The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000. Differences are found to some extent between what is found and classic conceptual models in that (1) the horizontal str...The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000. Differences are found to some extent between what is found and classic conceptual models in that (1) the horizontal structure is asymmetric and variable so that the low-value centers at low levels of the geopotential height field (or the high-value centers at high levels) do not necessarily coincide with the high-value centers of the temperature field; (2) the vertical structure is also variable in the allocation of the anomalies of the geopotential height field between low values at low levels and high values at high levels. It is especially noted that the centers of the anomalies are tilting at both high and low levels or the high level is only at the edge of a high-pressure zone. There is not any significant high-value anomalous center in a corresponding location with the tropical cyclone. The structure of tropical cyclone in the TOVS is also used as reference to modify the structure of typhoon BOGUS in the numerical prediction model system of tropical cyclones. It is found that the modified BOGUS performs better in coordinating with the environment and predicting the track of the tropical cyclone. The demonstration is two-fold the structure of the typhoon BOGUS is such that it means much in the track prediction and the use of the TOVS-based tropical cyclone structure really helps in improving it. It provides the foundation for modification and evolution of typhoon BOGUS.展开更多
This study evaluates the impact of atmospheric observations from the Tropospheric Airborne Meteorological Data Reporting (TAMDAR) observing system on numerical weather prediction of hurricane Ike (2008) using three-di...This study evaluates the impact of atmospheric observations from the Tropospheric Airborne Meteorological Data Reporting (TAMDAR) observing system on numerical weather prediction of hurricane Ike (2008) using three-dimensional data assimilation system for the Weather Research and Forecast (WRF) model (WRF 3D-Var). The TAMDAR data assimilation capability is added to WRF 3D-Var by incorporating the TAMDAR observation operator and corresponding observation processing procedure. Two 6-h cycling data assimilation and forecast experiments are conducted. Track and intensity forecasts are verified against the best track data from the National Hurricane Center. The results show that, on average, assimilating TAMDAR observations has a positive impact on the forecasts of hurricane Ike. The TAMDAR data assimilation reduces the track errors by about 30 km for 72-h forecasts. Improvements in intensity forecasts are also seen after four 6-h data assimilation cycles. Diagnostics show that assimilation of TAMDAR data improves subtropical ridge and steering flow in regions along Ike's track, resulting in better forecasts.展开更多
A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in orde...A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in order to provide longer time typhoon track forecast. The results show that T106L19 could provide a better forecast to typhoon tracks when the B-TC was added, especially when the typhoon vortex is even weaker. The sensitive experiments on where to add the B-TC show that the results from adding the B-TC into the first guess field are better. The results also show that the initialization smoothes the B-TC a lot and this will affect the typhoon track prediction.展开更多
This paper presents a composite interaction formula based on the discrete-interaction operator of wave-wave nonlinear interaction for deriving its adjoint source function in the wave assimilation model. Assimilation e...This paper presents a composite interaction formula based on the discrete-interaction operator of wave-wave nonlinear interaction for deriving its adjoint source function in the wave assimilation model. Assimilation experiments were performed using the significant wave heights observed by the TOPES/POSEIDON satellite, and the gradient distribution in the physical space was also analyzed preliminarily.展开更多
There was a new concept of ‘adaptive or targeting observation’ in recent years, which is anadditional and targeting observation based on the existing and fixed observing network for the atmosphere on theimpacted reg...There was a new concept of ‘adaptive or targeting observation’ in recent years, which is anadditional and targeting observation based on the existing and fixed observing network for the atmosphere on theimpacted region. Dropsonde is one of the important observing instruments in the adaptive or targetingobservation. In this paper, GRAPES, the next generation of numerical weather prediction system of China hasbeen used. The impacts on the typhoon Dujuan (No.200315) forecast in experiments with dropsonde have beenstudied and experiments on sensitivity have also been done. It was found that the forecasts of the elements havebeen improved obviously with the use of dropsonde, such as the path, the center location, and the intensity oftyphoon. It was also found in the sensitivity studies that the setting of deviation structure also has obviousimpacts on the forecast for typhoons. It is not true that the simulation is better when the proportion of the data ofdropsonde is larger in the course to modify the background.展开更多
Wind and solar energy are projected to be major sources of the world's power in the coming decades.In this study,we first introduce satellite observations for surface solar irradiance and wind,and then discuss usi...Wind and solar energy are projected to be major sources of the world's power in the coming decades.In this study,we first introduce satellite observations for surface solar irradiance and wind,and then discuss using the data for prediction and assessment of energy distribution.Using the current NCEP global forecast model (GFS),the global mean and standard deviation of solar power at the surface for the 5-d forecast are about 212 and 124 W/m2,respectively.For a 24-h forecast of a 3-h mean,the relative error is about 30%,and for a prediction of the daily mean,it is about 15%.The relative error of wind power forecasts for a 24-h forecast of a 3-h mean and a daily mean is 70% and 35%,respectively.The reanalysis results based on satellite observations and numerical weather prediction model are also used to study the distribution of solar and wind energy and the variation of the distribution related to climate change.No significant trend in downward solar radiation is found at the surface in the reanalysis data sets.Surface wind power however exhibits a significant positive trend as the global temperature is warming up.A comparison of a decadal mean wind energy between two decades (from 1949 to 1958 vs.from 1999 to 2008) shows that most of Asia had experienced a decrease in surface wind energy.Therefore,decisions about renewable energy developments need to consider such climate change scenarios.展开更多
基金Research on Monitoring & Forecasting Techniques for Calamities by Typhoons Making Landfall on China key project of Ministry of Sci. & Tech.(2001DIA20026) Study on Pre-warning Techniques for Calamities caused by Landfalls of South China Sea Tropical Cyc
文摘The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000. Differences are found to some extent between what is found and classic conceptual models in that (1) the horizontal structure is asymmetric and variable so that the low-value centers at low levels of the geopotential height field (or the high-value centers at high levels) do not necessarily coincide with the high-value centers of the temperature field; (2) the vertical structure is also variable in the allocation of the anomalies of the geopotential height field between low values at low levels and high values at high levels. It is especially noted that the centers of the anomalies are tilting at both high and low levels or the high level is only at the edge of a high-pressure zone. There is not any significant high-value anomalous center in a corresponding location with the tropical cyclone. The structure of tropical cyclone in the TOVS is also used as reference to modify the structure of typhoon BOGUS in the numerical prediction model system of tropical cyclones. It is found that the modified BOGUS performs better in coordinating with the environment and predicting the track of the tropical cyclone. The demonstration is two-fold the structure of the typhoon BOGUS is such that it means much in the track prediction and the use of the TOVS-based tropical cyclone structure really helps in improving it. It provides the foundation for modification and evolution of typhoon BOGUS.
基金funded by the Air Dat projectThe National Center for Atmospheric Research is sponsored by the National Science Foundation
文摘This study evaluates the impact of atmospheric observations from the Tropospheric Airborne Meteorological Data Reporting (TAMDAR) observing system on numerical weather prediction of hurricane Ike (2008) using three-dimensional data assimilation system for the Weather Research and Forecast (WRF) model (WRF 3D-Var). The TAMDAR data assimilation capability is added to WRF 3D-Var by incorporating the TAMDAR observation operator and corresponding observation processing procedure. Two 6-h cycling data assimilation and forecast experiments are conducted. Track and intensity forecasts are verified against the best track data from the National Hurricane Center. The results show that, on average, assimilating TAMDAR observations has a positive impact on the forecasts of hurricane Ike. The TAMDAR data assimilation reduces the track errors by about 30 km for 72-h forecasts. Improvements in intensity forecasts are also seen after four 6-h data assimilation cycles. Diagnostics show that assimilation of TAMDAR data improves subtropical ridge and steering flow in regions along Ike's track, resulting in better forecasts.
基金Key scientific research project for the State Meteorological Administration in the 9 five-year development plan (ZX95-01)
文摘A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in order to provide longer time typhoon track forecast. The results show that T106L19 could provide a better forecast to typhoon tracks when the B-TC was added, especially when the typhoon vortex is even weaker. The sensitive experiments on where to add the B-TC show that the results from adding the B-TC into the first guess field are better. The results also show that the initialization smoothes the B-TC a lot and this will affect the typhoon track prediction.
文摘This paper presents a composite interaction formula based on the discrete-interaction operator of wave-wave nonlinear interaction for deriving its adjoint source function in the wave assimilation model. Assimilation experiments were performed using the significant wave heights observed by the TOPES/POSEIDON satellite, and the gradient distribution in the physical space was also analyzed preliminarily.
基金Multiple time levels of Dynamic / Physical Processes with Lagrange Non-hydrostatic GlobalModel and Study on the Coordination of Correlation (40575050)
文摘There was a new concept of ‘adaptive or targeting observation’ in recent years, which is anadditional and targeting observation based on the existing and fixed observing network for the atmosphere on theimpacted region. Dropsonde is one of the important observing instruments in the adaptive or targetingobservation. In this paper, GRAPES, the next generation of numerical weather prediction system of China hasbeen used. The impacts on the typhoon Dujuan (No.200315) forecast in experiments with dropsonde have beenstudied and experiments on sensitivity have also been done. It was found that the forecasts of the elements havebeen improved obviously with the use of dropsonde, such as the path, the center location, and the intensity oftyphoon. It was also found in the sensitivity studies that the setting of deviation structure also has obviousimpacts on the forecast for typhoons. It is not true that the simulation is better when the proportion of the data ofdropsonde is larger in the course to modify the background.
基金supported by National Basic Research Program of China (Grant No. 2010CB951600)NOAA Center for Satellite Applications and Research
文摘Wind and solar energy are projected to be major sources of the world's power in the coming decades.In this study,we first introduce satellite observations for surface solar irradiance and wind,and then discuss using the data for prediction and assessment of energy distribution.Using the current NCEP global forecast model (GFS),the global mean and standard deviation of solar power at the surface for the 5-d forecast are about 212 and 124 W/m2,respectively.For a 24-h forecast of a 3-h mean,the relative error is about 30%,and for a prediction of the daily mean,it is about 15%.The relative error of wind power forecasts for a 24-h forecast of a 3-h mean and a daily mean is 70% and 35%,respectively.The reanalysis results based on satellite observations and numerical weather prediction model are also used to study the distribution of solar and wind energy and the variation of the distribution related to climate change.No significant trend in downward solar radiation is found at the surface in the reanalysis data sets.Surface wind power however exhibits a significant positive trend as the global temperature is warming up.A comparison of a decadal mean wind energy between two decades (from 1949 to 1958 vs.from 1999 to 2008) shows that most of Asia had experienced a decrease in surface wind energy.Therefore,decisions about renewable energy developments need to consider such climate change scenarios.