This graph is a log of cumulative values of the monthly Southern Oscillation Index for the last 139 years. High values of the SOI (contrary to NINO3.4 values for the ENSO index) relate to deluges in Australia and low values relate to droughts.
This is the CUSUM technique, invented in 1954 by E.S.Page.
Read the slopes on the graph.
I have identified major El Niño and La Niña events on the graph. La Niñas have extreme upward slopes and El Niños exteme downward slopes.
The main feature of the graph, which is obscure in graphs that do not use CUSUM, is that La Niñas dominated the 60-year period from 1917 to 1976, and El Niños dominated the 25-year period from 1976 to 2000. I have drawn linear trend lines to make this clear. The first trend line (La Niña dominant) begins at an SOI CUSUM value of -30 in May 1917 and ends at a value of +960 in February 1976, yielding a slope of +1.4 SOI units per month. The second trend line (El Niño dominant) ends at a value of -40 in December 1999, yielding a slope of -3.5 SOI units per month.
The tendency to El Niños in the second period was greater than the tendency to La Niñas in the first period by a factor of more than two.
Although the period since 2000 is very short, the trend seems to slope upward at about +1.0 SOI units per month.
I posted discussion of an earlier version of this graph in “Weatherzone” Forums >> Weather >> Climate and Climate Change >> ENSO Discussion 2012 Post #1103736
This post is the fifth in a set for the 12 calendar months. Graphs are sixteen-year logs of the monthly mean anomaly values of nine climate variables for Manilla, NSW, with fitted trend lines. I have explained the method in notes at the foot of the page.
Raw anomaly values for July
Extreme values of June anomalies in this period were:
Subsoil Temperature anomaly +3.2 deg: July 2012;
Temperature range anomaly (minus) -3.2 deg: July 2002;
Dew Point Anomaly +3.3 deg: July 1999;
Dew Point Anomaly -3.8 deg: July 2002.
Trend lines for July
The trend of mean temperature anomalies fell below zero in 2003 then rose to +1 by 2014.
The trend of daily maximum temperature anomalies fell more slowly to -0.5 in 2007, then rose to meet the mean in 2014. The trend of minimum temperature anomaly reched an early minimum in 2002. It rose to a broad peak (+1.4) in 2010, then declined. The subsoil temperature anomaly trend was slightly low in 2004 and very high (+1.9) in 2013.
Parametric plots of smoothed climate variables at Manilla
“July 2014 dry again”
July data (orange)
Most raw anomaly values for July have now moved back to be like the smoothed values during the summer drought. Very few of the partially-smoothed values during the last few months suggested a trend in this direction.
Fully smoothed data (red)
January 2014 is now the latest fully-smoothed data point. Through November, December and January all variables moved decisively away from drought, except for rainfall and daily minimum temperature. In those months, rainfall remained near a (drought) minimum. Daily minimum temperature (which has a cryptic relation to drought) increased, bringing very warm nights in autumn.
Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.
Normal values are based on averages for the decade from March 1999. They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.
The daily weather log
July sun heats the house
Normal sunny July weather was broken by two rainy days in mid-month and another “rainy” day later. With the first rain there was a very warm night of 11.0°, at the time when nights are usually at their coldest (1.8°).
Late in the month days and nights were two degrees warmer than usual.
Comparing July months
Average temperatures were normal, but the rainfall was low and the humidity (Dew Point) was very low. Recent July months have been quite different. Last July was very warm, July 2012 was very wet (ninth wettest), and July 2010 was very cloudy and wet, with warm nights. This month was not as dry as July 2011, which was not as dry as July in the drought year: 2002.
The total rainfall of 11.4 mm is in the 15th percentile. Taking rainfall totals for more than one month, the 4-month total of 83 mm is now a serious shortage (6th percentile). There are also serious shortages in the totals for 12 months (6th percentile), 15 months (8th percentile), and 18 months (9th percentile), Other totals have higher percentile values, and most totals for 36 months or more are above normal. In the very long term, the 30-year rainfall total (19,314 mm) has just fallen below the median for the first time since August 2010.
(Note. Figures for 30-year totals begin in 1914. The lowest 30-year total rainfall was 18,026 mm (601 mm per year) in November 1940; the highest was 21,031 mm (701 mm per year) in December 1978.)
Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.
This post updates a similar post that was based on data available in July 2011. I now have data from three more years.
World surface air temperature
The blue line shows how the air has warmed and cooled during the 21st century. It is based on GISS, which is one of three century-long records that estimate the surface air temperature of the whole earth. The other two are HadCRUT and NCDC.
Monthly values of GISS vary wildly, and I have smoothed them with a 37-month moving average. Ole Humlum uses 37-month smoothing in many graphs on his website.
The 37-month smoothing allows plotting only up to 18 months ago, in December 2012. As you see, the GISS air temperature anomaly (See Note 1.), when smoothed in this way, moves rather steadily in one direction for years at a time.
The world’s surface air warmed rapidly from early 2000 to late 2002, then warmed slowly to a peak in early 2006. This is the warmest the world surface air has been in hundreds of years. After that peak, the air cooled rapidly by two-thirtieths of a degree to a trough in late 2007. It warmed again slowly to a lower peak in early 2010, steadied for a year, then fell to a trough in January 2012 that was like the previous trough. The air warmed rapidly through 2012. Continue reading
This post is the fourth in a set for the 12 calendar months. Graphs are sixteen-year logs of the monthly mean anomaly values of nine climate variables for Manilla, NSW, with fitted trend lines. I have explained the method in notes at the foot of the page.
Raw anomaly values for June
Extreme values of June anomalies in this period were:
Daily Maximum Temperature anomaly -3.5 deg: June 2007;
Daily Minimum Temperature anomaly +3.1 deg: June 2009;
Subsoil Temperature anomaly +3.2 deg: June 2013;
Rainfall Anomaly +65 mm: June 2005
Temperature range anomaly (minus) +4.1 deg: June 2007;
Temperature range anomaly (minus) +3.5 deg: June 2013;
Percent Cloudy Days +40%: June 2013.
Trend lines for June
The trend of mean temperature rose from zero at first to stay at 0.5 deg from 2004 to 2010, then rose again.
The trends of daily maximum and daily minimum temperature anomalies were mirror-reversed about the mean trend line. The maximum line reached a peak in 2003 and a trough in 2009, while the minimum line did the reverse. The subsoil temperature anomaly trend was slightly low in 2004 and was high in 2014.
This post is the third in a set for the 12 calendar months. Graphs are sixteen-year logs of the monthly mean anomaly values of nine climate variables for Manilla, NSW, with fitted trend lines. I have explained the method in notes at the foot of the page.
Raw anomaly values for May
Extreme values of May anomalies in this period were:
Daily Minimum Temperature anomaly -3.6 deg: May 2006;
Morning Dew Point Anomaly +3.6 deg: May 1999;
Morning Dew Point Anomaly -3.9 deg: May 2006;
Morning Dew Point Anomaly -3.2 deg: May 2011;
Morning Dew Point Anomaly -4.4 deg: May 2012;
Temperature range anomaly (minus) -3.2 deg: May 2006.
Trend lines for May
The trends of all three air temperature anomalies were almost the same, except that anomalies of daily minimum temperature were more negative. All began high in 1999, reached a minimum in 2002, a maximum in 2007, and a minimum in 2011-12. The trend of subsoil temperature was contrary, and generally increasing.