Campaign : Cloud IOP

1998.04.27 - 1998.05.17

Lead Scientist : Gerald Mace

For data sets, see below.

Summary

Monday, April 27, 1998

IOP Opening Activities: Heavy rain (nearly 2.5" since 12Z 4/26/98) at the central facility (CF) dominated the first day of the Cloud Physics/Single Column Model IOP and limited the daily activities. A 1430 GMT sonde launch commenced the 3-hour sonde launch schedule at the CF and 4 boundary facilities (BFs).

Scientists/Instrumentation on Site:

Citation: Has arrived and is located at the Ponca City Airport. No flights are currently planned. Flights are tentatively planned for stratus sampling when precipitation ends.

UMASS (Steve Sekelsky) Cloud Radar is on site and is located next to the MMCR at IDP#2.

Mark Miller from Brookhaven National Laboratory is on site with the supplemental CIMEL sunphotometer and RSR.

Martin Platt from Colorado State University is on site with the Beam Filter IR radiometer.

Jay Mace indicated that no formal weather briefings would be held during the IOP. However, he will be making forecasts for flight activities.

Tuesday, April 28, 1998

Rain at the central facility continues to be the big news here in Northern, OK.

Scientists/Instrumentation On Site:

Citation: No flights planned for today. A flight may take place tomorrow for stratus sampling if the precipitation ends and the upper air temperatures increase.

UMASS (Steve Sekelsky) Cloud Radar is on site and calibrations will begin when the precipitation ends.

Martin Platt has set up his Beam Filter IR radiometer. Calibrations have begun and waiting on the weather to improve.

Eugene Clothiaux is on site.

Jim Liljegren is on site and is waiting for clear sky to work with the MWR's.

L Gary Hodges, from NOAA, will be running the Hemispheric Sky Imager for Chuck Long.

Wednesday, April 29, 1998

Rain at the central facility has ceased but cloudy conditions prevail.

Scientists/Instrumentation On Site:

Citation: A flight this afternoon around 2000 GMT was issued for liquid phase Stratus sampling.

UMASS Cloud Radar is operational and is currently running with the MMCR for comparison.

Martin Platt has set up his Beam Filter IR radiometer in the optical trailer. Calibrations have begun and waiting on the weather to improve.

Jim Liljegren is waiting for clear sky to work with the MWR's.

Gary Hodges, from NOAA is running the Hemispheric Sky Imager for Chuck Long along with a similar instrument from Yankee in the central cluster.

Thursday, April 30, 1998

The sky has cleared at central facility!

Citation: No flights are scheduled.

UMASS Cloud Radar is operational and is being calibrated.

Martin Platt is running the Beam Filter IR radiometer in the optical trailer.

University of Utah radar is now operational.

Gary Hodges from NOAA is running the Hemispheric Sky Imager for Chuck Long along with a similar instrument from Yankee in the central cluster.

Friday, May 1, 1998

Waiting for Cirrus!

Citation: No flights are scheduled. A calibration flight may occur this evening to test the turbulence sensors and wind sensors. Jay Mace indicates flights will happen this weekend if cirrus clouds move in.

UMASS Cloud Radar is operational.

Clear sky gave Jim Liljegren time to compare the MWRs.

Martin Platt is running the Beam Filter IR radiometer in the optical trailer and is waiting for cirrus clouds.

The University of Utah radar is now operational.

Gary Hodges from NOAA is running the Hemispheric Sky Imager for Chuck Long along with a similar instrument from Yankee in the central cluster.

Monday, May 4, 1998

Still waiting for Cirrus!

Ken Sassen, Chuck Long and Mike Jensen have arrived.

Citation: No flights are currently scheduled. Ken Sassen indicates a flight may occur later this afternoon if cirrus move in.

Ken Sassen has plans to set up next to the UMASS Radar in order to be located with the other IOP instruments.

Tuesday, May 5, 1998

Still waiting for Cirrus!

Citation: No flights are currently scheduled. Ken Sassen indicates a flight may occur later this afternoon if cirrus move in.

Ken Sassen has plans to set up next to the UMASS Radar in order to be located with the other IOP instruments. His instrumentation is scheduled to arrive tomorrow.

A power outage occurred at the central facility (CF) at approximately 4 a.m. CST and lasted until 6:45 a.m. CST. The outage was caused by a bird that wandered into a spark gap in a nearby transformer. The CF operators were able to get the 6:30 a.m. launch off by 7 a.m. Potential data loss is being evaluated.

Wednesday, May 6, 1998

Still waiting for Cirrus! Thunderstorms are occurring all around the Central Facility.

Citation: No flights are currently scheduled.

Ken Sassen instrumentation has arrived and is being set up next to the UMASS radar.

Ben Balsley has arrived.

Thursday, May 7, 1998

Still waiting for Cirrus!

Citation: No flights are currently scheduled. Ken Sassen indicates a flight may take place for cirrus moving in from the south.

Ben Balsley and Mike Jensen are testing the bug net to fly with his kite when wind speeds increase.

Friday, May 8, 1998

Cirrus, Cirrus, Cirrus ! Cirrus clouds have moved in.

Citation: A three hour flight took place this morning around 1530 GMT. A second flight began on 2030 GMT and will most likely last three hours. Especially if upper level cirrus move in from anvil blow off to the southwest.

All other IOP instruments are operational in conjunction with the Citation.

Tuesday, May 12, 1998

The sky is clear here at the Central Facility. Citation: No flights are scheduled.

Ben Balsely flew the kite and the blimp over the weekend and collected a few samples (bugs). The blimp flew this morning (see images below). Over 70 insects were collected in one hour at 500 m. A flight is currently taking place and will end around 1700 CST.

Thursday, May 14, 1998

Hazy sky here at the CF due in part to the smoke emitted from the agricultural burning in Central America.

Citation: No flights are currently scheduled.

Ben Baslely and Mike Jensen have wrapped up their activities.

Monday, May 18, 1998

The IOP is over.

Abstract

The Spring 1998 SCM/Cloud IOP was conducted from 27 April to 17 May 1998 at the ARM SGP site. All objectives outlined in the planning document were addressed to some degree. As is typical of mid-spring in Oklahoma, the meteorology was quite varied ranging from cold rain to severe thunderstorms to clear and hot. The majority of the period was clear, however.

The goals of the IOP included:

  • Intensive observations of cirrus clouds with in situ aircraft and surface-based and space-based remote sensors
  • Resolution of MMCR calibration uncertainty
  • In situ sampling of airborne insects that are causing non-cloud echoes in the MMCR radar data. (Summary of CU Kite-Borne Activities (Insect Studies) (pdf file))

In the following paragraphs, we will discuss the accomplishments in each of the above items.

Intensive Cloud Observation Periods: As mentioned above, the majority of the IOP period was relatively clear although several very interesting events were sampled. Surface observations during the IOP were augmented by the University of Mass. Cloud Profiling Radar System (CPRS), the University of Utah millimeter cloud radar (see image below) and Polarization Diversity Lidar (PDL - PDL data were collected from 8 May), and the Hemispheric Sky Imager. Additionally, the Penn State group collected raw voltages from the MMCR. The unaveraged voltages allow calculation of arbitrarily high velocity resolution Doppler spectra.

29 April - Liquid-phase boundary layer clouds: The University of North Dakota (UND) Citation flew ramps and spirals over the CART site in single and multi-layer boundary layer clouds. Aircraft observations showed regions of quite high (1g/m3) liquid water content.

2 May - Thunderstorm Anvil Cirrus: The progression from optically tenuous to quite thick cirrus detrained from thunderstorms were sampled by the UND Citation. This event coincided with two overpasses of the Tropical Rainfall Measurement Mission (TRMM) satellite. The figures below show sample data from this event.

8 May - Orographically generated cirrus transitioning to anvil cirrus (2 flights): The Citation performed steps and spirals through cirrus that appeared to form downwind of the Rocky mountains in New Mexico. Bullet rosettes and a 22o Halo were observed. This layer became mixed with convective cirrus during the afternoon. The second flight sampled the convective cirrus and included a 100 km turbulence leg and finished with legs over the CART site in the ragged cloud base (possibly mammatus).

14 May - Cirrus over a lower stratiform layer: A 3 km deep cirrus layer as sampled by the Citation. Cirrus was patchy with a persistent stratiform undercast.

A total of 21 aircraft hours were used including ferry time and a calibration flight. All instrumentation worked well except for the LiCor dewpoint sensor on 4/29, the ozone monitor on 4/29, and the inertial navigation system toward the end of the flight on 5/14. Notable was the exceptional performance of the cryogenic frost point hygrometer that failed briefly only twice during the climb out on two flights. Additional information can be found at the Desert Research Institute www site.

In Situ Sampling of Airborne Insects: Using a remotely operated capture device (See figure left) developed by Dr. Ben Balsley and flown from a tethered blimp and parafoil kite, insects were collected between the surface and 700 meters above ground level during several days of the IOP. The samples were photographed (See figure left), frozen and sent to Dr. John Westbrook of the USDA at Texas A and M. While analysis is ongoing, the insects collected during this period appear to be gnat-like and possibly of the family Simuliidae or Sciaridae. The physical characteristics of the average insect from a particular flight are:

  • Mean mass (4 specimens) = 0.1 mg
  • Wing length (1 specimen) = 4.34 mm
  • Wing width, widest = 1.57 mm
  • Abdomen length (1 specimen) = 1.59 mm
  • Abdomen width (1 specimen) = 0.96 mm
  • Body length (1 specimen) = 2.01 mm

In a typical flight, approximately 70 insects were collected during one hour at several hundred meters altitude. This equates to roughly one insect per range gate most of the time.

Resolution of MMCR Calibration Uncertainty: Comparison of MMCR and CPRS reflectivity from the Fall 1997 IOP revealed an approximately 4 dbZ difference with the MMCR lower than the CPRS. While plans were to collect additional data for intercomparison purposes to identify the source of this offset, the source was identified before the IOP by Dr. Ken Moran of the NOAA Environmental Technology Laboratory. The offset occurred due to an incorrect treatment of the Hanning Window when performing FFT’s to generate Doppler Spectra.

Performance of the visiting instruments was mixed. The University of Utah PDL did not arrive until the beginning of the second week of the IOP due to mechanical failure of the PDL van. The University of Utah millimeter radar was not able to collect polarization data although the radar appeared to be quite sensitive and did collect many hours of radar reflectivity and Doppler moments during cirrus cloud events. The digital signal processing board used by PSU to collect MMCR voltages had a problem with ringing in the analog to digital circuitry that caused some ambiguity in the signal although careful data processing will largely correct this problem. The hemispheric sky imager and the CPRS performed well.

In Summary, all IOP objectives were met, although only a few cloud events were available for sampling. Preliminary examination of the data is quite encouraging and analysis of these data will be ongoing.

Additional Information

Important Phone Numbers

Central Facility (Ground Operations)

Phone: 580-388-4053

Fax: 580-388-4052

E-mail: teske@ops.sgp.arm.gov

Ponca City Airport

Greenwood Aviation:

Phone: 580-762-2580

Fax: 580-762-8070

Citation

Phone: 580-765-4477

Data: 580-765-1406

Blackwell/Tonkawa Airport

Secretary: 580-363-0981

Fax: 580-363-0982

Pilots: 580-363-0980

Scientists: 580-363-0996

IOP Chief Scientist/Weather Cell Phones

Cloud IOP - Jay Mace: 630-767-8624

Weather - Mike Splitt: 630-624-6166

Other Contacts

Doug Sisterson, SGP CART Site Program Manager Marv Wesely, ARM SGP Instrument Team Leader Dan Rodriguez, Randy Peppler, Data and Science Integration Team (DSIT) Contacts


Campaign Data Sets

IOP ParticipantData Source DescriptionFinal Data
PoellotCitation Order Data
SekelskyCPRS: U. Mass. 33/95 GHz Cloud Profiling Radar System Order Data