Two Papers More Papers On The Important Role Of Regional Circulations on Climate Including Extreme Weather Events

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The importance of regional atmospheric and ocean circulations has been a major theme in my posts on the possible role of humans on the climate system; e.g. see

What is the Importance to Climate of Heterogeneous Spatial Trends in Tropospheric Temperatures?

The most significant effect of human climate forcing  (as well as from natural forcing) is any change in these circulation features over time. A global, annual average surface temperature trend is a useless metric for this purpose.

There is another such regional circulation feature that is the focus of two research papers that has received less scutiny than others such as ENSO, the NAO and the PDO [although colleagues such as Peter Webster and Madhav Khandekar are certainly aware of this climate feature]. This circulation feature is called the Indian Ocean  Dipole (IOD).  The two new papers are

Netrananda Sahu, Swadhin K. Behera, Yosuke Yamashiki, Kaoru Takara and Toshio Yamagata, 2011: IOD and ENSO impacts on the extreme stream-flows of Citarum river in Indonesia, Climate Dynamics 2011, DOI: 10.1007/s00382-011-1158-2

The abstract reads [highlight added]

Extreme stream-flow events of Citarum River are derived from the daily stream-flows at the Nanjung gauge station. Those events are identified based on their persistently extreme flows for 6 or more days during boreal fall when the seasonal mean stream-flow starts peaking-up from the lowest seasonal flows of June–August. Most of the extreme events of high-streamflows were related to La Niña conditions of tropical Pacific. A few of them were also associated with the negative phases of IOD and the newly identified El Niño Modoki. Unlike the cases of extreme high streamflows, extreme low streamflow events are seen to be associated with the positive IODs. Nevertheless, it was also found that the low-stream-flow events related to positive IOD events were also associated with El Nino events except for one independent event of 1977. Because the occurrence season coincides the peak season of IOD, not only the picked extreme events are seen to fall under the IOD seasons but also there exists a statistically significant correlation of 0.51 between the seasonal IOD index and the seasonal streamflows. There also exists a significant lag correlation when IOD of June–August season leads the streamflows of September–November. A significant but lower correlation coefficient (0.39) is also found between the seasonal streamflow and El Niño for September–November season only.

The second paper is

Sahu et al 2012: Large impacts of Indo-Pacific Climate Modes on Extreme Streamflows of Citarum River in Indonesia. J. of Global Environmental Engineering. Vol. 17, pp. 1-8.

The abstract reads [unfortunately, a url does not exist for the paper that I or the author can find].

Large impacts of climate variations modes are found on the extreme stream-flow events of Citarum River derived from the daily stream-flows at the Nanjung gauge station. Extreme events are identified based on their persistent flow for 5 or more days in DJF and MAM seasons when the seasonal mean stream-flows are high. During DJF the positive phases of the Indian Ocean Dipole (IOD) are associated with extremely low-stream-flow events. Except for  one independent IOD events, all low-stream-flow events related to positive IOD events were also associated with El Niño events. However, none of the low-stream-flow events were uniquely associated with El Niño events independent of IOD events in the Indian Ocean. In addition, a few rare low-stream-flow events in DJF associated with La Niña are also accompanied by positive IOD. Therefore, the positive IOD has overwhelmingly negative impacts on stream-flows of Citarum River. The extreme events of high-stream-flows were mostly related to La Niña conditions during DJF  and MAM. Some of the extreme high-flow events were also associated with the negative phases of IOD with a characteristically opposite conditions to that of the positive phase.  Interestingly, La Niña Modokis dominantly influenced the low-stream-flow events when cold anomalies of sea surface temperature flanked the coast of Java-Sumatra in MAM.

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