# Presentation: 066140

## Comparison of HALOE and MLS HCl with Calculated Time Series from Several Photochemical Models 

**R. J. Salawitch**** ****1****, D. K. Weisenstein****2****, J. Anderson****3****, J. Russell III****3****, **
**E.-S. Yang****4****, L. Froidevaux****1****, T. Canty****1****, J. W. Waters****1****,**
**A. Douglass****5****, E. Fleming****5****, C. Jackman****5****, S. Montzka****6****, D. Waugh****7**

- 1 Jet Propulsion Laboratory, Caltech, Pasadena CA
- 2 Atmospheric and Environmental Research, Lexington MA
- 3 Hampton University, Hampton, VA
- 4 Georgia Institute of Technology, Atlanta, GA
- 5 NASA Goddard Space Flight Center, Greenbelt, MD
- 5 NOAA CMDL, Boulder, CO
- 7 Johns Hopkins Univ., Baltimore, MD

- Aura Science Team Meeting
- Den Haag, Netherlands
- November 2005

## Introduction

- •  Zonal, monthly mean HALOE HCl agrees fairly well with this 2D model calculation
- •  Model run:   GSFC 2D model with climatological transport
- 	       Jackman et al., JGR, 2005
- •  Focus on:
-                      **Factors that govern this comparison**
-                      **        ********  ****age of air (**_**mean value**_** & **_**shape of distribution**_**)**
**                             ********  ****contribution from ****very short lived**** ****(VSL)**** organics to Cl****y**** **

**  **Error bars –
-           Std Dev of Data in Monthly, Zonal Mean
-   NOTE: Uncertainty in MLS zonal, monthly
-               mean is 5-6 times better than these
-               error bars

## Cly appears as DOTTED LINES

- Cly appears as DOTTED LINES

**Dotted Line: Cl****y****, GSFC 2D Model**

**45****o****N, 55 km**

**3.7 ppb level indicated**
**on all plots**

## PSS Model Results appear as BLUE LINES

**PSS Model**

**45****o****N, 55 km**

## Three PSS Lines representing air with Same Mean Age, different “Age Spectra”

- Three PSS Lines representing air with _*Same Mean Age*_, different “Age Spectra”

**PSS Model,**
_**3 age spectra**_

**45****o****N, 55 km**

- Three age of air spectra included for all PSS simulations:
- 	 Mean age of 6 years
- 	 Widths of 0.01, 2.0, and 3.0 yrs

**FREQUENCY**

- Waugh et al., GRL, 2001 :
-         All distributions have mean age of 6 yrs
-         Mean ages of 0.5, 2, and 4 years

## PSS (Photochemical Steady State) Model

- • HALOE CH4 used to calculate N2O (Michelsen *et al*., *GRL*, 1998)
- • Cly and NOy estimated from N2O using standard correlations
- • O3, Surface Area, H2O, etc from HALOE and SAGE II
- • dN2O/dt, dCH4/dt, Age of Air, and CCly vs time considered

**Tropospheric CCl****y**** at surface vs time**

**3.7 ppb**

**Same m****odeling approach used to analyze aircraft & balloon data**
**(Salawitch et al., Osterman et al., Sen et al., Jucks et al., etc)**

**AGAGE-CMDL + 700 ppt**
**Cl****y**** time series used by Froidevaux**
**(S. Montzka)**

## 45N

- • GSFC HCl indicative of wide age spectrum
-   for all altitudes
- • Age spectrum more important ~1997 to 2002
- • Models using WMO Cly underestimate MLS HCl
-   above 40 km

## 45N, 120 ppt offset

-   If VSL compounds contribute 120 ppt to Cly
-   PSS model:
-         agrees well with MLS HCl all altitudes (mid 2004 to present)
-         overestimates HALOE HCl all altitudes, most times
- 			(1992 to present)

## 35N

**35****o****N**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y**

## 35N, 120 ppt offset

**35****o****N**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y ****+ ****120 ppt**

## 05N

**5****o****N**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y**

## 05N, 120 ppt offset

**5****o****N**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y ****+ ****120 ppt**

## 05S

**5****o****S**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y**

## 05S, 120 ppt offset

**5****o****S**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y ****+ ****120 ppt**

## 35S

**35****o****S**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y**

## 35S, 120 ppt offset

**35****o****S**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y ****+ ****120 ppt**

## 45S

**45****o****S**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y**

## 45S, 120 ppt offset

**45****o****S**
**   ****** **GSFC model: WMO Cl****y**
**   ******** ****PSS model: WMO Cl****y ****+ ****120 ppt**

## Sensitivity of HCl to mean age and width35oN, 40 km, No VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs & width = 3 yrs  **GREEN CURVE**

## Sensitivity of HCl to mean age and width35oN, 40 km, No VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs & width = 3 yrs  **GREEN CURVE**

## Sensitivity of HCl to mean age and width35oN, 55 km, No VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs & width = 3 yrs  **GREEN CURVE**

## Sensitivity of HCl to mean age and width35oN, 55 km, 120 ppt VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs & width = 3 yrs  **GREEN CURVE**

## Summary 

- •  Model HCl in middle to upper stratosphere depends on:
-          – assumed Cly time series
-          – mean age of air
-          – _width_ of the “age of air spectrum”, particularly between ~1997 and 2002
- •  Assuming a mean age of ~6 years and a width of 2 to 3 years:
-           UARS **HALOE HCl** generally consistent with **WMO Cl****y**** loading**
-           Aura **MLS HCl** generally consistent with **~120 ppt contribution from VSL species to Cl****y**** **
- •  VSL contribution to Cly is an area of active research :
-            Chapter 2, Ko, Poulet et al., “Orange Book” (WMO/UNEP 2002 Ozone Assessment)
-            Quantification may require accurate measurements of HCl and VSL compounds in UT/LS
-            HCl solubility suggests Cly from VSL compounds might be “washed out”
-            Heterogeneous liberation of HCl from aerosols could “interfere with aerosol wash out of HCl”
-            Candidate VSL chlorine compounds:
- 		Species	 (days)	Cl content (ppt)
- 		C2H4Cl2	    70	   ~ 30
- 		CHCl3	  150	   ~ 30
- 		CH2Cl2	  140	   ~ 26
- 		C2Cl4	    70	   ~ 12
-             These species, or their decomposition products, *could* deposit Cly just above the tropopause
-           ***ODP (Ozone Depletion Potential) of bromine is quite sensitive ***
***to the Cl******y****** abundance in the lowermost stratosphere***

## Extra Material To Follow

## HCl Validation

## HCl Validation

## Waugh et al., GRL, 2001

**Surface CCl****y**

**CCl****y**** ****from HALOE HCl**

- Comparison of CCly inferred from HALOE HCl, 0.46 mbar, with expected time series
- for CCly with mean age of **6 years**, but various age spectra, as indicated.
**Note: CCl****y**** peaks just below 3.6 ppb in this analysis**

## Sensitivity of HCl to mean age and width45oN, 55 km, No VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs and width = 3 yrs

## Sensitivity of HCl to mean age and width45oN, 55 km, 120 ppt VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs and width = 3 yrs

## Sensitivity of HCl to mean age and width45oN, 40 km, No VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs and width = 3 yrs

## Sensitivity of HCl to mean age and width45oN, 40 km, No VSL Contribution

- Darryn Waugh:  Mean age likely 6  (+1, 0.5) yrs
- 	       H2O tape recorder & HCF134 data indicate width of 2 to 3 yrs
- John Anderson: HALOE HF consistent with age = 6 yrs and width = 3 yrs