bluewave

https://www.nature.com/articles/s41586-019-1764-4 Article Published: 27 November 2019 Twofold expansion of the Indo-Pacific warm pool warps the MJO life cycle Nature volume 575, pages647–651(2019)Cite this article Article metrics 23 Altmetric Metrics details M. K. Roxy, Panini Dasgupta, Michael J. McPhaden, Tamaki Suematsu, Chidong Zhang & Daehyun Kim Abstract The Madden–Julian Oscillation (MJO) is the most dominant mode of subseasonal variability in the tropics, characterized by an eastward-moving band of rain clouds. The MJO modulates the El Niño Southern Oscillation1, tropical cyclones2,3 and the monsoons4,5,6,7,8,9,10, and contributes to severe weather events over Asia, Australia, Africa, Europe and the Americas. MJO events travel a distance of 12,000–20,000 km across the tropical oceans, covering a region that has been warming during the twentieth and early twenty-first centuries in response to increased anthropogenic emissions of greenhouse gases11, and is projected to warm further. However, the impact of this warming on the MJO life cycle is largely unknown. Here we show that rapid warming over the tropical oceans during 1981–2018 has warped the MJO life cycle, with its residence time decreasing over the Indian Ocean by 3–4 days, and increasing over the Indo-Pacific Maritime Continent by 5–6 days. We find that these changes in the MJO life cycle are associated with a twofold expansion of the Indo-Pacific warm pool, the largest expanse of the warmest ocean temperatures on Earth. The warm pool has been expanding on average by 2.3 × 105 km2 (the size of Washington State) per year during 1900–2018 and at an accelerated average rate of 4 × 105 km2(the size of California) per year during 1981–2018. The changes in the Indo-Pacific warm pool and the MJO are related to increased rainfall over southeast Asia, northern Australia, Southwest Africa and the Amazon, and drying over the west coast of the United States and Ecuador. Fig. 1: A twofold expansion of the warm pool. Fig. 2: Changes in the MJO life cycle. Fig. 3: Correlation between MJO phase duration and ocean–atmosphere conditions. Fig. 4: Changes in global rainfall in response to the changes in MJO phase duration. Extended Data Fig. 1 Typical life cycle of the MJO. Extended Data Fig. 2 Annual average period of MJO events. Extended Data Fig. 3 Warm pool area in multiple datasets and breakpoint analysis. Extended Data Fig. 4 Correlation between MJO phase duration and ocean–atmosphere conditions, without removing the trends.

Every month since April has featured top 3 warmth in the Arctic. This is a first for April through October. https://www.esrl.noaa.gov/psd/data/timeseries/

Similar to the findings in this recent paper. https://advances.sciencemag.org/content/4/8/eaat6773 DISCUSSION Implications and outlook The doubling of BG halocline heat content over the past three decades appears attributable to a warming of the source waters that ventilate the layer, where this warming is due to sea ice losses in the Chukchi Sea that leave the surface ocean more exposed to incoming solar radiation in summer. The effects of an efficient local ice-albedo feedback are thus not confined to the surface ocean/sea ice heat budget but, in addition, lead to increased heat accumulation in the ocean interior that has consequences far beyond the summer season. Strong stratification and weak mechanical mixing in the BG halocline ensure that significant summertime heat remains in the halocline through the winter. With continued sea ice losses in the Chukchi Sea, additional heat may continue to be archived in the warm halocline. This underscores the far-reaching implications of changes to the dynamical ice-ocean system in the Chukchi Sea region. However, there is a limit to this: Once the source waters for the halocline become warm enough that their buoyancy is affected, ventilation can be shut off. Efficient summertime subduction relies on the lateral surface front in the NCS region between warm, salty water that is denser to the south and cooler, fresher water that is less dense to the north. For longer-duration solar warming (that is, longer-duration ice-free conditions in the region), SSTs on the south side of the front may become warm enough (around 13°C, under the assumption of a 1.5-month ice-free period dominated by solar absorption) that the lateral density gradient is eliminated [see (24)]. It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics of the Arctic halocline. In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

Updated for the 9th warmest October at EWR and 7th warmest at ISP.

According to the NSIDC data, October 2019 beat 2012 for the lowest monthly average extent. This makes the 3rd new lowest monthly extent record for 2019. It’s also the 10th new lowest monthly extent since 2016. ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Monthly_Data_with_Statistics_G02135_v3.0.xlsx 1 2019 5.66 2 2012 5.89 NSIDC lowest average monthly extents Jan...2018 Feb...2018 Mar...2017 Apr....2019 May...2016 Jun....2016 Jul.....2019 Aug...2012 Sep...2012 Oct...2019 Nov...2016 Dec...2016

While the ESS is finally freezing up, Chukchi extent remains at record low levels for the end of October.

Daniel Swain is probably one of the best sources of information on this topic. While all these California wildfire posts probably belong in a different thread, the information below helps people understand the issues involved. https://insideclimatenews.org/news/13112018/california-deadly-wildfires-climate-change-dry-autumn-late-rainy-season-swain-interview What does the recent data show in California? And how are these changes impacting overall rainfall? We are starting to see a trend towards drier autumns in California. It's somewhat new, it's just emerging from the noise, one might say, but it is actually there. This year is going to add another data point in that direction. It matches climate projections. There has long been an expectation that California's so-called shoulder season precipitation would probably decrease—that's autumn and spring. Now what we're starting to see is, especially in the autumn, that process now appears to be underway. It's both an emerging observation but also a projection for the future, a future that maybe isn't really the future any more. That actually doesn't necessarily mean the overall amount of precipitation is decreasing. There's a growing overall concentration of water in the rainy season. Our research suggests that concentration will be a pretty strong indicator of California's future climate. You've made the point that it's problematic to ask whether climate change causes a specific event. Why is that? In any sort of natural system there's never really, in any context, a singular cause of anything. It depends how you define causation, which then is a non-trivial task. It ends up being more meaningful to say, look, we're going to have fires no matter what. Whether they're caused naturally by lightning, by totally innocent human error or by more malicious human intent. It doesn't really matter what started the fire. But the question is, what factors contribute to what happened after the fire starts. The real question is not so much what caused it, because ultimately it doesn't really matter. The question is what made it as bad as it was. Then you can get an answer that, yes, there is a link between wildfire behavior intensity and climate change. As climate change progresses, what is expected to happen with wildfire season? When it comes to wildfire trends, the last five years in California have really been something else. It's really been hard to watch. it's pretty rare to see such large, dramatic step changes as what we've seen in California in the last five to 10 years. We've broken every record, and we've broken them several times. Largest, most destructive, deadliest—all

Highest rainfall total in CT again. https://nwschat.weather.gov/p.php?pid=201910280141-KOKX-NOUS41-PNSOKX WESTPORT 3.04 801 PM 10/27 CWOP

NSIDC put out a tweet about the new record departure.

It sure is.

This was the warmest June through September melt season on record.The earlier areas of open water had more time to absorb the extra heat. So now it’s taking longer for the Arctic Ocean to release the extra heat back to the atmosphere. Perhaps warm water influx through the Bering Strait also played a role. But I have no way of measuring that. Recent winds (drift circulation) and warmer ocean waters from heat gained during the early spring melt-out

2019 continues to expand its record breaking daily low extents for late October. The NSIDC 5 day extent is now 5.503 million sq km as of October 20th. This is well below the previous lowest for the date set in 2007 at. 5.946 million sq km. It also places this year 726 k lower than 2012 which was 6.229 million sq km.

That anomaly grew a little from yesterday. Now at -3.075 as of October 18th. So 2019 continues as the lowest at 5.310 compared to the 5.663 in 2007 and 5.852 in 2012.

Updated for the second breaking storm of the month. New October Record Low Pressures in New England https://www.washingtonpost.com/weather/2019/10/17/powerful-weather-bomb-socks-new-england-with-wind-gusts-mph-knocking-out-power-more-than-half-million/

Updated for 10-16-19 10-17....Norwich, CT...6.15”...numerous 3.00”+ amounts across the area https://nwschat.weather.gov/p.php?pid=201910171436-KOKX-NOUS41-PNSOKX

They usually release it in December.

The Arctic Ocean must have absorbed an impressive amount of heat over the summer. Current 5 day NSIDC extent as of 10-16 is 5.170 million sq km. Extent was 5.422 on 10-16-12. So the unusually slow extent gain pattern continues.

The very slow Arctic sea ice extent gains continue. The NSIDC 5 day extent just fell below 2012 for a new mid-October record low of 5.118 million sq km. The previous record lowest extent value for October 15th was 5.240 million sq km.

Updated for the first record breaking storm system to make headlines this October. 2019 Record Early Season Snows For Upper Rockies And Plains https://weather.com/storms/winter/news/2019-10-14-record-snowiest-start-season-october-northern-rockies-plains

Absolutely. Records have been falling throughout the year since 2016. The 2012 minimum is the one record that hasn’t been surpassed since then. Probably a less important data point relative to the bigger picture. Data courtesy of Zack Labe and NSIDC Record low #Arctic sea ice extent months - @NSIDC data (satellite-era from 1978/1979) --------------------- 2018 : January 2018 : February 2017 : March 2019 : April 2016: May 2016: June 2019: July 2012: August 2012: September 2012: October 2016: November 2016: December

This is the 3rd October stall in extent gains since 2016. But 2019 is starting from a lower point so it was able to drop lower than 2012.

The one day NSIDC extent figure is in a virtual tie with 2012 as of October 11th. 2019...4.998 million sq km....2012...4.964 Five day average difference is a little greater. 2019...4.959...2012....4.684 This is only the second time that the sea ice extent was still below 5 million sq km as late as October 11th.

Impressive stall in sea ice extent gains this week. It allowed 2019 to pull a little closer to 2012. NSIDC extent

It was the latest 95 degree day at JFK by 3 weeks. The heat was so extreme for this late in the season, that JFK beat the previous highest October record of 90 in 2007 by a full 5 degrees.

Updated for the new all-time October record high temperatures across the region.