In this paper, we have examined the relationships between the characteristics of interplanetary coronal mass ejections (ICMEs) and geoeffectiveness in the declining phase of Solar Cycles 23 and 24. We discuss the results in comparison with those of the rising phase. Major results of this study are as follows: The ICMEs in the declining phase of Cycle 23 have generated higher storm strength than those in Cycle 24. The mean storm strength of the sheath and ICME for each cycle in the declining phase is greater than in the rising phase. This indicates that the declining phase is more geoeffective than the rising phase. Cycle 24 events seem to be slightly more geoeffective towards the second half of the cycle even though the cycle is weak in the rising phase. The mean radial size of ICMEs is ∼ 0.36 $\sim~0.36$ AU in Cycle 23 and ∼ 0.32 $\sim 0.32$ AU in Cycle 24. Around 25% of the ICMEs in Cycle 23 and 15% in Cycle 24 exceed ∼ 0.5 $\sim 0.5$ AU in size at 1 AU. The correlation between the southward magnetic component ( B s ${B}_{s}$ ) and the storm strength they cause is decisive in both cycles. This substantiates that the storm strength of the ICMEs strongly relies on the ICME B s ${B}_{s}$ in both cycles. The correlation between the storm strength/ B s ${B}_{s}$ and the size of sheath/ICME seems insignificant, which suggests that the storm strength is independent of the size of the ICMEs. Almost 80% of geomagnetic storm peaks occurred in the ICME duration of the declining phase of Cycles 23 and 24, which is substantially identical to the rising phase. Summing up, this sort of study will be eminent to emphasize the variations in the rising and declining phases of solar cycles. The ICMEs are dominant in generating storms both in the rising and declining phases of a solar although in the declining phase they seem to generate more geoeffectiveness than in the rising phase.

中文翻译：

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行星际日冕物质抛射特征与太阳周期23和24下降阶段地球有效性的关系

在本文中，我们研究了行星际日冕物质抛射 (ICME) 特征与太阳活动周期 23 和 24 下降阶段的地球有效性之间的关系。我们将结果与上升阶段的结果进行比较。本研究的主要结果如下： 周期 23 下降阶段的 ICME 产生的风暴强度高于周期 24 的风暴强度。下降阶段每个周期的护套和 ICME 的平均风暴强度大于上升阶段。这表明下降阶段比上升阶段更具地质效益。尽管周期在上升阶段疲软，但周期 24 事件似乎在周期的后半段更具地理效应。ICME 的平均径向尺寸在周期 23 中为 ~ 0.36 $\sim~0.36 $ AU 和 ~ 0.32 $\sim 0。第 24 周期中的 32$ AU。第 23 周期中大约 25% 的 ICME 和第 24 周期中 15% 的 ICME 在 1 AU 时超过了 0.5 $\sim 0.5 $ AU。南向磁分量（ B s ${B}_{s}$ ）与其引起的风暴强度之间的相关性在两个周期中都是决定性的。这证实了 ICME 的风暴强度在两个周期中都强烈依赖于 ICME B s ${B}_{s}$。风暴强度/B s ${B}_{s}$ 与鞘层/ICME 的大小之间的相关性似乎不显着，这表明风暴强度与ICME 的大小无关。几乎 80% 的地磁暴峰值发生在周期 23 和 24 下降阶段的 ICME 持续时间，这与上升阶段基本相同。总而言之，这种研究将突出强调太阳周期上升和下降阶段的变化。