Within the Zebiak‐Cane model, we identify two types of initial errors that have significant season‐dependent evolutions related to the spring predictability barrier (SPB) for El Niño events. One type includes the sea surface temperature anomaly (SSTA) errors that have a zonal dipolar pattern with positive anomalies in the central equatorial Pacific and negative ones in the eastern equatorial Pacific; the other type consists of the SSTA errors with a spatial structure opposite to that of the former type, the zonal dipolar pattern shows negative anomalies in the central equatorial Pacific and positive anomalies in the eastern equatorial Pacific. The patterns of these two types of errors are nearly opposite of each other. The former causes the El Niño event to be underpredicted, and the latter causes the El Niño event to be overpredicted. For strong El Niño events the former tends to have a larger effect on the predictions than the latter, but for weak El Niño events, it is very difficult to determine which type of initial errors results in worse predictions. It is thought that strong (weak) El Niño events could be affected by strong (weak) nonlinearities. There are also other initial errors; however, they do not yield considerable season‐dependent evolutions nor can a common characteristic be extracted from their patterns. The two types of initial errors suggest two dynamical behaviors of error growth related to the SPB: in one case, the initial errors grow in a manner similar to the El Niño events; in the other case, the initial errors develop with a tendency opposite to the El Niño events. The two types of initial errors may capture the errors that exhibit significant season‐dependent evolutions related to the SPB. In addition, they may provide information regarding the “sensitive area” of ENSO predictions because of their localized regions. Therefore, if these types of initial errors exist in the realistic El Niño–Southern Oscillation (ENSO) predictions and if a data assimilation or a target method can filter them, the ENSO forecast skill may be improved. For ensemble forecast studies, different signs of prediction errors caused by the two types of initial errors could illustrate why the ensemble mean offers a better forecast than a single prediction.

Abstract:In the summertime, convective cells occur frequently over the Tibetan Plateau (TP) because of the large dynamic and thermal effects of the landmass. Measurements of vertical air velocity in convective cloud are useful for advancing our understanding of the dynamic and microphysical mechanisms of clouds and can be used to improve the parameterization of current numerical models. This paper presents a technique for retrieving high-resolution vertical air velocities in convective clouds over the TP through the use of Doppler spectra from vertically pointing Ka-band cloud radar. The method was based on the development of a "small-particle-traced" idea and its associated data processing, and it used three modes of radar. Spectral broadening corrections, uncertainty estimations, and results merging were used to ensure accurate results. Qualitative analysis of two typical convective cases showed that the retrievals were reliable and agreed with the expected results inferred from other radar measurements. A quantitative retrieval of vertical air motion from a ground-based optical disdrometer was used to compare with the radar-derived result. This comparison illustrated that, while the data trends from the two methods of retrieval were in agreement while identifying the updrafts and downdrafts, the cloud radar had a much higher resolution and was able to reveal the small-scale variations in vertical air motion.

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Background:The prognosis for advanced hepatocellular carcinoma (HCC) remains clinically unsatisfying.Apatinib has proven to be a very effective treatment for advanced HCC in our previous retrospective study.Our aim in this study was to evaluate the efficacy, safety, and toxicity of apatinib in patients with advanced HCC.Methods: This single-arm, open-label phase II clinical trial enrolled patients with advanced HCC. These patients received apatinib, 500 mg once daily, until disease progression, unacceptable toxicity, consent withdrawal, or death. One treatment cycle consisted of 4 weeks of apatinib treatment. The response evaluation criteria in solid tumors (RECIST) was used to assess tumor response every 1-2 cycles. The primary endpoint was the objective response rate (ORR), while the secondary endpoints were the overall survival (OS), progression-free survival (PFS), disease control rate (DCR), and toxicity. Results:Between December 2016 and June 2018, 23 patients were enrolled in the study, 22 of whom were available for response evaluation. The cutoff date was August 10, 2018. The overall ORR and DCR were 30.4% and 65.2%, respectively. The median OS and PFS were 13.8 (95% CI: 5.3-22.3) and 8.7 (95% CI: 5.9-11.1) months, respectively. The most common treatment-related adverse events were proteinuria (39.1%), hypertension (34.8%), and hand-foot-skin reaction (34.8%).Conclusions: Apatinib showed robust clinical activity in patients with advanced HCC. Moreover, apatinib was safe to use, well tolerated, and had acceptable toxicity. (NCT03046979).