Installation of the new CAPS (Cloud Aerosol and Precipitation Spectrometer) probe on the nose of the DOE G-1 Research Aircraft Facility.  The probe, manufactured by Droplet Measurement Technologies, provides high-resolution size distributions of droplets from ~0.5 to 1550 um.  The time response is better than 1-s.  These data are used to study growth processes of cloud droplets.

Intercomparison of aerosol instrumentation between the DOE G-1 Research Aircraft Facility and the CIRPAS Twin Otter.  Side-by-side sampling was done on July 4, at Mather Airport in Sacramento, CA.

MASE Participants (left to right): Dick Hone, Co-pilot; Bob Hannigan, Pilot; Jim Hudson, DRI;  Tervor Macduff, PNNL; John Hubbe, PNNL; Peter Daum, BNL;  Yin-Nan Lee, BNL; Jian Wang, BNL; and Gunnar Senum, BNL.

July 6, 2005

The G-1 flew this AM over the Pt Reyes site and then west over the Pacific at latitude of 38:05 between longitudes -123:30 and -124:30. We joined by the CIRPAS Twin Otter during the flight over Pt Reyes. Cloud tops at Pt. Reyes were about 1000 ft msl; bottoms were near the surface. The G-1 flew 5 patterns over the site, one above cloud at ~1200 ft and four patterns in-cloud at an altitude of ~800 ft. The Twin Otter flew at about 1000 ft above cloud top during the latter part of the G-1 flight, and then dropped down to sample in-cloud after the G-1 departed. Cloud tops to the west of Pt Reyes were variable and lower (600-800 ft msl) than they were over the site. Transects were made at cloud top, and in-cloud at 500 ft msl and 300 ft msl. Cloud base appeared to extend nearly to the surface as the ocean was only seen sporadically from 300 ft.

There will be no flight tomorrow 7/7 to resolve a maintenance issue on the G-1. Pending correction of that problem and met conditions, flights will resume on Friday.
 

July 11, 2005

The G-1 has not flown for the last five days because of a problem with the landing gear that remains unresolved. Bob Hannigan and his crew have been working hard, but the source of the problem has not been identified. Weíve taken the down-time to calibrate the instruments and to resolve problems revealed by our previous flights. Weíll be ready to go whenever the aircraft is returned to service.
 

July 13, 2005

The G-1 flew yesterday afternoon between approximately, 1500-1700 local time. Temperatures were very high yesterday , reaching nearly 105 in Sacramento. Winds at Pt Reyes and to the west were from the NNW at over 20 kts leading to small craft advisories due to the and to the wave heights (6-8 ft). Skies were clear at Pt. Reyes and to the west, so we did several low altitude (800ft msl) passes over the Pt Reyes site and then some low level tracks (300 ft msl) from Pt Reyes to about 50 miles offshore. At 300 ft accumulation mode aerosol number concentrations were 100-200/cm³, indicating the formation of sea-salt aerosols from the wave action that was observed. Unfortunately the landing gear problem re-occurred and we will not fly again until it is fixed.
 
 

July 15, 2005

The G-1 took off at 10:00 AM local time. Flew to Pt Reyes and then south to 36:34:00 N, 122:29:00 W for a rendezvous with the CIRPAS Twin Otter. The flight to the rendezvous point was made at 300 ft (msl). At this altitude we were in and out of cloud base, mostly in. Then flew a triangular pattern in conjunction with the Twin Otter above, below and in cloud. Clouds were extremely uniform, extending from ~300 - 1100 ft msl. CCN at 1% supersaturation was 300 - 500/cc below cloud, and somewhat higher above cloud. Cloud liquid water content increased with height and was ~.3 or so near cloud top. On the way back we attempted to sample clouds above Pt Reyes, but the clouds were to low to do this safely so we returned to Sacramento.
 

July 16, 2005

The G-1 took of at 10:00 AM local time. Flew to Pt Reyes and then south for a joint flight with the CIRPAS Twin Otter. Cloud tops at Pt Reyes were below our minimum sampling altitude so after one pass over the site we turned south. The entire 100-mile track south to meet with the Twin otter was done in a solid cloud deck at 600 ft msl. Met up with the Twin Otter at about 11:15 local time. Flew a rectangular pattern just under cloud base at 300 ft and successive in-cloud patterns at 600 and 900 ft msl. Cloud tops were at about 1200 ft msl. Clouds were quite uniform with CDNC on the order of several hundred/cc. CCN at 1% ranged between 200 and 400/cc. Noted a layer of pollution just above cloud top that extended to about 5500 ft msl. Flew back to Pt Reyes at 300 ft msl, mostly below cloud base. Pt Reyes was only partly cloudy when we arrived ~1330 PDT. Returned to Sacramento and landed at ~13:50 PDT.
 

July 17, 2005

The G-1 took off at 9:30 AM local time, which was 30 minute earlier than before due to the high ground temperatures at Sacramento, reaching 106 degrees in the late afternoon. The G-1 flew to Pt.Reyes and the cloud tops, 850 ft MSL were just above our minumum sampling height of 800 ft MSL. Consequently, only one pass was done at Pt.Reyes and the G-1 proceded to the rendezvous site to meet up with the CIRPAS Twin Otter. The G-1 flew at 300 ft MSL the rectangular pattern with the Twin Otter at higher elevation, and the cloud base was still below this. The water surface could barely be seen. The G-1 did the next rectangular pattern at 600 ft MSL, in cloud, and then the next at 1300 ft MSL, about 200 ft above the cloud tops. The G-1 then returned to 300 ft MSL, hoping that the cloud base had risen, but it had not. Typically, in cloud, the PCASP would range from 100-200 particles/cc, and the CAS 300 to 400 particles/cc.

An SO₂ plume was intersected three times during the three rectangular pattern traverses at the most easterly edge. The concentrations ranged from 3 to 13 ppb, and the PCASP spiked to 1000 to 4500 particles/cc and the CAS to about 800 particles/cc. Sulfate and organics were detected in this plume by the AMS. The plume was most likely emitted from a ship.

The G-1 returned to the Pt. Reyes site, and at 800 ft MSL was totally above the cloud top. Only one pass was then done at Pt.Reyes. The G-1 then returned to Sacramento. Total flight time was about 4 hours.
 

July 18, 2005

G-1 took off at 9:30AM local time and flew to Pt. Reyes. At Pt Reyes, the cloud tops were around 950 ft msl. G-1 flew over the ARM mobile facility site three times, twice inside the clouds at altitudes of 800 and 900 feet, and the third time over the cloud top at 1400 feet. We then turned south and sampled along the same rectangular track west of Monterey as during flights on July 16 and 17. Cloud tops increased from 1200 to 1500 feet from the east end to the west end of the track. Sampled at 1500, 1000, 800, 600, and 300 feet. At 300 feet, we were mostly out of clouds. CCN concentrations were around 800/cc at 1% below cloud. A plume was sampled at 300 ft along the east side of the track. Inside the plume, CN concentration increased from 800 to over 6000/cc, and high organic mass was observed by AMS. We then turned north, flew at 300 feet (mostly out of cloud) and reached Pt. Reyes. Flew over Pt. Reyes at 800 feet inside the clouds before returning to Sacramento. Total flight time is 4 hours.
 

July 19, 2005

Aircraft took of at ~10:00 local time for a flight over Pt Reyes and to the west over the Pacific. Subtle changes in the synoptic meteorology deepened the marine boundary layer causing the formation of thicker and higher clouds than we have previously observed. Upon reaching Pt Reyes we observed that cloud tops were about 1700 ft msl. Flew the pattern over Pt Reyes just above cloud, then in-cloud at altitudes of 1300, 1000, and 800 ft msl. We then flew just offshore to sample below cloud base and observed that at 300 ft msl we were in and out of cloud. The aircraft then headed west at 1000 ft msl in solid cloud to the start of our pattern location at 38:16:00N-123:58W. Once there, we flew the pattern above cloud, at four altitudes in-cloud, and finally at 300 ft in an attempt to get below cloud. The latter was about half in-cloud and half below cloud. During our flight above cloud we noted a layer of high aerosol concentration (~1000/cm³)just above cloud top which we sampled in some detail. The aerosol appeared to be constituted mostly of organic material with a little sulfate. We returned to Pt Reyes, did another pass in-cloud, and then returned to Sacramento. This was the best flight of the program thus far.
 

July 20, 2005

The G-1 took off at 9:30 PDT and headed for the Port Reyes site with the synoptic conditions being very similar to July 19. The cloud tops were about 1300 ft MSL at the site and one sample was taken at about 1400 ft MSL about the clouds. A second sample was at 1000 ft MSL in-cloud and a third at 800 ft MSL, still in-cloud. The G-1 headed off the coast of Pt Reyes to the second sampling site and a sample was taken at 300 ft MSL. This area was still slightly in-cloud, with the sea surface being seen. The G-1 then headed 55 miles off the coast, WNW of Pt Reyes to a sampling pattern of a SW-NE 35 mile line, extending further off the coast. The cloud tops were at about 1345 ft MSL and the pattern was flown at 1550, 1150, 900, 700, 500 and 300 ft MSL. The cloud tops and bases were slightly higher by a few hundred feet at one end of the pattern than the other. The samples at 300 ft MSL at one end were mostly below the cloud base. The cloud LWC (liquid water content) decreased from 0.6 g/m³ at 1150ft MSL to less than 0.1 at 300 ft MSL. The cloud particle size distribution at 1150 ft MSL was more or less very sharp with a maximum diameter at about 21 microns, and this decreased and broadened with lowering samplimg altitude.

A layer of high aerosol concentration was again observed above the cloud tops. The PCASP aerosol concentrations were very uniform at about 800 particles per cc. The AMS observed that these were organic aerosol particles. On its return to Pt Reyes, the G-1 sampled this layer and it was observed to be about 400 ft thick with a sharp falloff above to clean maritime air and a similar falloff below at the cloud tops.

The G-1 flight lasted slighlty over 4 hours.
 

July 22, 2005

The G-1 took off at 9:28 PDT and headed for the Pt Reyes site. The cloud top and base were about 2400 ft and 1800 ft MSL at the site, respectively. Samples were taken at about 2200 ft, 2700 ft, and 1600 ft. The G-1 headed off the coast of Pt Reyes to the northern site over the ocean. Samples were taken at about 2500 ft, 2200 ft, 2000 ft, 1000 ft, and 300 ft between point A and point B, and then climbed up to Pt Reyes, doing a vertical sounding. There were clear differences in cloud tops between A (2400 ft) and B (2500 ft); cloud bases lied at about 1000 ft. The clouds were patchy and looked dissipating with time. Cloud top and base were 1950 and 1640 ft over the Pt Reyes during the second sampling. There was sudden change of CAS spectra during the flight. A layer of high aerosol concentration was again observed above the cloud tops. The PCASP aerosol concentrations could reach as high as 800 particles per cc. The AMS observed that these were likely organic aerosol particles. The PCASP concentrations were about 60 in the clouds, 200 outside the clouds. The aircraft landed at about 13:13 PDT.
 

July 25, 2005

The G-1 departed at 9:30 PDT for Pt Reyes, and observed that the cloud tops were about 1150 ft. MSL. A sample was take at 1400 ft MSL and a second sample at 800 ft. MSL, incloud. The LWC was at about 0.25 g/m³ with the mean cloud particle diameter sharply centered at 15 microns. The G-1 then proceeded to the offshore sampling pattern, which has been sampled in several previous flightdays. At this pattern the winds were observed to be 20 to 25 knots and whitecaps were observed on the sea. The sampling pattern was started at 300 ft. MSL and incremented by 200 ft for each sample. The marine stratus was sparse, especially moreso in the further offshore SW corner of the pattern. It was notice in the PCASP that aerosol particle concentration were higher than seen earlier in the lower sampling levels at about 300 particles/cc, and indeed it was observed this organic aerosol was more or less rather unifromly distributed up to 2800 to 2900 ft. MSL with cloud tops being abour 1100 ft. MSL This contrasts with earlier sampling at the pattern in which the organic aerosol layer was above the cloud tops. This was the first sampling in which the AMS detected ammonium and nitrate in these aerosol samples.

After sampling at this offshore pattern the G-1 returned to the Pt Reyes site for two additional samples, one incloud at 800 ft. MSL and the other above cloud at 1400 ft. MSL. As the G-1 approached the shore at Pt Reyes at 800 ft. MSL, the LWC approached 0.4 g/m³.

The flight lasted a little more than 4 hours.

 

July 27, 2005

The G-1 left for Pt Reyes at 9:30 PDT and the cloud tops were at 1450 ft. MSL. Three samples were taken at Pt Reyes, on at 1600 ft, above cloud tops and two in-cloud at 1200 and 800 ft. MSL. At 1200 ft. MSL it was observed that LWC was about 0.6 g/m³ , with a bimodal cloud particle size distribution, one sharply centered at 21 microns and the other at about 0.7 to 0.8 microns, that is, a cloud and a haze. The G-1 proceeded to the off-shore sampling pattern, the same one sampled on 7/25. The marine stratus clouds were observed to be horizonally consistant over the 35 miles sampling line. Samples were taken below cloud at 300 ft, in-cloud at 500, 700, 900,1100, and 1300 ft MSL. The LWC uniformly increased from 0.2 at 300 ft to 0.6 at 1300. Likewise, the mean cloud particles size increased from 6 microns at 300 to 21 microns at 1300 ft. MSL. Drizzle was observed in this marine stratus cloud.

The AMS detected organic aerosol consistently at a lower level at the incloud sampling levels. The PCASP was about 200 particles/cc in-cloud. The G-1 also sampled at 1500 ft MSL, above the marine stratus cloud tops, and the organic aerosol increased to 6 microgm/m³ with a consistant PCASP measurement of 600 to 800. The G-1 proceeded higher and it was observed that the organic aerosol layer ended at 2000 ft. MSL with the PCASP falling to 50, indicative of clean maritime air. The G-1 did another sample at 1500 ft. MSL allowing the AMS to gather more data on this organic aerosol layer. The G-1 at one point skirted the cloud tops and the organic aerosol increased to 8 ug/m³ with sulfate aerosol at 2 to 4 ug/m³ .

The G-1 returned to the Pt Reyes site at 900 ft. MSL in-cloud, and did one sample at 800 ft MSL below cloud at Pt Reyes. Another sample in-cloud at 1000 ft. MSL was also taken. This flight lasted about 4 hours.

This is the last flight of the MASE 2005 field campaign.