Posted by Dee Norris
Can you figure out what happened at Mohonk Lake, NY?
Get out your slip-sticks and put on your thinking caps, gentle readers. We need to solve the mystery of the temperature record at at Mohonk Lake NY.
On Monday, the New York Times had this to say about the temperature record at Mohonk Lake:
The record shows that on this ridge in the Shawangunk Mountains, about 20 miles south of the better-known Catskills, the average annual temperature has risen 2.7 degrees in 112 years. Of the top 10 warmest years in that time, 7 have come since 1990.
Now I just happen to live in the Catskills (the Shangra-La of New York State, IMBO) and a 2.7 degree (I am assuming F, not C) increase sounded pretty high for the ‘Gunks’ so I turned to this handy tool at www.CO2Science.org for a quick look-see at the USHCN data for the Mohonk Lake (41.77.N, 74.16W; 379m) site. Here is what I found:
Since I live in the general area, I have previously used the data from a site in nearby Maryland, NY (42.52N, 74.97W; 363m) in a local lecture. I was sure I remembered that the station in Maryland had not exhibited a trend like this. Double checking the ol’grey matter, I got this graph:
Both sites are at the same altitude and in the same general vicinity. I know that climate change can’t be that localized, so it has to be something else.
I hope to get down to Mohonk Lake this weekend if possible for a closer inspection, but in the meantime, here is an opportunity for all the climate sleuths out there to take a shot at solving The Mystery at Mohonk Lake.
UPDATE: The Mystery Deepens
In a converstion today with Paul Huth at Mohonk Preserve, I was assured that the station did not have the latest electronic MMTS measurement system and that they still used the original system installed in 1896, but an inquiry at NCDC provided the following equipment:
An appointment for a site inspection has been set up for the middle of next week.
Does this site have more cloud cover? The first graph seems to have a larger ratio of warm nights.
Warm nights, that seems to be a recurring bias in most of the UHI Effect.
Something is bottling up the heat at night.
That’s not a typical site by any means. Look at the Terrain map on Google Maps. The lake is about 800 feet up on a mountain.
http://maps.google.com/maps?ll=41.766111,-74.156944&spn=0.1,0.1&q=41.766111,-74.156944
Has Hansen ever stayed there?
Eric Anderson,
Right, I chose 1925 because one of the three, Walden, I think, only had data going back that far. So to compare apples to apples, I chose that date range for all three.
Something that changed about 50 years ago: Fire suppression (ie, “Smokey the Bear”). The region’s forests are pine barrens and chestnut oak, which are dependent upon regular fire… and they’ve been burning regularly for 9,000 years. The result tends to be grassy or herb ground cover with tall-limbed large trees, and often it’s easy to walk (or drive a horse-drawn carriage) through. That’s not what recent photos show.
http://www.savethegunks.com/npj112303.htm
http://www.gunksfireplan.org/fire_biodiversity.html
http://www.ecostudies.org/ecofocus_2008-05-11.html
http://www.forestsandrangelands.gov/success/documents/2006_ny_fs_shawaangunks_hfr.pdf
http://en.wikipedia.org/wiki/Shawangunk_Ridge
At least here in the Catskills, all the forest cover had been removed by the 1930s for tannic acid production. Under FDR, the CCC replanted millions of maple trees to reforest the area.
I suspect the Gunks got the same treatment.
“Ron McCarley (11:50:37) :
Has Hansen ever stayed there?”
Don’t know, but Gore stayed at the closest holiday Inn and it made him real smart.
Using MS Paint I overlayed one over the other and noticed that they are scaled differently. Mohonk Lake x scale is 41-51 degrees, while Maryland is 40-49 degrees.
Once I approximated the scales it looks like they match pretty well up to about 1942/3 (except for the early 1920s where Mohonk gets a big peak and trough, where Maryland doesn’t). Then Mohonk seems to add 2-3 degrees on all subsequent readings. The movements roughly match, just Mohonk is always up on the peaks and troughs.
What could add 2/3 degrees on every subsequent reading virtually over night?
Anthony – great job.
Any chance of overlaying the 2 graphs and scaling on the web page so all
can see what I’m on about?
Reply – The data for all the sites discussed here is available at the CO2Science.org’s USHCN Trend Calculations — New York. Once you plot the site and the time period, a link to the data will appear below the data on the trend line. Just pop the data in Excel for a quick comparison. – Dee Norris
Here is a link to a page comparing Mohonk Lake with Poughkeepsie and Falls Village. Mohonk and Falls Village are very similar until the warming at Mohonk in the mid-nineties. This data is from the NOAA GHCN database.
http://www.appinsys.com/GlobalWarming/MohonkLake.htm
See also the comparison of New York City with its rural neighbors, showing a case of urban warming.
http://www.appinsys.com/GlobalWarming/NewYorkCity.htm
Mohonk suffers from UHI as NYC metro went from several million to 20 million in the past century, along with more recent siting/instrument changes. Look at the Walden graph – there is a problem with the 1959-1970 period. Looks like they entered a mini ice age!
The article mentions that the observers have to trek up the gray granite rock outcropping. This gived me the impression that the weather station is far enough from the buildings/parking lots to avoid their affects.
Also, if the weather station is located on or very near granite, how would this affect the observations?
Scott Covert (11:12:55) :
It is a hilly area, so it’s less prone to cold lows due to radiational cooling. Chilled air in the hills flow down to the valleys where the spectacular radiational cooling reports come from. Also, the inversion that forms in valleys blocks nighttime winds, so there can be much better mixing 100′ above the valley.
So it may be not so much bottling up the warm air as not trapping the cold air. I’m assuming the thermometers are above where radiational cooling has a substantial effect. If not, it could be that the combustion air used during the winter uses up the radiationally cooled air and the lake area may not have as severe radiational cooling as when they closed up during the winter.
Were they really closed completely in the winter? I was there in March. I think. Snowfree at the time.
novoburgo (13:26:20) :
I wouldn’t expect NYC UHI to have much impact. Winds in the northeast are usually either NW or SW. SE to NE winds generally mean coastal storms Mohonk is due north of NYC. The Catskills were quite rural the last time I was in the area.
Reply – The Gunks are not part of the Catskills and MetroNorth, a commuter rail out of NYC, reaches almost that far north in near by Orange County where there has been a boom in McMansions turning the area into a bedroom community for NYC. Similar development projects have been thwarted in the Gunks. – Dee Norris
Normally a lurker but can’t resist a challenge!
Given that the USHCN Trend Calculations are correct, I dug up the closest 4 temperature histories to Mohonk Lake that date past 1896. Those were Port Jervis, Poughkeepsie, Maryland and Troy… all in the general area of Mohonk. From those, I computed the temperature anomaly from each stations average. From that I computed the difference between Mohonk’s anomaly and the other station’s anomalies. I then color coded them and started looking for odd stuff to pop up. Here’s what I have:
1: The temperature data for Maryland matches Mohonk EXACTLY from 1898 to 1903 and 1921 to 1924.
2: The Mohonk temperature anomaly was exceptionally low compared to other stations in the area between 1898 and 1901. Excluding the duplicate Maryland data, Mohonk’s average anomaly was over 3 degrees lower than everything else in the area for this period. 1920 and 1923 were also exceptionally cool years for Mohonk compared to other stations. 1924 and 1925 were exceptionally warm compared to the surrounding area.
3: From 1896 to 1951 (First half of data), Mohonk’s anomaly was lower than the surrounding stations 34 times and higher 22 times while the average anomaly was .46 degrees lower in Mohonk than in the surrounding stations. From 1952 to 2005, Mohonk’s anomaly was lower than the surrounding stations 14 times and higher 40 times while the average anomaly was .48 degrees higher in Mohonk than in the surrounding stations.
4: Pinning down a specific event from the data isn’t quite as easy. 1984 is a suspiciously warm year but this is the only year from 1950 to 1983 where Mohonk’s anomaly was higher than all other area anomalies. The one area that sticks out is from 1997 to 2005 when the Mohonk anomaly consistently ran hotter than anything in the surrounding area. This is especially dominant from 1999 where Mohonk was running an anomaly 1.5 to 2 degrees higher than all other stations.
My guess based on the data (provided it is accurate and I analyzed anything meaningful): Mohonk saw a lot of locally cool weather during the first half of the century followed by an influx of tourism in the late 90s. I’d look for something that might have been build or installed in 1997 or 1999.
I should note that this is just 4 stations and all of the stations reported temperature anomalies that weren’t seen by the other stations in the area in various years.
My guess is that they built that lovely hotel or drained the lake 🙂
ok i’ll try…given mr watts background, i would guess, based on reading of the article, someone suspects something is wrong with the weather station box or the manually resetting of its components…its interesting nevertheless, how the mohonk’s profess ecological eden while building anthropogenic hotels, spas and research facilities while fighting all other developement that encroaches their resort…
I found a couple of old pictures which may shed some light:
http://i1.ebayimg.com/03/i/001/0c/de/fcf2_1.JPG
This is the ebay description of the picture
LAKE MOHONK MOUNTAIN HOUSE FROM SKY TOP NEW YORK NY ’38
Here is another ebay postcard from 1907:
http://www.luckpostcards.com/2008/8-19-08/postcard0181.jpg
Heres another from 1918:
http://www.luckpostcards.com/2008/8-19-08/postcard0184.jpg
Has the turbidity of the lake increased due to increased nutrients. If so, the surface waters would be warmer (in summer) and may influence the station. It would be interesting to see the water temperature record for the lake.
Looking at the Mohonk graph, about 1957, 1967 and 1978 there are fairly flat sections with 1968-1970 staying at about 46.5 – did the low/high points on the day/night thermometer get stuck?
Ric (14:03:46), I got to slightly disagree with you. The Newburgh/Poughkeepsie area has changed considerably in the past century and is almost an extension of the greater NY metro area. FYI almost every transiting Low (of which we have a large yearly number) results in a period of S to SE winds in the area. While it’s not a prevailing wind it’s enough to have a small effect throughout the Hudson Valley and surrounding areas.
I personally think most of the rise can be attributed to unmentioned changes at the observation site and no, there isn’t any proof that Henry Hudson set up the Wx station.
Mohonk Lake is no different than the nearby stations. Here is a graph of 4 of the area stations (including Mohonk Lake). The plots are virtually indistinguishable.
http://www.appinsys.com/GlobalWarming/MohonkLake2.htm
REPLY: Alan thank you. Would you be so kind to to cite (with a URL also) the source data used?
Mohonk Mountain House is in New Paltz.
http://www.newpaltz.org/historynp.html
” the motor car started replacing the train and in the early 1950’s, the New York State Thruway was built and brought New Paltz, as Exit 18, fully in touch with the world. ”
1958 was the coldest year. Then it started to warm.
Al those people streaming by on the Thruway couldn’t cause a change .. could it?
Wind will go uphill to the top of a mountain. Unless stopped by tree cover. Maybe the canopy changed below the peak? Winds can warm a person (and a thermometer) right up, if the wind is coming from a heat island. I would look below the hotel to see what has been happening surrounding the mountain.
“The Stevenson Screen thermometer. shelter and US Weather Bureau rain gauge have never. been moved from their original locations.”
http://www.google.com/search?hl=en&q=%22and+methodology.+The+Stevenson+Screen+thermometer%22
Well my guess is they build a tennis court around the Stevenson Screen, just like the one at Lake Tahoe. See the Tahoe City post on Anthony Watts Surface Station data base here: http://gallery.surfacestations.org/main.php?g2_itemId=694 What do you think?
Reply to reply of my previous post:
The graphs in the links of my previous two posts are from the NOAA GHCN database. The graphs are created at:
http://www.appinsys.com/GlobalWarming/climate.aspx
That page provides links to the source data at NOAA (and for data at Hadley).