Diurnal variation of cloud radiative forcing (CRF) is a major factor that controls the global radiation balance. This study presents multi-year seasonal mean diurnal variations of longwave cloud radiative forcing (LWCRF) and daytime shortwave cloud radiative forcing (SWCRF) at the top of atmosphere over tropics, derived from the broadband radiation measurements made by ScaRaB/3 onboard the low-inclination Megha-Tropiques satellite. The largest LWCRF (60–80 Wm⁻²) occurs over the oceanic regions of the east equatorial Indian Ocean and the western Pacific during all seasons, as well as the South Pacific Convergence Zone, the northeast Bay of Bengal, Amazon region, central and southern Africa and north Indian landmass (monsoon trough) during the local summer. Diurnal variations of 15–25 Wm⁻² in LWCRF (20–35% of the mean) are observed with peak values occurring at 18–21 local time (LT) over continents and 00–06 LT over oceans. The minimum LWCRF occurs at 09–12 LT throughout the tropics. Over convective regions, SWCRF maximizes at 12–15 LT (− 220 to − 300 Wm⁻²) and has a higher magnitude over continents due to early convection occurrence, indicating the importance of diurnal phase. Certain specific features including the CRF associated with the double inter-tropical convergence zone, day-night changes in net CRF, and the effect of El Ni\(\stackrel{\sim }{\mathrm{n}}\)o on CRF are also presented. The net CRF and its zonal variations are strikingly similar during the normal and El Ni\(\stackrel{\sim }{\mathrm{n}}\)o periods because the changes in LWCRF and SWCRF are mutually compensated.

云辐射强迫（CRF）的日变化是控制全球辐射平衡的主要因素。这项研究显示了热带地区大气顶部长波云辐射强迫（LWCRF）和白天短波云辐射强迫（SWCRF）的多年季节平均日变化，这是根据低空卫星上ScaRaB / 3进行的宽带辐射测量得出的Megha-Tropiques卫星的倾角。在所有季节中，最大的低WCRF（60–80 Wm ^-2）发生在赤道东印度洋和西太平洋的海洋区域，以及南太平洋汇聚区，孟加拉东北湾，亚马逊地区，中部和中部。南部非洲和北印度的陆地（季风槽）在当地夏季。15–25 Wm ^-2的日变化在LWCRF中观测到（平均值的20-35％），峰值出现在各大陆的18-21本地时间（LT），而发生在海洋的00-06 LT。整个热带地区，最低的LWCRF出现在09-12 LT。在对流区域，SWCRF在12-15 LT（-220至-300 Wm ^-2）时最大，由于早期对流的发生，在大陆上具有更高的强度，表明昼夜相的重要性。某些特定功能包括与双重热带收敛带相关的CRF，净CRF的昼夜变化以及El Ni \（\ stackrel {\ sim} {\ mathrm {n}} \） o对CRF的影响还介绍了。在正常和El Ni期间，净CRF及其区域变化非常相似。（\ stackrel {\ sim} {\ mathrm {n}} \）o个周期，因为LWCRF和SWCRF的变化是相互补偿的。