# Presentation: 949172

## The ARM Mobile Facility

**Mark Miller**
**Team: Mary Jane Bartholomew, Larry Jones, Kim Nitschke, Doug Sisterson**
**Chief Engineer: Kevin Widener**

## MASRAD

***MArine Stratus Radiation, Aerosol, and Drizzle (MASRAD)—Multiple ARM PI’s***
***DOE Atmospheric Science Program: Pete Daum (BNL), John Ogren (CMDL) and others***
***Office of Naval Research: John Seinfeld (Caltech)***
***Anthony Wexler (UC Davis)***
***Scientific Objectives***
***(1) Investigate the general relationship between cloud liquid water structure, aerosols, cloud microphysics, drizzle and radiation in marine stratus clouds***
***(2) Investigate the aerosol effects on the amount of solar radiation absorbed by marine stratus clouds****** ***
*** ***

**Notes:**
Two aircraft (DOE G1—PNNL; Office of Naval Research Twin Otter)

## Pt. Reyes National Seashore

- San Francisco

- Monterey

**Coastal Northern California**

**Notes:**
Penninsula north of SFO

## Site

- Pt. Reyes Light

- Wind

## Conditions

**Conditions**

**5.5 months duration**
**Low cloud bases and frequent fog**
**Predominantly “marine” air masses**
**HYSPLIT**
**MJ Bartholomew**

*M. Dunn / BNL*

## Systematic Variation of 

- From Delene and Ogren, 2000
- Courtesy of E. Andrews and J. Ogren

**Backscatter fraction**

**Single scattering albedo**

**Scattering Coefficient (Mm****-1****)**
**aerosol cross-sectional area for scattering for a unit volume of air  (10****-6**** m****-1**** = 1M m****-1****)**

- Pt Reyes

- Pt Reyes

- Systematic Variation of
- Aerosol Optical Properties

**Notes:**
Extinction=Scattering plus Absorption
Single scattering describes the fraction of the total extinction due to scattering
Single scattering albedo increases as pollution increases
The 'wet' nephelometer measures light scattering over a range of relative humidities between approximately 40% and 90%. Humidity in the wet nephelometer is increased during the first part of each hour and decreased in the second part of each hour. Light scattering tends to increase with increasing humidity and vice versa
An integrating “dry” nephalometer and particle-soot absorption photometer (PSAP) were used to measure aerosol light scattering and absorption coefficients, respectively.
Three wavelength integrating nephalometer measures at three wavelenghts (450, 550, 700 nm)
--Nep measures forward and backscatter coefficients

The nephelometer is an instrument that measures aerosol light scattering. It detects scattering properties by measuring light scattered by the aerosol and subtracting light scattered by the gas, the walls of the instrument and the background noise in the detector. The three-wavelength model (TSI 3563) splits the scattered light into red (700 nm), green (550 nm), and blue (450 nm) wavelengths. The TSI neph measures back-scattered light at these wavelengths as well. The one wavelength Radiance Research nephelometer measures forward scattering at 550 nm only. 
Design Features  
TSI 3563 Nephelometer schematic courtesy of TSI Incorporated
The main body of the TSI 3563 nephelometer is a 10 cm diameter aluminum tube, 90 cm long. Along the axis is an 8 cm diameter tube set with aperture plates. The plates range from 7 - 170o on the horizontal range of the lamp. The backscatter shutter allows blocking of the angles from 7 - 90o so that only backscattering is measured. The light trap provides a dark reference against which to measure the scattered light.
The receiving optics are located on the other side of the tube from the trap. The light that passes through the lens is is separated by dichroic filters into three wavelengths. The first is a color splitter that passes 500-800 nm light and reflects 400-500 nm light. The reflected light passes through a filter centered at 450 nm (blue) into a photomultiplier tube (PMT). The light that passes through the first splitter goes to a second splitter which passes 500-600 nm light and reflects 600-800 nm light. The reflected light passes through a filter centered at 700 nm (red) into a second PMT. The light that passes through both splitters passes through a filter centered at 550 nm (green) into a third PMT.
The reference chopper, shown below, is used for calibration of the nephelometer. It consists of three zones. The signal zone allows light to pass through unaltered. The dark zone allows no light to pass, and is used to measure the background noise of the instrument. The calibrate zone allows approximately 0.1% of the light to pass and is used to measure lamp stability over time. The chopper rotates 

PSAP measures light absorption by particles depositing on a white filter

## July

- DOY, 2005 (100= April 10)

- Scattering (Mm-1)

- Absorption (Mm-1)

- Sub 5um
- Sub 1um

- Bond et al., 1999 standard correction for scattering may be too large for sea salt dominated aerosol.

- The large difference in scattering between sub5-um and sub1-um aerosol is likely due to sea salt.

- What’d we see?  Aerosol scattering and absorption

- Courtesy of E. Andrews
- and J. Ogren

## Cloud Droplet Nucleation

***Cloud Condensation Nuclei (CCN) Activation Spectrum***** **
**Number CCN activated as a function of supersaturation**

**Aerosols have different**
**Sizes**
**Nucleation properties**

**Number of**
**Cloud Droplets**

## In-cloud Vertical Velocity

- M. Dunn/BNL

## Cloud Droplet Nucleation

- Cloud Condensation Nuclei (CCN) activity spectrum measured continuously
- See our poster

**Observed Range**
**of Updrafts**

## RADAGAST

- Radiative Divergence using AMF, GERB, and AMMA Stations
- Tony Slingo, PI
- Niamey, Niger: Jan-Dec 2006
- Operational
- Broadband Heating Rate Profile
- GERB—Geostationary Broadband sensor on METEOSAT8

## Niger

## Micropulse Lidar 

**North Winds**

**Southwest Winds**

**Negligible**
**Return**

**Cloud **
**Droplets**

**Cloud**
**and/or**
**Aerosol**

**0000**

**Negligible**
**Return**

**Cloud **
**Droplets**

**Cloud**
**and/or**
**Aerosol**

## Summary of Winter Conditions

- Decoupling
- Multiple stacked mixed layers
- Frequent cirrus
- Thin liquid clouds at the freezing level
- Major dust storm

**Courtesy of Ben Mohammed**

- V=4500m

**Courtesy of Ben Mohammed**

- V=700m, Mass Concentration=1,700g m-3

**Courtesy of Ben Mohammed**

## March 8-11 Dust Storm

**Total**
**Irradiance**

**Source: Data Quality Office**

**Direct Normal**

**Diffuse**

**Direct Normal<200 Wm****-2****!!**

**Diffuse ~ 800**** ****Wm****-2**

## Courtesy of 

**Dust product (upper) and GERB OLR (lower) for 1200UT on 8 March 2006**

**Courtesy of **
**Anthony Slingo**

## March 9

**0000**

**1200**

**0**

**5**

**10**

**15**

**20**

**Time (UTC)**

**Height (km)**** **

**0000**

**Negligible**
**Return**

**Cloud **
**Droplets**

**Cloud**
**and/or**
**Aerosol**

## 500 nm

- RV Ron Brown
- Central Pacific
- AOT=0.08

- Sea of Japan
- AOT=0.98

- AMF
- Niamey, Niger
- AOT=2.5-3

## 3.2 mm Cloud Radar in Niamey

**Courtesy of Kevin Widener**

## Slide 24

## Summary

## Cloud Liquid Water Path (LWP)

- Low LWP’s problematic
- AERI-MWR combination promising

**AERI + MWR**
**MWR Physical**
**MWR Stat2**
**Original MWR**

**Negative LWPs**

**Consensus**
**At LWP>50**
**MWR only**

## Data Status

- Low cloud base and extremely low cloud liquid water
- 3.2 mm cloud radar (WACR) and Microwave Radiometer (MWR) operating at edge of capability
- MWR
- Dave Turner testing algorithms
- WACR
- Artifacts
- Doppler Velocity algorithm development (P. Kollias and M. Dunn)
- Reflectivity not yet addressed

**Notes:**
Artifacts in the near field—radar physics
Research radar—some operational issues, particularly in early June