Posts tagged ‘temperature’

Jul 24

Stop Hiding Behind a Shield

Get better air temperature accuracy with this new method

ATMOS 41 weather station standing in a field

Accurate air temperature is crucial for microclimate monitoring

The accuracy of air temperature measurement in microclimate monitoring is crucial because the quality of so many other measurements depend on it. But accurate air temperature is more complicated than it looks, and higher accuracy costs money. Most people know if you expose an air temperature sensor to the sun, the resulting radiative heating will introduce large errors. So how can the economical ATMOS 41’s new, non-radiation-shielded air temperature sensor technology be more accurate than typical radiation-shielded sensors?

We performed a series of tests to see how the ATMOS 41’s air temperature measurement compared to other sensors, and the results were surprising, even to us. Learn the results of our experiments and the new science behind the extraordinary accuracy of the ATMOS 41’s breakthrough air temperature sensor technology.

In this brief 30-minute webinar, find out:

Why you should care about air temperature accuracy
Where errors in air temperature measurement originate
The first principles energy balance equation and why it matters
Results of experiments comparing shielded sensor accuracy against the ATMOS 41 weather station
The science behind the ATMOS 41 and why its unshielded measurement actually works

Watch the webinar

See weather sensor performance data for the ATMOS 41 weather station.

Explore which weather station is right for you.

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Apr 10

Where Will the Next Generation of Scientists Come From?

The Global Learning and Observations to Benefit the Environment (GLOBE) Program is an international science and education program that provides students and the public worldwide with the opportunity to participate in data collection and the scientific process.

Smiling students standing in a huge line

GLOBE has a huge impact in schools around the world.

Its mission is to promote the teaching and learning of science, enhance community environmental literacy and stewardship, and provide research quality environmental observations. The GLOBE program works closely with agencies such as NASA to do projects like validation of SMAP data and the Urban Heat Island/Surface Temperature Student Research Campaign. The figure below shows the impact GLOBE is having in schools worldwide.

Places, schools, teachers, pre-service, students, alumni, and GLOBE observations chart

Dixon Butler, former GLOBE Chief Scientist, is excited about the recent African project GLOBE is now participating in called the TAHMO project. He says, “Right now, in Kenya and Nigeria, GLOBE schools are putting in over 100 new mini-weather stations to collect weather data, and all that usable data will flow into the GLOBE database.”

Students standing together in front of their school

Participating in real science at a young age gets youth more ready to be logical, reasoning adults.

Why Use Kids to Collect Data?

Dixon says kids do a pretty good job taking research quality environmental measurements. Working with agencies like NASA gets them excited about science, and participating in real science at a young age gets them more ready to be logical, reasoning adults. He explains, “The 21st century requires a scientifically literate citizenry equipped to make well-reasoned choices about the complex and rapidly changing world. The path to acquiring this type of literacy goes beyond memorizing scientific facts and conducting previously documented laboratory experiments to acquiring scientific habits of mind through doing hands-on, observational science.”

Dixon says when GLOBE started, the plan was to have the kids measure temperature. But one science teacher, Barry Rock, who had third-grade students using Landsat images to do ozone damage observations, called the White House and said, “Kids can do a lot more than measure temperature.” He gave a presentation at the White House where he showed a video of two third grade girls looking at Landsat imagery. They were discussing their tree data, and at one point, one said to the other, ‘That’s in the visible. Let’s look at it in the false color infrared.’ At that point, Barry became the first chief scientist of GLOBE, and he helped set up the science and the protocols that got the program started.

Students standing around and talking before class

GLOBE uses online and in-person training and protocols to be sure the students’ data is research quality.

Can GLOBE Data be Used by Scientists?

GLOBE uses online and in-person training and protocols to be sure the students’ data is research quality. Dixon explains, “There was a concern that these data be credible, so the idea was to create an intellectual chain of custody where scientists would write the protocols in partnership with an educator so they would be written in an educationally appropriate way. Then the teachers would be trained on those protocols. The whole purpose is to be sure scientists have confidence that the data being collected by GLOBE is usable in research.”

Today GLOBE puts out a Teacher’s’ Guide and the protocols have increased from 17 to 56. The soil area went from just a temperature and moisture measurement to a full characterization. Dixon says, “We’ve been trying to improve it ever since, and I think we’re getting pretty good at it.”

GLOBE students were the only ones going around looking up at the sky doing visual categorization of clouds and counting contrails. It was just no longer being done, except by these students.

What About the Skeptics?

If you ask Dixon how he deals with skeptics of the data collected by the kids, he says, “I tell them to take a scientific approach. Check out the data, and see if they’re good. One year, a GLOBE investigator found a systematic error In U-tube maximum/minimum thermometers mounted vertically, which had been in use for over a century, that no one else found. The GLOBE data were good enough to look at and find the problem. There are things the data are good for and things they’re not good for. Initially, we wanted these data to be used by scientists in the literature, and there have been close to a dozen papers, but I would argue that GLOBE hasn’t yet gotten to the critical mass of data that would make that easier.”

GLOBE did have enough cloud data, however, to be used in an important analysis of geostationary cloud data where the scientist compared GLOBE student data with satellite data Dixon adds, “GLOBE students were the only ones going around looking up at the sky doing visual categorization of clouds and counting contrails. It was just no longer being done, except by GlOBE students. Now GLOBE has developed the GLOBE Observer app that lets everyone take and report cloud observations.”

Young boys smiling at the camera together

Young minds need to experience the scientific approach of developing hypotheses, taking careful, reproducible measurements, and reasoning with data.

What’s the Future of GLOBE?

Dixon says GLOBE’s goal is to raise the next generation of intelligent constituents in the body politic. He says, “I thought about this a lot when I worked for the US Congress. In addition to working with GLOBE, I now have a non-profit grant-making organization called YLACES with the objective of helping kids to learn science by doing science. Young minds need to experience the scientific approach of developing hypotheses, taking careful, reproducible measurements, and reasoning with data. Inquiries should begin early and grow in quality and sophistication as learners progress in literacy, numeracy, and understanding scientific concepts. In addition to fostering critical thinking skills, active engagement in scientific research at an early age also builds skills in mathematics and communications. These kids will grow up knowing how to think scientifically. They’ll ask better questions, and they’ll be harder to fool. I think that’s what the world needs, and I see the environment and science as the easiest path to get there.”

Learn more about GLOBE and its database here and about YLACES at www.ylaces.org.

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Mar 20

New Weather Station Technology in Africa

Weather data, used for flight safety, disaster relief, crop and property insurance, and emergency services, contributes over $30 billion in direct value to U.S. consumers annually. Since the 1990’s in Africa, however, there’s been a consistent decline in the availability of weather observations. Most weather stations are costly and require highly trained individuals to maintain. As a result, weather stations in African countries have steadily declined over the last seventy years. Oregon State University’s, Dr. John Selker and his partners intend to remedy the problem through his latest endeavor— the Trans African Hydro Meteorological Observatory (TAHMO).

Image of the earth and a huge storm on the surface

Weather data improve the lives of many people. But, there are still parts of the globe where weather monitoring doesn’t exist.

Origins of TAHMO

TAHMO is a research-based organization that aims to deploy 20,000 all-in-one weather stations across the continent of Africa in order to fill a hole that exists in global climate data. TAHMO originated from a conversation between Selker and Dr. Nick van de Giesen from Delft University of Technology while doing research in Ghana. Having completed an elaborate study on canopy interception at a cocoa plantation in 2006, they hit a “data wall.” There was virtually no weather data available in Ghana, a problem shared by most African countries. This opened the door to what would later become TAHMO.

Students standing around an installation site

The majority of weather stations are being installed at local schools where teachers are using the data in their classroom lessons.

Logistics and Equipment

Originally Selker and van de Geisen set out to make a $100 weather station, which Selker admitted, “turned out to be harder than we thought.” Not only was making a widely-deployable, affordable, research-grade, no-moving-parts weather station difficult, but additional challenges presented themselves.

“The model of how we might measure the weather in Africa, the whole business model, the production model, infrastructure support, the database and delivery system, the agreements with the countries, agreements with potential data-buyers, that all took us a long time to sort out.” Despite these challenges, in 2010 it started to look feasible. “That’s when we really started to figure out what the technology we were going to use was going to look like.”

After giving a lecture at Washington State University, Selker spoke with Dr. Gaylon Campbell about the project, which led to a long development-deployment-development cycle. Eventually, the final product emerged as a low-maintenance, no-moving-parts, cellular-enabled, solar-powered weather station.

Young boy carrying a bag on his head and walking down the road

An estimated 60 percent of the African population earn their income by farming.

Agricultural Benefits of Weather Stations

Crop insurance, a service that is widely used in developed countries, relies on weather data. Once historical data exists, insurance rates can be set, and farmers can purchase crop insurance to replace a crop that is lost to drought, weather, wildfire, etc. On a continent with the largest percentage of the total population subsistence farming, this empowers farmers to take larger risks. Without insurance, farmers need to conserve seed, saving enough to eat and plant again if a crop fails. With crop insurance, crop loss is not as devastating, and farmers can produce larger yields without worrying about losing everything. Hypothetically, this would lead to more food available to the global market, stabilizing food prices year over year.

Crop insurance aside, weather data provide growers with information like when to plant, when not to plant, what crops to plant, and when and if to treat for disease. For rainfed crops, this can mean the difference between a successful yield and a failure.

“Currently in most African countries, the production per acre is about one-sixth of that in the United States. That is the biggest opportunity, in my opinion, for sustainable growth without having to open up new tracts of land. The land is already under cultivation, but we can up productivity, probably by a factor of four, by giving information about when to plant,” Selker comments.

Despite the social benefits, Selker makes it clear that the TAHMO effort is based on mutual benefit: “We are here for a reason, we want these data to advance our research on global climate processes. This is a global win-win partnership.”

Learn how you can help TAHMO by getting active.

Next week: Read about some of the challenges facing TAHMO

See performance data for the ATMOS 41 scientific weather station.

Explore which weather monitoring system is right for you.

Download the “Researcher’s complete guide to soil moisture”—>

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Jan 2

Lysimeters Determine if Human Waste Composting can be More Efficient

In Haiti, untreated human waste contaminating urban areas and water sources has led to widespread waterborne illness. Sustainable Organic Integrated Livelihoods (SOIL) has been working to turn human waste into a resource for nutrient management by turning solid waste into compost. Read more…

Estimating Relative Humidity in Soil: How to Stop Doing it Wrong

Estimating the relative humidity in soil? Most people do it wrong…every time. Dr. Gaylon S. Campbell shares a lesson on how to correctly estimate soil relative humidity from his new book, Soil Physics with Python, which he recently co-authored with Dr. Marco Bittelli. Read more.…

How Many Soil Moisture Sensors Do You Need?

“How many soil moisture sensors do I need?” is a question that we get from time to time. Fortunately, this is a topic that has received substantial attention by the research community over the past several years. So, we decided to consult the recent literature for insights. Here is what we learned.

Data loggers: To Bury, or Not To Bury

Globally, the number one reason for data loggers to fail is flooding. Yet, scientists continue to try to find ways to bury their data loggers to avoid constantly removing them for cultivation, spraying, and harvest. Chris Chambers, head of Sales and Support at Decagon Devices always advises against it. Read more…

Founders of Environmental Biophysics: Champ Tanner

Image: http://soils.wisc.edu/people/history/champ-tanner/

We interviewed Gaylon Campbell, Ph.D. about his association with one of the founders of environmental biophysics, Champ Tanner. Read more…

And our three most popular blogs of all time:

Do the Standards for Field Capacity and Permanent Wilting Point Need to Be Reexamined?

We asked scientist, Dr. Gaylon S. Campbell, which scientific idea he thinks impedes progress. Here’s what he had to say about the standards for field capacity and permanent wilting point. Read more…

Environmental Biophysics Lectures

During a recent semester at Washington State University, a film crew recorded all of the lectures given in the Environmental Biophysics course. The videos from each Environmental Biophysics lecture are posted here for your viewing and educational pleasure. Read more…

Soil Moisture Sensors In a Tree?

Soil moisture sensors belong in the soil. Unless, of course, you are feeling creative, curious, or bored. Then maybe the crazy idea strikes you that if soil moisture sensors measure water content in the soil, why couldn’t they be used to measure water content in a tree? Read more…

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Nov 7

Mesh Wireless Sensor Networks: Will Their Potential Ever Be Realized? (Part 2)

Soil ecologist Dr. Kathy Szlavecz and her husband, computer scientist, Dr. Alex Szalay, both at Johns Hopkins University, are testing a wireless sensor network (WSN; Mesh Sensor Network), developed by Dr. Szalay, his colleague, computer scientist Dr. Andreas Terzis, and their graduate students (read part 1). Mesh networks generate thousands of measurements monthly from wireless sensors. The husband/wife team says that WSN’s have the potential to revolutionize soil ecology by generating a previously impossible spatial resolution. This week, read about the results of their experiments.

Overall, the experiments were a scientific success, exposing variations in the soil microclimate not previously observed.

Results and Challenges:

About the performance of the network, Kathy says, “Overall, our experiments were a scientific success, exposing variations in the soil microclimate not previously observed. However, we encountered a number of challenging technical problems, such as the need for low-level programming to get the data from the sensor into a usable database, calibration across space and time, and cross-reference of measurements with external sources.

The ability of mesh networks that generate so much data also presents a data management challenge. Kathy explains, “We didn’t always have the resources or personnel who could organize the data. We needed a dedicated research assistant who could clean, handle, and organize the data. And the software wasn’t user-friendly enough. We constantly needed computer science expertise, and that’s not sustainable.”

The team also faced setbacks stemming from inconsistencies generated by new computer science students beginning work on the project as previous students graduated. This is why the team is wondering if a commercial manufacturer in the industrial sector would be a better option to help finish the development of the mesh network.

Mesh Wireless Sensor Network on rocks in the Atacama desert

This deployment is located in the Atacama desert in Chile. Atacama is one of the highest, driest places on Earth. These sensors are co-located with the Atacama Cosmological Telescope. The goal of this deployment is to understand how the hardware survives in an extreme environment. In addition to the cold, dry climate, the desert is exposed to high UV radiation. These boxes are collecting soil temperature, soil moisture and soil CO2 data. (Image: lifeunderyourfeet.org)

What’s Next?

Kathy and Alex say that mesh sensor network design has room for improvement. Through their testing, the research team learned that, contrary to the promise of cheap sensor networks, sensor nodes are still expensive. They estimated the cost per mote including the main unit, sensor board, custom sensors, enclosure, and the time required to implement, debug and maintain the code to be around $1,000. Kathy says, “The equipment cost will eventually be reduced through economies of scale, but there is clearly a need for standardized connectors for connecting external sensors and in general, a need to minimize the amount of custom hardware work necessary to deploy a sensor network.” The team also sees a need for the development of network design and deployment tools that will instruct scientists where to place gateways and sensor relay points. These tools could replace the current labor-intensive trial and error process of manual topology adjustment that disturbs the deployment area.

Image of deployment locations in fields of the farming systems

This deployment is located in the fields of the farming system project at BARC. Soil temperature and moisture probes are placed at various locations of a corn-soybean-wheat rotation. The goal is to understand and explain soil heterogeneity and to provide background data for trace gas measurements. (Image: Lifeunderyourfeet.org)

Future Requirements:

According to Kathy, wireless sensor networks promise richer data through inexpensive, low-impact collection—an attractive alternative to larger, more expensive data collection systems. However, to be of scientific value, the system design should be driven by the experiment’s requirements rather than technological limitations. She adds that focusing on the needs of ecologists will be the key to developing a wireless network technology that will be truly useful. “While the computer science community has focused attention on routing algorithms, self-organization, and in-network processing, environmental monitoring applications require quite a different emphasis: reliable delivery of the majority of the data and metadata to the scientists, high-quality measurements, and reliable operation over long deployment cycles. We believe that focusing on this set of problems will lead to interesting new avenues in wireless sensor network research.” And, how to package all the data collected into a usable interface will also need to be addressed in the future.

You can read about Kathy’s experiments in detail at Lifeunderyourfeet.org.

Download the “Researcher’s complete guide to soil moisture”—>

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Oct 17

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Unraveling the Effects of Dams in Costa Rica

Thirty years ago, in Costa Rica’s Palo Verde National Park, the wetlands flooded regularly and eco-tourists could view thousands of waterfowl. Today, invasive cattail plants cover portions of the wetland which has subsequently dried up and become colonized by hardwoods. Consequently, the number of birds has fallen dramatically.

The number of birds on Palo Verde National Park has fallen dramatically. (Image: anywherecostarica.com)

Some people blame the dams built in the 1970s which introduced hydrological power and created a large irrigation district in the remote region. Dr. Rafael Muñoz-Carpena, Professor and University of Florida Water Institute Faculty Fellow and his research team are performing environmental studies on the wetlands, trying to unravel the effects of the dams and how to revert some of the damage. Rafael explains, “We have a situation where modern engineering brought about social improvements, helpful renewable resources, and irrigation for abundant food production. But the resulting environmental degradation threatens a natural region in a country that depends on eco-tourism.”

Birds in a river at Palo Verde National Park

“A vast network of mangrove-rich swamp, lagoons, marshes, grassland, limestone outcrops, and forests comprise the 32,266 acre Palo Verde National Park.” (Image and text: anywherecostarica.com)

Are The Dams Responsible?

Dr. Muñoz-Carpena says because of lack of historical data it’s difficult to untangle and separate all the factors that have caused the environmental degradation. He adds, “Thirty years ago Palo Verde National Park was part of a large wetland system which was important to all of Central America because it contained many endangered species and was a wintering ground for migratory birds from North America. The Palo Verde field station on the edge of the wetland, operated by the Organization of Tropical Studies (OTS), attracted birdwatchers and wetland scientists from all over the world.”

In the 1970’s, with international funding, a dam was built in the mountains to collect water from the humid side of Costa Rica in order to generate hydroelectric power. It was clean, abundant, and strategically important. With the water transferred to the dry side of the country, a large irrigation district was created to not only produce important crops to the region like rice and beans, but to distribute the land among small parcel settlers.

Flock of birds in the grasslands at Palo Verde National Park

“Birding is the principal draw of visitors to the park.” (Image and text: anywherecostarica.com)

Over the years, however, the wetland area slowly degraded to the point where its Ramsar Convention wetland classification is under question. Rafael says that understanding the causes of the degradation, the impacts of the human system, and how the natural and human systems are linked, is the big question of his research, and there are many factors to consider. “The release of the water, ground and surface water (over)use, agriculture, human development, and a larger population are all factors that could contribute to this degradation. Everything compounds in the downstream coastal wetlands. In collaboration with OTS and other partner organizations and universities, we are trying to disentangle these different drivers.”

Grasslands and swamps with mountains in the background

Understanding the causes of the degradation, the impacts of the human system, and how the natural and human systems are linked, is the big question of this research. (Image: anywherecostarica.com)

A Lack of Historical Data

One of the challenges the researchers face is to gather a sufficient amount of temporal and spatial information about what happened in the past forty years. There are no public repositories of data to tap, and the information is spotty and hard to access. Rafael says, “Thanks to the collaboration of many local partners, we have been able to gather enough information to stitch together a large database out of a collection of non-systematic studies. The biggest challenge is to harmonize data that has been collected by different people in non-consistent ways.” This large database now contains the best long-term record possible for key hydrologic variables: river flow, groundwater stage, precipitation, and evapotranspiration.

The team is also using remote sensing sources to try to obtain time-series data for land-use and vegetation change, and will have those data ground-truthed through instruments that are collecting similar time-series data. Rafael says, “The idea is to build a network that will allow us to overlap some of the previous data sources with our own, validate and upscale the ground data with remote sensing sources, enabling us to put together a detailed picture of what happened.”

Next Week: Find out how the researchers established connectivity in such a remote area, some of the problems associated with the research, and how the team has addressed those issues.

Download the “Researcher’s complete guide to soil moisture”—>

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Aug 15

1 Comment

Do Soil Microbes Influence Plant Response to Heat Waves?

Rachel Rubin, PhD candidate at Northern Arizona University, is interested in the intersection of extreme climate events and disturbance, which together have a much greater impact on plant communities. She and her team at Northern Arizona University are investigating the role soil microbes play in plant response to heat waves, including associated impacts to microbial-available and plant-available water.

Plants have a tight co-evolutionary history with soil microbes. It has been said that there is no microbe-free plant on earth.

Because heat waves threaten plant productivity, they present a growing challenge for agriculture, rangeland management, and restoration.

Can Soil Microbes Increase Heat Resistance?

Many plants maintain mutualistic associations with a diverse microbiome found within the rhizosphere, the region of soil that directly surrounds plant roots. These “plant growth-promoting rhizobacteria” and arbuscular mycorrhizal fungi provision limiting resources including water, phosphorus and nitrogen in exchange for photosynthetically derived sugars. However, we understand very little about whether extreme events can disrupt these interactions.

Fig. 1. Fine roots exploring the inoculum that was added as a band between layers of potting mixture.

Rachel and her team exposed rhizosphere communities to heat stress and evaluated the performance of native grasses both in the greenhouse, and transplanted under an artificial heat wave. They hypothesized that locally-sourced inoculum (a sample of local soil containing the right microbes) or even heat-primed inoculum would help alleviate water stress and improve survival of native grasses.

The Experiments

Rubin started in the greenhouse by planting Blue Grama (Bouteloua gracilis, C4 grass) and Arizona Fescue (Festuca arizonica, C3 grass) and assessed their responsiveness to locally collected soil inoculum that had either been left intact, pre-heated or sterilized (Fig. 1). Rubin says, “We expected that our plants would benefit the most from having intact soil microbe communities. But, we were surprised to find very large differences between plant species. Blue Grama performed the best with intact inoculum, whereas Arizona Fescue performed better with pre-heated or sterilized soil”. This could mean that Blue Grama is more dependent on its microbiome, whereas Arizona Fescue engineers a rhizosphere that contains more parasitic microbes rather than mutualistic microbes. Rachel says that understanding this relationship is important for tailoring plant restoration projects to local conditions. Plants that exhibit high levels of mutualisms with their rhizosphere might require an extra inoculum “boost” in order to successfully establish in highly degraded soil, whereas we should not bother to inoculate plants that tend to harbor parasites within their rhizosphere.

Research plot using infrared sensors and METER soil water content and soil water potential sensors

Fig. 2. A heated plot in the foreground connected to infrared lamps, water content and matric potential sensors, and EM50 data loggers.

After the team studied these responses, they planted the grasses into a degraded section of a grassland and installed an array of 1000-Watt ceramic infrared lamps mounted on steel frames (Fig. 2) to address whether inoculation influenced plant performance and survival. With help from a savvy undergraduate electrical engineering major (Rebecca Valencia), Rubin simulated a two-week heat wave while monitoring soil temperature and moisture using water content and water potential sensors. She also measured plant performance (height, leaf number and chlorophyll content) before, during, and after the event. Control plots had aluminum “dummy lamps” to account for shading.

An infrared photo, which is how Rachel determined that the heating footprint was evenly distributed on all the plants. The scale bar on the right is in degrees C.

Data obtained from soil sensors helped Rachel to measure heating treatment effects as well as rule out a potential cause for plant mortality: soil moisture. “Soil temperature was on average 10 degrees hotter in heated plots than control plots, but matric potential and soil water content were completely unaffected by heating. This tells us that the grasses died from reasons other than water stress– perhaps a top-kill effect.” Although growing concern over heat waves in agriculture is centered around accompanying droughts, this experiment demonstrates that heating can produce negative effects on some species even when water is in plentiful supply.

Next week: Learn the results of Rachel’s experiments, some of the challenges the team faced, and the future of this research.

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Jun 11

Founders of Environmental Biophysics: Champ Tanner

Champ Tanner (November 16, 1920 – September 22, 1990) Image: soils.wisc.edu

We interviewed Gaylon Campbell, Ph.D. about his association with one of the founders of environmental biophysics, Champ Tanner.

Who was Champ Tanner?

Champ Tanner was a dominant scientist in his time and a giant among his colleagues. He was the first soil scientist to be elected a member of the National Academy of Sciences: the highest honor a scientist can achieve in the United States. Some may not realize that throughout a career filled with achievements and awards, he battled the challenges of a debilitating illness. He didn’t let that limit his passion for science, however. His efforts to understand and improve measurements generally went beyond those of his fellow scientists. One of his colleagues once said of him, “Champ’s life exemplified goal-oriented determination and optimism regardless of physical or financial impediment.”

Dr. Tanner was one of the pioneers in applying micrometeorology to agriculture.

What were his scientific contributions?

Champ was an extremely careful experimentalist who was gifted at developing instrumentation. He started out making significant contributions in soil physics such as improved methods for measuring water retention, particle size distribution, air-filled porosity, and permeability. He was one of the pioneers in applying micrometeorology to agriculture and was passionate about finding ways to improve the precision and reliability of measurements. No measurement was too difficult. He designed and built his own precise weighing lysimeters which provided measurements of evapotranspiration in as little as 15 minutes. Later, he switched to plant physiology, reading almost every published paper on the subject and then building his own thermocouple psychrometer and plant pressure chambers, making important contributions in that field.

His largest contribution, however, was the measure of excellence he inspired in the students that he trained. I don’t know of anybody, anywhere in the world, that produced a crop of students that has attained the levels that his have. They’ve all made enormous contributions in many different fields. Perhaps it was because he was a pretty hard taskmaster. He expected the students to meet a standard, and the ones that struggled with that had a hard time. In fact, to this day one former student complains, “About once a year, I have a nightmare in which Champ appears.”

I don’t know of anybody, anywhere in the world, that produced a crop of students that has attained the levels that his have.

Champ wanted his students to measure up, but he also cared about them. His fellow scientist, Wilford Gardner, described him this way, “There was a transcendent integrity to his personality that permeated everything he did. He could be blunt, candid and forthright, but he was never lacking in compassion and concern for students, colleagues, and friends.”

What was your association with him?

I had a wonderful relationship with Champ, although I wasn’t one of his students. One of his former students came to WSU as a visiting scientist and told him about what I was working on. As a result, he brought me into his inner circle of associates and played a vital role in the success of my research. This association even extended to my family who were with me on one of my many trips to Madison. Despite my numerous and occasionally unruly progeny, he and his wife welcomed us like long lost relatives and made each of the children feel special. That’s who they were: the most caring and outgoing people.

Champ also had a sense of humor. He used to call me up to have long discussions about science, and because he was two time zones ahead, it would get pretty late for him. We’d be having an intense discussion about experimentation, and all of a sudden he’d stop and say, “Oh, I’d better cut this off, or I’ll get home to a cold supper and a hot wife.”

What kind of a person was he?

If you worked in his lab, you needed to tow the mark. You didn’t leave tools around, and you didn’t mess them up. If you left out a screwdriver, you’d find it on your desk the next morning with a terse note. And if you took the diagonal pliers, cut some hard wire with it and left some nicks, those would be on your desk too. It was a sort of tough love, but he used it to train his students to the highest possible level.

He taught his students to be rigorous in their measurement protocols

He wanted his students to stand up and argue for their point. If you were the kind of person that could stand your ground and put up a good defense, he loved that. Gardner described Champ in this way, “His work hours were legendary. His standards of science and personal integrity were almost unrealistically high. The stories his students now pass on to their students may sound apocryphal to those who did not know Champ. But it was impossible to exaggerate where Champ was concerned.”

What do you think scientists today can learn from him?

What we can learn from Champ Tanner is not to fool ourselves. He thought you should try to come to an answer in a few different ways, to be sure that it really was the answer. He taught his students to be rigorous in their measurement protocols in order to get the noise out of their experiments. He wanted them to dig to the bottom of problems and understand the details. In his mind, you couldn’t be a scientist and rely on somebody else to figure out heat transfer or radiation. He thought you should understand it well enough that you could defend it yourself.

You can read more about Champ Tanner’s life and scientific contributions in this biographical sketch, written for the National Academy of Sciences when he died.

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Jun 3

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Are Biodegradable Mulches Actually Better for the Environment? (Part II)

In a continuation of last week’s post, Henry Sintim, PhD student at Washington State University is investigating whether biodegradable mulches are, in fact, what they claim to be (see part I).

Resercher gathering data from an installation site

Lysimeter readings revealed higher EC measurements.

Leaching

Sintim and his team want to understand what’s leaching through the soil as the mulches degrade. He installed passive capillary lysimeters at a 55 cm depth to collect leachate samples for analysis of BDM particulates. He was surprised when the lysimeter readings revealed higher EC measurements. However, the EC in the PE, paper mulch, and no-mulch treatments were also high, hence that could be due to the leaching of accumulated salts in the soil surface. He says, “We have yet to examine the leachate samples for the presence of particulates.”

Installing lysimeters

Composting Alternatives

If the team finds that some of the BDMs do not biodegrade very well in the field, the alternative could be on-farm composting, which would be more viable than having to deal with polyethylene plastic. Sintim and his research team have set up a composting study where they have been digitizing the images of the mulches degrading. He adds, “We buried the mulches in a mesh bag, and periodically we retrieve the bags to study the mulch. There was some black staining on the mesh bag, which we suspect is a nanoparticle called, “carbon black,” used as reinforcing filler in tires and other rubber products.

Scientist studying how mulches degrade over time

The team buried the mulches in compost, and periodically they retrieve the mesh bags to study the mulch.

Sintim says the manufacturers do not disclose the actual constituents of their mulches, so he has arranged to examine the mesh bags with WSU’s scanning electron microscope in order to confirm that the stains were due to the presence of particulates. Sintim confirmed that carbon black was used in their experimental BDM, but they don’t know whether the carbon black was made from petroleum products, as there is non-petroleum-based carbon black. He is going to determine whether these particles leach through soil by examining leachate samples from the lysimeter. He will also perform more tests to make sure that these nanoparticles are not going to have any adverse effects on the agro-ecosystem.

What’s in the Future?

While Sintim and his colleagues have made important discoveries, there is still work to be done. He and his team are going to collect three more years’ worth of data to see if there really is a BDM that delivers on its promises and if leaching particles pose a threat to the groundwater.

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May 5

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Is Average Relative Humidity A Meaningless Measurement?

Relative humidity is one of the most widely reported weather parameters and is familiar to most people.

Scientists sometimes misunderstand relative humidity.

Still, it is not uncommon to encounter it being misused. Here are two examples:

My sister recently stated that her son was experiencing 45℃ and 100% humidity while walking around during the day in the Philippines.
In scientific literature, I often find figures displaying daily average relative humidity over a period of weeks or months.

Both of these examples show a misunderstanding of what relative humidity is and how it can be used.

What is relative humidity?

Relative humidity (h_r) is the ratio of the vapor pressure (e_a) in the air over how much vapor pressure there could be if the air were saturated at that air temperature (saturated vapor pressure, e_s(T_a)).

While vapor pressure is a reasonably conservative quantity, meaning it doesn’t change drastically with time (i.e.hours), e_s(T_a) is solely tied to temperature, shown by the empirical Tetens equation:

where T_a is air temperature, and b =17.502 and c = 240.97℃ (constants). As the equation shows, saturated vapor pressure is only a function of temperature, so relative humidity in natural conditions will simply show a sinusoidal pattern that is inverse to air temperature.

When humidity is higher, the vapor concentration difference is smaller so we lose less water, reducing our ability to cool.

Why do we estimate it poorly?

When temperatures are elevated above our comfort zone, we begin to feel hot. Our bodies, which are adept at keeping us cool, evaporate water from our skin to return us to a comfortable skin temperature. When humidity is higher, the vapor concentration difference is smaller so we lose less water, thus reducing our ability to cool. In an attempt to balance the humidity, our body moistens the skin surface with sweat, leaving us feeling damp and sticky. This makes us feel like the air is nearly saturated, but in reality, the higher humidity has simply limited our ability to cool ourselves.

It is a relatively simple thing to convince ourselves that daytime humidities are never 100% unless it’s raining. We know that daytime temperatures are almost always higher than nighttime, due to solar radiation. And, we are familiar with dew that forms on surfaces as nighttime temperatures cool to the point that they begin to condense water out of the air (dew point temperature). If we assume that the vapor pressure of the air (e_a) is the same as the saturation vapor pressure when the dew began to form (nighttime low temperature), then any air temperature throughout the day (T_a, which we assume would be higher) generates a saturation vapor pressure (e_s(T_a)) that is higher than e_a and thus, relative humidity would be less than 1.

So, what about my nephew in the Philippines? Right now, a typical low temperature is 24℃ with a high of 34℃ (when it’s not raining). Under that scenario, the relative humidity, although it would feel quite high, would only be around 56% at midday.

Next Week: Learn what’s wrong with using average relative humidity in scientific papers and what measurement should be used instead.

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