Tropical Cyclone Interaction with the Ocean: The Role of High-Frequency (Subdaily) Coupled Processes

Through tropical cyclone (TC) activity the ocean and the atmosphere exchange a large amount of energy. In this work possible improvements introduced by a higher coupling frequency are tested between the two components of a climate model in the representation of TC intensity and TC–ocean feedbacks. The analysis is based on the new Centro Euro-Mediterraneo per I Cambiamenti Climatici Climate Model (CMCC-CM2-VHR), capable of representing realistic TCs up to category-5 storms. A significant role of the negative sea surface temperature (SST) feedback, leading to a weakening of the cyclone intensity, is made apparent by the improved representation of high-frequency coupled processes. The first part of this study demonstrates that a more realistic representation of strong TC count is obtained by coupling atmosphere and ocean components at hourly instead of daily frequency. Coherently, the positive bias of the annually averaged power dissipation index associated with TCs is reduced by one order of magnitude when coupling at the hourly frequency, compared to both forced mode and daily coupling frequency results. The second part of this work shows a case study (a modeled category-5 typhoon) analysis to verify the impact of a more realistic representation of the high-frequency coupling in representing the TC effect on the ocean; the theoretical subsurface warming induced by TCs is well represented when coupling the two components at the higher frequency. This work demonstrates that an increased horizontal resolution of model components is not sufficient to ensure a realistic representation of intense and fast-moving systems, such as tropical and extratropical cyclones, but a concurrent increase in coupling frequency is required.

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The impact of climate model sea surface temperature biases on tropical cyclone simulations

Climate Dynamics ◽

10.1007/s00382-018-4577-5 ◽

2018 ◽

Vol 53 (1-2) ◽

pp. 173-192 ◽

Cited By ~ 5

Author(s):

Wei-Ching Hsu ◽

Christina M. Patricola ◽

Ping Chang

Keyword(s):

Tropical Cyclone ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Climate Model ◽

Sea Surface ◽

The Impact

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Configuration and Evaluation of a Global Unstructured Mesh Model based on the Variable-Resolution Approach

10.5194/gmd-2020-150 ◽

2020 ◽

Author(s):

Yihui Zhou ◽

Yi Zhang ◽

Jian Li ◽

Rucong Yu ◽

Zhuang Liu

Keyword(s):

Tropical Cyclone ◽

Transition Zone ◽

Climate Model ◽

Model Performance ◽

Horizontal Resolution ◽

Fine Scale ◽

Variable Resolution ◽

Model Based ◽

Mesh Model ◽

Scale Structures

Abstract. Targeting a long-term effort towards a global weather and climate model with a local refinement function, this study systematically configures and evaluates the performance of an unstructured model based on the variable-resolution (VR) approach. Aided by the idealized dry- and moist-atmosphere tests, the model performance is examined in an intermediate degree of complexity. The dry baroclinic wave simulations suggest that the 3D VR-model can reproduce comparable solutions in the refined regions as a fine-resolution quasi-uniform (QU) mesh model, although the global errors increase. The variation of the mesh resolution in the transition zone does not adversely affect the wave pattern. In the coarse-resolution area, the VR model simulates a similar wave distribution to the low-resolution QU model. Two multi-region refinement approaches, including the hierarchical and polycentric refinement modes, further testify the model performance under a more challenging environment. The moist idealized tropical cyclone test further enables us to examine the model ability in terms of resolving fine-scale structures. It is found that the VR model can have the tropical cyclone stably pass the transition zone in various configurations. A series of sensitivity tests examines the model performance in a hierarchical refinement mode, and the solutions exhibit consistency even when the VR mesh is slightly perturbed by one of the three parameters that control the density function. Moreover, only the finest resolution has a dominant impact on the fine-scale structures in the refined region. The tropical cyclone, starting from the 2nd-refinement region and passing through the inner transition zone, gets intensified and possesses a smaller area coverage in the refined regions, as compared to the QU-mesh model that has the same number of grid points. Such variations are consistent with the behavior that one may observe when uniformly refining the QU-mesh model. Besides the horizontal resolution, the intensity of the tropical cyclone is also influenced by the Smagorinsky horizontal diffusion coefficient. The VR model exhibits higher sensitivity in this regard, suggesting the importance of parameter tuning and proper model configurations.

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PARASO, a circum-Antarctic fully-coupled ice-sheet - ocean - sea-ice - atmosphere - land model involving f.ETISh1.7, NEMO3.6, LIM3.6, COSMO5.0 and CLM4.5

10.5194/gmd-2021-315 ◽

2021 ◽

Author(s):

Charles Pelletier ◽

Thierry Fichefet ◽

Hugues Goosse ◽

Konstanze Haubner ◽

Samuel Helsen ◽

...

Keyword(s):

Sea Ice ◽

Climate Model ◽

Regional Climate ◽

Ice Sheet ◽

Horizontal Resolution ◽

Fine Tuning ◽

Polar Regions ◽

Surface Mass ◽

The Impact ◽

Fully Coupled

Abstract. We introduce PARASO, a novel five-component fully-coupled regional climate model over an Antarctic circumpolar domain covering the full Southern Ocean. The state-of-the-art models used are f.ETISh1.7 (ice sheet), NEMO3.6 (ocean), LIM3.6 (sea ice), COSMO5.0 (atmosphere) and CLM4.5 (land), which are here run at an horizontal resolution close to 1/4°. One key-feature of this tool resides in a novel two-way coupling interface for representing ocean – ice-sheet interactions, through explicitly resolved ice-shelf cavities. The impact of atmospheric processes on the Antarctic ice sheet is also conveyed through computed COSMO-CLM – f.ETISh surface mass exchanges. In this technical paper, we briefly introduce each model's configuration and document the developments that were carried out in order to establish PARASO. The new offline-based NEMO – f.ETISh coupling interface is thoroughly described. Our developments also include a new surface tiling approach to combine open-ocean and sea-ice covered cells within COSMO, which was required to make this model relevant in the context of coupled simulations in polar regions. We present results from a 2000–2001 coupled two-year experiment. PARASO is numerically stable and fully operational. The 2-year simulation conducted without fine tuning of the model reproduced the main expected features, although remaining systematic biases provide perspectives for further adjustment and development.

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Atmospheric impacts of short-lived chlorinated species over the recent past: a chemistry-climate perspective

10.5194/egusphere-egu21-12824 ◽

2021 ◽

Author(s):

Ewa Bednarz ◽

Ryan Hossaini ◽

Luke Abraham ◽

Peter Braesicke ◽

Martyn Chipperfield

Keyword(s):

Atmospheric Chemistry ◽

Climate Model ◽

Stratospheric Ozone ◽

Lower Boundary ◽

Montreal Protocol ◽

Recent Past ◽

Substantial Impact ◽

Ozone Depleting Substances ◽

The Impact

The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl3) and dichloromethane (CH2Cl2), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised.&#160;&#160;We address this issue using the UM-UKCA chemistry-climate model (CCM). While not only the first, to our knowledge, model study addressing this problem using a CCM, it is also the first such study employing a whole atmosphere model, thereby simulating the tropospheric Cl-VSLSs emissions and the resulting stratospheric impacts in a fully consistent manner. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs.&#160;We examine the impacts of rising Cl-VSLSs emissions on atmospheric chlorine tracers and ozone, including their long-term trends. We pay particular attention to the role of &#8216;nudging&#8217;, as opposed to the free-running model set up, for the simulated Cl-VSLSs impacts, thereby demostrating the role of atmospheric dynamics in modulating the atmospheric responses to Cl-VSLSs. In addition, we employ novel estimates of Cl-VSLS emissions over the recent past and compare the results with the simulations that prescribe Cl-VSLSs using simple lower boundary conditions. This allows us to demonstrate the impact such choice has on the dominant location and seasonality of the Cl-VSLSs transport into the stratosphere.

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Experimental Tropical Cyclone Forecasts Using a Variable-Resolution Global Model

Monthly Weather Review ◽

10.1175/mwr-d-15-0159.1 ◽

2015 ◽

Vol 143 (10) ◽

pp. 4012-4037 ◽

Cited By ~ 21

Author(s):

Colin M. Zarzycki ◽

Christiane Jablonowski

Keyword(s):

High Resolution ◽

Tropical Cyclone ◽

Initial Conditions ◽

Weather Prediction ◽

Horizontal Resolution ◽

Hurricane Sandy ◽

Track Forecast ◽

Time Step ◽

Variable Resolution ◽

The Impact

Abstract Tropical cyclone (TC) forecasts at 14-km horizontal resolution (0.125°) are completed using variable-resolution (V-R) grids within the Community Atmosphere Model (CAM). Forecasts are integrated twice daily from 1 August to 31 October for both 2012 and 2013, with a high-resolution nest centered over the North Atlantic and eastern Pacific Ocean basins. Using the CAM version 5 (CAM5) physical parameterization package, regional refinement is shown to significantly increase TC track forecast skill relative to unrefined grids (55 km, 0.5°). For typical TC forecast integration periods (approximately 1 week), V-R forecasts are able to nearly identically reproduce the flow field of a globally uniform high-resolution forecast. Simulated intensity is generally too strong for forecasts beyond 72 h. This intensity bias is robust regardless of whether the forecast is forced with observed or climatological sea surface temperatures and is not significantly mitigated in a suite of sensitivity simulations aimed at investigating the impact of model time step and CAM’s deep convection parameterization. Replacing components of the default physics with Cloud Layers Unified by Binormals (CLUBB) produces a statistically significant improvement in forecast intensity at longer lead times, although significant structural differences in forecasted TCs exist. CAM forecasts the recurvature of Hurricane Sandy into the northeastern United States 60 h earlier than the Global Forecast System (GFS) model using identical initial conditions, demonstrating the sensitivity of TC forecasts to model configuration. Computational costs associated with V-R simulations are dramatically decreased relative to globally uniform high-resolution simulations, demonstrating that variable-resolution techniques are a promising tool for future numerical weather prediction applications.

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An Evaluation of the Impact of Horizontal Resolution on Tropical Cyclone Predictions Using COAMPS-TC

Weather and Forecasting ◽

10.1175/waf-d-13-00054.1 ◽

2014 ◽

Vol 29 (2) ◽

pp. 252-270 ◽

Cited By ~ 22

Author(s):

Hao Jin ◽

Melinda S. Peng ◽

Yi Jin ◽

James D. Doyle

Keyword(s):

High Resolution ◽

Tropical Cyclone ◽

Hurricane Katrina ◽

Wave Energy ◽

Cloud Microphysics ◽

Horizontal Resolution ◽

Hurricane Intensity ◽

Hurricane Wind ◽

Upper Level ◽

The Impact

Abstract A series of experiments have been conducted using the Coupled Ocean–Atmosphere Mesoscale Prediction System–Tropical Cyclone (COAMPS-TC) to assess the impact of horizontal resolution on hurricane intensity prediction for 10 Atlantic storms during the 2005 and 2007 hurricane seasons. The results of this study from the Hurricane Katrina (2005) simulations indicate that the hurricane intensity and structure are very sensitive to the horizontal grid spacing (9 and 3 km) and underscore the need for cloud microphysics to capture the structure, especially for strong storms with small-diameter eyes and large pressure gradients. The high resolution simulates stronger vertical motions, a more distinct upper-level warm core, stronger upper-level outflow, and greater finescale structure associated with deep convection, including spiral rainbands and the secondary circulation. A vortex Rossby wave (VRW) spectrum analysis is performed on the simulated 10-m winds and the NOAA/Hurricane Research Division (HRD) Real-Time Hurricane Wind Analysis System (H*Wind) to evaluate the impact of horizontal resolution. The degree to which the VRWs are adequately resolved near the TC inner core is addressed and the associated resolvable wave energy is explored at different grid resolutions. The fine resolution is necessary to resolve higher-wavenumber modes of VRWs to preserve more wave energy and, hence, to attain a more detailed eyewall structure. The wind–pressure relationship from the high-resolution simulations is in better agreement with the observations than are the coarse-resolution simulations for the strong storms. Two case studies are analyzed and overall the statistical analyses indicate that high resolution is beneficial for TC intensity and structure forecasts, while it has little impact on track forecasts.

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Testing robustness of co-existing climate states

10.5194/egusphere-egu21-9902 ◽

2021 ◽

Author(s):

Charline Ragon ◽

Valerio Lembo ◽

Valerio Lucarini ◽

Christian Vérard ◽

Jérôme Kasparian ◽

...

Keyword(s):

Climate Models ◽

Climate Model ◽

Water Mass ◽

Hydrological Cycle ◽

Initial Conditions ◽

Frictional Heating ◽

Horizontal Resolution ◽

Climate Dynamics ◽

Mechanical Work ◽

The Impact

The climate can be regarded as a stationary non-equilibrium statistical system (Gallavotti 2006): a continuous and spatially inhomogeneous input of solar energy enters at the top-of-atmosphere and compensates the action of non-conservative forces, mainly occurring at small scales, to give rise to a statistically steady state (or attractor) for the whole climate. Depending on the initial conditions and the range of forcing, all other parameters being the same, some climate models have the property to settle down on different attractors. Multi-stability reflects how energy, water mass and entropy can be re-distributed in multiple ways among the climate components, such as the atmosphere, the ocean or the ice, through a different balance between nonlinear mechanisms. Starting from a configuration where competing climate attractors occur under the same forcing, we have explored their robustness performing two kinds of numerical experiment. First, we have investigated the impact of frictional heating on the overall energy balance and we have shown that such contribution, generally neglected in the atmospheric component of climate models, has crucial consequences on conservation properties: it improves the energy imbalance at top-of-atmosphere, typically non negligible in coarse simulations (Wild et al. 2020), strengthens the hydrological cycle, mitigates the mechanical work associated to atmospheric circulation intensity and reduces the heat transport peaks in the ocean. Second, we have compared two bulk formulas for the cloud albedo, one where it is constant everywhere and the other where it increases with latitude, as implemented in the new version of the atmospheric module SPEEDY in order to improve comparisons with observational data (Kucharski 2013). We have checked that this new parameterization does not affect energy and water-mass imbalances, while reduces global temperature and water-mass transport on the attractor, giving rise to a larger conversion of heat into mechanical work in the atmosphere.In order to perform such studies, we have run the climate model MITgcm on coupled aquaplanets at 2.8 horizontal resolution until steady states are reached (Brunetti el al. 2019) and we have applied the Thermodynamic Diagnostic Tool (TheDiaTo, Lembo et al. 2019). &#160;References: Brunetti, Kasparian, V&#233;rard, Climate Dynamics 53, 6293 (2019)Gallavotti, Math. Phys. 3, 530 (2006)Kucharski et al., Bulletin of the American Meteorological Society 94, 25 (2013)Lembo, Lunkeit, Lucarini, Geoscientific Model Development 12, 3805 (2019)Wild, Climate Dynamics 55, 553 (2020)

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How Can Climate Change Affect the UNESCO Cultural Heritage Sites in Panama?

Geosciences ◽

10.3390/geosciences8080296 ◽

2018 ◽

Vol 8 (8) ◽

pp. 296 ◽

Cited By ~ 3

Author(s):

Chiara Ciantelli ◽

Elisa Palazzi ◽

Jost von Hardenberg ◽

Carmela Vaccaro ◽

Francesca Tittarelli ◽

...

Keyword(s):

Climate Change ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Construction Materials ◽

Horizontal Resolution ◽

Damage Functions ◽

Near Surface ◽

Heritage Sites ◽

The Impact

This work investigates the impact of long-term climate change on heritage sites in Latin America, focusing on two important sites in the Panamanian isthmus included in the World Heritage List: the monumental site of Panamá Viejo (16th century) and the Fortresses of Portobelo and San Lorenzo (17th to 18th centuries). First of all, in order to support the conservation and valorisation of these sites, a characterisation of the main construction materials utilized in the building masonries was performed together with an analysis of the meteoclimatic conditions in their vicinity as provided by monitoring stations recording near-surface air temperature, relative humidity, and rainfall amounts. Secondly, the same climate variables were analysed in the historical and future simulations of a state-of-the-art global climate model, EC-Earth, run at high horizontal resolution, and then used with damage functions to make projections of deterioration phenomena on the Panamanian heritage sites. In particular, we performed an evaluation of the possible surface recession, biomass accumulation, and deterioration due to salt crystallisation cycles on these sites in the future (by midcentury, 2039–2068) compared to the recent past (1979–2008), considering a future scenario of high greenhouse gas emissions.

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The impact of horizontal resolution on the CNOP and on its identified sensitive areas for tropical cyclone predictions

Advances in Atmospheric Sciences ◽

10.1007/s00376-011-1003-x ◽

2011 ◽

Vol 29 (1) ◽

pp. 36-46 ◽

Cited By ~ 18

Author(s):

Feifan Zhou ◽

Mu Mu

Keyword(s):

Tropical Cyclone ◽

Horizontal Resolution ◽

Sensitive Areas ◽

The Impact

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Chemical contribution to future tropical ozone change in the lower stratosphere

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-27855-2013 ◽

2013 ◽

Vol 13 (10) ◽

pp. 27855-27889

Author(s):

S. Meul ◽

U. Langematz ◽

S. Oberländer ◽

H. Garny ◽

P. Jöckel

Keyword(s):

Lower Stratosphere ◽

Climate Model ◽

Dominant Role ◽

Chemical Production ◽

Net Production ◽

Future Evolution ◽

Ozone Destruction ◽

Ozone Trend ◽

The Impact

Abstract. The future evolution of tropical ozone in a changing climate is investigated by analysing timeslice simulations with the state-of-the-art Chemistry-Climate Model EMAC. Between the present and the end of the 21st century a significant increase in ozone is found globally for the upper stratosphere and the extratropical lower stratosphere, while in the tropical lower stratosphere ozone decreases significantly. Different studies showed before that this decrease is connected to changes in tropical upwelling. By splitting the relative ozone change into the contributions from transport, chemical production, and chemical loss, the impact of chemical processes in addition to transport in this region is analysed. The dominant role of transport for future ozone changes is confirmed, but it is found that changes in ozone destruction and especially changes in the production of ozone do contribute to the relative ozone changes in the tropical lower stratosphere. The causes for the changing loss and production rates are studied by separating the contributions from the different catalytic loss cycles and the different production processes. It is shown that changes in the production are mainly due to changes in the overlying ozone column which are determined by both chemistry and transport. Changes in the ozone destruction can be attributed to a modified efficiency of the ClOx and NOx loss cycles in the lower and middle stratosphere and of the HOx loss cycle in the lowermost tropical stratosphere. The role of ozone transport in determining the ozone trend in this region is found to depend on the changes in net production, with a smaller contribution from transport to the ozone changes if the net production decreases.

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