Activity Summary for FIRE-ACE Phase I

The NCAR C-130 arrived at 7:00 pm from Boulder. Good measurements of several cloud systems, including ice particles, were made by a number of instruments. A spectacular rainbow greeted the C-130 just after the rain and snow stopped. All equipment was offloaded. The PIs and flight personnel began setting up in their respective offices. All telephones, fax machines, computer drops, and copy machines are ready for use.

The first attempt at communicating via HF radio with Taneil Uttal at the SHEBA ice station was not successful.

The FIRE.ACE website is now operational from Fairbanks at URL: fireace.fire.nasa.gov.

The C-130 support crew and instrument investigators continued to set up their equipment and laboratories.

A Mission Planning Meeting was conducted, at which all platforms (C-130, SHEBA, and ARM) reported that they were ready for operations. Consequently, a flight was scheduled for Monday.

A kick-off dinner was well attended, with copious quantities of Mongolian beef consumed.

The C-130 took off from Wainwright at 0930, refueled at Fairbanks International, and departed at 1030. It flew over Barrow at 1200 and arrived at SHEBA at 1300. The C-130 began radio contact with SHEBA about 1-hour before arrival to ensure that the SHEBA tethered balloons were safely on the ground. Conditions at SHEBA were water clouds at 1 km and below, with sporadic ice clouds up to 6 km. A series of cloud physics, radar validation, surface albedo, and lead interaction flight patterns were flown. The C-130 wasn't able to visually sight the downed tethered balloon, that had run away from SHEBA last week. The C-130 departed at 1730, passed over Barrow at 1830, and landed at Wainwright at 2000. There were some instrument anomalies, some of which were fixed in flight.

The LAN network administrator hooked up all requested computer connections to the FIRE.ACE LAN. Additional tables and desks were picked up and set up in the hangar. Permission to tarmac the C-130 in front of the hangar was granted. The ER-2 fuel cells were consequently moved from one side of the tarmac to the other and placed on a fuel containment bladder.

Unfortunately due to limited staffing capability, the Wainwright Air Traffic Control (ATC) tower will not be open on weekends. The weekend staffing of the Weather Operations is still pending. Both the C-130 and ER-2 have stated that, if the weather is good, they do not need ATC or Weather Ops for either take offs and landings at Wainwright. Fairbanks International could handle their needs. If the weather conditions were marginal, the ER-2 would then probably scrub, at least more so than if the ATC/Weather Ops were open. The C-130 could always land at Fairbanks International.

A survival-training course at Eielson AFB was held for all C-130 crew and passengers. An Investigators Meeting was held, at which George Isaac, Atmospheric Environment Service, gave a summary of the AES/NRC aircraft campaign that was completed last week. Of the 18 flights and 68 hours of flight measurements, there were good to excellent measurements of clouds and radiation. Some of the in-cloud legs were fairly short, due to the propensity of the instruments to ice up. Good measurements of Arctic cirrus clouds were made, as well as Arctic haze, sometimes up to 20,000'. Four flights were made over SHEBA, one in a boundary layer cloud that was mostly liquid and drizzle, two in thin ice clouds, and one in a multi layer liquid cloud. Measurements were made over leads, but as they were of the order or 200 m in width, couldn't determine from the instruments if there was any turbulence interactions.

An overall summary of the C-130 flight operations on May 4 was given. Several science patterns were flown, including cloud physics, radiation, boundary layer turbulence, cloud radar validation, surface albedo and physical features mapping, and lead interactions. Unfortunately, several instruments or systems experienced problems, including AIMR, MCR, 2D probes, front data system, etc. Some of the problems were fixed in flight; others still need to be fixed.

Future profile information will come predominately from either ramps or stair steps; spirals are not the most efficient use of the instruments.

It was recommended that future transits out to SHEBA be at a lower altitude, since the flight of over 2 hours at -45 d C cold-soaked the instruments, especially the ones in the exterior pods. Another recommendation was to perform all non-cloud flight patterns first, since in-cloud legs may ice up some instruments.

The C-130 made some overflights of instruments located on the ice floe, at the request of the SHEBA investigators. The C-130 not able to visually detect the tethered balloon that went down19 km from SHEBA.

There will be Mission Planning meeting at 1530 tomorrow, at which PIs will present some show and tell reports.

At the Mission Planning Meeting, Curry reported on some of the flight patterns that were flown on the Monday flight and the physical properties of the cloud systems measured. The boundary layer (bl) cloud was extremely homogeneous, both spatially and temporally (over the 5-hours of measurements). Based on the meteorology forecast for tomorrow and the SHEBA observations today, the possible C-130 flight tomorrow should experience the same homogeneous bl cloud measured on Monday, except that there will be some cirrus clouds aloft.

Valero reported that all the RAMS instruments worked well. The measurements inferred a cloud albedo of about 60% and absorption of 32%. Some instruments iced over during the long in-cloud legs, which then took about 30 minutes to evaporate. Valero recommended non-cloud patterns be performed at the beginning of the missions.

Rogers reported that the Counter Flow Diffusion Chamber and CN instruments also worked well. They measured supersaturations with respect to (wrt) water of 5% and wrt ice of 35%. This infers that ice-nucleating particles would nucleate very rapidly.

Hudson stated that the CCN/CN instruments worked as well, except that the "interstitial"(?) inlet was contaminated by an upstream exhaust port. The "community" inlet was clear. CN counts were in the range of 200 - 300/cc.

Jensen showed images of the ice particles from the CPI. These particles ranged in sizes from 30 to 800 microns.

Hallet's Cloudscope measured the evaporation rate of particles. Some particles had cores that did not evaporate past 5 microns in size, inferring hydroscopic particles. Some of these "black" particles were even measured outside of any clouds.

Laursen reported that most if not all instruments and systems have been fixed and that the C-130 is ready for a flight on Thursday.

The team concurred on a flight tomorrow.

A pre-flight weather update was given at 0730; the pre-flight meeting was held at 0800. Satellite imagery and SHEBA observations showed that a pervasive stratus layer would prevail over SHEBA. The C-130 took off from Wainwright at 0928, arrived over SHEBA at 1300, departed at 1700, and returned to Wainwright at 1930. Uttal reported from SHEBA that it was a very nice mission, which according to the C-130, "went like clockwork". There was a very thin cloud deck, lots of blue sky, and in general much clearer than it had been for several days, and all in all a good day for cloud microphysics, LES, and radiation mapping. The remote sensing types at the surface very much appreciated the passes directly above the ship, especially the one at 300 feet which looked like a strafing run.

The C-130 operations team had a full down day.

At the Instrument Investigators Preliminary Report Meeting, Curry reported that the C-130 mission on May 7 was successful, with interesting cloud/aerosol interactions. The bl cloud was very thin, only 100 m thick, and was homogeneous and mostly liquid water (0.2 gm/m3). The thin cloud was hard to detect by the SHEBA cloud radar and lidar. The cloud started collapsing to liquid water concentrations of 0.1-0.15 gm/m3 later during the run, but after most of the cloud patterns were conducted. The flight patterns performed included upper altitude mapping; slow descent to the surface; series of east-west legs over SHEBA at 30 m, 100 m, 100 m below cloud, 100 m above cloud, etc.; and 2 sets of 30x30 km boxes below, within, and above the clouds for good turbulence, radiation, convection, bulk cloud properties, etc.

SPEC showed images from selected portions during the flight, ranging in sizes from 20 to 800 microns. Some of the images showed classical dendrites, with riming forming on the edges. RAMS showed simultaneous upwelling solar and infrared radiances, which displayed remarkable correlation (solar decreasing; IR increasing) as the C-130 crossed over a series of leads. NCAR microphysical probes measured a slight aerosol haze layer above the bl cloud.

Both SPEC and RAMS data appear on the FIRE.ACE Homepage.

There were no meetings.

At the Instrument Investigator Reports Meeting, Baumgardner reported that the boundary layer for the mission on Thursday, May 7, was extremely stable and well mixed. The met profile from the C-130 slow descent to the surface showed considerable humidity above the strong inversion, which maintained the stability of the bl.

The analysis of the RAMS measurements showed the transmission to be 0.75, reflectivity 0.72, absorption 0.10, and surface albedo 0.75.

Rogers reported that his instruments measured CN and IFN counts that increased considerably during one portion of the flight. Subsequent discussions revealed that it may be due to the C-130 flying over several (small) leads, indicating a source of CN. Rogers also recommended that subsequent mapping patterns be conducted with the legs starting on the downwind side. This would minimize possible sampling of aircraft exhaust from previous legs.

The meteorology for Monday predicted that a low would pass through the SHEBA area. The storm would include blowing snow at the surface and multiple cloud layers throughout the lower and middle troposphere to about 6 km.

The C-130 took off from Wainwright at 0915 for a flight to SHEBA. The meteorology was expected to be a storm over SHEBA with multiple clouds to 6 km. The flight patterns included upper altitude (7 km) mapping; slow descent to the surface; lead interactions; and multiple 20x20 km boxes below, within, and above the clouds. The C-130 returned about 1930.

The DFRC staff and operations team arrived and began setting up to receive the ER-2 on its arrival on Wednesday.

At the Instrument Investigator Preliminary Reports Meeting, Qing Wang reported on the C-130 mission to SHEBA on Monday, May 11. The C-130 flew a variety of patterns, including an upper z mapping, loitering above SHEBA (awaiting the clearance of the Twin Otter performing low z mapping patterns), slow descent to the surface, box patterns at various altitudes, lead interactions, and own-contrail seeking.

The bl was very shallow, only 290 m. It was mixed phase (liquid water and ice), with a very dry layer above. One cloud layer was at 1300-1500, and others up to 6 km. The SHEBA sonde showed significant moisture above the tropopause.

The microphysics instruments on the C-130 did not conclusively detect an increase in CN when the plane flew over several leads. There was, however, a good correlation with CN when the plane flew through its own contrails (one parallel intersection; four perpendicular intersections). The CPI did detect an increase in small particles over leads and the larger particles showed riming on the edges. All of the AIMR channels were operational for the first time. It detected more open leads and water, including the first break up of the Yukon River. (SHEBA reported also an increase in open water).

The meteorology showed that the storm has just passed SHEBA when the C-130 arrived. The forecast for Friday (and Saturday) is for high easterly winds at SHEBA. There will also be high southerly (cross) winds at Wainwright on Saturday.

The C-130 had a hard down day for its operations and crew.

The ER-2 arrived at Wainwright at 1345. The pilot, Ken Broda, reported that the flight was uneventful, with mostly solid clouds undercast all the way. He noted some problems with a few of the FIRE instruments. All indications are that the ER-2 will be ready for a flight on Friday. The ER-2 staff are still uneasy with the ER-2 not receiving written confirmation to fly within the Russian Flight Information Region. They have been told that the Russians have been informed of our intentions and have not indicated any problems. The ER-2 staff seek more concrete assurances. They will try again immediately.

At the Instrument Investigator Preliminary Reports Meeting, AIMR reported that it measured the break up of the shore ice just west of Barrow, which is sooner than expected. The 90 GHz channel shows good images of both refrozen (close to SHEBA) and open water (further from SHEBA) leads. RAMS measurements of upwelling solar and infrared fluxes show very good correlation in the fine structure as the C-130 flew over the leads. DRI reported that, based on a series of tests, the interstitial inlet is indeed contaminated by the compressor exhaust of the air inside the aircraft. However, the community inlet appears to be working well, even in clouds. Baumgarder recommended comparing the CN measurements from the right side of the aircraft (DRI and CSU) with those on the left side (NCAR). The weather forecast for Friday at the ship predicts bl clouds with little of no middle level clouds. The winds should be from the east at 10-15 knots. The winds at Fairbanks may be less than 10 knots from the south (crosswind).

The C-130 agreed to move up their departure time from Wainwright to be before 0900, so that the ER-2 can be moved out of the hangar for pre-flight preparation at 0900, 2 hours before launch.

The ER-2 investigators (AMPR, HIS, and MAS) proceeded to set up their equipment. The National Stratospheric Balloon Facility (NSBF) also arrived and began equipment set up.

The University of Washington (UW) C-580 aircraft left Seattle and spent an overnight at Anchorage.

At the Mission Planning Meeting, the weather forecast indicated that a low will persist to the south west of SHEBA for tomorrow, leading to clouds and moderate east winds over SHEBA. The long range forecast for Monday is for clear skies.

The C-130 and ER-2 reported that both aircraft were ready for a flight tomorrow. All instrument also reported a go, with the exception of the MAS, which will be partially operational. The UW C-580 will not be ready for flight until Sunday 17.

The flight patterns will be designed to maximize the joint coverage over SHEBA between the C-130 and ER-2. The ER-2 will perform mostly north-south legs to keep the solar plane in parallel. The C-130 will perform its in-cloud legs also in N-S. There will be one long (50 km) in-cloud leg, but not performed until the end of the patterns to minimize icing of the instruments and aircraft.

The FIRE.ACE Open Inspection was held at 1500 - 1700. The C-130 and ER-2 were open for inspection. The aircraft investigators described their instrument, scientific objectives, and data products and preliminary results. Jim Barrilleaux and Mike King presented photos of Fairbanks and the ER-2 to Colonel Brophy, Deputy Commander, U.S. Army, Alaska. The ER-2 pilots autographed the photos.

The UW C-580 experienced equipment problems and remained in Anchorage. If it is repaired, the C-580 will leave for Barrow tomorrow.

The weather forecast for SHEBA is for broken clouds with cloud tops at about 2, 3, and 6 km. There will be cirrus clouds between Barrow and SHEBA all day. There will be good near-simultaneous overpasses of the AVHRR and DMSP over SHEBA.

The C-130 took off at 0900 and returned at 1900. The flight for the ER-2 was scrubbed, due to high cross winds forecast for Wainwright in the afternoon.

The UW CV-580 arrived in Barrow.

At the C-130 Instrument Investigators Preliminary Report and Mission Planning Meeting, Pinto reported on the May 15 flight of the C-130. An upper mapping pattern was performed at 4 km; a slow descent to the surface which showed two cloud layers, the upper (thin) layer at TBD, the lower layer between 160 - 490 m. The lower layer was very well mixed with a strong capping inversion above. A cloud sampling pattern was performed at multiple levels above, between, within, and below the cloud layers. A raster pattern was performed at 2 km for the AIMR. Two leads were overflown and three profiles over or near SHEBA were performed to 1500 m.

Most instruments operated well, except for some MCR channels and two radiometers. There was good AIMR and cloud microphysics data collected.

Hudson reported on the CNN/CN profiles for the flights performed so far. For May 15, the profile showed very efficient scavenging by the clouds as the CCN concentrations were considerably reduced to below 50 per cc within the bl cloud. The surface did not appear to be the source of the aerosols, which were postulated to be caused long range transport.

The CPI obtained considerable cirrus particle measurements, which showed bullet rosettes to 300-400 microns, some of which were clustered together, irregular spheroids of 20-30 micron size, and a few columns. In the bl over SHEBA, the instrument did not see mixed phase, but mostly (frozen) water, with only a few ice particles. Below the cloud, the few particles were homogeneous of 20-30 micron size, mostly droplets or frozen drops. Baumgardner reported that the NCAR microphysical probes showed that the upper layer was almost entirely ice; the lower one principally water.

The forecast for Sunday is for cirrus between Barrow and SHEBA. The low in the Bering Strait will recede to the south west. There will be all kinds of clouds at all altitudes over SHEBA with winds northeasterly at 15 knots. The conditions at Barrow today was for frozen rain, which is also expected for tomorrow. The winds at Fairbanks for Sunday are forecast to be low, but increasing on Monday.

Based on the likelihood of freezing rain at Barrow on Sunday, plus uncertainty of the UW CV-580 instrument checkout flight today, the ER-2 flight for Sunday was canceled, as well as the science flight for the UW CV-580.

The UW CV-580 did not fly, due to an engine malfunction. A part is being flown in so that the plane can be ready tomorrow for an instrument check out flight.

A joint C-130/ER-2/UW CV-580 flight is scheduled for Monday.

At the C-130 Instrument Investigators Preliminary Report and Mission Planning Meeting, AIMR reported that the there appears to be more water opening up due to the increase of number and size of the leads. Pinto reported on the two layer cloud system, of which the upper layer dissipated during the flight. All C-130 instruments (except several thermal channels on the MCR) and aircraft were ready for the next flight.

The ER-2 aircraft and instruments were ready likewise. The MAS dewers seemed to be holding the vacuum. The test continued for another 6 hours.

The meteorology at SHEBA has shown an increase in the occurrence of fog with accompanying low visibilities. The low has moved back into the Bering Strait now, but will move further to the south during the week. The high, which is located to the NE of SHEBA, will remain and even strengthen. This results in strong easterlies at SHEBA and at Barrow. Barrow will continue to have low clouds. Clouds between Barrow and SHEBA will be broken and at several levels. Fairbanks will see the winds picking up after today, but still remain in the 10 knot range out of the east.

Consequently, both C-130 and ER-2 planned to conduct a flight tomorrow to SHEBA. The ER-2 will design flight patterns to take advantage of overpassing satellites and solar azimuths for AirMISR. AirMISR will program Barrow as a varying slant angle site for both transits.

The UW CV-580 canceled its instrument checkout flight today.

The ER-2 may perform a flight with UW on Tuesday, depending on meteorology and aircraft readiness. The C-130 might conduct a flight on Wednesday, if it is clear at SHEBA.

At the C-130 Pre-Flight Briefing, the weather update indicated multiple cloud layers, with an altostratus (As) at the top, and a water bl at the bottom. The C-130 flew various flight patterns, including an East-West (E-W) raster at 5 km, descent to below As, E-W raster at 2.5 km, decent to surface, low level lead transects, sample leads, 20 km box at 50 m, ascent to above bl, 20 km box at 300 m above cloud, E-W transects through cloud, ascent to below As, North-South (N-S) transect below, within, and above As, long 50 km N-S transect in As at 1500 ADT, and 50 km N-S transect above cloud.

A videographer shot TV footage during the entire day, including the C-130 Pre-Flight Meeting, ER-2 instrument preparation, interview with Dr. King, ER-2 Aircraft Scientist, and the C-130 flight itself.

The C-130 took off at 0845 and completed its mission.

The ER-2 was delayed for 45 minutes due to an erroneous auto pilot error signal. Some legs were shortened as the ER-2 completed its mission at the scheduled time.

At the ER-2/UW Mission Planning Meeting, the satellite imagery showed a large clear area to the east of SHEBA. The As had moved to the NW also. There was also a report of fog at Barrow, even though the fog did not show up on the satellite images. Wylie speculated that it could be sea smoke from a moderate-size open water area due east of Barrow.

The long range forecast indicates that the best chance for clear skies at SHEBA is for Wednesday and/or Thursday. It may cloud over again on Friday.

The part that UW was expecting did nor get in until late evening. Consequently, the ER-2 flight with UW for Tuesday was canceled and rescheduled for Wednesday, May 20. The UW CV-580 will conduct an instrument checkout flight mid afternoon tomorrow.

At the ER-2 pilot debrief, Barrilleaux reported that only one instrument failure light flickered briefly (AMPR). The patterns were performed as logged on the green card, including straight and level legs for the satellite overpasses. Beginning 200 nm north of Fairbanks, he saw white all the way which he estimated was due mostly to upper clouds with some lower clouds below in the few gaps. He did not see any clear area to the east of SHEBA.

An instrument checkout flight was successfully conducted by the UW CV-580, which included measurements over the ARM site and off the coast.

At the Mission Planning Meeting, Wylie presented the meteorology forecast for the next several days. The high pressure system located to the north east of SHEBA is building up and may persist for several days. The humidity above the bl is drying up. This could lead to clearing skies for Wednesday and possibly Thursday. Winds over Fairbanks are expected to be low through Friday.

If clear at SHEBA, or if clouds are above 4 km, the C-130 will conduct a flight on Wednesday. The flight patterns would include upper altitude mapping, surface mapping, clear stable bl for LES modeling, turbulence, open water and lead interactions, and coordinated satellite and ER-2 overpasses.

King reported that the thermal channel on the MAS would be down for the next 5 days. On Wednesday, the ER-2 and UW CV-580 will perform coordinated flights in the vicinity of Barrow. The ER-2 will continue to SHEBA for coordinated C-130 and sea ice patterns.

At the C-130 Mid-Experiment Review, Curry outlined the current status of C-130 flight patterns conducted to date. Most have been successfully conducted. Those requiring clear skies or broken bl clouds and a precipitating storm need to be performed yet. Patterns designed for IRF, LES, and microphysics utility were also reviewed. Similar assessments for remote sensing validation were also summarized.

Baumgardner reported on the nine microphysics instruments that NCAR is operating. By the third flight all were operating correctly, except for the MASP which ices up for the remainder of a flight whenever it encounters significant liquid water. An assessment of the liquid water content was made for three probes, The FSSP-derived product may be overestimated, at least compared to the hot wire and PVM probes. Darrel is synthesizing the spectra from 10-second averages from four probes to produce a size distribution from 0.1 to 600 microns. Two overlap regions are suspect. The newly-developed Liquid Water Validator probe has been used on the FSSP-100, hot wire, and PVM probes to calibrate their responses to a constant liquid water drop at 100 m/s. The results look encouraging. This validation effort will be performed weekly. Similar Validators have been delivered to the NRC/AES Convair and the University of Washington Convair for similar calibrations.

The RAMS instruments have also operated well. Measurements have been obtained of cloud conditions such as stratus, cirrus, contrails, multi-layers, and thick stratus and cirrus. RAMS presented derived values for transmissivity, reflectance, absorption, and surface albedo for each of the five flights. RAMS is satisfied with the current flight patterns, except that they would prefer longer legs, more thick stratus, and clear skies. They look forward to collaboration with profile information from SHEBA; surface characterization with AIMR, MCR and video; and cloud properties with C-130 microphysical, ship lidar, and other ship instruments. Further analysis includes quality control, post-mission calibration, and C-130 navigation corrections and offsets.

CPI plans to derive several products from their direct measurements, including total concentration of ice and water drops, ice particle and water drop size distributions, ice water content, liquid water content, particle habit, scattering index, and crystal riming. The comparison with the FSSPs and 260x probes show good agreement in the ice portions of the size distribution (larger particles), but less in the water portion (smaller particles). Longer legs in clouds would be of benefit.

Once they return back to their lab, Cloudscope plans to derive mass for both ice and water, concentration distributions, and size distributions. They noted that their instrument is easy to ice over when in liquid water supercooled clouds.

Hudson reported on a number of observations performed by the DRI CCN and CN counters, as well as implications. Measurements have indicated that there is strong scavenging in the clouds, high stability above the clouds, well mixed bl, high cloud supersaturation, nucleation occurring above cloud CCN, long range transport, confidence in DRI and CSU CCN and CN probes, surprising low numbers of small particles of both CCN and CN, interstitial inlet does not work, community inlet does work, more CCN are sulfate, some CCN are less volatile than NaCl, some CN are not sulfate and could be anthropogenic, in situ particle production with low CCN, high CN, and volatile (Cotton speculated that it may be stratospheric intrusion), and leads as possible source of CN but that cloud scavenging may overwhelm this signal.

The CSU CCN and CN instruments will be used to address the role of Ice Nuclei (IN) in ice formation; study diamond dust in non- and polluted air; production, transport, removal, and modification mechanisms of IN; and determination of the physical nature of IN including, chemical, size distribution, and effectiveness. Other instruments include PIXE impactor, CFD impactor, and IN filter. Based on the distributions of temperature vs. % supersaturation of various flights and meteorological conditions, it is hoped to develop an empirical curve of the two parameters to be used in models. CSU is experiencing hard disk problems, having gone through three already. The CN counter may be suspect due to a possible leak. Comparison with the other two counters will be of value.

The MCR has been recently upgraded and modified for this experiment. Channel 7 (thermal) is not working yet. Processing will be done post-mission.

The AIMR and video are both working. As with the MCR, processing will be done post-mission.

Pinto reported on his work involving the effects of leads and recent new ice on temperature, relative humidity, and radiances. Measurements obtained near leads in the vicinity of SHEBA and from the C-130 will be used.

GSFC is deriving daily polar area maps of the sea ice derived from DMSP observations to track the time history of ice growth and decay, especially first year ice. AMPR measurements will be used to compare with the satellite-derived products.

LaRC will utilize AVHRR observations to derive a number of cloud and radiation products. The algorithms have not proven to be robust, due to the difficulty in detecting clouds over the sea ice. Comparisons with the aircraft and surface measurements will be of great assistance.

The MIR showed sample measurements from the first ER-2 flight performed yesterday. Emissivity is estimated to be 0.6-.8. Clouds, snow, and granular size could affect the measurements. These measurements will be used to infer water vapor profiles, clouds, precipitation, and possibly snow and ice.

Curry identified several highlights to date, including persistent mixed surface layer, the importance of low level humidity inversion in maintaining bl clouds, almost no open water at the surface, and leads as sources of CN. During the group discussion, several surprises were identified including, large drops at the top of the inversion layer that appear not to be dropping or appear at the bottom, the bi-modal distribution of cloud particles below the bl cloud, crystals that don't appear to be following theoretical growths or habits, and non-volatile centers of cloud particles.

Curry reviewed each of the approximately 30 science questions for FIRE.ACE, and assessed the status of accomplishment to date, and therefore which questions should be the focus of the future flights. The targets for the next several weeks are: clear sky, broken clouds, thick altostratus and cirrus, storm with significant precipitation, and open water surface/cloud interactions.

A discussion was held to see if the C-130 flight patterns were being conducted to the maximum benefit of the instruments on board, as well as other platforms like the ER-2 and satellite analyses. The only improvement identified was for longer legs, especially at the top cloud when the ER-2 was conducting a satellite underpass. One possibility is to perform this leg at the end of the missions if the two aircraft could leave SHEBA together.

At the Pre-Flight Briefing, Wylie showed satellite images and sonde profiles which indicate that the best chance for clear skies at SHEBA is for today. The ship reports that the skies are clear directly above, but that there is low-level haze which may be aerosols.

Consequently, there was a C-130 flight to SHEBA today, with good visibility expected for flight patterns for mapping of surface features and albedo, radiation, open water and lead interactions, possible aircraft exhaust, and clear stable bl. If the conditions at Barrow clear up, there may be a descent over open water near Barrow on the return leg.

There was an ER-2/UW CV-580 flight around Barrow also today. The ER-2 will continue to SHEBA for satellite underpass coordination.

At the Mission Planning Meeting, satellite imagery showed a cloud mass moving towards SHEBA from the northeast which could overpass later this afternoon. The forecast for the next few days is for winds from the southeast, with more middle level clouds. Barrow, which now has broken clouds allowing for the UW flight, may cloud over again with low visibilities and ceilings. There is open water to the west of Barrow. Fairbanks has a good chance of thundershowers for as early as Friday and most probable for Saturday. If one hits, there will be low visibility but not significant local winds.

At the ER-2 pilot debrief, the pilot reported clouds over the land and shoreline around Barrow and clear skies over the sea ice. There was open water to the west of Barrow. The ER-2 flew over clear skies to and from SHEBA. A stratus deck was noted to the northeast of SHEBA.

The UW CV-580 reported that they had a very good flight, with cloud measurements within the stratus deck over land and clear skies over the sea ice. They are prepared for a flight tomorrow.

However, the ER-2 will be down for tomorrow to install some hardware. Consequently, there will be no ER-2 flight tomorrow. The UW CV-580 will perform a flight in and around Barrow.

There was a hard down day for the C-130 operations.

There was no ER-2 flight. The UW CV-580 performed a flight in and around Barrow, and is now ready for a flight to SHEBA.

At the Mission Planning Meeting, Wylie noted that the satellite imagery showed that it was mostly clear over SHEBA yesterday, consistent with the aircraft and surface observations. There was a semi-transparent cloud to the northeast, a small tongue of which passed through SHEBA during the flights.. Barrow experienced a somewhat clearing of the clouds, which were constrained to the land and shoreline. He forecasted mostly clear through Saturday for SHEBA. Barrow should have clouds. Fairbanks should have rain showers Friday afternoon through Saturday as a low begins to move into the Fairbanks central valley.

King summarized yesterday's ER-2 flight with 2 hours of coordination with the UW CV-580 aircraft in the Arctic stratus over land and its breaking up over the tundra, and clear over the sea ice. The ER-2 observed clear skies for good radiation and sea ice mapping in its flight leg to SHEBA.

The ER-2 will plan a flight with UW tomorrow, over either SHEBA or Barrow if good clouds and SHEBA (without UW) if clear for a microwave AMPR/SSM/I mapping pattern.

Curry recapped the C-130 flight on May 20. An upper mapping pattern at 4 km was performed, as well as a 20 km box at 1.5 km, and a 30 m albedo mapping pattern in a series of nested boxes. The plan will be for the C-130 to fly on Sunday (preferred) or Saturday (if broken stratus is forecasted).

AMPR reported on its preliminary measurements that showed the four microwave channels can effectively discriminate between old and new ice, as well as detecting ice holes that have recently refrozen.

CPI showed the size distribution of ice particles measured in a cirrus cloud on the transit leg. The smaller particles have number concentrations three orders of magnitude larger than the large particles. In addition, the small particles appear to be somewhat spherical or nearly so. They were referred to as "ice balls", which has ramifications for radiation modeling of the small particles.

There was to be an ER-2 flight to SHEBA to conduct a microwave AMPR/SSM/I mapping pattern, as well as a good NOAA 14 underpass. However, on pre-flight checkout, the navigation system was not operating at 100%, so the ER-2 had to modify its patterns so as to not to fly outside the TACAN range of Barrow. Consequently, the same orientation mapping pattern was performed, but located over Barrow. Three legs of 260 km length were flown back and forth, the middle of one directly over the ARM site. The UW CV-580 flight was canceled to allow for inspection of the measurements obtained to date and some aircraft repair.

At the Mission Planning Meeting, the forecast for SHEBA this weekend was for southeast to south winds, bringing in low stratus. There may be some cirrus aloft. At Barrow, the forecast is for more stratus over the land and shore ice, with clearing off shore. Fairbanks will see the low move through by late Saturday.

Rogers reported that the hard disk problem has been solved. The IN measurements made on the last flight show concentrations to be nearly constant at about 8 per liter for the low level runs. This is considerably higher concentrations than measured during previous flights. No detectable differences in IN were measured during the descent over the open water near Barrow. Wylie pointed out the winds were greater than 20 knots.

Hudson reported the CCN and CN measurements were nearly constant at about 200 per cc during the descent over SHEBA in nearly cloud-free regions and similarly so over Barrow. This is in contrast to the dramatic decrease in concentrations when in bl clouds during other flights.

The ER-2 navigation system needs to be fixed. Consequently, there will be no ER-2 flight on Saturday. The C-130 will also stand down. Both planes plan for a flight on Sunday. The UW will fly on Saturday.

The group photo session was conducted immediately after the ER-2 landed.

There were no C-130 or ER-2 flights today. The UW Convair conducted a flight around Barrow in which cloud microphysics and radiation measurements were made within and between multilayered clouds. The navigation system of the ER-2 has not been repaired yet.

At the Mission Planning Meeting, Wylie showed the large stratus deck that is to the southeast of SHEBA, apparently associated with a surface high also to the southeast. As the high appears to be moving to the east, he is not sure if the prevailing southeasterly winds will be enough to move the status over SHEBA. He forecasts that the cirrus will not appear over SHEBA until Tuesday. For Barrow, the stratus that has been there for the last month will remain. Winds will continue to be easterly to southeasterly. Fairbanks will have light winds for the next several days.

The C-130 will conduct a flight to SHEBA tomorrow, with the object of clear sky patterns for albedo mapping and lead interactions. They will only scrub if the stratus moves in and is so low that the C-130 cannot get below it (<100 m).

The ER-2 will also fly tomorrow to Barrow for a coordinated overflight with the UW Convair. If the navigation is fixed, the ER-2 will continue to SHEBA.

Hudson showed spikes in the CCN data from the last flight which may have been correlated with either leads or aircraft exhaust. The low levels runs resulted in remarkably consistent values of CCN about 200 per cc and CN about 325 per cc.

Jensen showed the vertical structure of cloud particle concentrations from the CPI for each of the C-130 flights. The profiles whenever the bl was in cloud showed large spikes at the top of the bl, with drastic decreases to low values lower in the bl.

The C-130 will probably fly again on Wednesday, May 27. Only if the meteorology was good for Tuesday and not Wednesday would the C-130 fly on Tuesday. The ER-2 and UW

At the Pre-Briefing, the meteorology for SHEBA was for clear skies so the C-130 conducted a series of surface albedo mapping and lead interaction patterns. It measured the cirrus clouds on the way out and the low stratus clouds over the sea ice off Barrow on the way back. The winds were not high enough for a stable bl to exist. Barrow had low status over the land and shore ice regions, with clear skies over the sea ice and open water to the west. The ER-2 conducted a coordinated mission with the UW Convair in the Barrow and westward area. The navigation system of the ER-2, while apparently fixed, needed to have an in-flight check so the ER-2 did not continue out to SHEBA.

The C-130 took off at 0900 for a flight to SHEBA. The ER-2 took off at 1200, after an hour delay to accommodate the UW delayed takeoff, for a flight to Barrow.

There were no C-130 or ER-2 flights.

At the Mission Planning Meeting, the forecast for SHEBA was for clouds moving in on Tuesday with the possibility of a storm moving in on Wednesday. Barrow will have good aircraft operating weather, as will Fairbanks.

A clear sky mapping pattern for the C-130 flight on Sunday was conducted successfully, with an extremely dry lower troposphere. The cloud structure north of Barrow was measured, which comprised of altostratus, cirrus, and lower clouds.

The ER-2 flight was also conducted with a microwave pattern over and west of Barrow. The navigation system is now operational so the ER-2 can proceed to SHEBA.

The UW Convair engine indicator light needs to be replaced. A part is being shipped up today so the UW may be able to fly a flight late tomorrow afternoon.

For tomorrow, the ER-2 will fly a microwave pattern to SHEBA. The next, and last, C-130 flight will be on Wednesday to SHEBA. The ER-2 and UW will also fly around Barrow on Wednesday, with the ER-2 continuing on to SHEBA with the C-130.

Revercomb presented HIS data for the ER-2 portion of the flight over stratus and sea ice. There was very little spectra signature differences for the two situations, except for small differences in the 10-13 and 3.7-5 micron regions.

The C-130 took off at 0900. The ER-2 took off at 1100. Part of the ER-2 pattern flew into the Russian Flight Information Region. The part for the UW Convair did not arrive until last night, so no flight was performed. It should be ready for a flight tomorrow afternoon.

At the Mission Planning Meeting, the meteorology forecast for SHEBA is for multiple clouds, with the possibility of freezing rain or snow for Wednesday. A surface low may move through the area sometime between Wednesday and Friday. Barrow should continue to be covered with stratus. The winds at Fairbanks should be mild.

The C-130 and ER-2 will plan a coordinated flight to SHEBA tomorrow.

Pilewskie reported on the SSFR instrument. He showed upwelling and downwelling flux spectra for times over sea ice followed by stratus. There appears to be a signal difference in the near IR region, with stratus being more reflective than sea ice. The entire solar and thermal regions are covered by the SSFR and HIS, except between 2.2-2.8 microns.

At the ER-2 Pilot Debrief, he reported that there were clouds all the way to just past SHEBA. They were mostly cirrus and multilayers below. The ER-2 flew successfully into the Russian Flight Information Region as planned.

At the Pre-Brief, the weather at SHEBA was freezing rain and lots of clouds. A low pressure storm moved through SHEBA in the afternoon.

The C-130 performed a series of patterns to measure the precipitation event, as well as the change in surface albedo. Very little precipitation was measured however. There were multiple cloud layers at SHEBA.

The ER-2 flew to Barrow, turned southwestward over the open water, and turned north to SHEBA for underflights of the NOAA 14 and DMSP satellites. Clouds were viewed all the way to SHEBA, with cirrus, middle layers, and low stratus.

The part for the UW arrived, but another part is required. The UW completed the repairs and performed a flight around Barrow.

At the End-of-C-130/Mid-ER-2/Mid-UW CV-580 Review, Dr. Akasofu, Director, Geophysical Institute, welcomed the FIRE experiment to the GI. Randall outlined the background of FIRE and pointed out that the prediction of global warming is most severe in the northern polar regions. Most if not all models do not properly model the seasonal changes in total cloudiness for this region of the globe.

Curry summarized the experiment objectives and emphasized FIRE's commitment to integrated radiative flux, LES, and single column modeling. The methodology for improving remote sensing will use the ARM instruments to validate the satellites; the insitu aircraft will validate the surface sensors; and the ER-2 will be used to advance sensors not yet on satellites.

Wylie presented an overview of the meteorology conditions for some of the flight days.

Doelling showed preliminary results of retrievals from AVHRR of particle size and other cloud parameters. These retrievals are challenging over the sea ice.

Curry reviewed the C-130 flight missions for various cloudy and clear conditions as well as the flight patterns performed for these conditions.

Pinto outlined his research on the variability of surface conditions from both surface and C-130 observations. The goals will be to study the effects of clouds on the SW radiative flux over the sea ice, the variation of the surface properties, and the correlation with temporal changes in cloud conditions. The surface temperature over a lead that was freezing showed that the temperature decreased as the ice thickened.

MacFarlane analyzed the microphysical retrievals from the NCAR hot wire probes and the FSSP. There is a factor of three differences in concentrations for supercooled liquid water drops, which result in a 80 watt/m2 variation in model calculations. Microphysical changes were also seen in measurements of the ship exhaust.

Tsudi reported on the AIMR, MCR, and video sensors on the C-130. The AIMR will be used to measure the width and orientation of developing leads and to determine between first and multi year ice. So far, leads comprise only 1~2 % of the sea ice, and are mostly refrozen with very little open water. The MCR is to be used for mapping of the surface as well as for clouds. Only channels 1, 4, and 6 are fully operational. The video provides observations on the leads and ridge structure with fine resolution.

The Cloudscope will be used to determine the physical properties of cloud particles, including the nucleation, growth and evaporation, and characterization of ice clouds, bl ice, and supercooled particles. The density, mass, habit, and information on primary or secondary nucleation will be determined. Giant nuclei concentrations are between 0.1 per l for patchy conditions and 10 per l for open water over leads. Characteristic concentrations range from 0.1~0.2 pl for fluffy ice to 0.8 pl for solid ice.

Jensen showed vertical profile concentrations for several flights. The peak concentrations ranged from 700 pl (flight 4) to 100 pl (flight 5). Size distributions were presented for various cloud conditions including above cloud, cirrus, water cloud, below cloud, and mixed phase cloud. Riming and some bursts were measured over leads, contrail measurements were not sure, particles were more dense (in structure) than expected, more side plane growth was measured, and riming at cloud temperatures and subsaturation conditions were measured.

The six radiometers of the RAMS package were used to determine, for typical conditions for each flight, transmittance, reflectivity, absorptance, and surface albedo. Heating rates, the ratios of direct to diffuse, and optical depths (at 500 nm) will be determined. The data will be quality controlled, post-mission calibrated, and navigation corrected.

Hudson reported that both CCN spectrometers worked well, with agreement between the two instruments in concentration, and between the CCN and CN sensors sometimes. During the experiment, there was great variability (three orders of magnitude) in CCN concentrations. Low concentrations were measured under and near low stratus, which implies cloud scavenging. Consistent concentrations were measured in clear conditions.

Rogers will use his IN and CN sensors to determine the role of IN in ice formation in clouds, local vs. long range productions, and the physical properties of IN. Measurements indicate that there were large variations in the vertical structure of CN and IN, the IN and CN concentrations were at times very small, but some very high concentrations were measured in the vicinity of leads. Filter and PIXE analyses need to be performed yet.

Gerber described the operations of the University of Washington Convair 580, deployed at Barrow. The Convair plans to perform coordinated flights with the ER-2 to determine the cloud radiative flux divergence (with SSFR), cloud radiative absorption (with SSFR and CAR), microstructure of clouds, bi-directional reflectance (BDRF) off of several surface types (with CAR), effects of Barrow pollutants, BDRF under and above stratus in the vicinity of SHEBA and ARM, and comparisons between the g-meter, FSSP, and CAR. The newly-developed g-meter will measure the scattering and extinction at 630 nm, asymmetry parameter, and back to forward scattering for cloud and water particles. Six flights have been performed to date, all in the vicinity of Barrow. The Validator appears to be working for the FSSP, may have damaged the hot wire probe, and does not work for the PVM.

King outlined the objectives of the ER-2, which are to determine the spectral properties of the sea ice and cloud layers, validation of the surface retrieval algorithms for MISR and MODIS, radiative energy budget of the clouds and sea ice, and compare satellite and surface observations of clouds and clear sky for both SHEBA and ARM. The mission on May 18 included coordination with ARM and C-130 over SHEBA. The May 20 flight included coordination with ARM and UW Convair, SHEBA, C-130, and NOAA 14.

The MAS cloud mask will be used to interpret between clear, cloudy, and shadow conditions. The MAS processed data is available within 3 days after flight. The information is available on the LaRC DAAC and experiment website.

LaFontaine reported on the AMPR, which will measure the surface emissivity associated with clouds, water vapor, and sea ice conditions.

The MIR will retrieve water vapor profiles. The 220 and 340 GHz channels may be sensitive to cirrus clouds. Comparisons with the AMPR show that the MIR can (barely) detect first and multi year ice.

Pilewskie reported on the SSFR which will be used to determine the solar radiative energy budget, cloud radiative effects, surface reflective properties, and microphysical properties. The SSFR is located on the ER-2, UW Convair, and SHEBA. All three platforms have the ability to perform in-field calibration of the absolute spectral radiances. Laboratory calibrations are traced to the same source as the MAS and CAR for both spectral and angular calibrations.

The HIS will be used to measure the impact on cloud and sea ice on IR radiances, retrievals of cloud and surface properties, and spectral signatures to discriminate between clouds, sea ice, and snow. The CO2 spectral region does not show any differences between clouds and sea ice, the 10-13 micron region does show differences of about 2 degrees, with stratus more "black" than ice, and 3.7-4.5 region shows that stratus is more reflective than ice.

The CLS data is post-flight processed within 20 hours. The quick look algorithm is robust for determining cloud boundaries. Other products are cloud structures for optically thin clouds, optical depths, emittances, effects of thin clouds on brightness temperature, and assist development of GLAS channel.

The AirMISR measures the calibrated radiances at several wavelengths and view angles. A radiance-based cloud mask will be used to determine the cloud albedo and stereo cloud products. The narrowband radiances will be converted to broadband albedos. The cloud radiances will be compared with changes as measured by the SHEBA radar and lidar profiles.

Curry noted that so far the data collected is extremely impressive and virtually unprecedented. However, a great deal of synthesis and modeling is required to fully mine the information. She noted that most, if not all, of the 30-odd FIRE objectives cannot be met by a single instrument or platform. Future measurements need to be collected for meteorology conditions of broken stratus, thick altostratus and cirrus, storm with precipitation, and changes in surface albedo and physical properties of the sea ice as the summer approaches.

The C-130 left to return to Boulder. There was an ER-2 and UW Convair flight to SHEBA.

At the Mission Planning meeting, the weather at Fairbanks was forecasted for tomorrow to be windy in the late afternoon, which might affect an ER-2 landing. SHEBA will have broken, lower level clouds. Barrow might have stratus clouds also. A low will form due west of Barrow on Sunday, bringing clouds and winds to Barrow and also SHEBA.

An ER-2 and UW mission was tentatively planned for Saturday, depending on the conditions at Barrow and Fairbanks. A decision was to be made at the weather briefing Saturday morning.

After the Weather Briefing for an ER-2 flight to SHEBA, the ER-2 experienced an problem with the emergency system that resulted in a scrub to the mission. As the repair would best be done at Dryden, the ER-2 returned to DFRC.

The UW flew to SHEBA.

No UW flights scheduled.

The ER-2 was repaired at DFRC, finally completed at 9:30 pm. Consequently, the ER-2 is scheduled to return to Fairbanks on Monday.

The UW flew to SHEBA.

At the Mission Planning Meeting, the weather for SHEBA for the next several days is for multilayer clouds, with some low level fog. Barrow will have low status, with some periods of broken clouds. Fairbanks will have some precipitation tomorrow, which may lead to some higher winds and possible cross winds.

SHEBA is undergoing a crew rotation with the Twin Otter for June 1-2. It is not recommended to fly to SHEBA during this period.

Madison Post will be replacing Janet Intrieri to serve as FIRE's SHEBA Surface Scientist responsible for sending daily surface reports, sonde profiles, observations, recommendations, radio liaison with FIRE aircraft, etc. Janet, and Taneil Uttal before her, have served admirably in this critical role.

The UW Convair performed a flight today around Barrow.

The ER-2 arrived at 1830, ADT. The pilot reported multiple cloud types on the trip up from DFRC. All instruments that were on appeared to be operating correctly.

The ER-2 and UW Convair performed a coordinated mission in the vicinity of Barrow. The ER-2 continued on to SHEBA. At the pilot debrief, he reported that there were clouds all the way except for a region just south of Barrow. There was also a very clear area to the north of SHEBA. On the way back, it had cleared over Barrow.

Science crew rotation at SHEBA was completed.

The ER-2 and UW Convair performed a coordinated mission at SHEBA.

At the Mission Planning Meeting, the forecast was for multi layer clouds at SHEBA and Barrow for the next several days. Fairbanks may experience some moderate south (cross) winds beginning as early as Thursday.

At the pilot debrief, all instruments appeared to have worked well. Solid multi-layer cloud decks were visually observed, with occasional breaks appearing later in the flight. A clear area was noted just northwest of SHEBA.

Three ER-2 flights remain over the next 4 days. It was decided to schedule the flights consecutively, and make the final go decision based on meteorology at both SHEBA and Fairbanks at the Weather Briefing each morning.

In lieu of a Final ER-2/Mid-UW Review on Monday, June 8, a Summary Report will be prepared by Steve Platnick and Mike King, with inputs from Peter Hobbs, ER-2 PIs, Satellite, and Forecasting Scientists, due on Saturday, June 6.

The ER-2 conducted a flight to SHEBA. A cirrus shield associated with a major low over northern Russia moved over SHEBA. The UW Convair did not fly.

The Mission Planning Meeting was canceled.

At the ER-2 pilot debrief, he reported that there were clouds all the way toSHEBA, both back and forth. Based on unsuitable wind conditions forecasted for Wainwright on Friday, no ER 2 flight was planned. The next meeting will be at the 0700 Weather Briefing on Saturday.

It was decided that the investigator inputs should be sent, not to the ER-2 Aircraft Scientist, but to Steve Ackerman, University of Wisconsin, for consolidation into one package. These are due Saturday. Steve will forward this to Judy Curry.

There was a full down day by the ER-2.

The ER-2/UW flew a coordinated mission to Barrow. The pilot reported that there were extensive low level clouds throughout the Barrow area, except for a area about 50 nm south of Barrow. No cirrus or open water was noted. The CLS remained down.

Investigator inputs for the Summary Report were due to Steve Ackerman.

The ER-2 flight was canceled due to high crosswinds. The UW Convair will fly to SHEBA. There are no more ER-2 flights. The UW Convair will continue until June 21, with SHEBA being the principal point of focus.

ER-2 will return to Dryden on Monday, June 8. The Project Office will close after COB, Monday, June 8.

The Project Office will be open July 5 for Phase II.