In this study, we examined the temporal variations of the El Niño-Southern Oscillation (ENSO) prediction skill during 1958–2016 in the context of the evolution in the tropical Pacific subsurface ocean observing system. To examine the temporal variations of the seasonal prediction skill, spatial correlation skill (SCS) of the predicted SST anomalies (SSTA) in the tropical Pacific Ocean within 10^oS-10^oN and temporal correlation skill (TCS) of the area-averaged SSTA throughout the same basin for the four periods of 1958–1978, 1979–1994, 1995–2005 and 2006–2016 were evaluated. These periods correspond to low amount, first increase, medium amount and second increase of the subsurface ocean temperature observations. Our results show that the influence of the observing system is detectable in the skill increase—both in SCS and TCS metrics—during the period 1995–2005. However, the impact of the subsurface ocean observing system is difficult to quantify in the prediction skill metrics during 2006–2016. It is shown that SCS is determined to a large extent by the magnitude of the observed SSTA in the target month. There is visible skill increase in the TCS before and after 1979, but this appears to be the result of variations in the properties of the verifying SST. Thus, potential impacts of the observing system are masked by climate variations of SST at decadal time scales, which may be real or result of variations in the SST observing system. In particular, the multidecadal modulations of the tropical Pacific SST associated with the climate shifts in the late 1970s and the early 2000s have more significant influence on prediction skill than the changes in observing system.

在这项研究中，我们研究了1958-2016年厄尔尼诺-南方涛动（ENSO）预测技能在时间上的变化，其背景是热带太平洋海表下海洋观测系统的演变。为了检查季节性预报技巧的时间变化，我们将在10 ^o S-10 ^o内将热带太平洋的SST异常预报（SSTA）的空间相关技巧（SCS）对1958–1978年，1979–1994年，1995–2005年和2006–2016年这四个时期的同一盆地面积平均SSTA的N和时间相关技能（TCS）进行了评估。这些时期对应于地下海洋温度观测的少量，第一次增加，中等数量和第二次增加。我们的结果表明，在1995年至2005年期间，无论是SCS还是TCS指标，在技能提升中都可以检测到观测系统的影响。然而，在2006-2016年期间，很难用预测技能指标来量化地下海洋观测系统的影响。结果表明，SCS很大程度上取决于目标月份中观测到的SSTA的大小。1979年前后，TCS的技能有了明显的提高，但这似乎是验证SST属性变化的结果。因此，SST观测系统的潜在影响被年代际尺度上的SST气候变化所掩盖，这可能是真实的，也可能是SST观测系统变化的结果。特别是，与观测系统的变化相比，1970年代末期和2000年代初与气候变化相关的热带太平洋海表温度的多年代际调制。