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- Author or Editor: A. P. Mitra x
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Abstract
An atmospheric model for the height range 100–700 km, likely to hold for solar minimum conditions, has been developed. The flux density of solar radiation at 10.7 cm wavelength (F 10.7) is taken to be 70 × 10−22 w m−2 (cps)−1. The model is based on extrapolation to 70 units, of density and density scale heights at different solar activity periods, in the height range of 250–700 km, deduced from drag observations of 46 satellites (King-Hele and Walker, 1961; Martin et al., 1961; King-Hele and Rees, 1963; King-Hele and Quinn, 1965) during the period 1958 (F 10.7 ∼ 230 units) to early 1964 (F 10.7 ∼ 80 units), for diurnal minimum and maximum conditions. In the range of 100–250 km, density values obtained from various rocket flights to early 1964 (F 10.7∼80 units) have been used. The model gives the distribution of neutral particles, i.e., n(O2), n(N2), n(O), n(He), n(H); atmospheric scale height (H); mean molecular mass (m¯); atmospheric temperature (T) and atmospheric pressure (p) with height up to 700 km. Diffusive equilibrium for N2, O2 and O has been assumed to hold above 130 km, for He above 100 km and for H above 500 km. In the region of dissociation, observed values of n(O)/n(O2) of Schaefer and Brown (1964) have been adopted. The results are discussed and compared with those given by other workers.
Abstract
An atmospheric model for the height range 100–700 km, likely to hold for solar minimum conditions, has been developed. The flux density of solar radiation at 10.7 cm wavelength (F 10.7) is taken to be 70 × 10−22 w m−2 (cps)−1. The model is based on extrapolation to 70 units, of density and density scale heights at different solar activity periods, in the height range of 250–700 km, deduced from drag observations of 46 satellites (King-Hele and Walker, 1961; Martin et al., 1961; King-Hele and Rees, 1963; King-Hele and Quinn, 1965) during the period 1958 (F 10.7 ∼ 230 units) to early 1964 (F 10.7 ∼ 80 units), for diurnal minimum and maximum conditions. In the range of 100–250 km, density values obtained from various rocket flights to early 1964 (F 10.7∼80 units) have been used. The model gives the distribution of neutral particles, i.e., n(O2), n(N2), n(O), n(He), n(H); atmospheric scale height (H); mean molecular mass (m¯); atmospheric temperature (T) and atmospheric pressure (p) with height up to 700 km. Diffusive equilibrium for N2, O2 and O has been assumed to hold above 130 km, for He above 100 km and for H above 500 km. In the region of dissociation, observed values of n(O)/n(O2) of Schaefer and Brown (1964) have been adopted. The results are discussed and compared with those given by other workers.
Abstract
In spite of the summer monsoon’s importance in determining the life and economy of an agriculture-dependent country like India, committed efforts toward improving its prediction and simulation have been limited. Hence, a focused mission mode program Monsoon Mission (MM) was founded in 2012 to spur progress in this direction. This article explains the efforts made by the Earth System Science Organization (ESSO), Ministry of Earth Sciences (MoES), Government of India, in implementing MM to develop a dynamical prediction framework to improve monsoon prediction. Climate Forecast System, version 2 (CFSv2), and the Met Office Unified Model (UM) were chosen as the base models. The efforts in this program have resulted in 1) unparalleled skill of 0.63 for seasonal prediction of the Indian monsoon (for the period 1981–2010) in a high-resolution (∼38 km) seasonal prediction system, relative to present-generation seasonal prediction models; 2) extended-range predictions by a CFS-based grand multimodel ensemble (MME) prediction system; and 3) a gain of 2-day lead time from very high-resolution (12.5 km) Global Forecast System (GFS)-based short-range predictions up to 10 days. These prediction skills are on par with other global leading weather and climate centers, and are better in some areas. Several developmental activities like coupled data assimilation, changes in convective parameterization, cloud microphysics schemes, and parameterization of land surface processes (including snow and sea ice) led to the improvements such as reducing the strong model biases in the Indian summer monsoon simulation and elsewhere in the tropics.
Abstract
In spite of the summer monsoon’s importance in determining the life and economy of an agriculture-dependent country like India, committed efforts toward improving its prediction and simulation have been limited. Hence, a focused mission mode program Monsoon Mission (MM) was founded in 2012 to spur progress in this direction. This article explains the efforts made by the Earth System Science Organization (ESSO), Ministry of Earth Sciences (MoES), Government of India, in implementing MM to develop a dynamical prediction framework to improve monsoon prediction. Climate Forecast System, version 2 (CFSv2), and the Met Office Unified Model (UM) were chosen as the base models. The efforts in this program have resulted in 1) unparalleled skill of 0.63 for seasonal prediction of the Indian monsoon (for the period 1981–2010) in a high-resolution (∼38 km) seasonal prediction system, relative to present-generation seasonal prediction models; 2) extended-range predictions by a CFS-based grand multimodel ensemble (MME) prediction system; and 3) a gain of 2-day lead time from very high-resolution (12.5 km) Global Forecast System (GFS)-based short-range predictions up to 10 days. These prediction skills are on par with other global leading weather and climate centers, and are better in some areas. Several developmental activities like coupled data assimilation, changes in convective parameterization, cloud microphysics schemes, and parameterization of land surface processes (including snow and sea ice) led to the improvements such as reducing the strong model biases in the Indian summer monsoon simulation and elsewhere in the tropics.
