Factors Limiting the Forecast Skill of the Boreal Summer Intraseasonal Oscillation in a Subseasonal-to-Seasonal Model
| العنوان: | Factors Limiting the Forecast Skill of the Boreal Summer Intraseasonal Oscillation in a Subseasonal-to-Seasonal Model |
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| المؤلفون: | Zheng He, Yingxia Gao, Tongwen Wu, Xiangwen Liu, Pang-Chi Hsu |
| المصدر: | Advances in Atmospheric Sciences. 36:104-118 |
| بيانات النشر: | Springer Science and Business Media LLC, 2018. |
| سنة النشر: | 2018 |
| مصطلحات موضوعية: | Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, Anomaly (natural sciences), Forecast skill, Vorticity, 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, Climatology, East Asian Monsoon, Hindcast, Environmental science, Outgoing longwave radiation, 0105 earth and related environmental sciences |
| الوصف: | In this study, we evaluate the forecast skill of the subseasonal-to-seasonal (S2S) prediction model of the Beijing Climate Center (BCC) for the boreal summer intraseasonal oscillation (BSISO). We also discuss the key factors that inhibit the BSISO forecast skill in this model. Based on the bivariate anomaly correlation coefficient (ACC) of the BSISO index, defined by the first two EOF modes of outgoing longwave radiation and 850-hPa zonal wind anomalies over the Asian monsoon region, we found that the hindcast skill degraded as the lead time increased. The ACC dropped to below 0.5 for lead times of 11 days and longer when the predicted BSISO showed weakened strength and insignificant northward propagation. To identify what causes the weakened forecast skill of BSISO at the forecast lead time of 11 days, we diagnosed the main mechanisms responsible for the BSISO northward propagation. The same analysis was also carried out using the observations and the outputs of the four-day forecast lead that successfully predicted the observed northward-propagating BSISO. We found that the lack of northward propagation at the 11-day forecast lead was due to insufficient increases in low-level cyclonic vorticity, moistening and warm temperature anomalies to the north of the convection, which were induced by the interaction between background mean flows and BSISO-related anomalous fields. The BCC S2S model can predict the background monsoon circulations, such as the low-level southerly and the northerly and easterly vertical shears, but has limited capability in forecasting the distributions of circulation and moisture anomalies. |
| تدمد: | 1861-9533 0256-1530 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_________::6d8c2b1db2197816b18f13a9805e9ad9Test https://doi.org/10.1007/s00376-018-7242-3Test |
| حقوق: | CLOSED |
| رقم الانضمام: | edsair.doi...........6d8c2b1db2197816b18f13a9805e9ad9 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 18619533 02561530 |
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