey availability in North America, e.g., 2.6% of that of wolves in northeastern Minnesota.

scholarly journals Influence of Northern Hemispheric Winter Warming on the Pacific Storm Track

2021 ◽  
Author(s):  
Hyung-Ju Park ◽  
Kwang-Yul Kim
Keyword(s):  
Heat Flux ◽  
Global Warming ◽  
Energy Conversion ◽  
Storm Track ◽  
The Arctic ◽  
Late Winter ◽  
Turbulent Heat ◽  
Early Winter ◽  
Eddy Heat Flux ◽  
Northern Hemispheric

AbstractEffect of global warming on the sub-seasonal variability of the Northern Hemispheric winter (NDJFM) Pacific storm-track (PST) activity has been investigated. Previous studies showed that the winter-averaged PST has shifted northward and intensified, which was explained in terms of energy exchange with the mean field. Effect of global warming exhibits spatio-temporal heterogeneity with predominance over the Arctic region and in the winter season. Therefore, seasonal averaging may hide important features on sub-seasonal scales. In this study, distinct sub-seasonal response in storm track activities to winter Northern Hemispheric warming is analyzed applying cyclostationary empirical orthogonal function analysis to ERA5 data. The key findings are as follows. Change in the PST is not uniform throughout the winter; the PST shifts northward in early winter (NDJ) and intensifies in late winter (FM). In early winter, the combined effect of weakened baroclinic process to the south of the climatological PST and weakened barotropic damping to the north is responsible for the northward shift. In late winter, both processes contribute to the amplification of the PST. Further, change in baroclinic energy conversion is quantitatively dominated by eddy heat flux, whereas axial tilting of eddies is primarily responsible for change in barotropic energy conversion. A close relationship between anomalous eddy heat flux and anomalous boundary heating, which is largely determined by surface turbulent heat flux, is also demonstrated.

Life cycles of four species of Pseudocalanus in Nova Scotia

1989 ◽  
Vol 67 (3) ◽  
pp. 552-558 ◽  
Author(s):  
I. A. McLaren ◽  
Estelle Laberge ◽  
C. J. Corkett ◽  
J.-M. Sévigny
Keyword(s):  
Life Cycle ◽  
Nova Scotia ◽  
First Generation ◽  
Early Summer ◽  
Life Cycles ◽  
The Arctic ◽  
Late Winter ◽  
Early Winter ◽  
Temperature Dependent ◽  
Scotian Shelf

The primarily arctic Pseudocalanus acuspes, relict in Bedford Basin, Nova Scotia, produces a first generation (G1) in late winter; most G1 individuals mature in late spring. The G1 then produces a G2, most of which "rest" in copepodite stages III and IV until early winter. These stages store large amounts of lipid in early summer, which slowly diminish subsequently. A small number of G2 individuals continue to develop at temperature-dependent rates, maturing in early autumn and producing G3 adults in November. Copepodites developing in winter and spring store less lipid. The primarily arctic Pseudocalanus minutus, rare in Bedford Basin and on the Scotia Shelf, is strictly annual, developing to a lipid-filled copepodite stage V after spawning in late winter. The arctic–temperate Pseudocalanus newmani is abundant on the Scotian Shelf, but may not be self-sustaining when advected into Bedford Basin. It stores little lipid and appears to have at least three mature generations at temperature-dependent intervals over Browns Bank between May and November. It may rest in winter, or its life-cycle synchrony by spring could result from food-limited development during winter. The temperate Pseudocalanus moultoni appears to have a life cycle similar to that of P. newmani, but was less common during summer on Browns Bank. These life cycles are appropriately adapted to the geographical ranges of the species, and show some parallels with species of Calanus.

scholarly journals Separating the Indian and Pacific Ocean impacts on the Euro-Atlantic response to ENSO and its transition from early to late winter

2020 ◽  
pp. 1-57
Author(s):  
Muhammad Adnan Abid ◽  
Fred Kucharski ◽  
Franco Molteni ◽  
In-Sik Kang ◽  
Adrian M. Tompkins ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Oscillation ◽  
Wave Train ◽  
Tropical Indian Ocean ◽  
Atmospheric Model ◽  
Positive Phase ◽  
Late Winter ◽  
Early Winter ◽  
Atlantic Sector ◽  
Nao Pattern

AbstractThe present study focuses on the mechanism that controls the transition of the Euro-Atlantic circulation responses to the El Niño-Southern Oscillation (ENSO) from early (December) to late winter (February) for the period 1981-2015. A positive phase of ENSO induces a precipitation dipole with increased precipitation in the western and reduced precipitation in the eastern tropical Indian Ocean; this occurs mainly during early winter (December) and less so in late winter (February). It is shown that these inter-basin atmospheric teleconnections dominate the response in the Euro-Atlantic sector in early winter by modifying the subtropical South Asian jet (SAJET) and forcing a wavenumber-3 response which projects spatially onto the positive North Atlantic Oscillation (NAO) pattern. On contrary, during late winter, the response in the Euro-Atlantic sector is dominated by the well-known ENSO wave-train from the tropical Pacific region, involving extratropical anomalies that project spatially on the positive phase of the Pacific-North American (PNA) pattern and the negative phase of the NAO pattern. Numerical experiments with an atmospheric model (AGCM) forced by an Indian Ocean heating dipole anomaly support the hypothesis that Indian Ocean modulates the SAJET and enforces the Rossby wave propagation to the Euro-Atlantic region in early winter. These phenomena are also investigated using the ECMWF SEAS5 re-forecast dataset. In SEAS5, the ENSO inter-basin tropical teleconnections, and the response of the Euro-Atlantic circulation anomalies and their change from early to late winter are realistically predicted, although the strength of the early winter signal originated from the Indian Ocean is underestimated.

High vs. low latitude influence on seasonal stratospheric pathways in the atmospheric model ICON

2021 ◽  
Author(s):  
Raphael Köhler ◽  
Dörthe Handorf ◽  
Ralf Jaiser ◽  
Klaus Dethloff
Keyword(s):  
Large Scale ◽  
Arctic Oscillation ◽  
Southern Oscillation ◽  
Polar Vortex ◽  
Atmospheric Model ◽  
The Arctic ◽  
Late Winter ◽  
Stratospheric Polar Vortex ◽  
Enso Events ◽  
Hemisphere Winter

&lt;p&gt;Stratospheric pathways play an important role in connecting distant anomaly patterns to each other on seasonal timescales. As long-lived stratospheric extreme events can influence the large-scale tropospheric circulation on timescales of multiple weeks, stratospheric pathways have been identified as one of the main potential sources for subseasonal to seasonal predictability in mid-latitudes. These pathways have been shown to connect Arctic anomalies to lower latitudes and vice versa. However, there is an ongoing discussion on how strong these stratospheric pathways are and how they exactly work.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;In this context, we investigate two strongly discussed stratospheric pathways by analysing a suite of seasonal experiments with the atmospheric model ICON: On the one hand, the effect of El Ni&amp;#241;o-Southern Oscillation (ENSO) on the stratospheric polar vortex, and thus the circulation in mid and high latitudes in winter. And on the other hand, the effect of a rapidly changing Arctic on lower latitudes via the stratosphere. The former effect is simulated realistically by ICON, and the results from the ensemble simulations suggest that ENSO has an effect on the large-scale Northern Hemisphere winter circulation. The ICON experiments and the reanalysis exhibit a weakened stratospheric vortex in warm ENSO years. Furthermore, in particular in winter, warm ENSO events favour the negative phase of the Arctic Oscillation, whereas cold events favour the positive phase. The ICON simulations also suggest a significant effect of ENSO on the Atlantic-European sector in late winter. Unlike the effect of ENSO, ICON simulations and the reanalysis do not agree on the stratospheric pathway for Arctic-midlatitude linkages. Whereas the reanalysis exhibits a weakening of the stratospheric vortex in midwinter and a connected tropospheric negative Arctic Oscillation circulation response to amplified Arctic warming, this is not the case in the ICON simulations. Implications and potential reasons for this discrepancy are further analysed and discussed in this work. &amp;#160;&lt;/p&gt;

scholarly journals Vorticity-Divergence semi-Lagrangian Global Atmospheric Model SL-AV20: Dynamical Core

2016 ◽  
Author(s):  
Mikhail Tolstykh ◽  
Vladimir Shashkin ◽  
Rostislav Fadeev ◽  
Gordey Goyman
Keyword(s):  
Numerical Solutions ◽  
Climate Modeling ◽  
Region Of Interest ◽  
Weather Forecast ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Medium Range Weather Forecast ◽  
Variable Resolution ◽  
Dynamical Core ◽  
Global Atmospheric Model

Abstract. SL-AV (Semi-Lagranginan Absolute Vorticity) is a global atmospheric model. Its latest version SL-AV20 provides global operational medium-range weather forecast with 20 km resolution over Russia. The lower resolution configurations of SL-AV20 are being tested for seasonal prediction and climate modeling. The article presents the model dynamical core. Its main features are vorticity-divergence formulation at the unstaggered grid, high-order finite-difference approximations, semi-Lagrangian semi-implicit discretization and the reduced latitude-longitude grid with variable resolution in latitude. The accuracy of SL-AV20 numerical solutions using reduced lat-lon grid and the variable resolution in latitude is tested with two idealized testcases. The results agree well with other published model solutions. It is shown that the use of the reduced grid having up to 25 % less grid points than the regular grid does not significantly affect the accuracy. Variable resolution in latitude allows to improve the accuracy of solution in the region of interest.

scholarly journals Vorticity-divergence semi-Lagrangian global atmospheric model SL-AV20: dynamical core

2017 ◽  
Vol 10 (5) ◽  
pp. 1961-1983 ◽  
Author(s):  
Mikhail Tolstykh ◽  
Vladimir Shashkin ◽  
Rostislav Fadeev ◽  
Gordey Goyman
Keyword(s):  
Numerical Solutions ◽  
Climate Modeling ◽  
Region Of Interest ◽  
Weather Forecast ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Test Case ◽  
Medium Range Weather Forecast ◽  
Variable Resolution ◽  
Dynamical Core

Abstract. SL-AV (semi-Lagrangian, based on the absolute vorticity equation) is a global hydrostatic atmospheric model. Its latest version, SL-AV20, provides global operational medium-range weather forecast with 20 km resolution over Russia. The lower-resolution configurations of SL-AV20 are being tested for seasonal prediction and climate modeling. The article presents the model dynamical core. Its main features are a vorticity-divergence formulation at the unstaggered grid, high-order finite-difference approximations, semi-Lagrangian semi-implicit discretization and the reduced latitude–longitude grid with variable resolution in latitude. The accuracy of SL-AV20 numerical solutions using a reduced lat–lon grid and the variable resolution in latitude is tested with two idealized test cases. Accuracy and stability of SL-AV20 in the presence of the orography forcing are tested using the mountain-induced Rossby wave test case. The results of all three tests are in good agreement with other published model solutions. It is shown that the use of the reduced grid does not significantly affect the accuracy up to the 25 % reduction in the number of grid points with respect to the regular grid. Variable resolution in latitude allows us to improve the accuracy of a solution in the region of interest.

Rights Over the Arctic

1930 ◽  
Vol 24 (4) ◽  
pp. 703-717 ◽  
Author(s):  
W. Lakhtine
Keyword(s):  
North America ◽  
Arctic Ocean ◽  
Far East ◽  
The Other ◽  
The Arctic ◽  
The North ◽  
Arctic Regions ◽  
The Far East ◽  
The Arctic Ocean ◽  
The One

The transarctic flights of 1926 and 1928 demonstrate the possibility of establishing communication by air across the Arctic regions between Europe, on the one side, and North America and the Far East on the other. Quite aside from the saving of time owing to shorter distance, the establishment of such communication presents considerably less diiSculty than air communication over the Atlantic: a conclusion derived from the transatlantic flights of the last three years. The experience of the airship Italia in May, 1928, does not at all nullify this conclusion. It serves merely to show that the organization of transarctic communication requires special prearrangements, such aa wireless stations, meteorological stations, landing-places, air-bases, the construction of which on the shores, islands, and even on the ice of the Arctic Ocean, appears to be quite feasible. The necessity for such stations has aroused in the governments of the North countries an increased interest in the Arctic regions which heretofore has been restricted to scientific circles.

The Early Winter Sea Ice Variability under the Recent Arctic Climate Shift

2014 ◽  
Vol 27 (13) ◽  
pp. 5092-5110 ◽  
Author(s):  
Xiao-Yi Yang ◽  
Xiaojun Yuan
Keyword(s):  
Sea Ice ◽  
Phase Relationship ◽  
Stationary Wave ◽  
The Arctic ◽  
Late Winter ◽  
Rapid Decline ◽  
Early Winter ◽  
Flux Divergence ◽  
Sea Ice Extent ◽  
Barents And Kara Seas

This study reveals that sea ice in the Barents and Kara Seas plays a crucial role in establishing a new Arctic coupled climate system. The early winter sea ice before 1998 shows double dipole patterns over the Arctic peripheral seas. This pattern, referred to as the early winter quadrupole pattern, exhibits the anticlockwise sequential sea ice anomalies propagation from the Greenland Sea to the Barents–Kara Seas and to the Bering Sea from October to December. This early winter in-phase ice variability contrasts to the out-of-phase relationship in late winter. The mean temperature advection and stationary wave heat flux divergence associated with the atmospheric zonal wave-2 pattern are responsible for the early winter in-phase pattern. Since the end of the last century, the early winter quadrupole pattern has broken down because of the rapid decline of sea ice extent in the Barents–Kara Seas. This remarkable ice retreat modifies the local ocean–atmosphere heat exchange, forcing an anomalous low air pressure over the Barents–Kara Seas. The subsequent collapse of the atmospheric zonal wave-2 pattern is likely responsible for the breakdown of the early winter sea ice quadrupole pattern after 1998. Therefore, the sea ice anomalies in the Barents–Kara Seas play a key role in establishing new atmosphere–sea ice coupled relationships in the warming Arctic.

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