Long-term Activity Cycle of the WPac

[TyphoonNara]

While some meteorologists have discussed the existence of a long-term activity cycle for the North Atlantic, not many have put an eye on the Western Pacific. Therefore, I have analysed the data of historic typhoon seasons from 1945 to 2018, and discovered that there is likely to be a cycle of rising and dropping activity in the WPac once every 30-40 years.

From the 1945 to the 1960s, there was a notable rising cycle in both the number of tropical storms and typhoons. In the 1970s the early 1980s, tropical activity has lessened. Starting from mid-1980s to 1997, we have seen another active phrase for the basin. Meanwhile, from the late 1990s to 2011, there was a period of low tropical activity. From 2012 onward, tropical activity in WPac seems to have picked up again. This may indicate that Wpac activity may eventually peak in the 2020s.

It is important to note that the number of cat-5 storms did not increase in every rising cycle. In the 1945-1960s rising cycle, as well as the present rising cycle, we have seen a general increase in the number of cat-5 typhoons per year. On the contrary, in the rising cycle from the 1980s to the 1990s, there is no significant increase in the number of cat-5 typhoons (with the exception of 1997 of course - the season with 10 cat-5s!)



This is the database I have compiled by myself. All the data are based on JTWC best-track.

Year TD+ TS+ C1+ C2+ C3+ C4+ C5
1945 26 26 13 4 2 1 1
1946 19 19 17 11 10 5 0
1947 27 27 19 15 11 2 0
1948 26 26 15 8 5 3 0
1949 34 28 14 12 7 3 0
1950 18 18 12 7 6 2 0
1951 31 25 16 14 11 6 1
1952 29 29 20 13 11 7 5
1953 24 24 17 14 14 8 4
1954 33 19 15 12 10 6 4
1955 39 31 20 13 9 7 3
1956 39 26 18 13 9 6 3
1957 27 22 18 17 15 11 4
1958 24 23 21 16 15 11 7
1959 33 25 17 16 12 11 6
1960 39 30 20 12 9 7 0
1961 53 35 20 11 9 9 5
1962 38 31 23 14 12 8 5
1963 36 26 19 15 14 10 2
1964 58 40 26 15 13 8 5
1965 44 35 21 16 15 12 8
1966 51 33 20 16 8 5 2
1967 40 38 20 14 12 7 3
1968 39 29 20 14 13 8 4
1969 34 21 13 10 7 3 1
1970 30 25 12 12 11 8 4
1971 55 32 23 17 10 8 5
1972 38 30 22 15 14 6 1
1973 25 21 12 7 4 3 2
1974 35 32 16 8 3 2 0
1975 25 20 14 8 5 4 1
1976 30 25 14 9 9 8 1
1977 26 20 11 7 4 3 0
1978 35 29 15 7 3 2 1
1979 54 23 14 12 8 4 2
1980 44 24 15 12 9 4 1
1981 52 28 16 11 6 4 1
1982 29 25 19 15 12 6 2
1983 33 23 12 7 6 6 4
1984 44 27 16 10 8 7 1
1985 57 27 17 12 6 1 1
1986 48 29 19 15 8 4 2
1987 32 25 18 15 12 8 4
1988 52 29 14 9 7 6 1
1989 55 31 21 12 9 7 4
1990 41 31 21 16 8 7 4
1991 38 30 20 15 11 9 3
1992 40 32 21 14 11 9 3
1993 49 30 21 12 10 6 1
1994 52 36 21 16 13 11 1
1995 47 26 15 10 7 6 3
1996 52 33 21 15 10 8 4
1997 47 31 23 16 12 11 10
1998 32 18 9 7 5 4 1
1999 45 24 11 4 4 1 1
2000 51 25 15 11 8 6 3
2001 45 29 20 16 11 5 2
2002 44 27 18 14 12 10 3
2003 45 21 17 13 11 9 2
2004 45 32 19 17 14 12 4
2005 33 24 18 13 10 9 2
2006 40 23 14 12 11 10 4
2007 34 23 16 10 9 8 1
2008 40 28 12 11 8 5 1
2009 41 24 15 10 7 7 4
2010 29 16 9 5 4 2 1
2011 39 18 10 8 7 7 3
2012 35 25 15 11 10 7 3
2013 49 29 16 13 11 8 3
2014 32 22 13 9 8 8 7
2015 39 28 21 18 17 15 5
2016 51 27 17 12 11 10 5
2017 41 26 13 11 5 3 0
2018 44 29 16 12 9 7 6
2019 2 1 0 0 0 0 0

Note: It is highly probable that some data are missing for the seasons before the 1960s.

Do you guys have any thoughts on this?

[tolakram]

Good stuff, hopefully more will comment. I think there's a lot of these cycles that have yet to be studied in depth.

[Ptarmigan]

I am pretty sure that the West Pacific has active phase and less active phase like the North Atlantic.

[TyphoonNara]

I am pretty sure that the West Pacific has active phase and less active phase like the North Atlantic.

It is clear that there is a cycle. However, it seems that there is a general decrease in the number of tropical storms and typhoons over these 50 years. The peaks and troughs of each cycle are getting lower and lower.

[euro6208]

It's scary. Every doomsday scenario predicted for the other basins to happen in decades from now...The WPAC is already there. Wpac living the future.

[TyphoonNara]

It's scary. Every doomsday scenario predicted for the other basins to happen in decades from now...The WPAC is already there. Wpac living the future.

I have read some papers about how climate change will lead to changes in global tropical cyclone activity. In these papers, counterintuitively, there is a common consensus that tropical activity will decrease globally, with the greatest decline lead by WPac and SPac. Activity in the Indian Ocean will remain steady, while activity in NAtl and Epac will increase. It is also worth noting that CPac activity will skyrocket in the predicted future.

It is mentioned in one of the papers that the average ACE of EPac+CPac will exceed that of the WPac in around 2100.

I think the general decreasing trend of activity in the WPac somewhat affirms with what these various papers have predicted. In the 1960s and 1970s, we were seeing an average 30 tropcial storms and over 20 typhoons per year (even in the less active years). From 2000s to 2010s, WPac was generally performing badly (with less than 20 tropical storms and 10 typhoons in some years). In addition, the insane Epac and CPac activity starting from 2010s (esp in 2018 and 2015) also aligns with the predictions. It is scary and sad to see the climate change scenario is happening.

[Chris90]

I have read some papers about how climate change will lead to changes in global tropical cyclone activity. In these papers, counterintuitively, there is a common consensus that tropical activity will decrease globally, with the greatest decline lead by WPac and SPac. Activity in the Indian Ocean will remain steady, while activity in NAtl and Epac will increase. It is also worth noting that CPac activity will skyrocket in the predicted future.

It is mentioned in one of the papers that the average ACE of EPac+CPac will exceed that of the WPac in around 2100.

I think the general decreasing trend of activity in the WPac somewhat affirms with what these various papers have predicted. In the 1960s and 1970s, we were seeing an average 30 tropcial storms and over 20 typhoons per year (even in the less active years). From 2000s to 2010s, WPac was generally performing badly (with less than 20 tropical storms and 10 typhoons in some years). In addition, the insane Epac and CPac activity starting from 2010s (esp in 2018 and 2015) also aligns with the predictions. It is scary and sad to see the climate change scenario is happening.

Would you possibly have some links you could provide to those articles? I would like to read the research you mention if possible. It sounds really interesting.

[TyphoonNara]

I have read some papers about how climate change will lead to changes in global tropical cyclone activity. In these papers, counterintuitively, there is a common consensus that tropical activity will decrease globally, with the greatest decline lead by WPac and SPac. Activity in the Indian Ocean will remain steady, while activity in NAtl and Epac will increase. It is also worth noting that CPac activity will skyrocket in the predicted future.

It is mentioned in one of the papers that the average ACE of EPac+CPac will exceed that of the WPac in around 2100.

I think the general decreasing trend of activity in the WPac somewhat affirms with what these various papers have predicted. In the 1960s and 1970s, we were seeing an average 30 tropcial storms and over 20 typhoons per year (even in the less active years). From 2000s to 2010s, WPac was generally performing badly (with less than 20 tropical storms and 10 typhoons in some years). In addition, the insane Epac and CPac activity starting from 2010s (esp in 2018 and 2015) also aligns with the predictions. It is scary and sad to see the climate change scenario is happening.

Would you possibly have some links you could provide to those articles? I would like to read the research you mention if possible. It sounds really interesting.

Here are some of the links

https://journals.ametsoc.org/doi/10.1175/3240.1
https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00678.1
https://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0129.1
https://journals.ametsoc.org/doi/10.1175/2008JCLI1921.1

[Chris90]

Here are some of the links

https://journals.ametsoc.org/doi/10.1175/3240.1
https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00678.1
https://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0129.1
https://journals.ametsoc.org/doi/10.1175/2008JCLI1921.1

Thanks so much! I'll try to read through some of these this evening and hopefully I'll be back with some thoughts later. I think this is an interesting topic of discussion, especially in regards to global TC activity as a whole. I think reliable records on tropical activity provide such a small sample size when compared to how long tropical activity has been occurring on this planet that we still have so far to go in truly understanding the climate cycle for this planet in regards to tropical activity.

[TyphoonNara]

Here are some of the links

https://journals.ametsoc.org/doi/10.1175/3240.1
https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00678.1
https://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0129.1
https://journals.ametsoc.org/doi/10.1175/2008JCLI1921.1

Thanks so much! I'll try to read through some of these this evening and hopefully I'll be back with some thoughts later. I think this is an interesting topic of discussion, especially in regards to global TC activity as a whole. I think reliable records on tropical activity provide such a small sample size when compared to how long tropical activity has been occurring on this planet that we still have so far to go in truly understanding the climate cycle for this planet in regards to tropical activity.

It is very true that more study has to be conducted into different factors affecting the long-term changes in global TC activity. Even though global warming may have contributed to the change, it is still very probable that other factors, such as ocean currents and atmospheric circulations, have played their parts as well.

[Ptarmigan]

I am pretty sure that the West Pacific has active phase and less active phase like the North Atlantic.

It is clear that there is a cycle. However, it seems that there is a general decrease in the number of tropical storms and typhoons over these 50 years. The peaks and troughs of each cycle are getting lower and lower.

It would be nice to have typhoon data that stretches back to at least to the 19th century. Atlantic data goes back to 1851.

[TyphoonNara]

I am pretty sure that the West Pacific has active phase and less active phase like the North Atlantic.

It is clear that there is a cycle. However, it seems that there is a general decrease in the number of tropical storms and typhoons over these 50 years. The peaks and troughs of each cycle are getting lower and lower.

It would be nice to have typhoon data that stretches back to at least to the 19th century. Atlantic data goes back to 1851.

I think this would be quite difficult, considering WPAC only has complete data since 1970s.

[Hayabusa]

Why would 'AGW' decrease TC activity in the WPAC yet other basins are 'predicted' to increase in TC activity?

[TyphoonNara]

Why would 'AGW' decrease TC activity in the WPAC yet other basins are 'predicted' to increase in TC activity?

It is predicted by various computer models that activity in WPAC and SPAC will decrease, while activity in other basins, especially EPAC and ATL will increase. Even though sea surface temperatures of all the basins are predicted to increase due to AGW, increases in shear due to changes in atmospheric circulation in WPAC and SPAC will offset the effects of the increasing heat potential from the ocean. Meanwhile, shear is expected to decrease in EPAC and CPAC for similar reasons.

Here are actually some links to the related papers:
https://journals.ametsoc.org/doi/10.1175/3240.1
https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00678.1
https://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0129.1
https://journals.ametsoc.org/doi/10.1175/2008JCLI1921.1

[Yellow Evan]

Please keep in mind in the 1960's, records in terms of intensity at the very least are highly suspect.

[TyphoonNara]

Numbers in the 2018 and 2019 season are finalized and updated respectively. Pabuk is counted as the first storm in 2019. We my see an active season ahead of us due to the developing El-Nino.

[TyphoonNara]

Well with the 2020 WPAC season nearing its end it is safe to say this year's season is well below average.

Interesting to see since 2010 only 3 years (2012, 2015, 2018) managed to get the average (302 per year) or above-average ACE.

[Ed_2001]

hmm just discovered this, an interesting read, although I wonder if the data in the 1960s are artificially bumped up at least slightly due to storms being overestimated.

Out of curiosity I calculated the decadal ACE average since the 1950s, the 2010s were indeed on the inactive side.

1950s: 328.9
1960s: 360.1
1970s: 258.6
1980s: 276.9
1990s: 348.8
2000s: 307.6
2010s: 266.5

[TyphoonNara]

hmm just discovered this, an interesting read, although I wonder if the data in the 1960s are artificially bumped up at least slightly due to storms being overestimated.

Out of curiosity I calculated the decadal ACE average since the 1950s, the 2010s were indeed on the inactive side.

1950s: 328.9
1960s: 360.1
1970s: 258.6
1980s: 276.9
1990s: 348.8
2000s: 307.6
2010s: 266.5

Typhoons in the 1960s have always been thought to be over-estimated. Mostly because of Typhoon Nancy which managed to reach 185 knots 1-min sustained wind speed, which was thought to be impossible. However, with Hurricane Patricia, now we cannot say for sure.

Regardless of whether actually reaching 185 knots, Nancy was an exceptionally intense storm, considering it has maintained pressures of under 900mb for 2.5 days.

[euro6208]

hmm just discovered this, an interesting read, although I wonder if the data in the 1960s are artificially bumped up at least slightly due to storms being overestimated.

Out of curiosity I calculated the decadal ACE average since the 1950s, the 2010s were indeed on the inactive side.

1950s: 328.9
1960s: 360.1
1970s: 258.6
1980s: 276.9
1990s: 348.8
2000s: 307.6
2010s: 266.5

Typhoons in the 1960s have always been thought to be over-estimated. Mostly because of Typhoon Nancy which managed to reach 185 knots 1-min sustained wind speed, which was thought to be impossible. However, with Hurricane Patricia, now we cannot say for sure.

Regardless of whether actually reaching 185 knots, Nancy was an exceptionally intense storm, considering it has maintained pressures of under 900mb for 2.5 days.

Exactly. When you have Patricia (185 knots, recon) and three typhoons peaking at 170 knots (no recon) since 2013, i think those people that say that typhoons during the past especially during the 60's are overestimated should think otherwise. These typhoons have been waiting forever to get recognized.