Advertisement
If you have a new account but can't post, please email Niamh on [email protected] for help to verify your email address. Thanks :)
New AMA with a US police officer (he's back!). You can ask your questions here

Were dry years more common during maunder minimum in Ireland?

  • 12-04-2018 11:12pm
    #1
    Registered Users Posts: 8,672 ✭✭✭ Say my name


    With all the talk about how we could be about to enter a Maunder minimum period. I was just wondering were dry years more common during our last MM?

    Maybe that should be phrased as was our weather not as zonal (coming from the Atlantic on a strong jet) then?

    It's interesting to note though that there was a drought spell in the early 1700's in Ireland that supposedly lasted 4 years which resulted in a mass migration of Ulster Scots to America.
    http://www.pascalbonenfant.com/18c/weather.html

    I think drought spells are more likely to occur here when ENSO is in neutral territory just edging slowly upwards on the scale?

    Another thing I've wondered is if a Maunder minimum brings a halt or slows zonality over Ireland does that mean that it's difficult for an El Nino to become established during this time perhaps favouring slipping into La Nina or neutral the whole time?


Comments

  • Registered Users Posts: 12,554 ✭✭✭✭ sryanbruen


    It's too late to be talking about this, especially with the detail I want to respond so I'll try do so tomorrow. Interesting question and choice of discussion though Say my name.

    Weather and climate site - https://www.ukandirelandclimate.com/ (advised to view on PC, not optimised for mobile)

    Photography site - https://www.sryanbruenphoto.com/



  • Registered Users Posts: 13,182 ✭✭✭✭ M.T. Cranium


    I think in general the Maunder has a reputation as being cool and wet rather than cool and dry. The summers of the 1690s were very wet in parts of Europe. There was probably a lot of blocking but with the jet depressed well to the south few of these episodes would have been warm and dry blocking. As you may know, the Central England temperature series covers the Maunder minimum since it begins in 1659, just about when the Sun was going quiet. Most of the years have mean temperatures 1 to 2 degrees lower than even the warmer parts of 18th and 19th centuries. One or two years go to a warmer and presumably drier pattern, in particular 1686 was a warm year. Also, the great fire of London took place in 1666. However, there is a lot of anecdotal evidence about flooding and poor harvests due to excessive rain and cool weather in the last quarter of the 17th century. There were also several notably cold winters, 1684 and 1709 are considered exceptional.

    The climate period that we should perhaps be more interested in comparing would be the Dalton (roughly 1795 to 1835), a period of lower solar activity. This period has rainfall records available as well as temperatures. There is evidence of a more continental climate and a range of conditions from wet to dry, so perhaps as long as we don't go to the full shutdown mode of the Maunder, there is some chance of getting into a period of more highly variable weather. You could say that since the warm period around the mid-2000 decade, the trend has been towards this more variable climate and it seems generally more wet than dry especially this far west, the tendency may be more to drought in southeast England and parts of the continent.


  • Registered Users Posts: 99 ✭✭ Periscal


    I would say that during Dalton Minimum you have to consider the volcanic eruption of Mt.Tambora which would have had a huge influence on the persistent weather pattern. From what I remember the summers in continental Europe were wet and miserable quite often, like 130 days of rain near lake Geneva, which would indicate a pattern of southerly tracking jet stream and a gulf of Genoa Low or a Mediterranean low which would last forever, this would perhaps mean higher then normal pressure around Scotland and northern Europe, which wouldn't be bad for summers in Ireland, but on the other hand there must have been other years with persistent wet patterns in the summer.
    Have to ask myself a question would you trade absolutely horrible summer for a nice dry one next year or will you be happy with south westerlies and Euro high as per last decade or so.

    I would choose the first option


  • Registered Users Posts: 12,554 ✭✭✭✭ sryanbruen


    The problem with answering this question is the lack of data available for the period of time. The Maunder Minimum is the name used for the period 1645 to 1715 when sunspots became extremely rare which tended to create blocking frequently up to the north. Using the weather knowledge you know, this would usually help to create drier Winters as some of the driest Winters are those that are cold and or blocked. However, for other seasons, it's not all that simple as blocking a lot of the time tend to create very wet months with a southerly tracking jet stream.

    The England and Wales Precipitation (EWP) dataset is the longest running dataset related to rainfall I am aware of but this only goes back to 1766 so after the Maunder Minimum and therefore, you cannot compare. This is why we tend to compare the Dalton Minimum instead to modern day rainfall - MT already mentioned this above.

    The Dalton Minimum occurred from around the 1790s to 1820 or 1830. During this period, we had several notable events, two of these included the drought Summer of 1798 which of course was the year of the Irish rebellion and the severe flooding of December 1802 in Dublin. According to some weather observations from the rebellion, the late Spring and Summer of 1798 was exceptionally dry and warm resulting in a prolonged spell of anticyclonic conditions. Maximilian Faviere's account of the weather describes that the period between May 23rd 1798, when the ill-fated Dublin uprising took place, and the battle of Vinegar Hill on June 21st coincided almost exactly with a spell of fine weather between May 19th and June 19th. During this period, he recorded only one day with showers whilst most days are described as dry and very fine. http://www.met.ie/climate-ireland/weather-events/Summer1798.pdf. With one day of such, this would make it one of the most significant droughts in the Irish climate. The most significant short-term drought (as in, over a monthly period than two-three years) since the beginning of the 20th century remains the 3rd April-10th May 1938 for Limerick. This period consisted of the driest April of the 20th century.

    1802 was a year of very wet weather in general for Ireland (whilst the southeast of the UK was very different in comparison, kind of like 2011 in a way) going back to the Summer and Autumn before the December 1802 floods took off. This meant that river levels were already high before heavy rain commenced in December. Rainfalls of over 75mm were recorded in a 30-hour period on the 2nd/3rd December 1802 in Dublin. This amount represents what would normally be expected to fall in the entire month of December in Dublin. The majority was covered by floodwater with 3 metres of water reported in the lower Castle Yard and Patrick Street. http://www.met.ie/climate-ireland/weather-events/Dec1802_floods.pdf

    1816, 1817, 1819, 1821, 1824 and 1828 of the Dalton Minimum were all very wet years. Whilst the 1790s was rather benign with some warm summers and not as cold winters, the early 19th century saw a return to often harsh winters and unsettled, cold and wet summers. http://www.pascalbonenfant.com/18c/weather.html

    In terms of the Dalton Minimum, I don't see that dry years were more common during this period. This is an index of the most significant long-term droughts to occur since the mid-19th century in England & Wales - Ireland was affected by some of these too.

    These droughts are 1854-60, 1887-88, 1890-1910, 1921-22, 1933-34, 1959, 1974-76, 1990-92, 1995-97 and 2004-06. This was wrote before the 2010-12 drought took place, you can find the article to that drought in the link below the first one here. Of course, now we've had the 2016-17 drought too to add here.

    1887 stands to this day as Ireland's driest year on record. Glasnevin, Co. Dublin had only 356.6mm of rainfall that year which is around 14 inches. This included the warm and dry Summer of 1887 and Ireland's all-time highest maximum temperature of 33.3c on 26th June 1887. This is the only year where Ireland had a higher absolute maximum temperature than the UK. For England and Wales, it was the third driest year on record behind 1788 and 1921. The monthly totals (mm) for EWP in 1887 are:

    Jan 71.8
    Feb 24.1
    Mar 49.8
    Apr 36.6
    May 54.0
    Jun 20.8
    Jul 38.1
    Aug 53.4
    Sep 94.2
    Oct 71.4
    Nov 86.1
    Dec 69.0

    Data comes from the UK Met Office.

    https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/wea.67

    https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/wea.2101

    In conclusion, I don't know how to answer the original question in terms of the Maunder Minimum but in comparing the Dalton Minimum to modern day, I think droughts and dry years have become more common.

    If you want to have a look at ENSO yourself, hers are my ENSO tables:

    5FMRzt9.png

    Vmz201x.png

    NTM4a0f.png

    *As of recently, NOAA have revised their ENSO anomalies with 1950-51 being regarded as ENSO neutral and 2014-15 being regarded as weak El Nino now.

    Weather and climate site - https://www.ukandirelandclimate.com/ (advised to view on PC, not optimised for mobile)

    Photography site - https://www.sryanbruenphoto.com/



Advertisement