NOAA Teacher at Sea
Aboard R/V Roger Revelle
November 6 — December 10, 2011
Mission: Project DYNAMO
Geographical area of cruise: Leg 3, Eastern Indian Ocean
Date: November 24, 2011
Weather Data from the R/V Revelle Meteorological Stations
Wind Direction: 246.10
Wind Speed (m/s): 9.3
Air Temperature (C): 27.4
Relative Humidity: 86.1%
Dew Point: (C): 25.10
Precipitation (mm): 25.1
PAR (Photosynthetically Active Radiation) (microeinsteins): 177
Long Wave Radiation (w/m2): 454.3
Short Wave Radiation (w/m2): 36.7
Surface Water Temperature (C): 300
Sound Velocity: 1545.9
Salinity (ppm): 35
Fluorometer (micrograms/l): 0.9
Dissolved Oxygen (mg/l): 2.6
Water Depth (m): 4637
Wave Data from WAMOS Xband radar
Wave Height (m) 2.2
Wave Period (s): 15.3
Wavelength (m): 290
Wave Direction: 29000
Science and Technology Log
The Aerosols Group consists of Derek Coffman, Langley Dewitt and Kristen Schultz from the NOAA Pacific Marine Environmental Lab (PMEL) in Seattle, Washington. The Aerosols group measures the chemical, physical, and optical properties of sub and supermicron aerosols (liquids or solids suspended in gas) in the lowest layer of the troposphere. Aerosols are important in the study of climate change and the largest unknown due to the complicated nature of the particles. Aerosols are being studied in the MJO experiment to determine how they affect the radiative balance and how the MJO affects aerosols.
The measurements and analyses include:
- real-time and filter-based analysis of the aerosol chemical composition
- size distributions from 20 nm to 10 microns (aitken mode to course mode aerosols)
- particle number concentrations
- aerosol scattering and absorption
- cloud condensation nuclei (CCN)
- total mass of filtered collected aerosol
- O3 and SO2 gas phase measurements.
Aerosols are captured via an opening in the inlet (mast). The base of the inlet consists of 21 individual sample lines. The inlet is designed to collect particles in average marine conditions without preferentially selecting particles and is efficient in collecting particles up to 10 microns in diameter. Each sample line connects to a specific instrument for analysis. The captured aerosols are sampled for physical, chemical, and optical properties. . In general, for the ocean, particle sizes that are <1 micron are typically more anthropogenic, while particles >1 micron are sea salts and generated by wind and rain.
Impactors are attached to the sample lines to separate and collect aerosols. Each impactor has a filter to capture a particular particle size range. The filters are removed from the Impactors in a clean lab for analysis. Half of the samples collected are analyzed on the ship and the remaining samples are analyzed at the NOAA PMEL Lab in Seattle, WA. Analytical methods used on the ship to measure chemical species are ion chromatography, liquid chromatography with mass spectrometry (LCMS), total organic carbons (TOC), and organic carbon and elemental carbon (OCEC). The optical properties measured include scattering and absorption. Scattering is measured by an instrument called a nephelometer and absorption is measured by a Particle Soot Absorption Photometer (PSAP). The physical properties measured are total particle concentration and size distribution of the particles. Condensation particle counters (CPCs) measure the particle concentrations and size distribution is measured by a Scanning Mobility Particle Sizer (SMPS), The Aerosol Mass Spectrometer measures the size and chemical composition of non-refractory submicron aerosols.
Thanksgiving week proved to be the most interesting weather of the cruise. The winds picked up to 48 knots on Thanksgiving Day. This made for a real exciting time on the winch. During several drops (each time Chameleon is lowered in the water column), I had to hold on to the canopy with one hand, and the winch with the other so I would not fall over when the swells hit the stern of the ship.
I was surprised that Chief Scientist Jim Moum continued to work on his computer and did not run out to snatch me away from his valuable research instrument! If he had that much confidence in my ability to handle the situation, I had to prevail. Just as I was convincing myself I had to prevail, I heard the bridge call on the hand-held radio. I could not understand the communication and did not want to release the winch since it was difficult to control in the wind. Someone from the Ocean Mixing Group came out to tell me that the bridge called and could not control the ship direction and to take Chameleon out of the water. By this time Chameleon was trailing behind the ship and I could not see if it had gone under the ship. A bit of chaos ensued and I saw a boat hook out of the corner of my eye as crew prepared to get Chameleon out. Somewhere in the midst of the chaos, Jim Moum came on deck and decided that profiling could continue. By that time the ship had re-positioned, however, the wind speed was the same. Jim surveyed the situation and said that he had profiled in far worse weather conditions and went back to his work. I breathed a huge sigh of relief when my shift was over that night and Chameleon was not damaged.
Thanksgiving Day was another day of collecting data. The cooks prepared a Thanksgiving Dinner and I think I speak for all of the scientists when I say we appreciated the turkey and all the trimmings.
Scott, a Wiper in the Engineering Department asked me if I would like an interesting video of a crew job for the website. Scott is a polite crew member and has an interest in education. My first question was “What is the job description for a wiper?” I was told that a wiper is an unlicensed engine room staff member. According to Scott, he empties trash, cleans, and performs other projects as needed such as needle gunning (removing paint and rust from metal surfaces) natural air vent shafts as seen in the video below. I wasn’t prepared for the noise when I shot this video.
There are no gorgeous sunrise and sunset photographs to end this blog – we are probably in the beginning stages of the MJO. There is a tropical cyclone to our north and the outer bands were reaching the ship. We are experiencing squalls with high winds. It is unusual to have cyclones during the MJO event – they usually develop in the wake of the cycle according to the Atmospheric Soundings Group. I get dressed in rain boots and gear and run to the winch and run back inside when my shift is over. Although I am sure you would like to see a photo, it is not exactly a desirable Kodak moment for cameras. Stay tuned, the weather is bound to change.
For this post’s quiz, please answer in the comments of this post:
Using the Aerosol source diagram above, what particle size aerosols are dominant in
continental air masses and what particle size aerosols are dominant in clean marine air masses?