scholarly journals Advance forecasting of cyclone track over north Indian Ocean using a global circulation model

MAUSAM ◽  
2021 ◽  
Vol 57 (1) ◽  
pp. 111-118
Author(s):  
P. GOSWAMI ◽  
A. MANDAL ◽  
H. C. UPADHYAYA ◽  
FREDERIC HOURDIN
Keyword(s):  
Tropical Cyclones ◽  
Circulation Model ◽  
North Indian Ocean ◽  
Critical Parameters ◽  
Limited Area ◽  
Global Circulation Model ◽  
Pressure System ◽  
Global Circulation ◽  
Global Circulation Models ◽  
Increasing Demand

&  m".kdfVca/kh; pØokr lewps fo’o esa vf/kdka’k rVorhZ {ks=ksa esa xaHkhj vkSj fodjky Mj mRiUu djrs jgrs gSaA blfy, m".kdfVca/kh; pØokrksa ds laca/k esa vf/kd lVhd vkSj yEch vof/k ds iwokZuqeku dh ek¡x c<+rh tk jgh gSA ;|fi dkQh le; ls lhfer {ks= fun’kZ ¼,y- ,- ,e-½ m".kdfVca/kh; pØokrksa ds xfrdh; iwokZuqeku ds fy, ijEijkxr lk/ku jgs gSa fQj Hkh bl ckr ls Hkh badkj ugh fd;k tk ldrk gS fd pØokrksa dh xfrdh; izÑfr ds izLrqrhdj.k esa HkweaMyh; ifjlapj.k fun’kkZsa ¼th- lh- ,e-½ ds mi;ksx ds Qy Lo:Ik dkQh lq/kkj vk;k gSA mnkgj.k ds fy, caxky dh [kkM+h ds dqN pØokr rks caxky dh [kkM+h esa gh fodflr gksrs gSa fdarq cgqr ls pØokr [kkM+h ds iwoZ dh rjQ cus fuEu nkc {ks= ds l?ku gksus vkSj [kkM+h dh vksj c<+us ds dkj.k curs gSa ftlls ;g Li"V gS fd pØokr ds iwokZuqeku ds fy, pØokr ds mRiUu gksus ds foLr`r {ks= dks 'kkfey djus dh vko’;drk gSA bl 'kks/k&i= esa geus crk;k gS fd ,y- ,- ,e- vkSj th- lh- ,e- dh la;qDr fo’ks"krk rqyukRed :Ik ls uohu Js.kh ds HkweaMyh; ekWMyksa ¼th- lh- ,e-½ ls pØokr ds ekxZ vkSj mldh rhozrk tSls dqN vR;ar egRoiw.kZ y{k.kksa  ds laca/k eas yEch vof/k ds vkSj vf/kd lVhd rjg ds iwokZuqeku nksuksa miyC/k djk ldrs gSaA lkr pØokrksa ls lacaf/kr fofHkUu LFkkuksa] _rqvksa] o"kZ vkSj mudh rhozrk] izfr:fir ekxksZa vkSj pØokrksa ds ySaMQky ds LFkyksa ds ik¡p fnuksa ls Hkh vf/kd le; igys dh mudh vkjafHkd voLFkkvksa vkSj muds laca/k esa leqnz lrg rkieku ¼,l- ,l- Vh-½ ds ekfld tyok;q foKku ds 48 ?kaVs igys tkjh fd, x, gSaA buesa rkRdkfyd izpkyukRed iwokZuqeku ds leku gh =qfV;k¡ ikbZ xbZ gSaA Tropical cyclones pose a serious and growing threat to many coastal areas world over; there is increasing demand for better accuracy as well as longer range for tropical cyclone forecasts. While the traditional tool for dynamical forecasting of tropical cyclones has been Limited Area Models (LAM), there are reasons to believe that use of Global Circulation Models (GCM) may result in improved representation of cyclone dynamics. Over Bay of Bengal, for example, while some cyclones develop in situ, many result from intensification of low pressure system that travel from the east, implying need for consideration of a large domain. We show here that a relatively new class of Global Circulation Models (GCM), combining the advantages of LAMs and GCMs, can provide both longer range and better accuracy for such critical parameters like track and intensity. For seven cyclones representing different locations, seasons, years and strength, simulated tracks and land-fall locations show, with initial condition more than 5 days ahead and only monthly climatology of sea surface temperature (SST), errors comparable to those from current operational forecast 48 hours in advance.  

scholarly journals IGCM4: a fast, parallel and flexible intermediate climate model

2015 ◽  
Vol 8 (4) ◽  
pp. 1157-1167 ◽  
Author(s):  
M. Joshi ◽  
M. Stringer ◽  
K. van der Wiel ◽  
A. O'Callaghan ◽  
S. Fueglistaler
Keyword(s):  
Climate Model ◽  
Circulation Model ◽  
Research Process ◽  
Wave Drag ◽  
Global Circulation Model ◽  
Primitive Equation ◽  
Global Circulation ◽  
Global Circulation Models ◽  
Mean Climate ◽  
Physical Changes

Abstract. The IGCM4 (Intermediate Global Circulation Model version 4) is a global spectral primitive equation climate model whose predecessors have extensively been used in areas such as climate research, process modelling and atmospheric dynamics. The IGCM4's niche and utility lies in its speed and flexibility allied with the complexity of a primitive equation climate model. Moist processes such as clouds, evaporation, atmospheric radiation and soil moisture are simulated in the model, though in a simplified manner compared to state-of-the-art global circulation models (GCMs). IGCM4 is a parallelised model, enabling both very long integrations to be conducted and the effects of higher resolutions to be explored. It has also undergone changes such as alterations to the cloud and surface processes and the addition of gravity wave drag. These changes have resulted in a significant improvement to the IGCM's representation of the mean climate as well as its representation of stratospheric processes such as sudden stratospheric warmings. The IGCM4's physical changes and climatology are described in this paper.

scholarly journals The cloudy shape of hot Jupiter thermal phase curves

2020 ◽  
Vol 501 (1) ◽  
pp. 78-108 ◽  
Author(s):  
Vivien Parmentier ◽  
Adam P Showman ◽  
Jonathan J Fortney
Keyword(s):  
Heat Transport ◽  
Strong Dependence ◽  
Circulation Model ◽  
Equilibrium Temperature ◽  
Brightness Variation ◽  
Phase Curve ◽  
Global Circulation Model ◽  
Hot Jupiters ◽  
Global Circulation ◽  
Global Circulation Models

ABSTRACT Hot Jupiters have been predicted to have a strong day/night temperature contrast and a hotspot shifted eastward of the substellar point. This was confirmed by numerous phase curve observations probing the longitudinal brightness variation of the atmosphere. Global circulation models, however, systematically underestimate the phase curve amplitude and overestimate the shift of its maximum. We use a global circulation model including non-grey radiative transfer and realistic gas and cloud opacities to systematically investigate how the atmospheric circulation of hot Jupiters varies with equilibrium temperature from 1000 to 2200 K. We show that the heat transport is very efficient for cloudless planets cooler than 1600 K and becomes less efficient at higher temperatures. When nightside clouds are present, the day-to-night heat transport becomes extremely inefficient, leading to a good match to the observed low nightside temperatures. The constancy of this low temperature is, however, due to the strong dependence of the radiative time-scale with temperature. We further show that nightside clouds increase the phase curve amplitude and decrease the phase curve offset at the same time. This change is very sensitive to the cloud chemical composition and particle size, meaning that the diversity of observed phase curves can be explained by a diversity of nightside cloud properties. Finally, we show that phase curve parameters do not necessarily track the day/night contrast nor the shift of the hotspot on isobars, and propose solutions to to recover the true hotspot shift and day/night contrast.

scholarly journals Objective Debiasing for Improved Forecasting of Tropical Cyclone Intensity with a Global Circulation Model

2011 ◽  
Vol 139 (8) ◽  
pp. 2471-2487 ◽  
Author(s):  
P. Goswami ◽  
S. Mallick ◽  
K. C. Gouda
Keyword(s):  
Tropical Cyclone ◽  
Sample Size ◽  
Circulation Model ◽  
Skill Score ◽  
Limited Area ◽  
Global Circulation Model ◽  
Tropical Cyclone Intensity ◽  
Cyclone Intensity ◽  
Global Circulation ◽  
Skill Scores

AbstractThe damage potential of a tropical cyclone is proportional to a power (generally greater than one) of intensity, which demands high accuracy in forecasting intensity for managing this natural disaster. However, the current skill in forecasting cyclone intensity is rather limited, especially over the north Indian Ocean, with very little improvement over the years. A methodology is presented here for objective nonlinear debiasing to generate intensity forecasts with enhanced reliability from raw forecasts. The intensity forecast is generated using an optimized configuration of a variable resolution global circulation model (VR-GCM) that combines the advantages of a limited area model and a global model. The hindcasts were carried out in a completely operational setting, that is, without assuming any observed information beyond the day of the initial condition. The VR-GCM and a nonlinear debiasing were found to provide skill (skill score ~0.5) in forecasting tropical cyclone intensity 2–7 days (variable depending on event) in advance for the 30 cases including storms and cyclones representing different locations, seasons, and years (1990–2005) over the Bay of Bengal. Two types of debiasing are considered: nonlinear debiasing with all observations (potential skill) and nonlinear debiasing for realizable skill (training without in-sample data). It is shown that while skill scores without debiasing are only marginally better than a climatological forecast (null hypothesis), the skill score with a nonlinear debiasing is appreciable. The climatological forecast has zero skill score, a mean absolute error of 12.9 m s−1, and 20% of the cases are in the error bin −5 to +5 m s−1; the corresponding numbers for debiased forecasts for realizable skill are 0.65, 6.4 m s−1, and 57%. It is further shown that the nonlinear debiasing is also effective in improving forecast of (3-hourly) intensity change. While a strict comparison of skill with other methods requires experiments to be carried out for the same events, a comparison of the skill of other methods and over different ocean basins based on available data shows the present method to have comparable skill. However, it may be noted that the present conclusions are based on a relatively small (30 events) sample size; evaluation with a much large sample size is desirable for actual application.

scholarly journals A Comparative Evaluation of a Mesoscale Model and Atmospheric Global Circulation Model for Air Quality Simulation: A Multiscale, Multisite Evaluation

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
P. Goswami ◽  
J. Baruah
Keyword(s):  
High Resolution ◽  
Mesoscale Model ◽  
Large City ◽  
Circulation Model ◽  
Urban Pollution ◽  
Atmospheric Pollutants ◽  
Scale Model ◽  
Global Circulation Model ◽  
Global Circulation ◽  
Meso Scale

Concentrations of atmospheric pollutants are strongly influenced by meteorological parameters like rainfall, relative humidity and wind advection. Thus accurate specifications of the meteorological fields, and their effects on pollutants, are critical requirements for successful modelling of air pollution. In terms of their applications, pollutant concentration models can be used in different ways; in one, short term high resolution forecasts are generated to predict and manage urban pollution. Another application of dynamical pollution models is to generate outlook for a given airbasin, such as over a large city. An important question is application-specific model configuration for the meteorological simulations. While a meso-scale model provides a high-resolution configuration, a global model allows better simulation of large-sale fields through its global environment. Our objective is to comparatively evaluate a meso-scale atmospheric model (MM5) and atmospheric global circulation model (AGCM) in simulating different species of pollutants over different airbasins. In this study we consider four locations: ITO (Central Delhi), Sirifort (South Delhi), Bandra (Mumbai) and Karve Road (Pune). The results show that both the model configurations provide comparable skills in simulation of monthly and annual loads, although the skill of the meso-scale model is somewhat higher, especially at shorter time scales.

scholarly journals THOR: A NEW AND FLEXIBLE GLOBAL CIRCULATION MODEL TO EXPLORE PLANETARY ATMOSPHERES

2016 ◽  
Vol 829 (2) ◽  
pp. 115 ◽  
Author(s):  
João M. Mendonça ◽  
Simon L. Grimm ◽  
Luc Grosheintz ◽  
Kevin Heng
Keyword(s):  
Circulation Model ◽  
Planetary Atmospheres ◽  
Global Circulation Model ◽  
Global Circulation

scholarly journals True dipole wander

2018 ◽  
Vol 215 (3) ◽  
pp. 1523-1529
Author(s):  
Peter Olson ◽  
Maylis Landeau ◽  
Evan Reynolds
Keyword(s):  
Circulation Model ◽  
Global Circulation Model ◽  
Polar Wander ◽  
Global Circulation ◽  
True Polar Wander ◽  
Symmetric Pattern ◽  
Asymmetric Pattern ◽  
Heterogeneous Mantle ◽  
Geocentric Axial Dipole ◽  
Geomagnetic Dipole

SUMMARY A fundamental assumption in palaeomagnetism is that the geomagnetic field closely approximates a geocentric axial dipole in time average. Here we use numerical dynamos driven by heterogeneous core–mantle boundary heat flux from a mantle global circulation model to demonstrate how mantle convection produces true dipole wander, rotation of the geomagnetic dipole on geologic timescales. Our heterogeneous mantle-driven dynamos show a dipole rotation about a near-equatorial axis in response to the transition in lower mantle heterogeneity from a highly asymmetric pattern at the time of supercontinent Pangea to a more symmetric pattern today. This predicted dipole rotation overlaps with a palaeomagnetically inferred rotation in the opposite direction and suggests that some events previously interpreted as true polar wander also include true dipole wander.

scholarly journals The Use of Radiocarbon Measurements in Atmospheric Studies

Radiocarbon ◽  
1990 ◽  
Vol 32 (1) ◽  
pp. 37-58 ◽  
Author(s):  
M R Manning ◽  
D C Lowe ◽  
W H Melhuish ◽  
R J Sparks ◽  
Gavin Wallace ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Circulation Model ◽  
Current Data ◽  
Atmospheric Methane ◽  
Global Circulation Model ◽  
Fossil Carbon ◽  
Global Circulation ◽  
Methane Source ◽  
Clean Air ◽  
Source Current

14C measured in trace gases in clean air helps to determine the sources of such gases, their long-range transport in the atmosphere, and their exchange with other carbon cycle reservoirs. In order to separate sources, transport and exchange, it is necessary to interpret measurements using models of these processes. We present atmospheric 14CO2 measurements made in New Zealand since 1954 and at various Pacific Ocean sites for shorter periods. We analyze these for latitudinal and seasonal variation, the latter being consistent with a seasonally varying exchange rate between the stratosphere and troposphere. The observed seasonal cycle does not agree with that predicted by a zonally averaged global circulation model. We discuss recent accelerator mass spectrometry measurements of atmospheric 14CH4 and the problems involved in determining the fossil fuel methane source. Current data imply a fossil carbon contribution of ca 25%, and the major sources of uncertainty in this number are the uncertainty in the nuclear power source of 14CH4, and in the measured value for δ14C in atmospheric methane.

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