We show that the time series of sunspot group areas has a gap, the so-called Gnevyshev gap (GG), between ascending and descending phases of the cycle and especially so for the even-numbered cycles. For the odd cycles this gap is less obvious, and is only a small decline after the maximum of the cycle. We resample the cycles to have the same length of 3945 days (about 10.8 years), and show that the decline is between 1445 – 1567 days after the start of the cycle for the even cycles, and extending sometimes until 1725 days from the start of the cycle. For the odd cycles the gap is a little earlier, 1332 – 1445 days after the start of the cycles with no extension. We analyze geomagnetic disturbances for Solar Cycles 17 – 24 using the Dst-index, the related Dxt- and Dcx-indices, and the Ap-index. In all of these time series there is a decline at the time, or somewhat after, the GG in the solar indices, and it is at its deepest between 1567 – 1725 days for the even cycles and between 1445 – 1567 days for the odd cycles. The averages of these indices for even cycles in the interval 1445 – 1725 are 46%, 46%, 18%, and 29% smaller compared to surrounding intervals of similar length for Dst, Dxt, Dcx, and Ap, respectively. For odd cycles the averages of the Dst- and Dxt-indices between 1322 – 1567 days are 31% and 12% smaller than the surrounding intervals, but not smaller for the Dcx-index and only 4% smaller for the Ap-index. The declines are significant at the 99% level for both even and odd cycles of the Dst-index and for the Dxt-, Dcx- and Ap-indices for even cycles. For odd cycles of the Dxt-index the significance is 95%, but the decline is insignificant for odd cycles of the Dcx- and Ap-indices.

中文翻译：

---

偶数和奇数太阳周期 SC17 – SC24 期间地磁指数的比较：地磁活动中格涅维雪夫间隙的特征

我们表明，太阳黑子群区域的时间序列在周期的上升和下降阶段之间存在间隙，即所谓的格涅维雪夫间隙（GG），尤其是偶数周期。对于奇数周期，这种差距不太明显，只是在周期的最大值之后小幅下降。我们对周期重新采样，使其具有相同的 3945 天（约 10.8 年）长度，并表明偶数周期的周期开始后 1445 至 1567 天之间下降，有时会延长至 1725 天。循环。对于奇数周期，差距稍早，即周期开始后 1332 – 1445 天，没有延长。我们使用 Dst 指数、相关的 Dxt 和 Dcx 指数以及 Ap 指数分析了太阳周期 17 – 24 的地磁扰动。在所有这些时间序列中，太阳指数中 GG 的时间或之后都有下降，并且在偶数周期的 1567 - 1725 天和奇数周期的 1445 - 1567 天之间达到最深. 与 Dst、Dxt、Dcx 和 Ap 的类似长度的周围间隔相比，这些指数在 1445 – 1725 区间内的偶数周期的平均值分别小 46%、46%、18% 和 29%。对于奇数周期，1322 至 1567 天之间的 Dst 和 Dxt 指数的平均值比周围间隔小 31% 和 12%，但 Dcx 指数不小，Ap 指数仅小 4%。对于 Dst 指数的偶数和奇数周期以及偶数周期的 Dxt-、Dcx- 和 Ap 指数，下降幅度均在 99% 的水平。对于 Dxt 指数的奇数周期，显着性为 95%，