Ryan N. Maue's Seasonal Tropical Cyclone Activity Update

Northern Hemisphere 2009 Year in Review --> Final Statistics

North Atlantic Hurricane Season ends -- > Houston Chronicle

November 30, 2009: With the official end of the 2009 North Atlantic hurricane season, it is time to put the season in perspective and compare to the past 70-seasons. In terms of the Accumulated Cyclone Energy index [ACE], 2009 tallied ~52 ACE points which is less than half of normal. Here is a listing of the past 70-years of ACE values for the North Atlantic Listing . 2009 was the quietest year since 1997 (ACE= 41) and the 16th slowest since 1940. Interestingly, 2009 saw 1/5th of the activity of 2005, the most active ACE season on record. 3 storms out of the total of 9 accounted for 85% of the total ACE (Bill, Fred, and Ida). These 3 storms were the only hurricanes out of the total 9 tropical storms.

Newsbusters.org Piece on Al Gore's New Book Photoshopping Hurricanes -- Ryan Maue's simple bookstore research -- Link

Denver Examiner: Hurricanes and Tornadoes at below normal levels in 2009 -- Link

Houston Chronicle Article on Tropical Storms and Global Warming -- Link

North Atlantic Hurricane Season slowest since 1997 -- Figure

Global and Northern Hemisphere Tropical Cyclone Activity remains near 30-year historical lows -- three years in a row now of considerably below-average activity globally. -- Figure

Consequence of the transition from La Nina to El Nino during the past year

The best of 2009: Hurricane Bill, Hurricane Fred, Hurricane Rick, Super Typhoon Melor, Typhoon Parma

Important Links

The Raw Data -- Accumulated Cyclone Energy (ACE) valid February 09, 2010 12Z

The current ACE represents the tropical cyclone activity from January 1, 2009 until the date indicated. This is readily compared to the YEARLY value which is the previous 30-year average from Jan 1 - Dec 31 or the calendar year. The values for 2008 and 2007 are included for reference as well. There is considerable year-to-year variability across the basins, of which understanding motivates the updating and maintainance of this site.

BASIN	2009-10 CURRENT	30-YR AVG	2008	2007	2006
N Hemisphere	461	563	431	386	554
S Hemisphere	95	204	190	176	160

Note: The Accumulated Cyclone Energy metric combines frequency, duration, and the intensity of tropical cyclones into one value that can be calculated from historical storm records as well as current operational center (i.e. NHC) advisories. The ACE is simply the wind speed squared (times 10^4 kts^2) for each 6-hour storm location and intensity estimate -- added up for an entire season or whatever period you wish to define. CLIMO based upon 1979-2008 climatology

2010 Southern Hemisphere Tropical Cyclones

Maximum Wind Speed & ACE per storm

Southern Indian Ocean
Anja (105 ACE = 12.4925)
Bongani (40 ACE = 1.29)
Cleo (115 ACE = 10.47)
Mick (70 ACE = 3.215)
David (55 ACE = 4.6785)
Laurence (130 ACE = 17.2325)
Edzani (140 ACE = 21.21)
Magda (65 ACE = 2.8225)
Olga (50 ACE = 2.375)
Nisha (50 ACE = 2.1575)
Eleven (35 ACE = 0.8575)
Oli (115 ACE = 13.755)
Fami (40 ACE = 0.2825)
Pat (65* ACE = 2.285*)
Gelane, Hubert, Imani, Joel, Kanja
Lunda, Mohono, Nigel, Olympe, Pamela
Quentin, Rahim, Savana, Themba, Uyapo
Viviane, Walter, Xangy, Yemurai, Zanele

24-Month Running Sums of Global Tropical Cyclone Accumulated Cyclone Energy (ACE)

Global tropical cyclone activity remains near 30-year + lows

Figure: 24-month running sum of tropical cyclone accumulated cyclone energy for the entire globe (top black squares / time series) and the Northern Hemisphere only (bottom green squares / time series). The difference between the two time series is the Southern Hemisphere total. Data is shown from January 1979 - December 31, 2009 mainly because intensity estimates of SH cyclones are often missing in the JTWC best-tracks prior to 1980. See notes.

24-Month Running Sums of ACE from 1959-2009

2008-2009 Southern Hemisphere Tropical Cyclones
Asma (55 ACE = 2.885)
Anika (60 ACE = 1.76)
Bernard (40 ACE = 0.565)
Cinda (55 ACE = 2.81)
Billy (105 ACE = 13.44)
Dongo (55 ACE = 2.08)
Charlotte (35 ACE = 0.3675)
Eric (35 ACE = 1.1025)
Fanele (100 ACE = 5.36)
Dominic (50 ACE = 0.735)
Hettie (35 ACE = 0.245)
Ellie (40 ACE = 0.6875)
Gael (120 ACE = 18.5125)
Freddy (55 ACE = 2.1775)
Innis (40 ACE = 0.65)
Hina (65 ACE = 2.5475)
Gabrielle (35 ACE = 0.735)
Hamish (130 ACE = 21.5)
19S (35 ACE = 0.1225)
Joni (55 ACE = 2.775)
Ken (70 ACE = 2.7)
Ilsa (105 ACE = 11.6575)
Jasper (45 ACE = 0.97)
Izilda (65 ACE = 2.5225)
Lin (50 ACE = 1.145)
Jade (65 ACE = 4.9675)
Kirrily (40 ACE = 0.8475)

Southern Hemisphere ACE = 106 for 2008-2009

Total Tropical Storms + 27

Total Cyclones (64 kts+) 9

Four cyclones account for > 60% of the seasonal ACE

Notes on Data and Methods and Citation and Funding Sources

This page can be cited as ongoing research related to my dissertation and publications resulting from it.
Maue, R. N., 2009: Northern Hemisphere Tropical Cyclone Activity. Geophys. Res. Lett., 36, L05805, doi:10.1029/2008GL035946. Abstract

Funding is provided in part by a variety of sources. COAPS is funded by NOAA and Ryan Maue received a NASA Earth Systems Fellowship during the years of 2006-2009. Additional funding has been provided to my major professor Mark A. Bourassa by NASA and other agencies in order to support publications, travel, and research. The author of this website is very appreciative of $upport.

Climatology is based upon the past 30-years of tropical cyclone activity (1979-2008). Historical tropical cyclone tracks are obtained from two sources: National Hurricane Center (NHC) for Eastern Pacific and North Atlantic basins and the Joint Typhoon Warning Center (JTWC) for the Western Pacific, Northern and Southern Indian Oceans, and the South Pacific including the Australian region. Best-track data when cyclones are in an extratropical phase are disregarded, where this is included in the datasets.

While there are several other sources of best-track hurricane data for the different basins around the globe, it is not apparent which source of tropical cyclone intensity estimates is the best, most correct, or most consistent throughout the past 30-years. Until that research is completed, it is my policy to use NHC and JTWC data for global tropical cyclone data. I will attempt to use RSMC (Tokyo) and the IBTrACS merged database for comparison purposes in the near future. (Update: June 24, after calculating ACE using the IBTrACS mean intensity, which can include from 1-4 different reporting centers, the differences are negligible. Therefore, it is appropriate to use the NHC+JTWC for global studies on yearly time scales. Naturally differences crop up when examining storm by storm and observation by observation differences. This is a disasterous complication when doing count/frequency studies such as Webster et al. (2005) but is mitigated with accumulated cyclone statistical studies (i.e. Emanuel 2005; Maue 2009).