February 3, 2015 [Facility News, Feature Stories and Releases]

North Slope Megasite Preparations Take Form

Third mobile facility completes first year of data collection in northern Alaska

This fall, the AMF3 installation was completed with the addition of scanning and vertical-pointing radars, as well as a Raman lidar.
This fall, the AMF3 installation was completed with the addition of scanning and vertical-pointing radars, as well as a Raman lidar.
Another first of many to come for the North Slope site, the third mobile facility (AMF3) for the ARM Climate Research Facility completed 1 year of data collection at Oliktok Point, Alaska, on September 30, 2014, with 4 years remaining in this extended deployment as currently planned. Led by Sandia National Laboratories, data are being gathered by the AMF3 to better understand Arctic aerosol, cloud and radiative transfer processes that may play an important role in Arctic climate change. Data from the AMF3 will complement data collected since 1997 by ARM’s long-term site in Barrow, Alaska.

In September 2014, the Department of Energy Climate and Environmental Sciences Division, within the Office of Biological and Environmental Science, held a workshop focused on scientific priorities for observational and high resolution modeling activities in the North Slope of Alaska (NSA) region. The workshop was the second in a series focusing on key scientific needs, gaps, and priorities in linking ARM observational data to improved process model understanding and climate model prediction through the strategic deployment and operation of routine high-resolution modeling at the future ARM megasites at the NSA and Southern Great Plains (SGP). The AMF3 is expected to be an essential part of the North Slope megasite, although details are still under discussion with the ARM user community. The North Slope workshop report will be available in spring 2015.

"The workshop was an intense day and a half of brainstorming and information gathering," said Mark Ivey, NSA site manager from Sandia. "We feel it was a great success thanks to the efforts of participants and contributors who were willing to help us distill more than a dozen white papers to lists of essential science needs, gaps, and observations."

Expanding Measurements in a Challenging Environment

The challenging environment at Oliktok Point made itself known in December 2014 with snow drifts reaching the tops of the AMF3 shelters.
The challenging environment at Oliktok Point made itself known in December 2014 with snow drifts reaching the tops of the AMF3 shelters.
Phase two of the AMF3 installation was completed in October 2014 with the installation of scanning and vertically-pointed cloud radars and two Raman lidar shelters. With only a handful of Raman lidars (light detection and ranging capability) around the world, this unique instrument uses pulses of laser radiation to probe the atmosphere. A telescope collects the backscattered radiation that returns and the optics inside the laboratory shelter use that radiation to derive time- and altitude-resolved profiles of atmospheric water vapor, aerosols, clouds, and temperature. The system is housed in two standalone shelters; one serves as a laboratory enclosure, and the other contains support systems such as HVAC services and power conditioning.

Dedicated technicians stay with the AMF3—even during the severest of weather conditions.
Dedicated technicians stay with the AMF3—even during the severest of weather conditions.
A group of radars—the Ka-ARM Zenith Radar (KAZR), Ka-Scanning ARM Cloud Radar (KA-SACR) and W-Band Scanning ARM Cloud Radar (W-SACR), and Radar Wind Profiler (RWP)—were also installed at Oliktok this past year. The KAZR, KA-SACR, W-SACR, and RWP will provide the high-resolution cloud data needed to achieve megasite modeling goals.

"We operated our new radars at Oliktok successfully during the first winter following their installation during the summer of 2014, although we are facing big challenges with wind and drifting snow occurring this winter. We are looking forward to an innovative evaluation of the dual-frequency radar at Oliktok this spring." Ivey said.

In December 2014, the challenges of operating the AMF3 in the harsh arctic climate became a reality. The microturbines that generate electricity for the site were affected and power had to be supplemented with back diesel generators. The AMF3 shelters and exterior instruments iced over during phase 3 weather conditions—whiteout weather with visibility limited to feet or even inches. Low temperatures and high winds required staff to stay inside. Keeping the instruments warm and operating in these circumstances required extreme dedication by the two site technicians who stay at the site full time. Through their hard work and the arctic hardening of instrumentation, the AMF3 did not sustain irrevocable damage. The microturbines were fixed in January 2015 and full power was restored.

New Capabilities, New Uses

The team is preparing for the Evaluation of Routine Atmospheric Scientific Measurements using Unmanned Systems (ERASMUS), a two-week campaign at Oliktok Point in April 2015. This campaign serves two main purposes: to support the set of atmospheric measurements obtained concurrently by the third ARM Mobile Facility stationed at Oliktok Point; and to evaluate the potential for future routine unmanned aerial systems operations to gather atmospheric measurements at Oliktok Point. The campaign will improve understanding of the lower Arctic atmosphere, including aerosols and clouds, by providing vital data for analyses and model studies.

Also in 2015, the ARM Airborne Carbon Measurement (ACME) campaign moves to the North Slope of Alaska. The ARM Aerial Facility’s Gulfstream-159 (G-1) will be based out of Deadhorse, Alaska, near AMF3 at Oliktok Point. For three months in the summer of 2015, the G-1 will obtain measurements in this area to continue the study of atmospheric composition and carbon cycling.

# # #

The ARM Climate Research Facility is a national scientific user facility funded through the U.S. Department of Energy's Office of Science. The ARM Facility is operated by nine Department of Energy national laboratories.

January 23, 2015 [Data Announcements]

New MICROARSCL Evaluation Data Released for Barrow, Alaska

Four of the roughly 30 variables provided by MICROARSCL are shown here for February 13, 2012, in Barrow, Alaska.
Four of the roughly 30 variables provided by MICROARSCL are shown here for February 13, 2012, in Barrow, Alaska.

A new evaluation release of 18 months of data from Barrow, Alaska, provides the first KAZR-based Micro-Active Remote Sensing of Clouds (MICROARSCL) data from this North Slope of Alaska (NSA) site. The addition of the KAZR data to the NSA site adds additional temporal and spatial resolution relative to the retired Millimeter Wavelength Cloud Radar (MMCR). The improved resolution provided from the KAZR also diminishes spectral artifacts in the data, which provides more accurate information on cloud dynamics. This announcement follows a mid-2014 release that offered a mix of five years of data from the Southern Great Plains and Tropical Western Pacific sites and the Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) campaign ARM Mobile Facility deployment in the Azores.

Since 2004, the ARM Climate Research Facility has established the continuous recording of profiling radar Doppler spectra. The recorded spectra offer a powerful means for overcoming the dependency of radar measurements on particle size (proportional to the sixth power of particle diameter) thus enabling the identification of both small and large particle populations in a radar sampling volume. This advances the ability to study and understand the microphysical and dynamical processes underlying the production and evolution of hydrometeors in clouds and precipitation.

While direct observations of radar Doppler spectra sometimes hold the key to new insight, it is often more useful to work with spectra indirectly through their extended moments (e.g. skewness and kurtosis) and other parameters that compactly capture the shape and complexity of their information. This is the purpose of the new value-added product (VAP) MICROARSCL currently under evaluation. This new VAP contains a familiar name—Active Remote Sensing of Clouds—but with a host of new complementary parameters to facilitate process studies down to the micro-scale.

Feedback and use of the data are welcomed and encouraged. For questions or to report data problems, please contact Mike Jensen or Ed Luke. To access this data sets, browse the ARM Data Archive. (Go here to request an account).

January 6, 2015 [Facility News, Feature Stories and Releases]

Eastern North Atlantic Site Expands Data Capabilities

First Year of Operations Completed in the Azores

Situated near the airport on Graciosa Island, the newest ARM facility operates 24/7 to collect climate data.
Situated near the airport on Graciosa Island, the newest ARM facility operates 24/7 to collect climate data.

Situated off the coast of Portugal in the Azores, Graciosa Island hosts one of ARM’s newest observation facilities, the Eastern North Atlantic, or ENA. The now one-year-old climate research site has filled with instruments that will lead to cutting-edge research data. ENA’s baseline suite of instruments monitors the interaction of clouds, aerosols, and precipitation in this region.

The ENA site provides a rare data set from the subtropical marine boundary layer where climate models show the greatest discrepancy in how clouds change. ENA data support climate and process-based numerical climate models, which require statistically robust and physically accurate observational data sets obtained over long periods of time. ARM, through Los Alamos National Laboratory (LANL), began working on international contracts, site design, and instrument selection in late 2012 and shipped the first 12 instrument systems to Graciosa Island for installation in late September of 2013.

Site Installation 101

Richard Coulter (instrument mentor from Argonne National Laboratory) and Carlos Sousa (site operations) assemble the radar wind profiler.
Richard Coulter (instrument mentor from Argonne National Laboratory) and Carlos Sousa (site operations) assemble the radar wind profiler.

Overcoming shipping delays and severe weather, the team ran fiber-optics, got the power grid running, and set up data systems to promptly get data flowing back to the national laboratories that operate ARM in the U.S.

"This site installation is a good example of the entire ARM team coming together to do what we do best. We make climate measurements where they are needed most, usually in challenging places," said Paul Ortega, ENA site manager from LANL and the install team leader. "Many collaborators came together to create a world-class climate research facility we can all be proud of."

In February 2014, the international team added a hydrogen generation system, a remote balloon launcher, and refined the aerosol measurement system. Over the summer months, an eddy correlation flux with surface energy balance system (ECOR/SEBS) was added to estimate the total surface energy balance. In addition, the Ka-ARM zenith radar, W-Band Scanning ARM Cloud Radar, radar wind profiler, Doppler lidar, and 2-D video disdrometer instrumentation was also added. (See the ENA photo set in Flickr.)

The site has continued to grow at exceptional rates with the installation of the first of many guest instruments. In December, a field mill sensor from Laboratory of Atmospheric Electricity University of Évora, Portugal, was installed.

Big Installations, Big Plans

A meeting to be held in late January in Lisbon, Portugal, introduced the facilities capability and provided groundwork for a science workshop at the ENA site in the near future. In February 2015, the team will install the last major instrument proposed for ENA, the X-Band Scanning ARM Precipitation Radar, a newer measurement capability for ARM that supports cloud formation and velocity research.

Next spring, a custom sophisticated optics system known as a Raman lidar will be installed and housed in two 20-foot sea containers. This ground-based laser remote sensing instrument measures vertical profiles of water-vapor mixing and several cloud and aerosol-related quantities. To provide profiles of atmospheric constituents, an Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST) that measures infrared spectral zenith radiance at high spectral resolution is also scheduled to be installed.

"Much of the credit for the successful development of the ENA facility is due to the University of the Azores," said Kim Nitschke, ARM Facilities Manager for ENA from LANL. "The collaborative support provided by Professor Eduardo Azevedo and his team aids all aspects of the facilities operations."

# # #

The ARM Climate Research Facility is a national scientific user facility funded through the U.S. Department of Energy's Office of Science. The ARM Facility is operated by nine Department of Energy national laboratories.

February 4, 2013 [Blog]

Recycling: A Lesson from Manus Island

Guest post and photos by Chad Baldi, Project Engineer, ProSensing Inc.

Three of us from ProSensing recently made a trip to Manus Island in Papua New Guinea to perform some upgrades to two ARM radars. We made a few interesting discoveries.

In 2011, the ARM zenith cloud radar Ka-band antenna was replaced, and the old antenna was scrapped. As seen in the picture, the local villagers salvaged the scrapped antenna and are now using it to collect rain water for the community. The rain water drains off the roof of the house into the antenna, serving as a catch basin. When we told the property owner what a brand new antenna costs, he had a good laugh.

The other photo is a picture of wood-crafted shed. This is an office/study built by a local man using the materials from the wooden shipping crate that contained the new antenna. The crate provided enough material for him to construct the shed and some furniture inside. Talk about a new perspective on shipping crates!

Now that's some creative recycling.

October 1, 2012 [Feature Stories and Releases]

Ahoy! It’s MAGIC in the Pacific

A crane operator carefully moves the AMF2’s Roll-Pitch-Yaw stabilization platform into position on the bridge of the <em>Horizon Spirit</em>. Antennas for the cloud radar and radar wind profiler are already installed on the large container on the left.
A crane operator carefully moves the AMF2’s Roll-Pitch-Yaw stabilization platform into position on the bridge of the Horizon Spirit. Antennas for the cloud radar and radar wind profiler are already installed on the large container on the left.

All aboard! And by "all" we mean the more than two dozen atmospheric research instruments recently installed on the Horizon Spirit container ship. Through funding from the Department of Energy’s ARM Climate Research Facility, these instruments are obtaining measurements from the sky above the ship as it routinely transits between California and Hawaii. Scientists will use these data to study how cloud systems transition from cumulus to stratocumulus along this route of the Pacific Ocean. Due to lack of data, computer models currently have difficulty simulating these cloud processes, which play an important part in the global climate system.

The Marine ARM GPCI Investigation of Clouds, or MAGIC, will give researchers the data they need to improve these models, leading to better simulations of Earth’s climate system. The acronym GPCI refers to the study comparing how different models simulate cloud processes in the Pacific. Led by Ernie Lewis, principal investigator from DOE’s Brookhaven National Laboratory, a team of scientists will take rotations onboard the ship to monitor the data and observe conditions in real time. For more information, see the Brookhaven press release.

A Sea Change for the ARM Mobile Facility

This ocean-going campaign is the first marine deployment of an ARM Mobile Facility (AMF)—there are currently two AMFs, with a third on the way. Operated by Argonne National Laboratory, the second unit, called AMF2, was first deployed throughout winter in Steamboat Springs, Colorado. It then moved to Gan Island in the Maldives, a small island chain in the Indian Ocean, until early 2012.

Since its return to the United States, AMF2 has been undergoing an extensive reconfiguration, with instruments getting calibrated, updated, and modified for MAGIC. To endure the strenuous sea voyage, many of the instruments had to be "hardened" to withstand the corrosive environment of sea salt, not to mention reinforcements for operating on an ocean vessel.

With deployment space on the Horizon Spirit at a minimum, the AMF2 team constructed new mounts for many instruments, moving them up off the ground onto containers. One container was reconfigured with custom shocks and mounts for the Ka-band ARM zenith radar and radar wind profiler antennas on its roof. A new stabilized platform was also developed to maintain the marine W-band ARM cloud radar in a steady vertical orientation while moving through the ocean.

Instruments for measuring clouds, aerosols, precipitation, and solar energy are securely fastened to the top of an AMF2 operations container on the Horizon Spirit, shown here at the Port of Los Angeles.
Instruments for measuring clouds, aerosols, precipitation, and solar energy are securely fastened to the top of an AMF2 operations container on the Horizon Spirit, shown here at the Port of Los Angeles.
From a data collection standpoint, ARM instrument mentors had to learn how their systems would perform under the stress of a marine environment and aboard a moving vessel. Data ingest and archival support was also heightened to handle new sea navigation data for the constantly changing roll, pitch, yaw, latitude, and longitude of the ship. These additional "SeaNav" data are included within many instrument systems.

"This is an exciting, cutting-edge deployment, requiring many new connections between the AMF2 instruments and data collection systems," said Nicki Hickmon, AMF2 Technical Operations from Argonne “Lots of people have put a lot of hard work into this, and it’s great to see it all come together.”

Good News on the Horizon

When looking for a vessel that could meet their science objectives, the MAGIC science team identified the Horizon Spirit, which transits their region of interest. They also estimated that the footprint on the ship’s bridge could accommodate the AMF2 space requirements, and indeed, the unique bridge deck on the Horizon Spirit provided more space than most cargo vessels.

With the understanding that AMF2 operations could not affect cargo operations, Horizon Lines graciously agreed to modifications on the bridge deck for stiffeners and welded mounting systems and sockets to secure the AMF2 hardware. All deck modifications were designed by a marine architect, approved by the American Bureau of Shipping, and then inspected and signed off on by the ABS. All modifications will be remediated at the end of the campaign.

"The Horizon Spirit is a ship of opportunity granting us the privilege of riding along with their cargo operations," said Hickmon. "Everyone at Horizon has been very accommodating, particularly the captains and crew, who are the feet-on-the-ground giving us access to the ship."

Except for the vessel’s 3-month dry-dock period between late February and early May 2012, the AMF2 will operate continuously through September 2013. In addition to the MAGIC science team members, at least two AMF2 technicians will be aboard the ship to monitor and maintain the instruments. More information about the MAGIC campaign, including links to more photos and a "ship locator” can be found on the AMF2 deployment web page.

September 4, 2012 [Data Announcements]

New Radar Data Lead to New Value-Added Product

This sample KAZR-ARSCL plot shows data from the SGP on April 26, 2011.  The top image shows the 'reflectivity_best_estimate' field, and the lower image shows cloud base and cloud top heights for all cloud layers detected on this day.
This sample KAZR-ARSCL plot shows data from the SGP on April 26, 2011. The top image shows the 'reflectivity_best_estimate' field, and the lower image shows cloud base and cloud top heights for all cloud layers detected on this day.
The Ka-band ARM zenith radars (KAZRs) have replaced the long-serving millimeter-wavelength cloud radars (MMCRs). As a result, the Active Remote Sensing of Clouds (ARSCL) value-added product (VAP), which is based on MMCR observations, is being replaced by a KAZR version, the KAZR-ARSCL VAP.

KAZR observations in this VAP are corrected for water vapor attenuation and velocity aliasing, and then significant detection masks are produced. Water vapor attenuation refers to radar signal power loss due to absorption of the signal by water vapor. Velocity aliasing corrections exclude velocities measured by the radars that are outside the radar's accurate detection range.

The corrected KAZR measurements are combined with observations from the micropulse lidar, ceilometer, balloon-borne radiosondes, rain gauge, and microwave radiometer to produce two datastreams: one with cloud base and cloud-layer boundaries, and one that also includes best-estimate time-height fields of radar moments.

KAZR-ARSCL evaluation data are available for the ARM Southern Great Plains site during the Midlatitude Continental Convective Clouds Experiment (MC3E), April to June 2011. Evaluation data are also available for the ARM Mobile Facility deployment at Gan Island, Maldives, for the ARM MJO Investigation Experiment (AMIE) from October 2011 to February 2012.

Additional information is available in the README file that accompanies the data files from the ARM Data Archive. Please send any comments and suggestions related to the product to Karen Johnson, kjohnson@bnl.gov. This feedback will assist in improving the product prior to its full release.

More information on the VAP is available at the product web page. To access these data, log in to the Data Archive. (Go here to request an account.)

August 20, 2012 [ARM Mobile Facility 2, Blog, Field Notes, MAGIC]

Raindrops and the Doppler Effect

Editor's note: As part of the preparations for the upcoming Marine ARM GPCI Investigations of Clouds (MAGIC) field campaign, principal investigator Ernie Lewis discusses how radars use the Doppler effect to determine raindrop sizes and speeds.

This illustration of the Doppler effect shows the change of wavelength caused by the motion of the source (in this case, raindrops).
This illustration of the Doppler effect shows the change of wavelength caused by the motion of the source (in this case, raindrops).
Most of us know that the Doppler effect pertains to the change in frequency of a wave emitted by or scattered from a moving object. Our familiarity with this phenomenon is predominantly with sound waves, but the effect is the same for any wave. When a siren, for example, is moving toward us, the pitch (i.e., the frequency of the sound) is greater, whereas when it is moving away from us the pitch is lower—this is the Doppler effect in a nutshell. The amount by which the pitch is greater or lower, called the Doppler shift, is related to the speed of the object and to the speed of sound. Similarly, for radars, the amount by which the frequency of the radio waves reflected from a moving object changes depends on the speed of the object and the speed of propagation of radio waves, which is the speed of light.

Radio waves consist of oscillations that occur a given number of times every second, which by definition is the frequency of the wave. Each of these oscillations propagates at the speed of light toward the receiver, where they will be detected at a later time that is determined by the distance to the object and the speed of light. Because all oscillations travel the same distance and at the same speed from the object to the receiver, the receiver detects the same number of oscillations every second as are being created by the object. In other words, it detects the wave at the same frequency at which it was emitted.

For the situation in which the object is moving toward the radar receiver, the same number of oscillations is being created every second, but each successive oscillation occurs closer to the receiver, and takes less time to travel to the receiver than the previous one. As the motion of the object toward the radar results in more oscillations being received by the radar every second, the frequency is higher. If the object is moving away from the radar the oscillations will be received less often, and the frequency will be lower.

How big are raindrops?

The Ka-band ARM zenith pointing radar (KAZR), shown here on Gan Island, is one of the radars that will be deployed for the MAGIC field campaign.
The Ka-band ARM zenith pointing radar (KAZR), shown here on Gan Island, is one of the radars that will be deployed for the MAGIC field campaign.
The Doppler effect is employed by the ARM radars to determine the sizes of raindrops. This may at first seem puzzling, as the magnitude of the Doppler effect depends on the speed of an object, not its size. The speed at which a drop is moving toward or away from the radar might not be the same as the speed at which it would normally fall because of updrafts and downdrafts in clouds (and in the atmosphere in general). In the simplest case, the Doppler signal measured by a vertically pointing radar consists of frequency shifts, each shift corresponding to a given speed. By employing the relation between this speed and raindrop size, the Doppler signal can be related to the raindrop sizes.

How fast do water drops fall?

For drops near the surface of the Earth, the following approximate values will give an idea of the speeds involved.

  • The terminal velocity of a cloud drop, with typical diameter 20 millionths of a meter (approximately one thousandth of an inch), is one centimeter (~1/2 inch) per second.
  • For drops comprising drizzle, which are perhaps ten times as large, it is 3/4 of a meter (2 feet) per second.
  • Small raindrops, with diameters of one millimeter, fall at 4 meters (13 feet) per second, and large raindrops, with diameters 5 millimeters, fall at 9 meters (30 feet) per second (20 mph).

Another way to look at this is to consider the times required to fall (in still air) a distance of ten meters, the height of a three-story building. Approximate values are fifteen minutes for cloud drops, fifteen seconds for drizzle drops, two second for small raindrops, and one second for large raindrops.

Not only do we know the relation between raindrop size and terminal velocity, we also know how strongly raindrops of a given size reflect radio waves back to the radar. This information means that from the strength of the Doppler signal at a given frequency shift we can determine how many raindrops of the corresponding size are in the volume of air sampled by the radar.

The sizes of the raindrops, plus the number of drops of each size, comprise an important quantity in meteorology known as the drop size distribution (DSD). If the DSD is known, we can calculate the rainfall rate, as we know how much water is in each size of raindrop, how many raindrops of each size there are, and how fast drops of each size are falling.

--Ernie Lewis, MAGIC principal investigator

August 7, 2012 [ARM Mobile Facility 2, Blog, Field Notes, MAGIC]

Alphabet Soup: Radars for MAGIC

Editor's note: As part of the preparations for the upcoming Marine ARM GPCI Investigations of Clouds (MAGIC) field campaign, principal investigator Ernie Lewis provided information about the types of radars that will be used during the campaign.

The aerosol observing system (left) and AMF2 Operations van (right) will join a Ka-band radar and a specially modified marine W-band radar.
The aerosol observing system (left) and AMF2 Operations van (right) will join a Ka-band radar and a specially modified marine W-band radar.
I visited Argonne National Laboratory earlier this week, where the ARM Mobile Facility instrumentation is being staged before it will be shipped to Los Angeles and loaded on the Horizon Spirit, the container ship that will host MAGIC. Most of the instruments were there and were being secured in the vans for shipment.

The radio waves used for radars are grouped into bands, each band covering a range of frequencies. Most of the bands consist of frequencies greater than those used for FM radio, which in turn are greater than those frequencies used for AM radio. Some of the main radar bands have rather cryptic designations, like L, S, C, X, K, Ka, and W. “L” stands for “long,” as the wavelengths are longer than those used in S-band radars, where “S” stands for “short”. L-band radars are used (among other purposes) for long-range air traffic control, whereas S-band radars are used for air traffic control at airports. The X-band was so named because the frequency was a secret during WW2. “K” stands for “kurz,” which is German for “short” (different viewpoints on what is short, I suppose). Ka-band radars have frequencies just above K-band radars, hence the “a.” Among other uses, Ka-band radars are employed by police to detect speeding motorists.

The two main radars that will be used during MAGIC are a Ka-band radar and a W-band radar. Ka-band and W-band radars have traditionally been thought of as cloud radars, meaning they are used to detect primarily cloud drops, whereas C- and S-band (and more recently X-band) radars have traditionally been thought of as precipitation radars, as they readily detect raindrops. This distinction isn’t strictly valid, however, as Ka-band radars can also provide some information on precipitation.

The interaction between electromagnetic radiation such as radio waves and an object such as a cloud drop or a raindrop depends mainly on the frequency of the radiation and the size of the object. Thus, radars of different bands will yield different results when aimed at a cloud or at a rainstorm, and radars of different bands can be used together to provide information about the numbers and sizes of the cloud drops or raindrops.

Besides the frequency of the wave and the size of the object, the interaction of radio waves with an object also depends on the shape of the object and its composition. Thus radars can determine whether objects being detected are cloud drops or ice crystals, for instance, or whether objects are birds, insects, or water drops. When cleverly employed, radars can determine how fast raindrops are falling, from which they can infer the sizes of the drops.

--Ernie Lewis, MAGIC principal investigator

March 27, 2012 [Publications]

New Year Brings New Documents

Each year, the ARM Climate Research Facility publishes a variety of technical reports and documents to inform users. The year is still young, but already eight technical documents have been published.

Two handbooks for Recovery Act instruments, the Doppler Lidar (DL) Handbook and the Ka-Band ARM Zenith Radar Handbook, document the functionality and operation of these new instruments.

In additional, two new technical reports document results from experiments designed to improve instruments: Parameterization of the Extinction Coefficient in Ice and Mixed-Phase Arctic Clouds during the ISDAC Field Campaign and Calibration and Laboratory Test of the Department of Energy Cloud Particle Imager.

Two value-added product (VAP) reports were also published in early 2012. The Sonde Adjust Value-Added Product Technical Report and Raman Lidar Profiles Best Estimate Value-Added Product Technical Report describe these VAPs.

The Atmospheric Radiation Measurement Climate Research Facility Operations Quarterly Report and ARM Climate Research Facility Quarterly Value-Added Product Report are published each quarter to provide updates on data availability, user statistics, and the progress of value-added products. Both reports are available for the first quarter of FY2012.

Be sure to check publications news for new additions and journal article references throughout the year!

November 7, 2011 [AMIE, ARM Mobile Facility 2, Blog, Field Notes]

Scientists and Clouds

University of Washington professor Bob Houze takes pictures of clouds at the SPol site.
University of Washington professor Bob Houze takes pictures of clouds at the SPol site.
If you observe the typical AMIE/DYNAMO scientist during a day in the Maldives, you'll find that they are rarely seen without a few key pieces of equipment—a laptop, a USB drive for sharing data, a notebook and pen for jotting notes, and a camera. The camera might seem more like a tourist accessory than a scientific tool, but if you check out those memory cards you'll find that the vast majority of them are filled with more pictures of clouds than of people! While one tropical cloud may look like another to most people, to the AMIE/DYNAMO scientists, they are all unique signatures of the weather conditions on a given day.

One of the interesting things that I have observed during AMIE is that the cloud field is often quite complicated. It is rare to see only a single type of cloud in the sky; usually there are a variety of different cloud types, often at different heights.

Cloud field looking south from the AMF2 site.
Cloud field looking south from the AMF2 site.
This picture is a good example—you can see some low-level puffy cumulus in the background of the picture. In the foreground, in front of the cumulus from our perspective, are some thin laminar layers that are likely mid-level altocumulus, and then the rest of the sky is filled with wispy cirrus (high ice clouds).

Picture looking directly up at the sky from the AMF2 site, while standing next to the Ka-band ARM Zenith Radar (KAZR).
Picture looking directly up at the sky from the AMF2 site, while standing next to the Ka-band ARM Zenith Radar (KAZR).
There are a couple of reasons for the complicated cloud structure at Gan. One is that there is often wind shear (winds moving in different directions at different heights), while the low convective cloud field might be moving in one direction, the mid-level or high-level outflow might move in a different direction. Another cause is that the atmospheric column at Gan is often much wetter than you find at the mid-latitudes, so clouds may remain around longer after they've stopped actively developing rather than evaporating as quickly as they would in a drier environment.

This plot is from the Ka-band ARM Zenith Radar (KAZR) on October 23.  Note that time in the radar plot is in GMT while the camera date stamp is in Gan local time, so the camera image corresponds to the radar profile at 05:35 GMT.
This plot is from the Ka-band ARM Zenith Radar (KAZR) on October 23. Note that time in the radar plot is in GMT while the camera date stamp is in Gan local time, so the camera image corresponds to the radar profile at 05:35 GMT.
Besides being pretty, these cloud pictures are useful for helping us understand the data that we are obtaining from all of our cloud-measuring instruments. Understanding the meaning of a radar reflectivity measurement is a lot easier when you can directly relate it to a visual cloud image. I often go out and snap a picture of the sky directly above the KAZR vertically pointing radar, such as this picture of the high-level ice cloud and then examine the radar display (below) to see what the clouds would look like if my eyes could see millimeter-wavelength radiation like the KAZR can.

--Sally McFarlane

September 7, 2011 [AMIE, ARM Mobile Facility 2, Blog, Field Notes]

Teamwork Keeps AMIE on Schedule

Picture of the C-SAPR site showing the C-band radar tower. AMIE-Manus radiometer system and CT25K ceilometer are circled in red.
Picture of the C-SAPR site showing the C-band radar tower. AMIE-Manus radiometer system and CT25K ceilometer are circled in red.

I recently traveled to Manus to set up the instrumentation for the ancillary variability site for AMIE. As both a member of the DYNAMO Science Steering Committee and PI for the AMIE campaigns, I've been quite busy interacting with the DYNAMO folks. In addition, I've been working with Lynne Roeder and the ARM Education and Outreach folks on the development of the AMIE website, signage, and education and outreach materials. With a tremendous amount of effort on everyone’s part, things are really coming along!

AMIE-Manus
Both Kevin Widener and Nitin Bharadwaj are still on site working on the various radar installations. The C-band radar (C-SAPR) made it through acceptance testing and is currently producing data. While no data are yet available from the ARM Archive, thanks to Kevin and Nitin, quicklook plots are available upon request. One of the advantages to setting up the C-SAPR site at the Lombrum navy base is that there is no need for an additional wireless network for internet connectivity to the C-SAPR site, meaning less possibility of problems.

I must say that the Manus site is looking ship-shape. Along with all the recent instrument upgrades there have been some upgrades to the facilities as well, for instance new seatainers for the SACR and AERI. Things are looking good on Manus!

AMIE-Gan

Initial installation at the main site on the Gan airport grounds.
Initial installation at the main site on the Gan airport grounds.
The AMF2 for AMIE-Gan will occupy two sites. The main site is located at the Gan airport, next to the Gan Maldivian Meteorological Service (MMS) offices. The other ARM site will be near the main wharf for the atoll, about 8.8 km (5.5 mi) up the atoll to the north from the main site. This is where the X/Ka SACR and ECOR systems will be deployed, as well as the NCAR SPolKa radar. Mike Ritsche and some of the AMF2 crew are currently on the Addu Atoll working with local contractors and officials to get the infrastructure in place for the AMF2 equipment. They are also starting to install what has arrived so far at the main site located at the Gan airport.

The C-band SMART-R radar will be located further north at what has been named the "Spit Site" because it is a small skinny "spit" of land sticking out into the water. This placement allows for Range Height Indicator (RHI) scans from the SACR, SPolKa, and SMART-R C-band radars over the main site where the KAZR will be located. Plus all three scanning radars have a very good unblocked horizon view toward the east, which is into the DYNAMO study area.

Major kudos to everyone involved for all their efforts and hard work! If it can be done, they will get it done!

If you'll be at the ASR Fall Working Group meetings, please plan on attending the MJO Breakout. Come with sleeves rolled up and ready to dig in! At long last AMIE is almost upon us. Time to get serious on how we can creatively put all the data to use toward improved understanding and modeling of the MJO.

Cheers,
Chuck Long

Editor’s note: The AMIE campaign is scheduled to begin on October 1, 2011, and run for 6 months. AMIE has two components, one on Manus Island, Papua New Guinea, and the other on the Addu Atoll in the Republic of the Maldives in the Indian Ocean. Both are associated with the larger DYNAMO and CINDY2011 campaigns to study the Madden-Julian Oscillation.

April 23, 2011 [Blog, Field Notes, MC3E]

MC3E Day 1 – The Beginning

MC3E sonde launch. Photo courtesy of S. Collis.
MC3E sonde launch. Photo courtesy of S. Collis.
As a fitting celebration of Earth Day, the MC3E field campaign officially began at 6:30 AM local time with the successful launch of radiosondes from all five boundary facilities and the Central Facility. Our daily morning briefing was focused on the possibility of aircraft operations as the ER-2 ferried from NASA’s Dryden Flight Research Center in California to Offutt Air Force Base in Nebraska. The forecast called for a SW-NE line of thunderstorms to form in the late afternoon just east of an Oklahoma City-Tulsa line. These storms would be too far to the south and east to be sampled by the MC3E radar systems but still looked like an excellent opportunity to get some good observations on the ER-2 ferry. The forecast proved to be excellent as an intense line of thunderstorms began forming at about 4:00 PM. The ER-2 began sampling along the line just before 5:00 PM and was soon joined by the UND Citation, where a couple stacked legs were flown in the anvil of the convective line. Coincident observations were also taken by the University of Oklahoma’s PRIME radar at Norman, OK. This line was very intense with frequent lightning. A tornado warning was issued in the region near our Morris, OK, where sounding staff were sent to their storm shelter in lieu of the 6:30 PM launch.  The lines of storms offered some impressive visual displays from the SGP site and on the drive back to Ponca City along I-35. The anvils covered most of the horizon, often with penetrating convective turrets and underlying mammatus. News reports later showed this same line of storms moving through the St. Louis area, giving rise to more tornadoes and causing significant damage to the airport terminal.
MC3E storms over the SACR and KAZR. Photo courtesy of S. Collis.
MC3E storms over the SACR and KAZR. Photo courtesy of S. Collis.

ER-2 and Citation in Anvil. Image courtesy of E. Zipser.
ER-2 and Citation in Anvil. Image courtesy of E. Zipser.

January 3, 2011 [Facility News]

Cloud Radar Overhauled and Renamed

The KAZR (left) is being tested with a 2-meter antenna used with MMCRs at other ARM sites.  This pre-operational test will help uncover any data anomalies prior to the KAZR being installed in its new home in the shelter on the right when it replaces the MMCR.
The KAZR (left) is being tested with a 2-meter antenna used with MMCRs at other ARM sites. This pre-operational test will help uncover any data anomalies prior to the KAZR being installed in its new home in the shelter on the right when it replaces the MMCR.
In mid-December 2010, a new Ka-band ARM zenith radar (KAZR) began a two-week pre-operational test alongside the ARM millimeter wavelength cloud radar (MMCR) at the Southern Great Plains site. This ushers in a new era for the fixed-position cloud data previously acquired by the MMCR. The MMCR will be retired at all of ARM’s permanent research sites in favor of the new KAZR, which is expected to provide significantly improved sensitivity.

Since it began operating in 1996, the MMCR set the standard for providing data about cloud boundaries, vertical velocity, and reflectivity. Through the American Recovery and Reinvestment Act of 2009, ARM was provided the opportunity to significantly update the radar’s technology. As a result, the KAZR is essentially a new radar. Sourced by a different manufacturer, it uses only two of the same components—the antenna and transmitter—as the previous model. Although the user community must familiarize itself with a new instrument name, the ingested data format is as similar as possible to the historical MMCR ingest. Additionally, the change should be transparent for researchers who use data from the MMCR through the widely used Active Remotely Sensed Cloud Locations, or ARSCL, value-added product.