A multi-model assessment of sub-monthly polar motion and the associated ocean bottom pressure variability

2020 ◽  
Author(s):  
Michael Schindelegger ◽  
Alexander Harker ◽  
David Salstein ◽  
Henryk Dobslaw
Keyword(s):  
General Circulation ◽  
Polar Motion ◽  
Circulation Model ◽  
Horizontal Resolution ◽  
Ocean Bottom ◽  
Model Assessment ◽  
Bottom Pressure ◽  
Max Planck ◽  
Ocean Bottom Pressure ◽  
Partial Representation

<p>Budgeting geophysical fluid excitations against space-geodetic observations of polar motion reveals non-negligible residuals on sub-monthly time scales, typically 1−2 cm when projected onto the Earth's surface. A possible source for these discrepancies are imperfections in the hydrodynamic models used to derive the required ocean excitation functions. To guide future model improvements, we present a systematic assessment of the oceanic component of sub-monthly polar motion based on three global time-stepping models which are forced by the same atmospheric data but considerably differ in their numerical setup and physical parameterizations. In particular, we use ocean bottom pressure output and angular momenta from (i) the finite-element 2 Dimensions Gravity Wave Model (Mog2D), (ii) the baroclinic Max-Planck-Institute Ocean Model (MPIOM) at 1° horizontal resolution, representing the current industry standard, and (iii) a more experimental, eddy-permitting setup of the MITgcm (MIT General Circulation Model). Validations of data from 2007 to 2008 are performed against observed polar motion and daily GRACE (Gravity Recovery and Climate Experiment) solutions, which resolve the broad scales of ocean bottom pressure variability relevant for angular momentum considerations. No definite quantitative results are available at the time of this writing, but a specific question we aim to answer is whether the MITgcm run outperforms the other models in our validations, given its higher resolution and partial representation of flow interactions with major topographic features.</p>

scholarly journals Sensitivity of Simulated Climate to Horizontal and Vertical Resolution in the ECHAM5 Atmosphere Model

2006 ◽  
Vol 19 (16) ◽  
pp. 3771-3791 ◽  
Author(s):  
E. Roeckner ◽  
R. Brokopf ◽  
M. Esch ◽  
M. Giorgetta ◽  
S. Hagemann ◽  
...  
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Horizontal Resolution ◽  
Boreal Winter ◽  
Cold Bias ◽  
Vertical Resolution ◽  
Max Planck ◽  
Mean Climate ◽  
The Impact ◽  
Mean Square Errors

Abstract The most recent version of the Max Planck Institute for Meteorology atmospheric general circulation model, ECHAM5, is used to study the impact of changes in horizontal and vertical resolution on seasonal mean climate. In a series of Atmospheric Model Intercomparison Project (AMIP)-style experiments with resolutions ranging between T21L19 and T159L31, the systematic errors and convergence properties are assessed for two vertical resolutions. At low vertical resolution (L19) there is no evidence for convergence to a more realistic climate state for horizontal resolutions higher than T42. At higher vertical resolution (L31), on the other hand, the root-mean-square errors decrease monotonically with increasing horizontal resolution. Furthermore, except for T42, the L31 versions are superior to their L19 counterparts, and the improvements become more evident at increasingly higher horizontal resolutions. This applies, in particular, to the zonal mean climate state and to the stationary wave patterns in boreal winter. As in previous studies, increasing horizontal resolution leads to a warming of the troposphere, most prominently at midlatitudes, and to a poleward shift and intensification of the midlatitude westerlies. Increasing the vertical resolution has the opposite effect, almost independent of horizontal resolution. Whereas the atmosphere is colder at low and middle latitudes, it is warmer at high latitudes and close to the surface. In addition, increased vertical resolution results in a pronounced warming in the polar upper troposphere and lower stratosphere, where the cold bias is reduced by up to 50% compared to L19 simulations. Consistent with these temperature changes is a decrease and equatorward shift of the midlatitude westerlies. The substantial benefits in refining both horizontal and vertical resolution give some support to scaling arguments deduced from quasigeostrophic theory implying that horizontal and vertical resolution ought to be chosen consistently.

scholarly journals Ensemble Held–Suarez Test with a Spectral Transform Model: Variability, Sensitivity, and Convergence

2008 ◽  
Vol 136 (3) ◽  
pp. 1075-1092 ◽  
Author(s):  
Hui Wan ◽  
Marco A. Giorgetta ◽  
Luca Bonaventura
Keyword(s):  
General Circulation ◽  
Statistical Tests ◽  
Low Frequency ◽  
Circulation Model ◽  
Internal Variability ◽  
Horizontal Resolution ◽  
Max Planck ◽  
Tropical Tropopause ◽  
Spectral Transform ◽  
Westerly Jets

Abstract The idealized test case proposed by Held and Suarez is carried out with the atmospheric general circulation model ECHAM5 of the Max Planck Institute for Meteorology. The aim is to investigate the sensitivity of the solutions of the spectral dynamical core to spatial and temporal resolution, and to evaluate the numerical convergence of the solutions. Low-frequency fluctuations at time scales as long as thousands of days are found in ultralong integrations. To distinguish the effect of changed resolution from the fluctuations caused by the internal variability, the ensemble method is employed in experiments at resolutions ranging from T31 to T159 with 16 to 81 vertical levels. Significance of the differences between ensembles is assessed by three different statistical tests. Convergence property of the numerical solution is concisely summarized by a ratio index. Results show that the simulated climate state in the Held–Suarez test is sensitive to spatial resolution. Increase of horizontal resolution leads to slight weakening and poleward shift of the westerly jets. Significant warming is detected in high latitudes, especially near the polar tropopause, while the tropical tropopause becomes cooler. The baroclinic wave activity intensifies considerably with increased horizontal resolution. Higher vertical resolution also leads to stronger eddy variances and cooling near the tropical tropopause, but equatorward shift of the westerly jets. The solutions show an indication of convergence at T85L31 resolution according to all the three statistical tests applied. Differences between integrations with various time steps are judged to be within the noise level induced by the inherent low-frequency variability.

scholarly journals Analysis of Ocean Bottom Pressure Anomalies and Seismic Activities in the MedRidge Zone

2021 ◽  
Vol 13 (7) ◽  
pp. 1242
Author(s):  
Hakan S. Kutoglu ◽  
Kazimierz Becek
Keyword(s):  
Time Series ◽  
Mass Change ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Vertical Movements ◽  
Ocean Bottom Pressure ◽  
Continuous Mass ◽  
Mediterranean Ridge Accretionary Complex ◽  
Gravity Recovery ◽  
Periodic Components

The Mediterranean Ridge accretionary complex (MAC) is a product of the convergence of Africa–Europe–Aegean plates. As a result, the region exhibits a continuous mass change (horizontal/vertical movements) that generates earthquakes. Over the last 50 years, approximately 430 earthquakes with M ≥ 5, including 36 M ≥ 6 earthquakes, have been recorded in the region. This study aims to link the ocean bottom deformations manifested through ocean bottom pressure variations with the earthquakes’ time series. To this end, we investigated the time series of the ocean bottom pressure (OBP) anomalies derived from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions. The OBP time series comprises a decreasing trend in addition to 1.02, 1.52, 4.27, and 10.66-year periodic components, which can be explained by atmosphere, oceans, and hydrosphere (AOH) processes, the Earth’s pole movement, solar activity, and core–mantle coupling. It can be inferred from the results that the OBP anomalies time series/mass change is linked to a rising trend and periods in the earthquakes’ energy time series. Based on this preliminary work, ocean-bottom pressure variation appears to be a promising lead for further research.

Near-field tsunami forecasting from cabled ocean bottom pressure data

2009 ◽  
Vol 114 (B6) ◽  
Author(s):  
Hiroaki Tsushima ◽  
Ryota Hino ◽  
Hiromi Fujimoto ◽  
Yuichiro Tanioka ◽  
Fumihiko Imamura
Keyword(s):  
Near Field ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Pressure Data ◽  
Ocean Bottom Pressure ◽  
Tsunami Forecasting

scholarly journals The HAMMONIA Chemistry Climate Model: Sensitivity of the Mesopause Region to the 11-Year Solar Cycle and CO2 Doubling

2006 ◽  
Vol 19 (16) ◽  
pp. 3903-3931 ◽  
Author(s):  
H. Schmidt ◽  
G. P. Brasseur ◽  
M. Charron ◽  
E. Manzini ◽  
M. A. Giorgetta ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Solar Cycle ◽  
General Circulation ◽  
Climate Model ◽  
Temperature Response ◽  
Circulation Model ◽  
Max Planck ◽  
Dynamical Processes ◽  
Mesopause Region ◽  
Height Range

Abstract This paper introduces the three-dimensional Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), which treats atmospheric dynamics, radiation, and chemistry interactively for the height range from the earth’s surface to the thermosphere (approximately 250 km). It is based on the latest version of the ECHAM atmospheric general circulation model of the Max Planck Institute for Meteorology in Hamburg, Germany, which is extended to include important radiative and dynamical processes of the upper atmosphere and is coupled to a chemistry module containing 48 compounds. The model is applied to study the effects of natural and anthropogenic climate forcing on the atmosphere, represented, on the one hand, by the 11-yr solar cycle and, on the other hand, by a doubling of the present-day concentration of carbon dioxide. The numerical experiments are analyzed with the focus on the effects on temperature and chemical composition in the mesopause region. Results include a temperature response to the solar cycle by 2 to 10 K in the mesopause region with the largest values occurring slightly above the summer mesopause. Ozone in the secondary maximum increases by up to 20% for solar maximum conditions. Changes in winds are in general small. In the case of a doubling of carbon dioxide the simulation indicates a cooling of the atmosphere everywhere above the tropopause but by the smallest values around the mesopause. It is shown that the temperature response up to the mesopause is strongly influenced by changes in dynamics. During Northern Hemisphere summer, dynamical processes alone would lead to an almost global warming of up to 3 K in the uppermost mesosphere.

scholarly journals Seafloor Crustal Deformation on Ocean Bottom Pressure Records With Nontidal Variability Corrections: Application to Hikurangi Margin, New Zealand

2019 ◽  
Vol 46 (1) ◽  
pp. 303-310 ◽  
Author(s):  
Tomoya Muramoto ◽  
Yoshihiro Ito ◽  
Daisuke Inazu ◽  
Laura M. Wallace ◽  
Ryota Hino ◽  
...  
Keyword(s):  
New Zealand ◽  
Crustal Deformation ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Ocean Bottom Pressure

scholarly journals Panama’s Current Climate Replicability in a Non-Hydrostatic Regional Climate Model Nested in an Atmospheric General Circulation Model

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1543
Author(s):  
Reinhardt Pinzón ◽  
Noriko N. Ishizaki ◽  
Hidetaka Sasaki ◽  
Tosiyuki Nakaegawa
Keyword(s):  
Regional Climate Model ◽  
Air Temperature ◽  
General Circulation ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Air Temperature ◽  
Circulation Model ◽  
Horizontal Resolution ◽  
Temperature And Precipitation ◽  
Current Climate

To simulate the current climate, a 20-year integration of a non-hydrostatic regional climate model (NHRCM) with grid spacing of 5 and 2 km (NHRCM05 and NHRCM02, respectively) was nested within the AGCM. The three models did a similarly good job of simulating surface air temperature, and the spatial horizontal resolution did not affect these statistics. NHRCM02 did a good job of reproducing seasonal variations in surface air temperature. NHRCM05 overestimated annual mean precipitation in the western part of Panama and eastern part of the Pacific Ocean. NHRCM05 is responsible for this overestimation because it is not seen in MRI-AGCM. NHRCM02 simulated annual mean precipitation better than NHRCM05, probably due to a convection-permitting model without a convection scheme, such as the Kain and Fritsch scheme. Therefore, the finer horizontal resolution of NHRCM02 did a better job of replicating the current climatological mean geographical distributions and seasonal changes of surface air temperature and precipitation.

Sign in / Sign up

Export Citation Format

Share Document