Early sailors traveling the world’s oceans were all too familiar with an area of the tropical seas characterized by lack of winds and violent thunderstorms.  They called this zone “the doldrums” and dreaded being “stuck in the doldrums.” In his Rhyme of the Ancient Mariner, English poet Samuel Taylor Coleridge offered the following description of the Pacific doldrums:

All in a hot and copper sky,
The bloody Sun, at noon,
Right up above the mast did stand,
No bigger than the Moon.

Day after day, day after day,
We stuck, no breath no motion;
As idle as a painted ship
Upon a painted ocean.

Today, we have a better understanding of this phenomenon and now know this area as the Intertropical Convergence Zone, or ITCZ.  It shapes atmospheric circulation patterns throughout the world and is considered to be the most prominent rainfall feature on the planet; critical in determining who gets fresh water and who doesn’t in the world’s equatorial regions.  The ITCZ is defined by the coming together, or convergence, of the northern and southern hemisphere trade winds and a decrease in the pressure gradient.  Specifically, in the north, trade winds move in a southwesterward direction originating from the northeast, with somewhat of the opposite effect in the southern hemisphere (where trade winds blow from the southeast to the northwest).

A) Idealized winds generated by pressure gradient and Coriolis Force. B) Actual wind patterns owing to land mass distribution.
From: Figure 7.7 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001.

The intense tropical sun pours heat into the atmosphere forcing the air to rise through convection and results in precipitation.  Rain clouds up to 9,144 m (30,000 ft) thick can produce up to 4 m (or 13ft) of rain per year in some places.  The ITCZ is not a stationary phenomenon nor are its movements symmetrical above and below the equator.  Many factors, including seasons and land masses, influence its overall movement.

Southern shift of ITCZ in January.
From Figure 7.9 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001.

Northern shift of ITCZ in July.
From Figure 7.9 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001.

With this knowledge in mind, we first encountered some of the effects of the ITCZ last year, as we approached the Caribbean coast of Panama aboard our sailing research vessel (RV) Llyr in July 2012. The map above shows the ITCZ located very near to Panama, the narrow strip of land that connects North, Central and South America.   At a latitude of about 9°North, we met up with the storms of the ITCZ during the night.  We could see the arrival of a band of storms on our ship’s radar and plotted a course to avoid them.  The storms had other plans, and we spent the night in their midst, at times feeling like they were chasing us as we tried to take evasive action while they kept building right overhead. Lightning lit the sea around us in an eerie glow and we could see, through the rain, bolts striking not far from the ship.  The next morning, tired but safe, we sailed into the harbor in Bocas del Toro, Panama, having had our introduction to the ITCZ.

Image of the RV Llyr. From Berkshire Sweet Gold

We came to Panama as part of a multi-year research expedition aboard RV Llyr, studying coral reefs, sustainable fisheries and changes taking place in the ocean.  As farmers, we have studied weather for many years, understanding oceans and atmospheric circulation as integrated systems that help produce weather at our forest farm in New England. As social scientists and human ecologists, our interest lies in researching the myriad links between biological and cultural diversity as key elements in sustainable development.  In the coming weeks, we will transit the famous Panama Canal aboard our 53′ steel ketch, and once again pass through “the doldrums” as we make passage for the Marquesas in French Polynesia.  During the 30+ day passage, we’ll be participating in global plankton studies and weather surveys. During our passages through the Pacific Islands, specifically French Polynesia, the Cook Islands, Tonga, and finally Fiji, we’ll perform reef surveys on scuba and hopefully meet with local schools to share the findings and experiences of our expedition.  We are a family of five, with three boys on board, and additional crew members and scientists joining us on expedition.  We look forward to sharing our journey.

Suggested activity: Do you live in a region affected by the ITCZ?  We’d love to hear about your experience as these storms pass through.  Send us a story or an image you have captured about the ITCZ either through a comment here, our website, or our Facebook page.  Be sure to collect temperature and precipitation data to document how your location is affected by the ITCZ, and think about what influence these two atmospheric variables may have on other GLOBE protocols.

The Maldives are a great location for such an experiment because during the months of November through March, the country experiences its dry season with respect to the monsoon, and pollutant heavy air can be seen traveling from thousands of kilometers away from countries like India and Pakistan.  Furthermore, the island nation has a low elevation and is extremely sensitive to changes in sea level rise.

A map of the Maldives. From Worldatlas.com

Through the research, Ramanathan and his colleagues discovered that these pollutants are primarily composed of black carbon soot that comes from the burning of fossil fuels and biomass.  With the longevity of the research, they were able to understand that there is a strong heating effect of these pollutants.   But black carbon soot affects more than air temperature – it destroys millions of tons of crops annually and causes human health concerns.  The good news is that this type of emission is easy to reduce due to the face that its lifespan in the atmosphere is short.

Sources of black carbon emission. From AGU.org

If these types of pollutants are reduced quickly, the long-term negative effects of climate change can be reduced by nearly 50% in the next 20-30 years.  With Ramanathan’s research, The Climate and Clean Air Coalition (CCAC) was established.  The CCAC is focusing on the reduction of short lived pollutants by nearly one third to protect and improve human health and agriculture.

And while the relationship between black carbon soot and warming is better understood, and has recently been presented by the International Global Atmospheric Chemistry Project, the affect the black carbon has on clouds and the type that form is still unknown.  Further research is necessary to understand the feedback between black carbon affected clouds and climate change.

Suggested activity: If you’re a GLOBE school in an area that sees seasonal fluctuations in air quality, you can perform your own research study to see the affect that air pollution has on your local temperature, cloud type and cloud cover.  Start by taking air temperature, cloud clover, cloud type and aerosol measurements and enter them into the GLOBE database.  Then as your database grows, start to examine the relationships that exist between the variables.  Then, be sure to tell us about it.  You can share your future research plans with us through a comment, email or on our Facebook Page.  For more information on Ramanathan’s research, watch this video.

-Jessica Mackaro

Surface temperature map of the United States, from the RUC analysis at 1800 UTC on 13 January 2013; Image courtesy of RAL Real-Time Weather Data

When we looked at the weather map, we were amazed to see such a strong temperature gradient, which is how quickly temperature changes over a given distance.  This was the result of a very strong cold front that moved across the country bringing chilling Arctic air into the heart of the U.S., where you can see some temperatures fell well below -17.8 °C (0 °F).  Ahead of the cold front, temperatures soared, however only until the cold front passed.  If you examine hourly observations from the Southeast U.S., you’ll find some dramatic temperature drops.  For example, in Memphis, TN, the temperature fell nearly 8°C (18°F) in only one hour and fifteen minutes.

Outside of the United States, there are many other countries experiencing extreme weather.  Thousands of people have had to evacuate their homes in Russia after a pipeline burst in the extreme and record cold and Jerusalem, Israel experienced a very rare snowfall last week.  Conversely, Australia is experiencing raging brush fires as the country is gripped by a record-breaking heat wave.  This heat wave has been so intense that road tar has melted and the Bureau of Meteorology had to add two new colors to its temperature maps.

Children play in front of the Dome on the Rock during the recent snowstorm in Israel; Photo from Reuters/Ammar Awad

A map from space showing hotspots from brushfires (red dots) in Tasmania; from NASA

While these are examples of weather extremes, they are not necessarily indicators of climate.  It is important to reiterate the difference between weather and climate, as these kinds of weather extremes often get people talking about how it relates to climate and climate change.  Weather is the current state of the atmosphere, the temperatures and weather systems that sweep through a nation over the course of a day or a week, while climate is the long-term average and trend of weather events over many years.  Thus, while these weather extremes are dramatic on both ends of the spectrum, they may not affect a location’s climate unless they occur repeatedly, for many years to come.  It is also important to realize that weather extremes are not uncommon; cold fronts often create sharp temperature gradients and weather patterns can set up to create heat waves or cold spells.  However these extremes may be occurring more frequently and at record-breaking levels due to climate change.

In order to document extreme weather and if it is occurring frequently enough to impact climate, it is important to collect data on a daily basis for many years.  Over time, these data help identify if any long-term trends are occurring.  The GLOBE Program sponsors the Great Global Investigation of Climate project to encourage GLOBE schools to collect regular, daily temperature and precipitation data for this very reason.  The data collection efforts of GLOBE schools help contribute valuable data to monitor weather and climate across the planet.  Just look at this example from Fayetteville High School in Arkansas.  The daily temperature observations of maximum temperature at their school over the past two weeks illustrate the warm up and then extreme cool down that occurred as the cold front passed on January 13th.   These kinds of weather data, recorded over long periods of time, are the key pieces of evidence needed to help decipher if these tales of weather extremes are leading us toward a change in climate.

Maximum daily air temperature (degrees C) recorded by Fayetteville High School in Arkansas between 1-14 January 2013.

Suggested activity: Have you been affected by this recent extreme weather?  Let us know about it by leaving a comment or sending us an email.  Also, use the recent extreme weather to develop and carryout a research topic, then email it to us at science@globe.gov.  And don’t forget to collect data for the Great Global Investigation of Climate, which repeats again in March!

- Jessica Mackaro and Sarah Tessendorf

The GLOBE surface temperature field campaign started this week with some record warm temperatures in the United States. Students in much of the United States enjoyed short sleeve weather for several days.

Schools have started to post observations on the GLOBE website. The GLOBE website has been changed dramatically over the last year. The GLOBE Program Office will be adding all teachers in a bulk transfer from the old database in the near future. Many teachers have also signed up on the GLOBE webpage and the help desk has set them up so they can enter data. The help desk has been doing a great job managing everyone.

Here are the schools that have posted observations so far.

Burlington County Institute Of Technology, New Jersey

West Union High School, Ohio

Birchwood School, Ohio – Hi Mrs. Brown.

Lakewood Catholic Academy, Ohio – Great that you got on Mrs. McGuire

Roswell-Kent Middle School, Ohio – Hi Mr. Frantz.

Brazil School, Brazil

Main Street School, Norwalk, Ohio – Hi Mrs. Burns.

The Morton Arboretum Youth Education Department, Illinois

This is a map from the GLOBE website that shows the schools that entered surface temperature data so far on Dec. 3, 2012. Please try to have your students get your data online as soon as possible so we can trouble shoot any problems.

As many of you know, I love snow. I love to ski and ice skate and sled. So far this winter has been a dud. There hasn’t been a lot of snow. Last winter was so warm, there was very little snow as well. As you can see in the attached figure, there is very little snow today in the lower 48 of the United States. That is the part of the United States that does not include Hawaii and Alaska. A storm recently laid down snow in Europe. The weather pattern is going to change in North America and bring the cold air from Alaska and northern Canada into the lower 48.

Snow and ice charts showing North America, Europe and Asia

Seasons and Biomes Frost Tube

I have taken frost tube observations for the Seasons and Biomes GLOBE project for the past 3 years. I tried to take an observation this morning only to find that the tube had broken and all of the water drained out. I wonder if the plastic had gotten brittle and when it froze it broken when the ice expanded. I’ll have to fix it this weekend before consistently cold temperatures arrive next week.

Dr. Czajkowski's son holding the frost tube before it was placed in the ground

I hope to see your data soon.

It continues to be really hot in the central part of the US. The thermometer at our house says 98 F (37 C) today which is July 4, 2012. The number of 90 F (32 C) plus days this year has been high as well. There have been 8 days about 90 F (32 C) a my house in Temperance, MI so far this June and July. Toledo has had 12 days 90 F (32 C).

Last week I took some surface temperature observations using the GLOBE protocol for infrared thermometer. I measured the temperature of a parking lot with a cover of asphalt, a grassy area and an area with bare soil where the ground had been dug up. Which one do you think was the hottest? The grass was 34 C (94 F), the asphalt was 52 C (126 F) and the bare soil was 64 C (148 F). I didn’t expect the bare soil to be so hot.
NASA has produced a temperature anomaly image from satellite imagery (see below). The red shows areas where the temperature was above average and the blue shows temperatures below average for June 28, 2012. You can see that a large part of the US was red, above average.

Temperature anomaly image of the United States from satellite imagery. From NASA

This heat has dried things out as well. I have been watering my garden every day. I really enjoy growing our own food. I knew it was dry because there was an area of the garden that the sprinkler missed watering. In that spot, even the weeds were dried up.

The Palmer Drought Severity Index in the image below shows that large parts of the United States are in drought right now. In fact, in northwest Ohio and southeast Michigan where I live, we have severe to extreme drought conditions.

Palmer Drought Severity Index from 26 June 2012. From NOAA

Yesterday, a friend of mine posted on Facebook that he saw a fire in the forest near his house in Michigan. In this dry, hot weather, brush fires can easily start anywhere. He called 911 for the fire department to put it out. That was a wise thing to do. If you come upon a similar situation, tell an adult and/or call 911.
The fires in Colorado are related to this dry weather. The satellite image below from the MODIS sensor on the Terra satellite shows the current fires out west from NASA. Colorado has clouds over the mountains so the smoke from the fires is not visible.

MODIS satellite image of fires in the western United States. From NASA

Why is it so hot? The upper atmosphere has been stuck in a pattern with a ridge over the center part of the US (see image below). This is a common summer time pattern with troughs over the western and eastern US. But, this summer it has been particularly persistent and hot. The troughs on the east and west coasts have kept those locations relatively cool. This image is the 500 mb map that is about 10 km (6 miles) above sea level. It is made by the National Weather Service using balloon observations at 0 UTM and 12 UTM.

500 mb map showing persistent ridging over the United States

Today was one of the hotter days that we have had in Toledo in a long time. The maximum temperature was 97 F (36 C). It is hot from the Rockies all the way to the east coast of the United States. On Sunday and Monday of this week, I was in Boulder, Colorado. The temperature reached 104 F (40 C) on Monday. What was interesting was that people were still out exercising or talking on the street. I had a really hard time believe that they could do it. But, to be honest, although it was hot, it did not seem oppressively hot. The reason was that the relative humidity was about 10%. The relative humidity is the ratio of the actual amount of water vapor in the air to the amount of water vapor the air can hold given its temperature. Warm air holds more water vapor than cold air with the amount increasing exponentially as temperatures get warmer. No wonder the relative humidity was so low. It was partly due to the temperature being so high and partly due to the low amount of water vapor in the air. Today in Toledo, the temperature was 95 F (35 C) but it felt much hotter. The relative humidity was about 40%. That means there was quite a bit of water vapor in the atmosphere. 40% relative humidity would still be considered pretty dry.

Below are the warnings on Friday, June 29, from the National Weather Service. You can see that there are large areas that are red in the image are heat warnings or fire warnings over large areas of the central US.

Watches and warnings for the United States from 29 June 2012. From NOAA

In Toledo, it is quite dry as well. The grass is all brown. In fact, the National Weather Service office has issued a fire warning for the area. This area is not known for its wildfires. You probably have heard by now of the devastating wild fires that are going on in Colorado. They have gotten worse since I came back.

The forecast is for the heat wave to continue. Stay cool. Stay in the shade if you are outside and drink lots of water. Heat stroke is very serious.

Dr. C

More information about Dr. Czajkowski: Dr. Czajkowski spent three years developing remote sensing research at the University of Maryland. Upon arrival at the University of Toledo, he established a research program in remote sensing and the Geographic Information Science and Applied Geographics (GISAG) Lab. His main areas of interest are remote sensing, climate change and K-12 outreach. His research includes the use of remote sensing to investigate water quality, i.e., assessing the source regions and destinations of contaminants in the Lake Erie watershed. He has developed a K-12 educational outreach program called Studnets and Teachers Exploring Local Landscapes to Investigate the Earth from Space (SATELLITES) that brings geospatial technology to K-12 students through teacher professional development and an annual student conference. He developed the surface temperature protocol through GLOBE so that students can investigate how land use where they live affects the energy budget. Each year he organizes the surface temperature field campaign.  Dr. Czajkowski is a blogger on his own, and this post comes from his blog, which you can find here.

Growing up, I always heard sayings about months and the corresponding weather patterns.  Some included “April showers bring May flowers” and then of course the one dealing with the month of March, “in like a lion, out like a lamb”.  With this March beginning with a tornado outbreak throughout the Ohio River Valley (131 reported tornadoes on March 2nd), some may wonder, will it actually go out like a lamb?  Is there any truth behind this saying, or is it just a phrase society has been hooked on?

NOAA's Storm Prediction Center reports for the March 2, 2012 tornado outbreak. Image courtesy of SPC http://spc.noaa.gov/climo/reports/120302_rpts_filtered.gif

When we examine March in terms of weather events, there is a large amount of variability.  In the northern hemisphere, March is a transitional period between the seasons with winter exiting and spring entering. The transition between the two seasons is what causes March to have its variability in terms of weather phenomena.  Growing up in northern Illinois in the central United States, I remember having Spring Breaks with snow falling and others with temperatures warm enough to do outdoor activities.  That is a substantial difference in terms of weather from year to year.  The transition period can be observed when the seasons change between winter and spring; it does not matter your location.  However, it can be more prevalent in regions with a more drastic change in the seasons opposed to regions that have the same weather variations throughout the year.

With the transition causing so many differences from year to year, it is hard to say, “in like a lion, out like a lamb” is always accurate.  Although it can be true some years where the beginning and end of March are considerably different.  In Illinois, the end of March is generally very pleasant.  Temperatures are getting warmer, the snow is melting, and there isn’t much variability in temperatures over a few days.  That is because spring is beginning to settle in and winter has exited.  Don’t forget, spring is still an active period for weather patterns, as it marks the beginning of the severe weather season in most locations.

Using your GLOBE data, how many years do you have with March that comes in like a lion and out like a lamb?  How many years are there that have no considerable change?  Do you believe March usually comes in like a lion and out like a lamb?  Try it out for yourself.  And, what other weather phrases have you heard?  Add a comment or send an email at science@globe.gov to let us know.

- Ashley Kaepplinger

The recent volcanic eruption in Iceland marked by the spectacular “curtain-of-fire” and near-complete shut-down of air travel in Europe in mid-April will probably earn a place in the history books (see pictures of the Icelandic volcano at the Washington Post.)

The Icelandic Volcano. Credit: Washington Post

Two of the most commonly cited volcanic eruptions in the climate literature are Krakatua (1883; Indonesia) and Mt. Pinatubo (1991; Philippines). The most massive explosions of Krakatua took place in August, 1883, and rank among the most violent volcanic events in recorded history. In the year following the eruption, average global temperatures reportedly fell by as much as 1.2 °C (2.2 °F). Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888. The eruption injected an unusually large amount of sulfur dioxide gas high into the stratosphere, which was subsequently transported by high-level winds all over the planet. This led to a global increase in sulfurous acid concentration in high-level cirrus clouds and the clouds became brighter. The increase in cloud reflectivity (or albedo) meant that more incoming light from the sun than usual was reflected back to space, and as a result, the entire planet became cooler, until the suspended sulfur fell to the ground as acid precipitation.

In June 1991, the best-documented explosive volcanic event to date and the second largest volcanic eruption of the twentieth century took place on the island of Luzon in the Philippines, a mere 90 kilometers northwest of the capital city Manila. Up to 800 people were killed and 100,000 became homeless following the Mount Pinatubo eruption, which climaxed with nine hours of eruption on June 15, 1991. On June 15, millions of tons of sulfur dioxide were discharged into the atmosphere, resulting in a decrease in the temperature worldwide over the next few years.

Pinatubo eruption provided scientists with a basis for constructing or modeling the change in Earth’s radiation balance (scientists like to call this change “radiative forcing”) due to explosive volcanoes. It is now well established that volcanic eruptions cause the stratosphere to warm and the annual mean surface and tropospheric temperature decreases during a period of two to three years following a major volcanic eruption. If you are interested in more technical details on how volcanoes affect climate, you can read a very good paper written by Alan Robock. Given that the Icelandic eruption is along a Mid-Ocean ridge and volcanic Hot spot, do you think the gases and aerosols will be of different composition than the Krakatoa and Pinatubo eruptions, which are associated with plate subduction along convergent plate boundaries? If there is a difference, what effect might that have on weather and climate over the next few years?

So the disruption of the air travel by the Iceland’s Eyjafjallajökull Volcanic eruptions is just the beginning; other weather and climatic effects will follow.  In the days and months ahead, we are likely to experience darkened sky and spectacular sunsets in different parts of the world.

It is true that volcanoes give off carbon dioxide. In fact, paleoclimatologists talk about “greenhouse worlds” with more carbon dioxide, much of which is thought to be from volcanoes. However, most of the time, the air at Mauna Loa is not influenced by volcanic gases released nearby. When air influenced by nearby volcanic gases is sampled, these data are not counted in the average. Similarly, at Cape Point, South Africa, which we visited during the GLOBE Learning Expedition, scientists try to avoid using data influenced by nearby Cape Town (see 11 Aug 2008 blog).

To see what the carbon dioxide trends are in different parts of the world, I went to the NOAA Earth System Research Laboratory Web Site). Here, you will find data from stations around the world. These measurements are taken at about 30 m above the surface. Figure 4 shows an example.

Figure 4. CO2 time series for Halley Station, Antarctica. From NOAA ESRL site (see text). The observations are the black points. The turquoise points are from the “Carbon-Tracker” model. USE graph without gap.

Just for fun, I looked at 15 such plots, and drew a line by eye (“faired” the line) to find the trend in carbon dioxide concentrations using the end points at the beginning (1 January 2000) and end (31 December 2008). Figure 5 shows what I did for the plot in Figure 4.

Figure 5. Figure 4 with the straight line I drew through the data (I tried to follow the black points, which are the observations). The values I read off are at the ends of the line, i.e., at the beginning of 2000 and the end of 2008.

Then I put the numbers in a table, and took the differences for each day. Figure 6 is a plot of the values at the beginning and end of the period for the 13 stations that didn’t have too much scatter. (The other two, in Europe, had considerable scatter, and higher rates of increase – around 2.6-2.7 parts per million (PPM) per year).

Figure 6. End points of the straight line drawn by eye through curves like that in Figure 3. Data from NOAA Earth System Research Laboratory/Global Monitoring Division.

It is interesting to see that the highest carbon-dioxide concentrations occur in the northern middle latitudes, where the most people (and cities, and factories, and cars) are. Even so, the carbon dioxide concentrations at the beginning and end of the period change little with latitude. Finally, the changes with time (over eight years) are about the same at all locations plotted. If we average the yearly trends, we find a carbon-dioxide increase of 2 PPM per year, with very little scatter (standard deviation 0.08 PPM per year, standard error 0.022 PPM per year).

Misconception: The warming pattern is related to the pattern of carbon dioxide concentration. Where carbon dioxide increases faster, the temperature is warming faster.

It is true the carbon dioxide has “weather.” Carbon dioxide concentrations near the surface can vary a lot (several tens of parts per million) from day to night, and from summer to winter at a given location (see 7 September 2007 blog) . Carbon dioxide concentrations tend to higher over more populated regions, as illustrated by Figure 7, with lower values over the ocean.

Figure 7. “Carbon-Tracker” model-based Carbon dioxide “weather” over North America based. The concentrations are the averages for a column of air. From http://www.esrl.noaa.gov/gmd/ccgg/carbontracker/co2weather.php.

However, as shown in Figure 6, the long-term trends in carbon dioxide don’t vary that much.

What then explains why some areas are warming more than others? Let’s start by thinking about what changes the temperature on a daily basis.

It is true that the “greenhouse” effect of both carbon dioxide and water vapor (which varies quite a bit) has an effect on temperature change through radiative processes. In fact, the water vapor content changes a lot more than the carbon dioxide content. Something closely related to “average column carbon dioxide content” is the “precipitable water,” or the amount of water vapor in a column, that, if condensed, would fall at the surface beneath that column. One can find examples of precipitable-water maps on the web. For example, visit http://weather.unisys.com/upper_air/ua_con_prec.html. You will find that precipitable water over the United States varies by a factor of five, ten, or more!

However, temperature changes near the surface are mostly driven by heating (or cooling) of the ground, and the ground in turn heating (or cooling) the air. Of course radiation plays an important part here, too. During the day, when the ground is heated, the heating is especially effective, since air warmed by the ground is buoyant. This buoyant air rises, carrying heat upward with it. Clouds also affect temperature change. Cloudy days are often cooler than days with clear skies, because less sunlight reaches the ground. Clouds at night “trap” heat near the ground, keeping the air from cooling off as much. The wind can bring in warmer air from the south and colder air from the north (in the Northern Hemisphere). And rain showers and thunderstorms also affect temperature.

(When you average over the whole Earth, many of these effects cancel – you are bringing heat to one area but taking it away from another. But, from the point of view of Earth versus space, only the radiative effects matter – those related to the mixture of gases in the atmosphere, and also aerosols and clouds. The other methods of heat transfer – conduction and convection, don’t work in the near-vacuum of space.)

The changes described above are rapid day-to-day changes – what we call weather. And the real question is why are some areas warming faster than others over decades? There are several reasons, depending on the part of the world we are thinking about. All of these are still areas of active research.

1. The warming of the high northern latitudes (Figure 1) is related to the reduction of time when the surface is covered by ice or snow. The warming of the high northern latitudes is often thought of as an example of a positive feedback loop: the more ice melts, the less sunlight is reflected away, which leads to more warming, which leads to more ice melting, and so on.

2. Uneven warming of the Earth causes a shift in the jet stream and storm track, which can influence temperature and rainfall. The best example of this is the highs and lows associated with continents and oceans in every introductory meteorology book. This influence of oceans versus continents is of course permanent except on geologic time scales.

But, in the last few decades, scientists have discovered that variations in the sea surface temperature over a few years influence where thunderstorms occur over the Pacific Ocean. The shift in the stormy areas influences the track of the jet stream, and hence weather downstream. Thus, for example, some locations in North America will have a greater chance of northerly winds aloft in some years, and thus have colder weather than when the northerly winds weren’t there.
Changes in the normal wind direction on the seacoasts influence whether or not there is upwelling, or water rising from lower levels. The water rising to the surface tends to be cooler, which cools the air temperatures over the adjacent land.

3. Scientists think that the loss of ozone over Antarctica has kept the temperatures at the South Pole from warming (See Figure 2). (may add two references here)

4. Changes in land use could be influencing the temperature trend in parts of the world. For example, an increase in green plants could lead to more sunlight being used for evapotranspiration and increasing the water vapor in the air at the expense of increasing the temperature. Another example is the warming produced in cities, not only be replacing vegetation with concrete (which heats up more readily when it’s dry), but also by the energy release associated with manufacturing, heating and cooling buildings, transport, and even human metabolism (see 7 Feb 2007 blog).

A post-script. The 16 January Science announces the impending launch of two new satellites, Japan’s GOSAT (Greenhouse Gases Observing Satellite) and US/NASA’s OCO (Orbiting carbon observatory). The GOSAT will be able to look at the relationship between carbon dioxide and weather patterns, while OCO will focus on carbon-dioxide patterns over longer times (a few weeks and longer).

Hardly a day goes by that we don’t hear about climate change in the media or from your friends. Not everything we hear is accurate. In this blog and the next one, I will describe some misconceptions about climate change that I have recently heard, and then describe what the situation really is.

Scientists are replacing the term “global warming” with the term “global climate change” because the climate isn’t really getting warmer anymore.

It is true that many scientists don’t like the term “global warming.” This is because it implies that the temperature is getting warmer everywhere, which isn’t true. I’ve often heard the analogy to a fever, as in “the planet has a fever.” Unfortunately, this analogy implies not only that the planet is getting warmer everywhere, but that it is getting warmer everywhere at the same rate. If you have a fever, the temperature is higher by about the same amount throughout the body. So, no matter where you measure the body temperature – either on the forehead, under the tongue, in the ear, or elsewhere.

In contrast to the fevered human body, the Earth’s surface temperature is warming at different rates at different places, and some places are even getting cooler. Figure 2 shows the annual temperature trend of the yearly averaged temperature from the National Climate Data Center (NCDC), taken from the 11 June 2008 blog. You can see that the greatest warming is in northern North America and Eurasia.

Figure 1. Linear trend of annual average temperature for 1905-2005. The gray areas don’t have enough data to get a good trend. The data were gathered by the National Climate Data Center (NCDC) from Smith and Reynolds (2005, J. Climate, 2021-2036). The figure and an excellent commentary on recent climate change are found at http://www.ncdc.noaa.gov/oa/climate/globalwarming.html.

Figure 2 shows the surface temperature change relative to the 1951-1980 average, from the NASA Goddard Institute of Space Studies, averaged by latitude. Note that there are data here for higher latitudes, since different data sources are used. Also, the time period is different. You can see that the temperature is rising much faster at the high northern latitudes than at the equator.

Figure 2. Departure of 2008 surface (~top 1 mm) temperature from 1951-1980 average, averaged at each latitude. From NASA/GISS.

Just as in the middle latitudes in Figure 1, the surface temperature trends in Antarctica (Figure 3) are complex, with some areas even cooling according to this plot. (Note there is an article on Antarctic warming in the 22 January issue of Nature magazine.)

Figure 3. Image of surface temperature change in Antarctica between 1981 and 2007. These are based on infrared radiation from the surface (upper 1 mm), obtained using National Oceanographic and Atmospheric Administration satellites. Since the data come from more than one satellite, carefully comparisons to “calibrate” the data to make a reasonably uniform record. The very strong warming (darker reds) around the coast often reflects replacement of ice by open water. For further information, see http://earthobservatory.nasa.gov/IOTD/view.php?id=8239.

Going back to Figure 2, imagine now averaging the temperature trend over the entire earth. Since all the numbers are positive, the temperature trend averaged over the entire earth will also be positive. A global average is the “warming” we normally refer to when talking (or writing) about “global warming.”

However, the climate is changing in other ways as well. Perhaps you have heard about the fact that more heavy rain events are possible, or that the water vapor content in the atmosphere is increasing along with the temperature. This is another reason to prefer the term “climate change.”

Figure 1. Map showing location of Boulder and CASES-99. The colors represent contours. The Rocky Mountains are yellow, orange, and red on this map. The colors denote elevation, with yellows, oranges and reds indicating higher terrain.

How does the air temperature relate to the surface temperatures that the students measured during Dr. C.’s field campaign? To answer this question, I looked at how the surface temperature related to the air temperature at our house.

The air temperature at our house was measured at 1-1.5 meters in our carport, and also on a thermometer I carried with me on our early-morning walk around the top of our mesa. That temperature, as noted above, was -21 degrees Celsius. To get the surface temperature, I put the thermometer I was carrying on the surface after I finished my walk. I am assuming that this temperature is close to the temperature that would be measured by a radiometer like the one used in GLOBE. I took the reading ten minutes later.

Just for fun, I also measured the temperature at the bottom of our snow (now 10 cm deep) and at the top of the last snow (about in the middle of the snow layer). At these two places, I put the snow back on top of the thermometer, waited ten minutes, and then uncovered the thermometer and read the temperature. The new snow was soft and fluffy, while the old snow was crusty; so it was easy to find the top of the old snow.

All of the measurements were taken close to sunrise, when the minimum temperature is normally reached, and the area where I took the measurements was in the shade.

Figure 2 shows the temperatures that I measured.

Figure 2. Temperature measurements at the snow surface, between the old and new snow, at the base of the snow layer, and at 1-1.5 meters above the surface at 7:30 in the morning, local time.

That is, the temperature was coolest right at the top of the snow. The temperature was warmer at the top of the old snow, and warmest at the base of the snow. As noted in earlier blogs, the snow keeps the ground warm.

The temperature at the top of the snow was also cooler than the air temperature. The surface temperature is often cooler than the air temperature in the morning, especially on cold, clear, snowy mornings like this one. However, on hot, clear, days in the summertime, the ground is warmer than the air.

Here are two sets of measurements taken in the Midwestern United States in October of 1999. Could you guess which measurements were taken at night, and which measurements were taken during the day even if the times weren’t on the labels? The first plot is from data taken after sunset, while the second plot was from data taken at noon.

Figure 3. Data from the 1999 Cooperative Atmosphere Exchange Study (CASES-99) program in the central United States, courtesy of J. Sun, NCAR.