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16 minutes ago, bluewave said:

Yeah, that is probably the case. Recent studies have shown how much lower the temperatures are under an urban tree canopy. The older Central Park observations weren’t located under the canopy like they are now. So it’s no surprise that NYC had more 90° and 100° days back then. This recent study found significant temperature differences between open and forested parts of parks. The differences in Central Park summer high temperatures before 1990 and after seem to match their study. The paper in the link goes into more detail than the news article. The 1990 date is around the time that the canopy began to cover the observation site.

https://www.ncel.net/2019/09/01/canopy-tree-cover-can-drastically-reduce-heat-island-effect/

Results: Researchers found an urban tree canopy of at least 40% results in the most cooling – as much as four to five degrees Celsius (seven to nine degrees Fahrenheit). Anything less than 40% canopy cover results in very small amounts of cooling.

Since this threshold was previously unknown, researchers hope this will guide strategies for increasing tree cover. Trees are often planted in wealthier neighborhoods. Therefore, distributing planting to be more equitable can help to not only lower temperatures but also bring mental and physical health benefits to the community. 

Resources:

  • Read the full study through PNAS.

 

did they research night time lows the same way?...its a hard way to radiate with a tree branch hanging over...

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12 minutes ago, uncle W said:

did they research night time lows the same way?...its a hard way to radiate with a tree branch hanging over...

They found the effect was greater on daily maximum temperatures than the minimums.

Variability in daytime air temperature within the urban landscape averaged 3.5 °C (range, 1.1–5.7 °C). Temperature decreased nonlinearly with increasing canopy cover, with the greatest cooling when canopy cover exceeded 40%. The magnitude of daytime cooling also increased with spatial scale and was greatest at the size of a typical city block (60–90 m). Daytime air temperature increased linearly with increasing impervious cover, but the magnitude of warming was less than the cooling associated with increased canopy cover. Variation in nighttime air temperature averaged 2.1 °C (range, 1.2–3.0 °C), and temperature increased with impervious surface. Effects of canopy were limited at night; thus, reduction of impervious surfaces remains critical for reducing nighttime urban heat. Results suggest strategies for managing urban land-cover patterns to enhance resilience of cities to climate warming.

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14 minutes ago, forkyfork said:

it hit 90 yesterday and will again tomorrow

 Newark was the only area to hit 90゚ yesterday The 5 boroughs Long Island most of northern New Jersey lower Hudson Valley were all between 82 and 87゚.  I think we gotta give the 90゚ threshold a break.  Normal highs in the urban areas are between 86 and 88, so 90゚ is 2 to 4゚ above normal. not very special any more especially in warming climate.  It's no different in Winter when a 35゚ high is not cold or remarkable when the normal high is 38.  95゚ should be the new threshold in this warming climate.   anyway a beautiful 71゚ dew point of 67 on July 13th In this new age of global warming

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1 hour ago, uncle W said:

then they don't care about the problem...it could be a question about who will pay for the foilage trimming...

I am wondering if it would take a scientific journal article on the cooling of NYC summer high temperatures? We have  shown on this forum how there has been a cooling since around 1990. Perhaps a well publicized scientific paper on how the quality of weather observations in our biggest city has been compromised would get the attention need for improvement. 

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38 minutes ago, bluewave said:

I am wondering if it would take a scientific journal article on the cooling of NYC summer high temperatures? We have  shown on this forum how there has been a cooling since around 1990. Perhaps a well publicized scientific paper on how the quality of weather observations in our biggest city has been compromised would get the attention need for improvement. 

day time highs could be as much as four degrees cooler and two degrees warmer for the lows...Central Park went down hill when the weather service moved out of NYC 50 miles east...

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We can go 90, 93, 93 and 90 over the next 4 days starting tomorrow And some would be impressed But that would be slightly above normal for mid July  and really nice weather for outdoor activities such as beaches pools barbecues.  Most reporting stations in the  metro area will still be slightly below normal or normall after this period except for Newark.  This will not be a July to remember except for convection and rains

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10 minutes ago, binbisso said:

We can go 90, 93, 93 and 90 over the next 4 days starting tomorrow And some would be impressed But that would be slightly above normal for mid July  and really nice weather for outdoor activities such as beaches pools barbecues.  Most reporting stations in the  metro area will still be slightly below normal or normall after this period except for Newark.  This will not be a July to remember except for convection and rains

It’s not really so much about the temperature it’s more about the Humidity

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8 minutes ago, thunderbolt said:

It’s not really so much about the temperature it’s more about the Humidity

 I agree but going off of today's 12ZGFS Dew points the next 4 days starting tomorrow are between 65 to 70  at 2:00 p.m. each day.  Obviously near the water on Long Island  and coastal New Jersey will probably be several degrees higher.  not that spectacular for mid July it could be much worse

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6 minutes ago, binbisso said:

 I agree but going off of today's 12ZGFS Dew points the next 4 days starting tomorrow are between 65 to 70  at 2:00 p.m. each day.  Obviously near the water on Long Island  and coastal New Jersey will probably be several degrees higher.  not that spectacular for mid July it could be much worse

it's when it's over 70 that it feels truly awful.

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54 minutes ago, uncle W said:

day time highs could be as much as four degrees cooler and two degrees warmer for the lows...Central Park went down hill when the weather service moved out of NYC 50 miles east...

They were going to close the site in the early 1990s when the NWS moved. So maybe they made the trade off just to keep the site going. But how hard can it be to manage the tree growth around the ASOS?

https://vlab.noaa.gov/web/nws-heritage/-/100-years-of-weather-observations-at-belvedere-castle-in-central-park

http://www.weather2000.com/ASOS/NYC_ASOS.html

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51 minutes ago, bluewave said:

They were going to close the site in the early 1990s when the NWS moved. So maybe they made the trade off just to keep the site going. But how hard can it be to manage the tree growth around the ASOS?

https://vlab.noaa.gov/web/nws-heritage/-/100-years-of-weather-observations-at-belvedere-castle-in-central-park

http://www.weather2000.com/ASOS/NYC_ASOS.html

This could easily be Fixed

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