rain

Reigning in the Rain with Satellite and Radar

By Marguerite Huber

When it rains, it pours!background_water_puddle

Actually, that phrase is not necessarily true. A rain shower can consist of just drizzle, a steady rain, a downpour, or even all three! Either way, accurate rain totals are the basis of watershed modeling for evaluating the water cycle.

Meteorological data (precipitation, temperature, humidity, etc.) required for watershed assessments have traditionally come from land-based weather gauge stations. They collect weather data from all over the country. Unfortunately, not all watersheds have meteorological stations. Some watersheds have too few, are too far away, or aren’t working properly to correctly represent precipitation totals or their distribution within the watershed. You can check the National Oceanic and Atmospheric Administration’s website to see how many weather gauge stations are in your watershed!

For accuracy, the best options for watershed modeling applications in the U.S. are rain gauges and weather radar data, but precipitation amounts can vary throughout the watershed. Where land-based stations are lacking, remote sensing and radar satellite data are increasingly being used to augment data in space and time.

EPA scientists were involved in a study aimed at providing options for watershed modelers. They did this by comparing precipitation data from radar-based stations to data from ground-based stations to see the effectiveness of using either one for watershed modeling, especially at locations where gauge stations were insufficient.

Because ground-based gauges are the norm, the scientists evaluated the efficacy of using radar or gauge precipitation data to support watershed modeling.

Researchers evaluated two areas in Wisconsin using hourly precipitation data from 2002-2011: the Manitowoc River Basin and Milwaukee area, which are approximately 84 miles apart.

National Climatic Data Center precipitation data from gauges on the ground were compared to two different types of satellite and radar data: North American Land Data Assimilation System and NEXt generation RADar Multi sensor Precipitation Estimates. Both were used to evaluate the reliability of radar and gauge precipitation data.

Results showed gauge and radar data at Milwaukee to be similar, while the Manitowoc River Basin had large differences in precipitation occurrence and totals, which strongly suggest radar data as being more reliable.The gauged precipitation at Manitowoc River Basin also poorly correlated with radar data, which can detect more frequent precipitation, drizzle, and small storms.

In the end, the researchers concluded that the use of radar precipitation data can be an acceptable alternative to the gauged data in Manitowoc River Basin. The results also show benefits from automating the collection process of radar data as an additional option in watershed modeling.

With options of using land-based or radar data, scientists will be able to conduct more accurate watershed assessments, providing important information for keeping our watersheds healthy.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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A Morning By The Lake

Greetings from New England!Each Monday we write about the New England environment and way of life seen through our local perspective. Previous posts

By Amy Miller

My family arrived at our campsite to a gray, evening drizzle. Not too wet to enjoy a kayak, nor too wet to keep us from making a fire and eating turkey dogs off sticks. The beach umbrella propped against a picnic table was ample protection. And we got our reward for persevering. “It doesn’t get much better than this,” remarked a woman on the lake trail as she ogled the double, 180-degree arch of vibrant color like you only expect in children’s books. I looked for the pot of gold.

The rain stopped in time to set up in the dark. The winds whispered above, sending droplets onto our tent. By morning the sky was clear and the islands of Pawtuckaway Lake were calling us out in our kayaks.

Pawtuckaway State Park sits in the middle of southern New Hampshire. Straddling the towns of Raymond and Nottingham, Pawtuckaway has trails, waterfront campsites, rock walls, marshes and a lake with nooks, crannies, big islands, little islands, blueberry-filled islands and a beach.

Unfortunately, it also can have contamination. The beach was half-closed when we were there. Not totally closed, but trimmed with yellow warnings signs that it might not be safe to swim. The problem, according to a nice woman who got my phone call, is that sometimes the bacteria count is too high at the beach. It was only 125 counts per 100 milliliters of water, close to the 88 count cut-off. Outside the beach area the lake was fine, and a few days later, by August, it was all fine again. The bacteria is caused by people and animals, mainly geese and recreating crowds. Beavers and other animals that love the marshes don’t help, nor does rain. But the warning signs didn’t seem to bother the hundreds of people grilling recipes from India, Malaysia, Dominican Republic, Jamaica and Maine. The sun blazing overhead, dozens of people were splashing about happily.

The state tests the water every other day or so. Since 1996, and more regularly since 2000, they have taken 461 samples. Of those, 34 have come back above acceptable standards. The geese, and people who feed them, are apparently among the first offenders.

When we tumbled out of our tent in the morning, a great blue heron was sitting comfortably at the water’s edge, as if to say “Welcome to my campsite; you may stay, if you like.” We stared at him for about 30 minutes.

Then we decided to make breakfast, smokey toast and hot cocoa. We knew not to share it with the ducks, and the heron knew not to ask.

More EPA info on beach monitoring in New England states, including New Hampshire lakes.

About the author: Amy Miller is a writer who works in the public affairs office of EPA New England in Boston. She lives in Maine with her husband, two children, eight chickens, dusky conure,  dog and a great community.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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The First Signs of Spring

Greetings from New England!Each Monday we write about the New England environment and way of life seen through our local perspective. Previous posts

By Dave Deegan

There are always a lot of weather clichés: If March comes in like a lion, it will  go out like a lamb, etc.

I wonder if there is a rule to February. If it kicks off with a huge blizzard, and ends with soggy ground, well then I guess we’re just heading into New England’s Mud Season.  It may not be the prettiest time of year, but it is at least a sign that winter is losing its grip and spring will come.

Everyone remembers how mild last year was: we had crocuses blooming on February 26th.

Just a few weeks ago we had one of the bigger blizzards anyone around here can remember. But in the past few days, the temperature stayed (just slightly) above freezing, so we had buckets of rain, instead of feet of snow. Of course, with the ground still frozen, all that rain means a lot of standing water on the ground until it eventually filters into the soil. A soggy mess, or a sign of spring: your call.

It seems as if everybody up in New England pays special attention to the length of days during this time of year.  Even by late January, you start to notice that “Hey, a month ago it was dark at 4:30, and now it’s light half an hour longer.”  Meaning that by now, in early March, I see daylight through much of my commuter train ride home, until close to 6PM.

Right now, we’re only a few weeks away from changing the clocks for daylight savings time.  If only the temperature would catch up as quickly as the light!

The last few mornings I’ve also been cheered to hear the familiar “wheat wheat wheat” call of our resident cardinals, a familiar sound that I associate with the transition to spring. Of course the cardinals are a welcome presence at our backyard feeders all through the winter, but it’s only now that their activity changes and they start singing more.

All of this means that it is high time to dust off our seed catalogs and gardening books, and start planning what our early season vegetable garden will need, and what care will be needed for our other plants that are just now peeking out from under winter’s snowbanks.

About the author:  Dave Deegan works in the public affairs office of EPA New England in Boston. When he’s not at work, he loves being outdoors in one of New England’s many special places.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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Science Wednesday – Modeling Matters: It Was Supposed To Rain!

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

By Tanya Otte

By early June, my yard was already parched. The drought-tolerant annuals planted to brighten things up were suffering, but relief was on the way. Yielding to the forecast and my shortage of time, I skipped watering the plants. When I got home, the rain gage was bone dry. Eyeing the wilted flowers, I muttered: “But it was supposed to rain today!”

Supposed to rain?!? As if the forecast was a guarantee.

Why are weather forecasts for rain so often wrong?

Forecasts for rain are seeded by weather models. While the science and computing power behind those models have advanced in recent years, rain prediction remains one of the most difficult tasks…even just a few hours ahead of time, and particularly in the summertime.

Precipitation is the result of extremely complex atmospheric processes, many of which are at time and space scales that are not well represented in the operational weather models. The models that provide insight into daily weather forecasts cover the forecast area (either the whole U.S. or some region) as tiles that are often about 7.5 miles on each side. Depending on the terrain elevation, land-water boundaries, and urban-rural distinctions, the weather conditions can be different even within each tile.

Predicting thunderstorm activity is challenging, even for the most experienced meteorologists. Models can tell us if the large-scale and the regional-scale weather conditions (e.g., low-pressure system, cold front, jet stream, sea breeze) would be conducive for thunderstorms to form in a certain area, but not exactly where and when. It’s like putting a pot of water on the stove with the heat on high. You’ve created conditions that will result in boiling (convective activity), but you won’t be able to predict where or when the first bubbles will form.

Rain is also sensitive to subtle changes in wind, moisture, temperature, and pressure in columns of air that extend from the ground upward. This can affect the rising and sinking of air and thus determine whether rainfall occurs. Slight errors in the predictions of any of these atmospheric characteristics will affect the accuracy of the precipitation forecast. Modeling precipitation is tricky business, and it can affect your air quality forecast, too!

Next time you think it’s supposed to rain, give your meteorologist a break!

About the author: Tanya Otte, a research physical scientist, has worked at EPA in atmospheric modeling and analysis since 1998.

Editor’s Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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Don’t Hate The Rain!

About the author: Lina Younes has been working for EPA since 2002 and chairs EPA’s Multilingual Communications Task Force. Prior to joining EPA, she was the Washington bureau chief for two Puerto Rican newspapers and she has worked for several government agencies.

If you live along the Eastern seaboard, you probably were overwhelmed by the incessant rain we had experienced for the two previous weeks. I guess many people suffered from cabin fever due to the dreary weather. Nonetheless, there are some benefits from the rain that we are now enjoying. What benefits, you may ask? Well, prior to these storms, there were areas in Maryland and other Eastern states that had deficits in precipitation for 2009. Groundwater levels had been approaching potential drought levels which seem to have been erased with the recent rains. Furthermore, just prior to these storms tones of brown and chartreuse dominated the landscape of lawns and gardens due to the various pollens in the air. Now, everywhere you look, the gardens have been painted with lush greens and bright spring blooms. Another added bonus, at least during the rain, the pollen is at its minimum—a temporary reprieve for allergy sufferers.

In spite of the benefits of spring showers, we should also be mindful to reduce runoff and non-point source pollution after the rain. Here are some tips:

·    Consider greenscaping to protect the environment.

·    Consider planting native shrubs and trees in your back yard to reduce erosion.

·    Wait for the storm to pass before fertilizing.

And lastly, one final benefit after the storm? We can always look forward to the sunshine. Have a great day!

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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No hay motivo para odiar la lluvia

Sobre la autor: Lina M. F. Younes ha trabajado en la EPA desde el 2002 y está a cargo del Grupo de Trabajo sobre Comunicaciones Multilingües. Como periodista, dirigió la oficina en Washington de dos periódicos puertorriqueños y ha laborado en varias agencias gubernamentales.

Si reside en algún estado a lo largo de la costa este de los Estados Unidos, probablemente ha estado apesadumbrado por la incesante lluvia que experimentamos por las últimas dos semanas. Creo que muchas personas se sentían algo claustrofóbicas debido al tiempo sombrío. No obstante, la lluvia trae muchos beneficios que tan sólo ahora estamos disfrutando. Usted se preguntará ¿cuáles beneficios? Bueno, antes de que comenzaran las lluvias, algunas áreas de Maryland y otros estados del este tenían un déficit de precipitación en los primeros meses del 2009. Los niveles de agua subterránea estaban registrando niveles de sequía potencial que fueron borrados por las recientes lluvias. Además, antes de estas tormentas, una variedad de tonos marrón y verde nilo dominaban los paisajes de céspedes y jardines. En la actualidad, por dondequiera que miramos, los jardines están pintados de unos verdes brillantes, frondosos arbustos rebosantes de la florecida primaveral. Y, ¿otro beneficio adicional? Pues, al menos durante las lluvias, los niveles de polen habían disminuido—un alivio temporal para aquellas personas que padecen de alergias.

A pesar de los beneficios de las lluvias de primavera, tenemos que ser conscientes de reducir las escorrentías y la contaminación de fuentes difusas después de la lluvia.

He aquí algunos consejos útiles:

·    Considere la jardinería ecológica para proteger el medio ambiente.

·    Siembre arbustos y árboles nativos en su jardín para reducir la erosión.

·    Deje que pase la tormenta antes de fertilizar.

Y finalmente, el mejor beneficio después de la tormenta? Siempre podemos esperar que salga el sol. ¡Que tenga un buen día!

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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