Iowa Flood Studies: Not Your Backyard Rain Gauge

As an undergraduate (from February 2008 to May 2009), I worked for Dan Ceynar, the engineer who coordinates the instrumentation networks for the Iowa Flood Center, and a large part of my job then and since returning to the Iowa Flood Center last October has been taking care of our rain gauges in the field.

For the IFloodS campaign itself, I have also been working with rain gauges. I have been a part of the process of developing these instruments all the way through their construction, deployment, and now maintenance.

April 15, 2013. Kara Prior installs a rain gauge and soil moisture platform in the Turkey River basin in northeast Iowa. Credit: Iowa Flood Center

We use what are called, tipping bucket rain gauges that are a couple steps up from what many people have in their yards. The most important part is a central swinging shaft: on the top are two small buckets, and on the bottom is a magnet. Each bucket holds exactly 1/100th of an inch of rain, and when one fills up it makes the shaft swing to the other side. As it swings, the magnet on the bottom passes over two wires and causes them to touch and complete an electrical circuit– and that’s how we record that rain has fallen.

The engineers I work with designed the electronics that sit under the rain gauges and record their tips. I built the electronics boxes, which sit inside the rain gauge platform and have a cell phone modem, computer, and battery, which the rain gauges use to communicate data back to us every 15 minutes. A network of these gauges like what we have now in the Turkey River Basin can give us very detailed information about where and when rain has fallen.

On the outside, a tipping bucket rain gauge looks like a typical plastic container. Credit: Kara Prior

The inside of a tipping bucket rain gauge is shown here. The rain enters through the black pipe on top and fills one of two triangular buckets, here, the one on the right. When it fills to 1/100th of an inch, the bucket tips downward, raising the bucket on the left to collect rain. Below the buckets (not pictured, but inside the gray compartment), is a magnet that swings and completes a circuit that records the data onto the computer. Credit: Kara Prior

I also helped build the platforms they sit on — starting by picking up 50-gallon trough/tubs from a farm supply store in Cedar Rapids. All of this is our own design — Jim Niemeier’s and Dan Ceynar’s — and we just order the tipping bucket rain gauges themselves.

When I started with the Iowa Flood Center last year, I also built the latest batch of stream-stage sensors. The ones I built that have been deployed thus far are in the Ames area. So, they are not directly in the IFloodS area of interest, but they are identical to the ones we have around the state. So I still feel connected to them all!

April 23, 2013. Setting up another rain gauge and soil moisture platform for IFloodS. Credit: Iowa Flood Center

The rain gauge and soil moisture sensor installations involve a fair amount of digging — and with the lingering winter, we did some of our digging with a pickaxe because the ground was still frozen solid! We had quite a few cold days, which made the few warm days feel like a gift. It was surprising a couple of times how much faster things went when our fingers weren’t cold and stiff!

I have loved getting to know this side of science research. Seeing all the different people and concerns that are a part of a project like this — getting to meet the landowners who let us install on their property — has been really cool.

Kara Prior is a research assistant at the Iowa Flood Center, where she helps oversee a network of rain gauges. She recently finished three years of study and teaching English in China and South Korea, where she earned a graduate certificate in Chinese studies from the Johns Hopkins University-Nanjing University Center for Chinese and American Studies. Kara also holds a BA/BS in international studies and environmental science from the University of Iowa. She has a strong interest in hydroscience and water resource management.

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Iowa Flood Studies: View of the Turkey River

Vijay Mishra and I went to do a maintenance check yesterday on one of the 4 X-band radars that the University of Iowa is contributing to the IFloodS field campaign. Below is a photo of the radar, located at a topographical high point near Elkader, Iowa.

Vijay Mishra performs maintenance on the X-Band radar in the Turkey River basin. Credit: Matt Schwaller/ NASA

The X-band radar has a panoramic view of part of the Turkey River basin. Another University of Iowa X-band radar is located about 20 kilometers away and has a similar view of the watershed, although from a different perspective, of course.

The Turkey River in northeastern Iowa. Credit: Matt Schwaller/ NASA

A significant amount of rain has fallen during the IFloodS campaign, some areas within the campaign area received more than 11 inches of rain since May 1. The Turkey River is now and at or above flood stage.

Matt Schwaller is the GPM Ground Validation project manager with responsibilities for coordinating the development and operations of GPM GV in the pre- and post-launch phases of the GPM mission. He also occasionally takes the role of a field campaign mission scientist.

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Iowa Flood Studies: Multi-wavelength View of Mammatus

Although the significant convection stayed well south of the IFloodS area of study on the evening of 28 May, the multiple wavelength radars at the NPOL site captured the large anvil spreading out from the convection and the associated undulations beneath, known as mammatus. Mammatus clouds are often (but not necessarily) associated with severe weather and form on the underside of anvils due to large temperature, density and wind shear gradients between the cloud and the air. These types of clouds are very photogenic, especially at sunset.

May 28, 2013. Panorama of D3R (left) scanning mammatus at sunset. Copyright B. Dolan, Colorado State University

May 28, 2013.The NPOL radar under a large anvil with mammatus. Copyright Brenda Dolan, Colorado State University.

This case provides an interesting perspective from three different radar wavelengths.  The S-band NPOL radar, with the longest wavelength of 10 cm, is less prone to attenuation (fading out over distance) and is most sensitive to precipitation-sized hydrometeors. NPOL captures the larger domain out to 135 km, with some indications of the undulations on the under side of the anvil and fingers of virga (rain evaporating before reaching the surface) beyond 50 km in range.

Range height indicator (RHI) of NPOL reflectivity through the anvil of a mescoscale convective system displaying small undulations on the underside (mammatus). Credit: NASA

The shorter wavelengths of the D3R are more sensitive to smaller hydormeteors, but subject to more significant attenuation and only see out to 40 kilometers. The Ku-band (2.2 cm) shows the incredible structure in this type of cloud, while the shortest wavelength Ka-band (0.85 cm) is somewhat attenuated by water vapor in the atmosphere, resulting in less reflectivity than the Ku-band frequency. Using these three wavelengths in concert helps to provide a more complete picture of these beautiful clouds.

Reflectivity RHI from D3R’s Ku-band radar. Credit: NASA

Reflectivity RHI from D3R’s Ka-band radar. Credit: NASA

From May 1 to June 15, NASA and Iowa Flood Center scientists from the University of Iowa will measure rainfall in eastern Iowa with ground instruments and satellites as part of a field campaign called Iowa Flood Studies (IFloodS). They will evaluate the accuracy of flood forecasting models and precipitation measurements from space with data they collect.

Brenda Dolan is a Research Scientist at Colorado State University, Fort Collins Colo. in the Radar Meteorology group. Her interests include cloud microphysics and polarimetric radar. During IFloodS, she is spending nearly two weeks as the overnight radar scientist at NPOL and sent these observation notes from the NPOL site near Traer, Iowa.

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Iowa Flood Studies: Tiny Things Matter

When I heard that student volunteers were needed for IFloodS, I knew I wanted to take part. I had had little experience with fieldwork in the past. Most of my graduate work has been spent in front of a computer, conducting data analysis and performing hydrological modeling. I had difficulty visualizing the information I was working on — I didn’t have a good sense of how much 20 mm of rainfall is. I wanted to get outside and see for myself!

I was one of three Iowa Flood Center students who helped set up the NASA NPOL radar near Waterloo. It was a wonderful experience. The radar is really impressive — the antenna is 10 meters in diameter! I got to talk with some of the NASA representatives about the radar. It represents the next generation of radar systems, and will provide much more accurate rainfall estimates.

Apr. 25, 2013. IFloodS has provided students at the University of Iowa a unique opportunity. Graduate student, Bo Chen (far right), helps install the NASA NPOL radar Credit: Aneta Goska, Iowa Flood Center.

It was chilly in the morning when we started work, but it warmed up a lot as the day progressed — we all got sunburned! I didn’t have a good idea what kind of clothes to wear for fieldwork — I learned that it’s best to wear clothes you don’t care too much about. We got pretty dirty.

I also helped install four observation stations (three rain gauges each) near Shueyville, south of Cedar Rapids. We go to Shueyville once a week to clean and maintain the gauges — since the instruments are deployed in farm fields, they get dirty very quickly. It’s important to clean them up regularly. We saw dust in the buckets in just a few days’ time. While we’re there, we also download the data from the data logger. It is then uploaded into the IFloodS portal where the science teams can access it and displayed on Iowa Flood Information System, IFIS.

Gilles Molinié, Université Joseph Fourier and Witold Krajewski, Jim Neimeier, and Bo Chen, Iowa Flood Center, discuss the location for a disdrometer for the IFloodS campaign. Molinié brought the disdrometer from Switzerland to collect data during the IFloodS campaign. Credit: Fred Ogden, University of Wyoming.

I worked with Jim Niemeier to install three rain gauges at an experimental Iowa State site near Des Moines. It was a tough day! We saw a lot of mice, and Jim explained that sometimes animals like to burrow in under the platforms. When we remove the platforms, who knows what might be waiting for us? Perhaps a scared and threatened animal. Animals also sometimes chew the wires, so we have to watch out for that.

For me, this fieldwork experience has been really fun. I now understand the importance of getting out into the field. Tiny things do matter — if it’s not done right, the data can be biased. I learned that careful fieldwork is vital for research. For instance, I learned that I can’t sit on the base of the rain gauges, because my body weight could destroy the level and bias the measurement. I caught myself just before I sat down. I jumped up and thought, “No, I can’t do that!”

I also learned that my professors in Engineering do make efforts to collect reliable firsthand data. I also found that fieldwork is difficult, and we have to be very careful in order to collect good data. Exposure to experiments like IFloods may help to build up our knowledge about fieldwork, and ultimately advance our understanding of complex natural processes.

Bo Chen is a doctoral student in the Civil and Environmental Engineering Department at the University of Iowa working with Professor Witold Krajewski. His research interests include enhancing flood prediction and hydrologic modeling, specifically the hillslope hydrological process and channel routing. During the IFloodS campaign, he is heading up a group of University of Iowa students in servicing and collecting data from one of the field sites.

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Iowa Flood Studies: XPOL Radars in Iowa’s Turkey River basin

Finding a location for two of the four University of Iowa XPOL radars was easy. They will remain at their current home base locations near Iowa City and Cedar Rapids overlooking the Clear Creek Watershed for the IFloodS campaign.  For the other two destined for the Turkey River basin in northeast Iowa — well, there was work to be done.

As is typical, finding the “ideal” radar locations proved to be challenging.  The primary goal was simple enough — a high spot with a good view.  Then we add in the need for power, communications, and access, and it becomes more complicated.

The Turkey River basin, unaltered by glaciers, is rugged and hilly by Iowa standards. Lots of great views, but the ruggedness that makes some of the land difficult to farm, and also means there are a lot of obstructions on the tops of hills, namely tall trees. This image is the “radar’s eye “ view from the St. Olaf site and demonstrates why it was chosen. Credit: Iowa Flood Center

After much planning, looking at satellite images, talking with local cities and groups, it was time to visit the basin for a reality check.  Many sites that had appeared so promising became distant memories, but new possibilities arose with help of local individuals from the City of Decorah, the City of Calmar, local IDNR staff, Northeast Iowa Community College, and others.  We are grateful for their “touring the countryside” time and cooperation.  In the end, two very attractive locations were secured, one in Calmar and one south of St. Olaf.

April 30, 2013, Calmar site: The XPOL installation at Calmar went smoothly enough. It was very windy, but sunny, with mild temperatures. For the follow-up installation of the communications, we dealt with very windy conditions and ice-covered surfaces. Credit: Iowa Flood Center

May 2, 201, St. Olaf Site: The St. Olaf installation was a bit better, 38 degrees F (warm??) , overcast, and very windy, with rain all day. Visiting scholar Jacopo Grazioli, Dan Ceynar, and Radek Goska of the Iowa Flood Center adjust the radar position on the cribbing. Credit: Iowa Flood Center

As many visiting researchers and NASA and scientist are now fully aware, the weather in Iowa is constantly changing, often between extremes. The weather during the installation of the XPOL radars was challenging, ranging mostly from cold, windy, and rainy to windy and icy. Very challenging indeed. Tenacity prevailed, and both new radar locations were successfully installed at the beginning of the month despite the adverse weather conditions.

From May 1 to June 15, NASA and Iowa Flood Center scientists from the University of Iowa will measure rainfall in eastern Iowa with ground instruments and satellites as part of a field campaign called Iowa Flood Studies (IFloodS). They will evaluate the accuracy of flood forecasting models and precipitation measurements from space with data they collect.

Dan Ceynar is a staff engineer at the Iowa Flood Center. He coordinates many of the Iowa Flood Center’s instrumentation networks across Iowa including stream sensors, rain gauges, and XPOL radars. This spring, he has been busy working with NASA and IFC staff to deploy instruments for the IFloodS campaign.

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