# Presentation: 490078

## Aerosol Indirect Effect Experiments on the J-31

- In coordination with the R/V Ron Brown
- (Radar data: Pavlos Kollias)

## Science Objectives

- Study effect of aerosol on cloud microphysics
- Compare different drop size retrieval methods
- Remote sensing from surface (radar/**wave on RHB)
- Remote sensing from J-31(SSFR)
- Remote sensing from P-3 (MIDAS, SSFR)
- In-situ from P-3 (FSSP)

## J31: 

**J31: **
- Aerosol and cloud radiative properties; AOT, aerosol extinction profiles, cloud optical depth, drop size, LWP
- _Instrumentation_: AATS-14, SSFR

**P-3:**
- Emphasis on gasphase chemistry, aerosol size distribution / composition and cloud radiative properties;
- longer range, chasing pollution plumes
- _Relevant Instrumentation_: SSFR, MIDAS, _FSSP_

## R/V Brown

**LWP**

**Lidar*****: ***
**backscatter**
**profiles**

**Surface aerosol**** **

**microwave **
**radiometer**

**effective **
**radius, *****r******e ******(z)***

**Radar**

**R/V Brown**

**Sunphotometer**

## AATS-14 + SSFR:

*r**e **,****d *, **, LWP
***(z)*

- J31

- Cloud free

**Aerosol:*** n(a), ****, ****, ***chem
**Cloud:*** r**e **, w, *LWP

- AOT,
***(z)*

## Method for Indirect Effect Studies

- Use Lidar backscatter or extinction *** *as proxy for CCN
- Various *r**e* retrievals
- Requires non-precipitating warm clouds (single layers) with high enough bases for lidar to sample aerosol (identified 5 possible candidates)

- IE= - dln*r**e*/dln**

## Stratocumulus observations after another front passage (14-15 July). The MWR measurements show good correspondence with the reflectivity structure and the ceilometer data along with the reflectivity data can be used to infer the cloud thickness

## Cloud Fraction during NEAQS from RHB 

- A _ceilometer_-based distribution of hourly averaged cloud fraction during NEAQS. More than
- 30% of the time, clear skies were observed, while overcast cloud and precipitation conditions
- occurred 25% of the time.

## NEAQS Leg-averaged cloud fraction. Note: During leg 2,

- More middle and upper clouds were observed and less BL clouds

## Ceilometer cloud base time series

- Ceilometer Hourly mean cloud base. Note: During the second leg very few boundary layer clouds were observed. Furthermore as the lower panel shows, many of the low level bases in leg one were associated with fog and frontal precipitation

- Precipitation hourly fractional coverage as observed by the _ceilometer_.
- High fractional coverage (close to 1) may mean continuous precipitating conditions

- Fractional Coverage

- Height, km

## LWP time series: Red shows periods with stratus clouds

- Clear Skies LWP

- Overcast BL clouds LWP

**Notes:**
pavlos kollias:
There are several questions regarding the calibration of the MWR and its ability to measure accurately the LWP of stratus clouds. 
This slide shows: (1) the distribution of LWP measurements when the ceilometer show no cloud returns (top left). 
It is apparent that there is a small (?) positive bias in the clear skies LWP measurements,  however when the data are partition in the first 
and second leg it is apparent that the clear skies LWP measurements during the second leg are worst. 
This is good news, since most of the boundary layer cloud returns are observed during the first leg of NEAQS, 
(2) shows the distribution of overcast BL LWP measurements which exhibits higher values of LWP 
and (3) shows the time series of LWP measurements during the cruise where red periods denote stratus cloud periods. 

## Components of aerosol-cloud interactions

**Cloud properties: *****r******e****** , ************d***** , reflectance,***** *********
*** *****Aerosol properties: ****	****size distr., composition, ****	****	****	****	****	*****f*****(RH), mass loading, ****	****	****	****	****	****extinction, scattering, CCN   **
** ****LWP**

**Verification/intercomparison of independent components **
**through redundant measurements**

**Changes in cloud parameters as a function of **
**changes in aerosol parameters**** **

## Detecting and Quantifying AIE

***(r******e ******, ************d ******, ************)                *****  *****(aerosol size distr., extinction, etc)***

**At constant LWP**

**Cloud**

**Aerosol**

**Changes in cloud parameters (*****r******e****** , ************d****** , ************) *****as a function of **
**changes in aerosol parameters**** **

- CCN proxies

## Radar

- Reflectivity

- Precipitation scavenging by Altocumulus

- July 10th

- Cloud base
- ~ 3km

- Scattering (R, G, B)

- 20:00 UTC