A Multimodel Intercomparison of an Intense Typhoon in Future, Warmer Climates by Four 5-km-Mesh Models

2017 ◽  
Vol 30 (15) ◽  
pp. 6017-6036 ◽  
Author(s):  
Sachie Kanada ◽  
Tetsuya Takemi ◽  
Masaya Kato ◽  
Shota Yamasaki ◽  
Hironori Fudeyasu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Boundary Conditions ◽  
General Circulation ◽  
Mesoscale Model ◽  
Future Climate ◽  
Japan Meteorological Agency ◽  
Near Surface ◽  
Control Simulation ◽  
The Future ◽  
Initial And Boundary Conditions

Intense tropical cyclones (TCs) sometimes cause huge disasters, so it is imperative to explore the impacts of climate change on such TCs. Therefore, the authors conducted numerical simulations of the most destructive historical TC in Japanese history, Typhoon Vera (1959), in the current climate and a global warming climate. The authors used four nonhydrostatic models with a horizontal resolution of 5 km: the cloud-resolving storm simulator, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model, the Japan Meteorological Agency (JMA) operational nonhydrostatic mesoscale model, and the Weather Research and Forecasting Model. Initial and boundary conditions for the control simulation were provided by the Japanese 55-year Reanalysis dataset. Changes between the periods of 1979–2003 and 2075–99 were estimated from climate runs of a 20-km-mesh atmospheric general circulation model, and these changes were added to the initial and boundary conditions of the control simulation to produce the future climate conditions. Although the representation of inner-core structures varies largely between the models, all models project an increase in the maximum intensity of future typhoons. It is found that structural changes only appeared around the storm center with sudden changes in precipitation and near-surface wind speeds as the radius of maximum wind speed (RMW) contracted. In the future climate, the water vapor mixing ratio in the lower troposphere increased by 3–4 g kg−1. The increased water vapor allowed the eyewall updrafts to form continuously inside the RMW and contributed to rapid condensation in the taller and more intense updrafts.

scholarly journals Future Changes in Structures of Extremely Intense Tropical Cyclones Using a 2-km Mesh Nonhydrostatic Model

2013 ◽  
Vol 26 (24) ◽  
pp. 9986-10005 ◽  
Author(s):  
Sachie Kanada ◽  
Akiyoshi Wada ◽  
Masato Sugi
Keyword(s):  
Global Warming ◽  
Tropical Cyclones ◽  
General Circulation ◽  
Potential Temperature ◽  
Circulation Model ◽  
Future Climate ◽  
Central Pressure ◽  
Near Surface ◽  
Nonhydrostatic Model ◽  
The Future

Abstract Recent studies have projected that global warming may lead to an increase in the number of extremely intense tropical cyclones. However, how global warming affects the structure of extremely intense tropical cyclones has not been thoroughly examined. This study defines extremely intense tropical cyclones as having a minimum central pressure below 900 hPa and investigates structural changes in the inner core and thereby changes in the intensity in the future climate. A 2-km mesh nonhydrostatic model (NHM2) is used to downscale the 20-km mesh atmospheric general circulation model projection forced with a control scenario and a scenario of twenty-first-century climate change. The eyewall region of extremely intense tropical cyclones simulated by NHM2 becomes relatively smaller and taller in the future climate. The intense near-surface inflow intrudes more inward toward the eye. The heights and the radii of the maximum wind speed significantly decrease and an intense updraft area extends from the lower level around the leading edge of thinner near-surface inflows, where the equivalent potential temperature substantially increases in the future climate. Emanuel’s potential intensity theory suggests that about half of the intensification (increase in central pressure fall) is explained by the changes in the atmospheric environments and sea surface temperature, while the remaining half needs to be explained by other processes. It is suggested that the structural change projected by NHM2, which is significant within a radius of 50 km, is playing an important role in the intensification of extremely intense tropical cyclones in simulations of the future climate.

An Adjoint Analysis of the Meridional Overturning Circulation in a Hybrid Coupled Model

2006 ◽  
Vol 19 (15) ◽  
pp. 3751-3767 ◽  
Author(s):  
Véronique Bugnion ◽  
Chris Hill ◽  
Peter H. Stone
Keyword(s):  
Boundary Conditions ◽  
Wind Stress ◽  
Ocean Circulation ◽  
General Circulation ◽  
Meridional Overturning Circulation ◽  
Global Ocean ◽  
Model Parameters ◽  
Overturning Circulation ◽  
Near Surface ◽  
Meridional Overturning

Abstract Multicentury sensitivities in a realistic geometry global ocean general circulation model are analyzed using an adjoint technique. This paper takes advantage of the adjoint model’s ability to generate maps of the sensitivity of a diagnostic (i.e., the meridional overturning’s strength) to all model parameters. This property of adjoints is used to review several theories, which have been elaborated to explain the strength of the North Atlantic’s meridional overturning. This paper demonstrates the profound impact of boundary conditions in permitting or suppressing mechanisms within a realistic model of the contemporary ocean circulation. For example, the so-called Drake Passage Effect in which wind stress in the Southern Ocean acts as the main driver of the overturning’s strength, is shown to be an artifact of boundary conditions that restore the ocean’s surface temperature and salinity toward prescribed climatologies. Advective transports from the Indian and Pacific basins play an important role in setting the strength of the overturning circulation under “mixed” boundary conditions, in which a flux of freshwater is specified at the ocean’s surface. The most “realistic” regime couples an atmospheric energy and moisture balance model to the ocean. In this configuration, inspection of the global maps of sensitivity to wind stress and diapycnal mixing suggests a significant role for near-surface Ekman processes in the Tropics. Buoyancy also plays an important role in setting the overturning’s strength, through direct thermal forcing near the sites of convection, or through the advection of salinity anomalies in the Atlantic basin.

Impact of Climate Change on River Flows in the Black Volta River

2014 ◽  
Vol 9 (4) ◽  
pp. 432-442 ◽  
Author(s):  
Nobuhiko Sawai ◽  
◽  
Kenichiro Kobayashi ◽  
Apip ◽  
Kaoru Takara ◽  
...  
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Future Climate ◽  
Precipitation Pattern ◽  
Present Climate ◽  
Rainfall Runoff ◽  
Maximum Rainfall ◽  
Impact Of Climate Change ◽  
The Future ◽  
The Impact

This paper assesses the impact of climate change in the Black Volta River by using data output from the atmospheric general circulation model with a 20-km resolution (AGCM20) through the Japanese Meteorological Agency (JMA) and the Meteorological Research Institute (MRI). The Black Volta, which flows mainly in Burkina Faso and Ghana in West Africa, is a major tributary of the Volta River. The basin covers 142,056 km2 and has a semi-arid tropical climate. Before applying AGCM20 output to a rainfall–runoff model, the performance of the AGCM20 rainfall data is investigated by comparing it with the observed rainfall in the Black Volta Basin. To assess the possible impact of rainfall change on river flow, a kinematic wave model, which takes into consideration saturated and unsaturated subsurface soil zones, was performed. The rainfall analysis shows that, the correlation coefficient of the monthly rainfall between the observed rainfall and AGCM20 for the present climate (1979–2004) is 0.977. In addition, the analysis shows that AGCM20 overestimates precipitation during the rainy season and underestimates the dry season for the present climate. The analysis of the AGCM20 output shows the precipitation pattern change in the future (2075–2099). In the future, precipitation is expected to increase by 3%, whereas evaporation and transpiration are expected to increase by 5% and by 8%, respectively. Also, daily maximum rainfall is expected to be 20 mm, or 60%, higher. Thus, the future climate in this region is expected to be more severe. The rainfall–runoff simulation is successfully calibrated at the Bamboi discharge gauging station in the Black Volta fromJune 2000 to December 2000 with 0.72 of the Nash–Sutcliffe model efficiency index. The model is applied with AGCM20 outputs for the present climate (1979–2004) and future climate (2075–2099). The results indicate that future discharge will decrease from January to July at the rate of the maximum of 50% and increase fromAugust to December at the rate of the maximumof 20% in the future. Therefore, comprehensive planning for both floods and droughts are urgently needed in this region.

scholarly journals Improving WRF-Chem meteorological analyses and forecasts over aerosol polluted regions by incorporating NAAPS aerosol analyses

2021 ◽  
Author(s):  
Brittany N. Carson-Marquis ◽  
Jianglong Zhang ◽  
Peng Xian ◽  
Jeffrey S. Reid ◽  
Jared Marquis
Keyword(s):  
Boundary Conditions ◽  
Surface Temperature ◽  
Great Plains ◽  
Transport Model ◽  
Weather Prediction ◽  
The United States ◽  
Northern Great Plains ◽  
Chemical Transport Model ◽  
Near Surface ◽  
Initial And Boundary Conditions

AbstractWhen unaccounted for in numerical weather prediction (NWP) models, heavy aerosol events can cause significant unrealized biases in forecasted meteorological parameters such as surface temperature. To improve near-surface forecasting accuracies during heavy aerosol loadings, we demonstrate the feasibility of incorporating aerosol fields from a global chemical transport model as initial and boundary conditions into a higher resolution NWP model with aerosol-meteorological coupling. This concept is tested for a major biomass burning smoke event over the Northern Great Plains region of the United States that occurred during summer of 2015. Aerosol analyses from the global Navy Aerosol Analysis and Prediction System (NAAPS) are used as initial and boundary conditions for Weather Research and Forecasting with Chemistry (WRF-Chem) simulations. Through incorporating more realistic aerosol direct effects into the WRF-Chem simulations, errors in WRF-Chem simulated surface downward shortwave radiative fluxes and near-surface temperature are reduced compared with surface-based observations. This study confirms the ability to decrease biases induced by the aerosol direct effect for regional NWP forecasts during high-impact aerosol episodes through the incorporation of analyses and forecasts from a global aerosol transport model.

Evaluation of climate change impacts and adaptation strategies for maize cultivation in the Himalayan foothills of India

2015 ◽  
Vol 6 (3) ◽  
pp. 596-614 ◽  
Author(s):  
Proloy Deb ◽  
Anthony S. Kiem ◽  
Mukand S. Babel ◽  
Sang Thi Chu ◽  
Biplab Chakma
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Circulation Model ◽  
Maize Yield ◽  
Future Climate ◽  
Future Climate Change ◽  
Daily Maximum ◽  
Study Region ◽  
Supplementary Irrigation ◽  
The Future

This study evaluates the impacts of climate change on rainfed maize (Zea mays) yield and evaluates different agro-adaptation measures to counteract its negative impacts at Sikkim, a Himalayan state of India. Future climate scenarios for the 10 years centered on 2025, 2055 and 2085 were obtained by downscaling the outputs of the HadCM3 General Circulation Model (GCM) under for A2 and B2 emission scenarios. HadCM3 was chosen after assessing the performance analysis of six GCMs for the study region. The daily maximum and minimum temperatures are projected to rise in the future and precipitation is projected to decrease (by 1.7 to 22.6% relative to the 1991–2000 baseline) depending on the time period and scenarios considered. The crop simulation model CERES-Maize was then used to simulate maize yield under future climate change for the future time windows. Simulation results show that climate change could reduce maize productivity by 10.7–18.2%, compared to baseline yield, under A2 and 6.4–12.4% under B2 scenarios. However, the results also indicate that the projected decline in maize yield could be offset by early planting of seeds, lowering the farm yard manure application rate, introducing supplementary irrigation and shifting to heat tolerant varieties of maize.

scholarly journals Development of an Integrated Approach for the Assessment of Climate Change Impacts on the Hydro-Meteorological Characteristics of the Mahaweli River Basin, Sri Lanka

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1218
Author(s):  
Hemakanth Selvarajah ◽  
Toshio Koike ◽  
Mohamed Rasmy ◽  
Katsunori Tamakawa ◽  
Akio Yamamoto ◽  
...  
Keyword(s):  
Climate Change ◽  
Sri Lanka ◽  
River Basin ◽  
General Circulation ◽  
Climate Change Impacts ◽  
Integrated Approach ◽  
Future Climate ◽  
Economic Damage ◽  
Basin Scale ◽  
The Future

Climate change is increasingly sensed by nations vulnerable to water-related disasters, and governments are acting to mitigate disasters and achieve sustainable development. Uncertainties in General Circulation Models’ (GCM) rainfall projections and seamless long-term hydrological simulations incorporating warming effects are major scientific challenges in assessing climate change impacts at the basin scale. Therefore, the Data Integration and Analysis System (DIAS) of Japan and the Water Energy Budget-based Rainfall-Runoff-Inundation model (WEB-RRI) were utilized to develop an integrated approach, which was then applied to the Mahaweli River Basin (MRB) in Sri Lanka to investigate climate change impacts on its hydro-meteorological characteristics. The results for the Representative Concentration Pathway (RCP8.5) scenario from four selected GCMs showed that, with an average temperature increase of 1.1 °C over the 20 years in future (2026 to 2045), the basin will experience more extreme rainfall (increase ranging 204 to 476 mm/year) and intense flood disasters and receive sufficient water in the future climate (inflow increases will range between 11 m3/s to 57 m3/s). The socio-economic damage due to flood inundation will also increase in the future climate. However, qualitatively, the overall trend of model responses showed an increasing pattern in future meteorological droughts whereas there is uncertainty in hydrological droughts. Policymakers can utilize these results and react to implementing soft or hard countermeasures for future policymaking. The approach can be implemented for climate change impact assessment of hydro-meteorology in any other river basin worldwide.

scholarly journals Climate change scenarios and its impact on water resources of Langtang Khola Basin, Nepal

2014 ◽  
Vol 364 ◽  
pp. 9-13
Author(s):  
T. Raj Adhikari ◽  
L. Prasad Devkota ◽  
A. Bhakta Shrestha
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Local Level ◽  
General Circulation Models ◽  
Temperature Data ◽  
Future Climate ◽  
Optimization Approach ◽  
Climate Change Scenarios ◽  
The Future ◽  
Precipitation And Temperature

Abstract. General Circulation Models (GCMs) successfully simulate future climate variability and climate change on a global scale; however, poor spatial resolution constrains their application for impact studies at a regional or a local level. The dynamically downscaled precipitation and temperature data were used for the future climate scenarios prediction for the period 2000–2050s, under the Special Report on Emissions Scenarios (SRES) A2 and A1B scenarios. In addition, rating equation was developed from measured discharge and gauge (stage) height data. The generated precipitation and temperature data from downscale and rating equation was used to run the HBV-Light 3.0 conceptual rainfall–runoff model for the calibration and validation of the model, gauge height was taken in the reference period (1988–2009). In the HBV-Light 3.0, a GAP optimization approach was used to calibrate the observed streamflow. From the precipitation scenarios with SRES A2 and A1B emissions at Kyanging, an increase of precipitation during summer and spring and a decrease during winter and autumn seasons was shown. The model projected annual precipitation for the 2050s of both the A2 and A1B scenarios are 716.4 mm and 703.6 mm, respectively. Such precipitation projections indicate the future increase of precipitation in all seasons except the summer. By the end of the 2050s simulation projects an increase maximum (minimum) discharge of 37.8 m3/s (13.9 m3/s) for A1B scenario and 36.2 m3/s (14.3 m3/s) for A2 scenario. A maximum projected discharge will increase for all seasons except for spring, whereas the minimum will decrease in summer.

Increased uncertainty in Land-Use change impacts on temperature due to Global Warming in CMIP6-LUMIP experiments

2021 ◽  
Author(s):  
Arshdeep Singh ◽  
Sanjiv Kumar
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Direct Method ◽  
Climate Change Impacts ◽  
Future Climate ◽  
Shortwave Radiation ◽  
Near Surface ◽  
Historical Climate ◽  
The Future

<p>Land-use change (LU) is a major regional climate forcing that affects carbon-water-energy fluxes and, therefore, near-surface air temperature. Although there are uncertainties in LU impacts in the historical climate, there is a growing consensus towards a cooling influence in the mid-latitudes. However, how a drier and warmer land surface condition in the future climate can change the LU impacts are not investigated well.</p><p>We use a comprehensive set of five coupled climate models from the CMIP6-LUMIP project to assess the changing influence of the LU change. We use two methodologies: (1) direct method – where LU impacts are estimated by subtracting the ‘no-LU’ climate experiment from the control experiment that includes LU, and (2) Kumar et al., 2013 (K13) method where LU impacts are estimated by comparing climate change impacts between LU and no-LU neighboring regions.</p><p>First, we compared the LU impacts in the historical climate and between the direct method and K13 methods using the multi-model analysis. In the North America LU change region, the direct method shows a cooling impact of (-0.14 ± 0.13°C). The K13 methods show a smaller cooling impact (-0.09 ± 0.08°C). In terms of energy balance, the direct method shows a reduction of net shortwave radiation (-0.82 ± 0.91 watts/m<sup>2</sup>) the K13 method shows a cleaner result of (-1.25 ± 0.60 watts/m<sup>2</sup>), as expected. We suspect that a more substantial influence of the LU change in the direct method is due to large-scale circulation driven response or due to the internal variability that has been canceled out in the K13 method.</p><p>Next, we extend the K13 method to assess the LU impacts in the future climate. Direct methods are not available for the future climate experiment in CMIP6-LUMIP datasets. We find that a cooling impact of LU change has become statistically insignificant in the future climate (-0.17 ± 0.19°C). A similar influence is also found in the reduction of the net shortwave radiation (-1.92 ± 3.34 watts/m<sup>2</sup>). We also found that climate change impacts on temperature are an order of magnitude greater than LU impact in the future climate. Hence, we hypothesize that higher warming has contributed to the larger uncertainty in LU impacts. We will also discuss LU impacts in Eurasia and Indian subcontinent.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.967d8b47f50063273001161/sdaolpUECMynit/12UGE&app=m&a=0&c=6fbaa64b9acfb208f665dca0184a6955&ct=x&pn=gnp.elif&d=1" alt=""></p><p> </p><p> </p><p>Reference</p><p>Kumar, S., Dirmeyer, P. A., Merwade, V., DelSole, T., Adams, J. M., & Niyogi, D. (2013). Land use/cover change impacts in CMIP5 climate simulations: A new methodology and 21st century challenges. Journal of Geophysical Research: Atmospheres, 118(12), 6337-6353.</p>

Long-Range Predictability in the Tropics. Part II: 30–60-Day Variability

2005 ◽  
Vol 18 (5) ◽  
pp. 634-650 ◽  
Author(s):  
Thomas Reichler ◽  
John O. Roads
Keyword(s):  
Boundary Conditions ◽  
Long Range ◽  
General Circulation ◽  
Initial Conditions ◽  
Southern Oscillation ◽  
Intraseasonal Variability ◽  
Intraseasonal Oscillation ◽  
Circulation Model ◽  
Lead Times ◽  
Initial And Boundary Conditions

Abstract It is suggested that the slow evolution of the tropical Madden–Julian oscillation (MJO) has the potential to improve the predictability of tropical and extratropical circulation systems at lead times beyond 2 weeks. In practice, however, the MJO phenomenon is extremely difficult to predict because of the lack of good observations, problems with ocean forecasts, and well-known model deficiencies. In this study, the potential skill in forecasting tropical intraseasonal variability is investigated by eliminating all those errors. This is accomplished by conducting five ensemble predictability experiments with a complex general circulation model and by verifying them under the perfect model assumption. The experiments are forced with different combinations of initial and boundary conditions to explore their sensitivity to uncertainties in those conditions. When “perfect” initial and boundary conditions are provided, the model produces a realistic climatology and variability as compared to reanalysis, although the spectral peak of the simulated MJO is too broad. The effect of initial conditions is noticeable out to about 40 days. The quality of the boundary conditions is crucial at all lead times. The small but positive correlations at very long lead times are related to intraseasonal variability of tropical sea surface temperatures (SSTs). When model, initial, and boundary conditions are all perfect, the useful forecast skill of intraseasonal variability is about 4 weeks. Predictability is insensitive to the El Niño–Southern Oscillation (ENSO) phenomenon, but it is enhanced during years when the intraseasonal oscillation is more active. The results provide evidence that the MJO must be understood as a coupled system. As a consequence, it is concluded that further progress in the long-range predictability effort may require the use of fully interactive ocean models.

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