NCDC

Climate in the Southeast in January 2014

February 01, 2014 by Brian Magi
Categories: Earth System Observer

Scientists studying the Earth’s climate system are supported by an immense and rich array of data. Sometimes it seems like you only have to be comfortable working with all this information. Programming languages help (matlab, R, python, NCL, for example). But even more accessible are incredible web resources. The USA High Plains Regional Climate Center updates their climate and weather relevant maps on a daily basis. Here are some figures showing where the country and the southeast USA stands. From NCDC time series plotter, the contiguous USA (no Alaska and Hawaii) was the 37th warmest year in the last 119 years, as shown in the graph below.
contiguous-USA-2013-T
In itself, 2013 wasn’t unusual. In recent memory, 2008 and 2009 were really similar to 2013. However, compared to the fanfare around the hottest year on record for the USA in 2012, it does seem different. Who can remember ought-8 and ought-9, right?

But even more to the point is what we feel where we live. Science and statistics are fine, but just like no one on Earth experiences the average global temperature, no one in the USA experiences the average USA temperature either! Let’s look at the Southeast. In 2013, drawing from the HPRCC link above for the figures below, the temperatures were cooler than average.
AnnDec13TDeptSERCC-2013-12-31
In the last 120 years, 2013 in the Southeast was about the 67th warmest. Most of the years in the past 120 years have been warmer! But this is really not that ususual. 4 of the last 10 years in the Southeast have been cooler than more than half the past 120 years. 10 years is a limited view, but I chose it because it’s a round number and because we remember the last 10 years. Going back to the USA, *none* of the last 10 years have been cooler than more than half of the past 120 years. Not really even close. You can verify this with NCDC data tools. What global warming? Well, that’s where perception matters. The Earth is warming, even if the Southeast seems to be avoiding the problem we’ve created with CO2 emissions.

Looking to the more recent period, we can also glean a little bit about our winter months with a 3 month average (Nov-Dec-Jan) using HPRCC again
Last3mTDeptSERCC-2014-01-31
We see that except for Florida, the Southeast is largely cooler than average. Here HPRCC is comparing against the 1981-2010 average temperature (temperature anomaly). Appalachia and further to the west are in a deep recession of the warmth we expect when we think of global warming.

Finally, we can look at January 2014 using HPRCC tools.
Last1mTDeptSERCC-2014-01-31
The Southeast is cold! Even poor Florida, which over the last 3 months is anomalously warm compared to the rest of the Southeast, is in a deep cold this past January. If we eyeball-average the data on the figure, we get a number of about 6-7 degrees F below the 1981-2010 average. Jeez. Where can we go for unseasonable warmth (retrospectively)? The West is certainly above average, and more importantly below average on precipitation, as the figures show below.
Last3mTDeptUS-2014-01-31
Last3mPNormUS-2014-01-31
Be thankful the Southeast is so stubbornly refusing to budge on global warming… but I worry that as a result of this stubborness, our legislators will forget this is a problem. North Carolina will be affected even if we are a hold out for now. Think global whenever you think of climate. Or, if you want, think of Bob Marley (one love, one heart). This figure from the recent IPCC report (WGIAR5-SPM_Approved27Sep2013) shows that there are only a couple of non-red areas on Earth (ie. they are not following the warming trend). The Southeast is one of them! But that is one scorched Earth otherwise.
ipcc-ar5-wg1-spm-fig1

Tags: climatedata visualizationNCDCNOAAnorth carolinaUSA

Ramping up for teaching with NOAA NCDC

August 07, 2013 by Brian Magi
Categories: Earth System Observer

Summer is a time of dedicated research for me. Finished one project, waiting for peer reviews on that manuscript, tinkering with twitter, planning out research conference travel in the next school year, and working on a grant proposal to NSF. The season of the classroom is nearly here though, so I’m slowly re-allocating my hours to teaching. A great early-career workshop for university and college faculty that I attended the last week of July helped me get into gear with teaching again. I need a workshop like that every summer!

Another way I start to think about teaching is to begin to browse through the data that I want to bring into the classroom. One site I haven’t visited in months, but that I prolifically visit throughout past school years, is the NOAA NCDC time series plotter. I had the pleasure of visiting the numbers again tonight and remain very impressed by NCDC outreach and transparency efforts. The new addition to the time-series plotter (which you can use to produce climate-relevant analysis at different spatial and temporal scales) is a slightly more friendly user-interface, and a few features that I think most stats people will really appreciate. Yes, it’s not a super fancy analysis package, but the statistical analysis you can do just via the webpage now includes two new options. One is the option to display the anomaly against a different base period rather than always using the 20th Century average. In other words, you can choose a base period of 1951-1980 like NASA GISS tends to use or you can play around and see what the effect of a different base period is. The other new option is a display of a trend line for any period. The first thing you can do with this is see how temperature (for example) trends in the early part of the century compare to the trends in the latter part of the century. Or you can mimic the cherry picking that climate data is sometimes a victim to and choose very specific start and end points to produce a trend that amplifies an argument you are making (“look, it’s getting colder!” or “look, it heating up super fast”). one exception to all this great online analysis is that it only applies at the “super” level for data in the contiguous USA. someday, i’ll ask NCDC scientists why this can’t be done for Alaska and Hawaii, and why the global analysis tools are more limited. either way, an exciting development in my virtual friendship with NOAA NCDC.

Tags: climatedata analysisdata visualizationNCDCNOAAnorth carolinateaching

May 2013 climate in North Carolina and the world

June 24, 2013 by Brian Magi
Categories: Earth System Observer

With global warming and all of the impacts, it’s very important to constantly consider the question of time and space scales. May 2013 is a good example for those of us living in the Southeastern USA or North Carolina. Namely, North Carolina’s normal-to-cool spring is not at all indicative of how the global temperature is evolving. Let’s see how we can quickly use NOAA NCDC graphs to figure this out.

Global warming refers to the increase in average temperature of the entire Earth. The last part – the entire Earth – is the spatial scale. And that’s a huge spatial scale! When a scientist talks about global warming or that global warming has been detected, you have to step back and say WOW. What on Earth could warm an entire planet? coal_fired_power_plantOver long time scales, of course there are a number of possible reasons (changes in the Sun, Earth’s orbital shape/proximity around the Sun, plate techtonics), but these take so long, they aren’t relevant to the concept of global warming. Even my statement that What on Earth could warm an entire planet? should be more precise and say something like What on Earth could warm an entire planet over a relatively short time period? The simplest, if somewhat incomplete, answer is the combination of greenhouse gases and aerosols emitted into the atmosphere from human activities. Period.

May 2013 analysis of global temperatures are trickling out. NOAA NCDC as always has a wonderfully complete report of climate news for May and for all previous months. My favorite part is the plethora of hyperlinks. NOAA NCDC should really be commended for their public outreach! Here is one of the figures from that webpage201305where you can see how different the Southeast USA is from the world in May 2013 – the world is shades of red, while the Southeast USA is shades of blue (cooler than normal). We’ve had a very pleasant spring in North Carolina. Pull back on the temporal (time) scale to see the March-April-May seasonal average201303-201305 and you can see that the cool spring extends well beyond May in terms of the anomaly. By this, I mean that the blues become deeper when you consider a three month period (March-April-May) and that implies without any quantitative work that March-April were more cooler-than-average. Pull back slightly further to the year-to-date rankings201301-201305and here you see that the Southeastern USA and in fact most of the USA and even Alaska have been right at the climatological normal (which for NCDC is the average temperature from 1981-2010). The short story is that North Carolina below average temperatures for the period from January to May, March to May or just plain old May are not indicative of global temperatures. The real question is why?

Tags: climatedata analysisdata visualizationglobal environmental changeglobal warmingNCDCNOAAnorth carolinaUSA

Cold spring and signs of summer

May 17, 2013 by Brian Magi
Categories: Earth System Observer

A great description of some of the unusual recent temperature swings in the north central part of the USA by Minnesota State Climatologist office with the original link here:

A taste of summer air surged into Minnesota on May 14th, sending the mercury soaring into the 80s and 90s across a good part of the state. A few locations even cracking 100 degrees. Notable exceptions were locations near ice covered lakes in northern Minnesota and near Lake Superior. At 2pm May 14th, the air temperature was 102 degrees at St. James and 44 degrees at Grand Marais. This kind of temperature range happens occasionally in the spring. One of the more dramatic episodes in recent years was May 19, 2009 when there was a difference of 66 degrees from Grand Marias to Granite Falls. The warmest temperatures found from a National Weather Service Cooperative site was 103 degrees from Sherburne 3 WSW in Martin County and Winnebago in Faribault County. Amboy also had reading of 102 degrees. Extremely dry air was in place as well, with desert-like relative humidity readings in the single digits at St. James. At 2pm while it was 102 degrees at St. James, the dew point temperature was only 28 degrees, creating a relative humidity of seven percent. Very low relative humidity readings happen on occasion. On April 28, 2004 the relative humidity dipped to just 2% at Pipestone. The lowest relative humidity reading ever recorded in the Twin Cities is 10% measured at 5pm April 22, 1953. The statewide hottest maximum temperature for the entire month of May is 112 degrees measured at Maple Plain in Hennepin County on May 31,1934. The Twin Cities had a high temperature of 98 degrees on May 14. This broke the old record high of 95 degrees that was set in 1932. This is also the hottest temperature recorded so early in the season for the Twin Cities. Ironically, despite how cool it has been this spring, 2013 had its first 90 plus degree day in the Twin Cities four days earlier than 2012, which hit 93 on May 18.

That last line is a pretty interesting weather tidbit, noting that the salient graphs from NCDC are below201304201302-201304 North Dakota had its coldest April in 119 years! Yow. Most of the central part of the country was colder than average, but by comparing the April 2013 to the multimonth average February-April 2013 plot, you can see signs of the transition out of spring to summer as well as parts of the country which had an above-average warm month (California, mid-Atlantic, Nevada, Arizona). More about this later – but these “extremes” are exactly the kind of weather we can expect as the Arctic warms or stays warmer than usual due to less sea ice. N_stddev_timeseries-2013-05The Sun will eventually win this battle and the mid-latitudes (southern USA) will inevitably heat up this year (at least I think so!). Here’s the temperature departure for the last week from HPRCC which clearly shows relatively warm temperatures creeping from the Pacific Northwest into the heretofore frozen Great Plains. 7dTDeptUS-2013-05-16 Summer is coming. Will Summer 2013 be like Summer 2012? Another question for another day.

Tags: climateglobal environmental changeNCDCtemperatureUSAWeather

North Carolina climate compared to the USA and globe

April 27, 2013 by Brian Magi
Categories: Earth System Observer

The first months of 2013 here in Charlotte have seemed unusually cool, but rather than relying on our gut feeling, let’s look at the numbers. Start by going to the NCDC website and mine out the data to find that in Charlotte, January was the 27th warmest in 118 years, February was the 40th coolest, and March was the 4th coldest in 118 years. Now a fair second question is how does Charlotte fit into the big picture? Namely, is Charlotte’s temperature ranking similar to that of the whole state of North Carolina, the USA, and even the world? With only a little bit of work, we can figure this out. The data below shows temperature anomaly compared to the 20th Century average as a +/- number, and the parenthetical numbers are the ranking in the overall temperature record (1 is hottest). USA has 119-120 years of data, while the global time series begins in 1880. 

                  Charlotte*    North Carolina   USA**        Global Land   Global***
    April 2012    +1.7 (31)     +1.1 (39)        +3.7 (3)     +1.1 (6)      +0.6 (7) 
      May 2012    +2.9 (13)     +2.9 (11)        +3.3 (2)     ? (7)         +0.5 (10) 
     June 2012    -1.5 (93)     -1.5 (98)        +2.0 (12)    +0.9 (4)      +0.6 (7) 
     July 2012    +2.4 (8)      +3.2 (2)         +3.3 (1)     +0.8 (5)      +0.6 (7) 
   August 2012    -1.3 (97)     -0.4 (69)        +1.7 (13)    +0.8 (2)      +0.6 (8) 
September 2012    -1.6 (83)     -0.9 (72)        +1.4 (23)    +0.9 (4)      +0.5 (8) 
  October 2012    -1.5 (81)     -0.6 (65)        -0.3 (73)    +1.1 (2)      +0.6 (8) 
 November 2012    -3.6 (109)    -3.6 (108)       +2.0 (20)    +1.1 (6)      +0.7 (5) 
 December 2012    +5.1 (8)      +5.5 (8)         +3.3 (10)    +0.2 (49)     +0.4 (18)
  January 2013    +2.8 (27)     +3.5 (24)        +1.5 (42)    +0.9 (13)     +0.5 (9)
 February 2013    -2.0 (80)     -0.8 (70)        +0.9 (49)    +1.0 (11)     +0.6 (9)
    March 2013    -6.7 (116)    -5.9 (114)       -0.8 (77)    +1.1 (11)     +1.0 (10)

What’s remarkable is that at first glance, it seems like the rankings of Charlotte and NC are essentially on the opposite end of the spectrum of rankings compared to the global rankings in the last 12 months. There’s an easy way to quantitatively evaluate the relationship between sets of numbers and that is by using the statistical correlation coefficient, usually represented by the variable r. A positive r value means the numbers go up and down together, while a negative r means one set of numbers go up while the other goes down. When r is +1 or -1, that means the two sets of numbers are perfectly correlated and perfectly anti-correlated, respectively. Perfect correlation or anti-correlation never happens with data, unless you calculate the correlation of a dataset against itself which isn’t very interesting. That being said, r near +1 or -1 usually indicates that the two datasets being compared are statistically related. To quantify “usually” from the previous sentence and to contextualize the r value, a corresponding statistic that accompanies r is the p value. The p value is a way to quantify the statistical significance of the r value and depends. A p value less than 0.05 means there’s a 95% chance that a random set of numbers is not better related than the numbers you are testing. Thus when p is less than 0.05, you can be confident there is “statistically significant” relationship – remembering that correlation does not imply causation. This kind of analysis is done all the time in all fields of science, which speaks to the idea that math is the universal language. In the table below, r is the +/- number, p is the parenthetical number.

                NC              USA           Global Land    Global
    Charlotte   +0.97 (<0.05)   +0.52 (0.08)  -0.43 (0.16)   -0.43  (0.16)
           NC   -               +0.48 (0.11)  -0.39 (0.21)   -0.44  (0.16)
          USA   -               -             -0.10 (0.77)   +0.002 (0.99)
  Global Land   -               -             -              +0.92  (<0.05)

Now we’re getting somewhere. Over the last 12 months, Charlotte and NC temperatures are, as expected, significantly correlated (r = +0.97, p < 0.05). If Charlotte sets a cold or warm record, so does NC. Global land and ocean ("global" in the table) and global land are significantly correlated (+0.92, p < 0.05) as well. Not that shocking. What I didn't expect until I started comparing the trend in the rankings is that NC and Charlotte rankings are not significantly related to the USA or global temperature rankings. This is evident by the high p values in parenthesis in the 1st and 2nd rows. Surprisingly, NC and Charlotte are nearly significantly anti-correlated (negative r values, see above) with global rankings, something that might be worth looking into with more data. What’s perhaps even more surprising to me is that USA temperature rankings are essentially unrelated to the either of the global temperature rankings. This means that any given month in the USA tells you absolutely nothing about the global ranking for the same month – you might as well just guess. More data will tell the a more complete story here (and provide better stats), but over the last 12 months, there are some interesting possible relationships (Charlotte and NC similar to the USA, but opposite of the globe), and then occasions where the two datasets have no idea the other exists (USA and the globe). No wonder people get mixed up when looking at the news about global warming and then try to relate it to what’s going on in their backyard.

* NC Climate Division 5
** Contiguous USA
*** Combined land and ocean since 1880, as opposed to “global land” which is only land surfaces. Note May 2012 T anomaly wasn’t listed on NCDC site, but the ranking was. My stats analysis was based on the ranking, so the “missing” data point is not relevant.
Tags: climatedata analysisglobal warmingNCDCnorth carolinastatisticsUSA

USA in December remains much warmer than average

December 17, 2012 by Brian Magi
Categories: Earth System Observer

A blowout in sports – whether it’s baseball, football, basketball, or soccer – is usually boring to watch. By blowout, I mean a game when one team obliterates the other. You know, 14-2 in baseball, 40-7 in football, etc. But in climate, the month-to-month ups and downs in temperature departures, are one example when a blowout is actually more fascinating to watch than another month of the “climate normal“.

As I mentioned earlier, December 2012 is setting the year 2012 to be a blowout in terms of the “competition” between years to be the warmest on the 118 year record. Here’s the updated evolution of December 2012 temperature departures from figures I got from the HPRCC map maker and laced together for an animated look at the month.

The most obvious feature is the continuing large and positive temperature departures for most of the country. You have to be a little careful because the figures have shifting colorbars on the bottom. Dark red doesn’t mean the same thing on every figure, but the message is clear as day. December is much much warmer than usual. The last week or so has continued the trend, although you do see the effect of the cold frontal passage around December 11-12 in the animation. Stay tuned, but based on a quick look at long-term weather model forecasts, I wouldn’t expect a dramatic change in the weather regime until at least December 25.

Tags: 2012global warmingNCDCRecord warmthUSA

Temperature departures discussion

December 16, 2012 by Brian Magi
Categories: Earth System Observer

I wanted to have a reference for any posts that talk about temperature and temperature departure (aka: temperature anomaly). This post shows an example of the calculation of a “temperature departure”.

Temperature departure is referring to the difference between temperature in the given month and the average temperature of that month over a range of years. For example, as shown in the table below, the average temperature for the month of November 2012 in the USA was 44 F. I got this from NCDC time series data which I downloaded a couple of weeks ago. You can calculate an average November temperature as well if you choose different average periods. Using the NCDC data, I calculated the 1981-2010 and 1900-1999 average November data, also shown in the table below.

                     T (F)   TD 81-10 (F)   TD 00-99 (F)
 November 2012       44.05   +1.28          +2.03
 November 1981-2010  42.77   N/A            N/A
 November 1900-1999  42.01   N/A            N/A

How does November 2012 compare to past Novembers? Well, it doesn’t make much sense to choose just any November unless you have a specific reason, such as comparing November 2012 to November 2011 so you can remember why you wore a sweater on Thanksgiving last year and didn’t have to this year. From a climate standpoint, it’s more informative to choose a LOT of Novembers and average those November temperatures together. How many is enough? A good place to start is 30 years. This is the length of time that the climate system typically needs to average out natural variations in temperature, such as effects of El Nino-Southern Oscillation and the corresponding La Nina, cooling from a large volcanic eruptions like in 1991-1992, or a less famous (than El Nino) form of variability that affects regional or global temperatures. NCDC uses the last century as a time length for calculating the “average” temperature. HPRCC and NCDC also use the 30 year average period between 1981-2010 and call this the “Climate Normal”. Both are completely valid as long as you understand what the temperature in any particular month is being compared to. The temperature departure for November 2012 (TD in the table) is calculated as T in November 2012 (44.05 F) minus the average November temperature. Comparison to 1981-2010 gives 44.05 F minus 42.77 F = +1.28 F. Similarly, comparison of November 2012 to 1900-1999 gives 44.05 F minus 42.01 F = +2.03 F. Hence the USA had a +2 F temperature departure in November 2012, as pointed out in a different post.

A discussion of temperature departures is peppered with specific statements of time and space scales. In November 2012 then, nothing changes about the average temperature (44 F), but if we compare this to the climate normal of 1981-2010, we (most likely) get a different departure than we would compared to 1900-1999. This is clear in the table. More to the point, temperature departure is a relative metric and temperature is an absolute metric. Temperature departures are usually more informative since it’s hard to just remember if it’s a little cooler or warmer any particular month, but temperature itself is of course more intuitive.

Tags: 2012NCDC

2012 Temperatures in North Carolina and USA

December 08, 2012 by Brian Magi
Categories: Earth System Observer

The big news, if you’re paying attention the inexorable increase in temperatures, is that the biggest contributor to fossil fuel carbon (the USA) is experiencing the hottest year in 118 years. We have one month remaining this year, but the record will be set unless the USA suddenly experiences the coldest December in 118 years (it won’t – we’re well on our way to a warmer than average December and there’s a weak-moderate El Nino in place right now too which tends to result in more mild winters for at least part of the USA). Certainly many locations in the contiguous USA will be cold, but it’s not the cold that matters though. It’s the comparison of the current temperature to an average of past temperatures that really highlights relative warmth or cold. Mining what has quickly become my favorite climate data source, at least for the USA, i went to the NCDC website and pulled down the data to look at how temperatures of our home state compare to those of our home country. Here’s what I got:

             North Carolina   NC Climate Division 5*  Contiguous USA
  January    +2.9 (92)        +3.1 (94)               +5.8 (115)
 February    +2.7 (88)        +2.3 (83)               +3.9 (104)
    March    +8.7 (117)       +9.8 (117)              +8.8 (118)
    April    +1.1 (80)        +1.7 (88)               +3.7 (116)
      May    +2.9 (108)       +2.9 (106)              +3.3 (117)
     June    -1.5 (21)        -1.5 (26)               +2.1 (107)
     July    +3.2 (117)       +2.4 (111)              +3.3 (118)
   August    -0.4 (50)        -1.3 (22)               +1.7 (106)
September    -0.9 (47)        -1.6 (36)               +1.4 (96)
  October    -0.6 (54)        -1.5 (38)               -0.3 (46)
 November    -3.6 (11)        -3.6 (10)               +2.0 (99)
 December    TBD (TBD)        TBD (TBD)               TBD (TBD)

*includes Charlotte and Mecklenburg County

The numbers with the + and – are the anomaly (departure) of that month’s temperature from the 20th Century average for that month. The numbers in parentheses are how the particular month for the particular region ranks (118 is hottest, 1 is coldest following NCDC protocol). The regions are NC, a smaller part of NC that includes CharMeck, and the USA minus Hawaii and Alaska. So, if you’re from North Carolina and can’t wait to have the dinnertime conversation with your friend/relative about how global warming is a joke/hoax/conspiracy, here is what you do. Pull up that table and you can heartily agree that, yes, North Carolina has been cooler than average, particularly since August. CharMeck (middle column essentially) has pretty much been the same, maybe even cooler. But then there’s the USA. The USA had below average temperatures in October, but the warmth has otherwise been shockingly constant. March and July 2012 were both the hottest in the 118 year record. On January 1, it’ll be clear that the USA has been warmer than it has been in over a century. North Carolina has finished cooler than average, but as I pointed out before, it was the warmth in the beginning of the calendar year that set the stage. And GLOBAL warming has never been about the warming or cooling of a particular US State – it is the response of an entire planet to the energy imbalance imposed on it by human activities. The data is mounting up though and the temperature trends of regions like the USA are slowly creeping out of the noise of the day-to-day variability.

Tags: 2012global warmingNCDCnorth carolinaRecord warmthUSA

Remembering the warmth with temporal averaging

October 15, 2012 by Brian Magi
Categories: Earth System Observer

It’s been cool in North Carolina and in Charlotte in August and September 2012, as I talked about on one of my posts. In that post, I said that if you really want to know whether the temperatures you are experiencing are representative of the bigger picture, you can “zoom out” from the city level (or Climate Division) to the state level and even to the country level. This is easy with the NCDC website which archives USA climate data. Another way to think about the temperatures in a particular month (like September 2012) is to zoom out in time. In other words, take a longer time average to see whether the temperature averaged over the last few months or even the whole year are at all like the temperature you are experiencing in the here and now. (we’re still talking about monthly temperature, not the weather).

Using figures that you can get at NCDC, I made the animation above. The figure shows the temperature averaged over progressively fewer months (starting with 12 months up to Sep 2012 and going down to just Sep 2012). I think the data in the figure shows that the temperatures departures over the last year (Oct 2011 to Sep 2012) in North Carolina were dominated by unusually large warm anomalies back in the winter months, from about Oct 2011 to Mar 2012. Starting in May 2012, the temperature anomalies in NC were below average, but these below-average temperatures we’ve been experiencing are swamped by the above-average temperatures from the what we did experience (but may have forgotten). When you look at the trend in the country as a whole, and focus on the Oct 2011 to Sep 2012 image when it pops up, you can see that most of the country is very warm compared to average.

Tags: global warmingNCDCRecord warmthspatiotemporal analysisUSA