Large‐scale features of satellite‐derived outgoing long‐wave radiation in relation to monsoon circulation over the indian region

Abstract

The monthly mean outgoing long-wave radiation data from June 1974 to May 1981 were analysed for dominant eigenvector patterns. The first three eigenvector patterns explain nearly 93 per cent of the total variance. The first eigenvector pattern exhibits an annual cycle with a pronounced variation in the outgoing long-wave radiation over the tropical belt between lo" and 2WN. This is largely indicative of strong seasonal shift of the major area of cloudiness associated with the Intertropical Convergence Zone. The second eigenvector pattern shows an out-of-phase relationship between north India and the equatorial region, having a pronounced semi-annual oscillation. The third eigenvector pattern exhibits the characteristic features of the north-east monsoon over south-east peninsular India. The first and second harmonics, corresponding to annual and semi-annual oscillations, exhibit the major characteristic features of the first two eigenvectors, respectively.The interannual variation of the outgoing long-wave radiation for the summer monsoon period shows a close association with the large-scale monsoon rainfall over India.It is concluded that the satellite-derived outgoing long-wave radiation can be used to monitor more comprehensively the large-scale monsoon circulation and its year-to-year variability in view of its spatial coverage over oceanic areas.

Role of Microphysics and Convective Autoconversion for the Better Simulation of Tropical Intraseasonal Oscillations (MISO and MJO)

“…The outgoing longwave radiation (OLR) is considered as an indicator of convection (Krishnamurti et al, 1989;Murakami, 1980) and is essential for monsoon circulations (Chaudhari et al, 2010;Prasad & Verma, 1985). Clouds play a seminal role in regulating OLR through the warming (cooling) effect by high (low) level clouds (Chaudhari et al, 2018(Chaudhari et al, , 2019.…”

Intraseasonal variability and possible causes of large-scale and convective precipitations over the Gangetic plain of India

“…It has already been stated that low values of OLR corresponds to strong convective activities in the lower atmosphere and maybe the possibility of precipitation (Prasad and Verma 1985;Arkin et al 1989;Xie and Arkin 1998;Prasad et al2000;Kumar et al 2021). So, the inverse relation between OLR and precipitation could be a tool to understand the behaviour of CP and LSP.…”

“…Since both types of precipitation are associated with convective activity, the LSP and CP may relate with the Outgoing Longwave Radiation (OLR). Earlier researchers (Heddinghaus and Krueger, 1981;Prasad and Verma, 1985;Muthuvel and Arkin, 1992;Xie and Arkin 1998;Kumar et al, 2021) have shown that the low value of OLR corresponds to intense convection whereas a high value of OLR shows cloud-free regions and therefore used for the study of the variability of precipitations. Therefore there may be the possibility of a link between the OLR and the variability in CP and LSP.…”

Forecasting Indian summer monsoon rainfall by outgoing longwave radiation over the Indian Ocean

“…The OLR data have been extensively used, apart from studying the earth radiation budget, in monitoring and understanding the tropical circulation changes and in modelling. Some examples are Murakami (1980), Prasad and Verma (1985), Horel et al (1989), Chelliah and Arkin (1992), Kousky and Kayano (1994) and Moron (1995).…”