Search Results
You are looking at 41 - 50 of 112 items for
- Author or Editor: T. N. Krishnamurti x
- Refine by Access: All Content x
Because of the initial data uncertainties, it is inevitable that operational hurricane track forecasting practice would, in the future, follow an ensemble forecast approach. The ensemble technique is becoming increasingly popular for the middle-latitude weather forecasts. This paper focuses on an ensemble forecast methodology for the hurricane track forecast procedure.
In this study, an ensemble perturbation method is applied for hurricane track predictions using the Florida State University's Global Spectral Model with horizontal spectral resolution of T63 and 14 vertical levels.
The method is based on the premise that (a) model perturbation grows linearly during the first few days of model integration, and (b) in order to make a complete set of ensemble perturbations of hurricane forecasts, both hurricane initial position and its structure and environment need to be perturbed. The initial position of the hurricane is perturbed by displacing its original position 50 km equally toward the north, south, east, and west directions. The hurricane environment and structure perturbations can be generated by implementing EOF analysis to the differences between forecasts starting from regular analysis and randomly perturbed analysis. Only the temperature and wind fields are perturbed with the order proportional to the respective observational error. The method generates 15 ensemble members for each hurricane.
The result shows that this ensemble prediction method leads to an improvement in the hurricane track forecasts. The track position errors are largely reduced by the ensemble prediction for most of the hurricane cases that have been tested, and these forecasts are superior to the results from single-model control experiments. It is also noted that the spread of the ensemble track forecasts is useful to assess the reliability of the predictions.
Because of the initial data uncertainties, it is inevitable that operational hurricane track forecasting practice would, in the future, follow an ensemble forecast approach. The ensemble technique is becoming increasingly popular for the middle-latitude weather forecasts. This paper focuses on an ensemble forecast methodology for the hurricane track forecast procedure.
In this study, an ensemble perturbation method is applied for hurricane track predictions using the Florida State University's Global Spectral Model with horizontal spectral resolution of T63 and 14 vertical levels.
The method is based on the premise that (a) model perturbation grows linearly during the first few days of model integration, and (b) in order to make a complete set of ensemble perturbations of hurricane forecasts, both hurricane initial position and its structure and environment need to be perturbed. The initial position of the hurricane is perturbed by displacing its original position 50 km equally toward the north, south, east, and west directions. The hurricane environment and structure perturbations can be generated by implementing EOF analysis to the differences between forecasts starting from regular analysis and randomly perturbed analysis. Only the temperature and wind fields are perturbed with the order proportional to the respective observational error. The method generates 15 ensemble members for each hurricane.
The result shows that this ensemble prediction method leads to an improvement in the hurricane track forecasts. The track position errors are largely reduced by the ensemble prediction for most of the hurricane cases that have been tested, and these forecasts are superior to the results from single-model control experiments. It is also noted that the spread of the ensemble track forecasts is useful to assess the reliability of the predictions.
Abstract
The heat budget of the Siberian high is investigated by using a compositing method. Ninteen cases of strong Siberian highs that moved over China from the northwest were selected from datasets covering five winters (December through February of 1980–1984). The apparent heat source (Q 1)and the apparent moisture sink (Q 2) were estimated via budget calculations. The diabatic heating terms were also calculated via direct use of physical parameterization schemes. The vertical transports of sensible and latent heat from subgrid-scale of motions were estimated as residuals from the thermodynamic energy equation.
Over the region of the region of the Siberian high, strong radiative cooling and large-scale descending motion (with large-scale mass convergence over the upper and middle tropospheric and divergence over the lower troposphere) contributes to a rapid buildup of the Siberian high. Heating in the upper troposphere due to subgrid-scale sensible heat transfer is also an important factor in the maintenance of mass convergence in the upper troposphere through enhancement of the warm upper-tropospheric anticyclone lying over the Siberian high.
The transformation of the Siberian high commences shortly after it moves away from its source region. As the high arrives at lower latitudes, the sensible heating due to condensation in the lower troposphere enhance the transformation process of the cold high.
A comparison of the heat budgets of the Siberian high at low latitudes is carried out over the land and the warm oceanic area to the southeast.
In section 7 of this paper we present some planetary-scale signatures associated with the motion of the Siberian high. This motion is shown to be accompanied by an eastward shift of the tropical planetary-scale divergent circulation. This aspect is very similar to a shift of divergent circulation centers that one finds between non-El Niñ and El Niñ years.
Abstract
The heat budget of the Siberian high is investigated by using a compositing method. Ninteen cases of strong Siberian highs that moved over China from the northwest were selected from datasets covering five winters (December through February of 1980–1984). The apparent heat source (Q 1)and the apparent moisture sink (Q 2) were estimated via budget calculations. The diabatic heating terms were also calculated via direct use of physical parameterization schemes. The vertical transports of sensible and latent heat from subgrid-scale of motions were estimated as residuals from the thermodynamic energy equation.
Over the region of the region of the Siberian high, strong radiative cooling and large-scale descending motion (with large-scale mass convergence over the upper and middle tropospheric and divergence over the lower troposphere) contributes to a rapid buildup of the Siberian high. Heating in the upper troposphere due to subgrid-scale sensible heat transfer is also an important factor in the maintenance of mass convergence in the upper troposphere through enhancement of the warm upper-tropospheric anticyclone lying over the Siberian high.
The transformation of the Siberian high commences shortly after it moves away from its source region. As the high arrives at lower latitudes, the sensible heating due to condensation in the lower troposphere enhance the transformation process of the cold high.
A comparison of the heat budgets of the Siberian high at low latitudes is carried out over the land and the warm oceanic area to the southeast.
In section 7 of this paper we present some planetary-scale signatures associated with the motion of the Siberian high. This motion is shown to be accompanied by an eastward shift of the tropical planetary-scale divergent circulation. This aspect is very similar to a shift of divergent circulation centers that one finds between non-El Niñ and El Niñ years.
Abstract
The eastern and the western tropical oceans usually show a considerable zonal asymmetry in the extent and depth of deep cumulus convection. Earlier versions of a simple cumulus parameterization based on GATE observations have revealed some limitations in differentiating this type of zonal asymmetry. The aim of the proposed scheme is to provide global statistical corrections to a Kuo-type cumulus parameterization scheme and thus to optimize the moistening, heating and rainfall rates over different regions. The base data for this study are the recently analyzed global FGGE IIIb datasets. Three months of daily datasets during the global experiment were utilized in order to evaluate the coefficients of a multiple regression analysis. These multiple regression coefficients vary in space and provide different measures of a moistening parameter b and a mesoscale convergence parameter η. A clear distinction in the strength of convection is found, based on the regression parameters, between the western and the eastern oceans. This generalization of a modified Kuo-type scheme is derived for a spectral resolution of 42 waves. The impact of the aforementioned scheme is investigated in several medium range prediction experiments. Forecast comparison with a simpler version of the Kuo scheme is also carried out. Our interest in these experiments is an evaluation of precipitation forecasts, for which the proposed global cumulus parameterization is compared with other experiments that were based on GATE coefficients and with the observed measures of precipitation. The results of the global forecasts show a very marked improvement in the short range (1 to 2 day) prediction from the use of the globally varying parameterization coefficients. On the other hand, the precipitation amounts predicted from an application of the local GATE coefficients underestimate the rainfall rates over most regions.
Abstract
The eastern and the western tropical oceans usually show a considerable zonal asymmetry in the extent and depth of deep cumulus convection. Earlier versions of a simple cumulus parameterization based on GATE observations have revealed some limitations in differentiating this type of zonal asymmetry. The aim of the proposed scheme is to provide global statistical corrections to a Kuo-type cumulus parameterization scheme and thus to optimize the moistening, heating and rainfall rates over different regions. The base data for this study are the recently analyzed global FGGE IIIb datasets. Three months of daily datasets during the global experiment were utilized in order to evaluate the coefficients of a multiple regression analysis. These multiple regression coefficients vary in space and provide different measures of a moistening parameter b and a mesoscale convergence parameter η. A clear distinction in the strength of convection is found, based on the regression parameters, between the western and the eastern oceans. This generalization of a modified Kuo-type scheme is derived for a spectral resolution of 42 waves. The impact of the aforementioned scheme is investigated in several medium range prediction experiments. Forecast comparison with a simpler version of the Kuo scheme is also carried out. Our interest in these experiments is an evaluation of precipitation forecasts, for which the proposed global cumulus parameterization is compared with other experiments that were based on GATE coefficients and with the observed measures of precipitation. The results of the global forecasts show a very marked improvement in the short range (1 to 2 day) prediction from the use of the globally varying parameterization coefficients. On the other hand, the precipitation amounts predicted from an application of the local GATE coefficients underestimate the rainfall rates over most regions.
Abstract
We contrast the 200 mb flow regimes during a drought year (1972) with those during a normal rainfall year (1967) over the global tropics for the northern summer months. It is shown that the deficient rainfall over central India and western Africa during 1972 may be related to the following: 1) warm sea surface temperatures over the equatorial Pacific; 2) excessive number of typhoon days over the western Pacific; 3) strong east-northeasterlies over the equatorial eastern Indian ocean (related to upper level outflows from typhoons); 4) weaker tropical easterly jet; 5) weaker meridional pressure gradient over India; 6) weaker Tibetan high; 7) a southeastward shift of the major circulation patterns as well as of several dynamical parameters; 8) weaker vertical wind shear and a weaker measure of the combined barotropic-baroclinic instability over West Africa; and 9) weaker westward steering for rain-producing disturbances over India and a consequent stronger influence of the mountains.
A sequential interrelationship of the above phenomenological aspects of the drought problem are discussed in this paper.
Abstract
We contrast the 200 mb flow regimes during a drought year (1972) with those during a normal rainfall year (1967) over the global tropics for the northern summer months. It is shown that the deficient rainfall over central India and western Africa during 1972 may be related to the following: 1) warm sea surface temperatures over the equatorial Pacific; 2) excessive number of typhoon days over the western Pacific; 3) strong east-northeasterlies over the equatorial eastern Indian ocean (related to upper level outflows from typhoons); 4) weaker tropical easterly jet; 5) weaker meridional pressure gradient over India; 6) weaker Tibetan high; 7) a southeastward shift of the major circulation patterns as well as of several dynamical parameters; 8) weaker vertical wind shear and a weaker measure of the combined barotropic-baroclinic instability over West Africa; and 9) weaker westward steering for rain-producing disturbances over India and a consequent stronger influence of the mountains.
A sequential interrelationship of the above phenomenological aspects of the drought problem are discussed in this paper.
Abstract
An assimilation of satellite low-cloud vector data and conventional meteorological data is presented in this paper. The domain of the study is the GATE A-scale area. The period is the summer months of 1972. Objective analysis of the data for 93 individual days was carried out for this entire domain. One of the important climatological findings of this study is the presence of a velocity maximum in the southeast trades along the Brazilian coast. Mean speeds for three months exceed 10 m/s in this region; daily values occasionally are as large as 25 m/s. Besides showing the monthly mean motion field, we have examined in detail one-level barotropic energy exchanges and fluxes in the GATE A-scale domain. The number of conventional plus non-conventional wind observations are about 400 per day. This is more than has been used in most previous studies. Some of these results of the energetics, especially with regards to the period when Hurricane Agnes formed, are thus of considerable interest.
Abstract
An assimilation of satellite low-cloud vector data and conventional meteorological data is presented in this paper. The domain of the study is the GATE A-scale area. The period is the summer months of 1972. Objective analysis of the data for 93 individual days was carried out for this entire domain. One of the important climatological findings of this study is the presence of a velocity maximum in the southeast trades along the Brazilian coast. Mean speeds for three months exceed 10 m/s in this region; daily values occasionally are as large as 25 m/s. Besides showing the monthly mean motion field, we have examined in detail one-level barotropic energy exchanges and fluxes in the GATE A-scale domain. The number of conventional plus non-conventional wind observations are about 400 per day. This is more than has been used in most previous studies. Some of these results of the energetics, especially with regards to the period when Hurricane Agnes formed, are thus of considerable interest.
Abstract
In this paper we present the results of a detailed synoptic compositing technique to determine the structure of a West African monsoon cyclone. The cyclone was in an early stage of development and was confined to the lower troposphere. Coastal weather along West Africa indicated the passage of this disturbance. This was noted from surface observations from ships of opportunity. A calculation of the meridional gradient of potential vorticity was carried out in the region of this disturbance. This calculation showed that the necessary condition for the existence of the combined barotropic-baroclinic instability was satisfied by these data. In order to go one step beyond the necessary conditions of this instability mechanism two very short range numerical prediction experiments are illustrated whose energetics confirm these results. Finally, we also present dynamic vertical motion distributions for this disturbance.
Abstract
In this paper we present the results of a detailed synoptic compositing technique to determine the structure of a West African monsoon cyclone. The cyclone was in an early stage of development and was confined to the lower troposphere. Coastal weather along West Africa indicated the passage of this disturbance. This was noted from surface observations from ships of opportunity. A calculation of the meridional gradient of potential vorticity was carried out in the region of this disturbance. This calculation showed that the necessary condition for the existence of the combined barotropic-baroclinic instability was satisfied by these data. In order to go one step beyond the necessary conditions of this instability mechanism two very short range numerical prediction experiments are illustrated whose energetics confirm these results. Finally, we also present dynamic vertical motion distributions for this disturbance.
Abstract
A high-resolution nested regional spectral model and an ensemble prediction system are combined to forecast the track, intensity, and flooding precipitation arising from Typhoon Winnie of August 1997, which eventually reached supertyphoon status. The prediction of floods is operationally challenging since rainfall distributions can have a high degree of spatial and temporal variability. Rare event probabilities, however, can be estimated more readily via ensemble forecasting. This technique is used to evaluate a typhoon flood event in which rainfall amounts greater than 200 mm led to landslides and major flooding of crops. Seven-member ensembles were generated using an EOF-based technique. An experiment was conducted with a regional model resolution of 0.5° latitude. A Mercator transform grid with a grid mesh size of approximately 55 km in the east–west and 48 km in the north–south was employed. The results indicated very accurate track and intensity forecasts for both the control and ensemble mean. Track position errors remained below 150 km through 72 h, while intensity errors were approximately 5 m s−1 at landfall. Qualitatively, the overall 5-day precipitation patterns appeared realistic and compared favorably with the observed data, while, quantitatively, the correlation coefficient was near 0.6. For stations near and north of where Winnie made landfall, ensemble-based predictions performed well. While the ensemble mean often underestimated the heaviest rainfall totals by approximately 25%–50%, the maximum values within the ensemble spread either exceeded or came within 10%–15% of the station totals. Finally, in a related experiment the horizontal resolution was increased to 0.25° latitude. Even though more precipitation was produced, especially in northeastern China, the ensemble mean was similar to the 0.5° latitude simulation.
Abstract
A high-resolution nested regional spectral model and an ensemble prediction system are combined to forecast the track, intensity, and flooding precipitation arising from Typhoon Winnie of August 1997, which eventually reached supertyphoon status. The prediction of floods is operationally challenging since rainfall distributions can have a high degree of spatial and temporal variability. Rare event probabilities, however, can be estimated more readily via ensemble forecasting. This technique is used to evaluate a typhoon flood event in which rainfall amounts greater than 200 mm led to landslides and major flooding of crops. Seven-member ensembles were generated using an EOF-based technique. An experiment was conducted with a regional model resolution of 0.5° latitude. A Mercator transform grid with a grid mesh size of approximately 55 km in the east–west and 48 km in the north–south was employed. The results indicated very accurate track and intensity forecasts for both the control and ensemble mean. Track position errors remained below 150 km through 72 h, while intensity errors were approximately 5 m s−1 at landfall. Qualitatively, the overall 5-day precipitation patterns appeared realistic and compared favorably with the observed data, while, quantitatively, the correlation coefficient was near 0.6. For stations near and north of where Winnie made landfall, ensemble-based predictions performed well. While the ensemble mean often underestimated the heaviest rainfall totals by approximately 25%–50%, the maximum values within the ensemble spread either exceeded or came within 10%–15% of the station totals. Finally, in a related experiment the horizontal resolution was increased to 0.25° latitude. Even though more precipitation was produced, especially in northeastern China, the ensemble mean was similar to the 0.5° latitude simulation.
This chapter distinguishes the mechanism of tropical convective disturbances, such as a hurricane, from that of the Madden–Julian oscillation (MJO). The hurricane is maintained by organized convection around the azimuth. In a hurricane the organization of convection, the generation of eddy available potential energy, and the transformation of eddy available potential energy into eddy kinetic energy all occur on the scale of the hurricane and these are called “in-scale processes,” which invoke quadratic nonlinearity. The MJO is not a hurricane type of disturbance; organized convection simply does not drive an MJO in the same manner. The maintenance of the MJO is more akin to a multibody problem where the convection is indeed organized on scales of tropical synoptic disturbances that carry a similar organization of convection and carry similar roles for the generation of eddy available potential energy and its conversion to the eddy kinetic energy for their maintenance. The maintenance of the MJO is a scale interaction problem that comes next, where pairs of synoptic-scale disturbances are shown to interact with a member of the MJO time scale, thus contributing to its maintenance. This chapter illustrates the organization of convection, synoptic-scale energetics, and nonlinear scale interactions to show the above aspects for the mechanism of the MJO.
This chapter distinguishes the mechanism of tropical convective disturbances, such as a hurricane, from that of the Madden–Julian oscillation (MJO). The hurricane is maintained by organized convection around the azimuth. In a hurricane the organization of convection, the generation of eddy available potential energy, and the transformation of eddy available potential energy into eddy kinetic energy all occur on the scale of the hurricane and these are called “in-scale processes,” which invoke quadratic nonlinearity. The MJO is not a hurricane type of disturbance; organized convection simply does not drive an MJO in the same manner. The maintenance of the MJO is more akin to a multibody problem where the convection is indeed organized on scales of tropical synoptic disturbances that carry a similar organization of convection and carry similar roles for the generation of eddy available potential energy and its conversion to the eddy kinetic energy for their maintenance. The maintenance of the MJO is a scale interaction problem that comes next, where pairs of synoptic-scale disturbances are shown to interact with a member of the MJO time scale, thus contributing to its maintenance. This chapter illustrates the organization of convection, synoptic-scale energetics, and nonlinear scale interactions to show the above aspects for the mechanism of the MJO.
Abstract
Modeling the geographical distribution of the phase and amplitude of the diurnal change is a challenging problem. This paper addresses the issues of modeling the diurnal mode of precipitation over the Tropics. Largely an early morning precipitation maximum over the oceans and an afternoon rainfall maximum over land areas describe the first-order diurnal variability. However, large variability in phase and amplitude prevails even within the land and oceanic areas. This paper addresses the importance of a multimodel superensemble for much improved prediction of the diurnal mode as compared to what is possible from individual models. To begin this exercise, the skills of the member models, the ensemble mean of the member models, a unified cloud model, and the superensemble for the prediction of total rain as well as its day versus night distribution were examined. Here it is shown that the distributions of total rain over the earth (tropical belt) and over certain geographical regions are predicted reasonably well (RMSE less than 18%) from the construction of a multimodel superensemble. This dataset is well suited for addressing the diurnal change. The large errors in phase of the diurnal modes in individual models usually stem from numerous physical processes such as the cloud radiation, shallow and deep cumulus convection, and the physics of the planetary boundary layer. The multimodel superensemble is designed to reduce such systematic errors and provide meaningful forecasts. That application for the diurnal mode appears very promising. This paper examines some of the regions such as the Tibetan Plateau, the eastern foothills of the Himalayas, and the Amazon region of South America that are traditionally difficult for modeling the diurnal change. In nearly all of these regions, errors in phase and amplitude of the diurnal mode of precipitation increase with the increased length of forecasts. Model forecast errors on the order of 6–12 h for phase and 50% for the amplitude are often seen from the member models. The multimodel superensemble reduces these errors and provides a close match (RMSE < 6 h) to the observed phase. The percent of daily rain and their phases obtained from the multimodel superensemble at 3-hourly intervals for different regions of the Tropics showed a closer match (pattern correlation about 0.4) with the satellite estimates. This is another area where the individual member models conveyed a much lower skill.
Abstract
Modeling the geographical distribution of the phase and amplitude of the diurnal change is a challenging problem. This paper addresses the issues of modeling the diurnal mode of precipitation over the Tropics. Largely an early morning precipitation maximum over the oceans and an afternoon rainfall maximum over land areas describe the first-order diurnal variability. However, large variability in phase and amplitude prevails even within the land and oceanic areas. This paper addresses the importance of a multimodel superensemble for much improved prediction of the diurnal mode as compared to what is possible from individual models. To begin this exercise, the skills of the member models, the ensemble mean of the member models, a unified cloud model, and the superensemble for the prediction of total rain as well as its day versus night distribution were examined. Here it is shown that the distributions of total rain over the earth (tropical belt) and over certain geographical regions are predicted reasonably well (RMSE less than 18%) from the construction of a multimodel superensemble. This dataset is well suited for addressing the diurnal change. The large errors in phase of the diurnal modes in individual models usually stem from numerous physical processes such as the cloud radiation, shallow and deep cumulus convection, and the physics of the planetary boundary layer. The multimodel superensemble is designed to reduce such systematic errors and provide meaningful forecasts. That application for the diurnal mode appears very promising. This paper examines some of the regions such as the Tibetan Plateau, the eastern foothills of the Himalayas, and the Amazon region of South America that are traditionally difficult for modeling the diurnal change. In nearly all of these regions, errors in phase and amplitude of the diurnal mode of precipitation increase with the increased length of forecasts. Model forecast errors on the order of 6–12 h for phase and 50% for the amplitude are often seen from the member models. The multimodel superensemble reduces these errors and provides a close match (RMSE < 6 h) to the observed phase. The percent of daily rain and their phases obtained from the multimodel superensemble at 3-hourly intervals for different regions of the Tropics showed a closer match (pattern correlation about 0.4) with the satellite estimates. This is another area where the individual member models conveyed a much lower skill.
Abstract
This study examines the impact of rain-rate initialization (RINIT), microphysical modifications, and cloud torques (in the context of angular momentum) on hurricane intensity forecasts using a mesoscale model [the Advanced Research Weather Research and Forecasting model (ARW-WRF)] at a cloud-resolving resolution of 2.7 km. The numerical simulations are performed in a triple-nested manner (25, 8.3, and 2.7 km) for Hurricane Dennis of 2005. Unless mentioned otherwise, all the results discussed are from the innermost grid with finest resolution (2.7 km). It is found that the model results obtained from the RINIT technique demonstrated robust improvement in hurricane structure, track, and intensity forecasts compared to the control experiment (CTRL; i.e., without RINIT). Thereafter, using RINIT initial conditions datasets three sensitive experiments are designed by modifying specific ice microphysical parameters (i.e., temperature-independent snow intercept parameter, doubling number of concentrations of ice, and ice crystal diameter) within the explicit parameterization scheme [i.e., the WRF Single-Moment 6-class (WSM6)]. It is shown that the experiment with enhanced ice mass concentration and temperature-independent snow intercept parameter produces the strongest and weakest storms, respectively. The results suggest that the distributions of hydrometeors are also impacted by the limited changes introduced in the microphysical scheme (e.g., the quantitative amount of snow drastically reduced to 0.1–0.2 g kg−1 when the intercept parameter of snow is made independent of temperature). It is noted that the model holds ice at a warmer temperature for a longer time with a temperature-independent intercept parameter. These variations in hydrometeor distribution in the eyewall region of the storm affect diabatic heating and vertical velocity structure and modulated the storm intensity. However, irrespective of the microphysical changes the quantitative amount of graupel hydrometeors remained nearly unaffected. Finally, the indirect effect of microphysical modifications on storm intensity through angular momentum and cloud torques is examined. A formulation to predict the short-term changes in the storm intensity using a parcel segment angular momentum budget method is developed. These results serve to elucidate the indirect impact of microphysical modifications on tropical cyclone intensity changes through modulation in cloud torque magnitude.
Abstract
This study examines the impact of rain-rate initialization (RINIT), microphysical modifications, and cloud torques (in the context of angular momentum) on hurricane intensity forecasts using a mesoscale model [the Advanced Research Weather Research and Forecasting model (ARW-WRF)] at a cloud-resolving resolution of 2.7 km. The numerical simulations are performed in a triple-nested manner (25, 8.3, and 2.7 km) for Hurricane Dennis of 2005. Unless mentioned otherwise, all the results discussed are from the innermost grid with finest resolution (2.7 km). It is found that the model results obtained from the RINIT technique demonstrated robust improvement in hurricane structure, track, and intensity forecasts compared to the control experiment (CTRL; i.e., without RINIT). Thereafter, using RINIT initial conditions datasets three sensitive experiments are designed by modifying specific ice microphysical parameters (i.e., temperature-independent snow intercept parameter, doubling number of concentrations of ice, and ice crystal diameter) within the explicit parameterization scheme [i.e., the WRF Single-Moment 6-class (WSM6)]. It is shown that the experiment with enhanced ice mass concentration and temperature-independent snow intercept parameter produces the strongest and weakest storms, respectively. The results suggest that the distributions of hydrometeors are also impacted by the limited changes introduced in the microphysical scheme (e.g., the quantitative amount of snow drastically reduced to 0.1–0.2 g kg−1 when the intercept parameter of snow is made independent of temperature). It is noted that the model holds ice at a warmer temperature for a longer time with a temperature-independent intercept parameter. These variations in hydrometeor distribution in the eyewall region of the storm affect diabatic heating and vertical velocity structure and modulated the storm intensity. However, irrespective of the microphysical changes the quantitative amount of graupel hydrometeors remained nearly unaffected. Finally, the indirect effect of microphysical modifications on storm intensity through angular momentum and cloud torques is examined. A formulation to predict the short-term changes in the storm intensity using a parcel segment angular momentum budget method is developed. These results serve to elucidate the indirect impact of microphysical modifications on tropical cyclone intensity changes through modulation in cloud torque magnitude.
