# Presentation: 498297

## 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****, E.-S. Yang****4****,**
**L. Froidevaux****1****, T. Canty****1****, J. W. Waters****1**

- 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

**Ross.Salawitch@jpl.nasa.gov**

## Motivation

- •  Zonal, monthly mean HALOE HCl agrees fairly well with this 2D model calculation,
-    particularly at the end of the time series
- •  Model run:  “AER” transport
- 	       Similar to AER model run shown in WMO 2002 (Orange Book)
- •  Focus on:
-                      **Factors that govern this comparison**
-                      **Aura MLS HCl**

- AER 2D Model

- HALOE : Error bars – Std Dev of Data that
-                                 comprise Monthly, Zonal Mean

## More Altitudes

- HCl

## 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

**Age of Air**

**CCl****y**** vs time**

**3.7 ppb level indicated**
**on many plots**

**–  ****Modeling approach developed originally to analyze aircraft data**
**– ****Applied recently to satellite data for “ozone trend attribution” calculations**
**      ****(Yang et al., JGR, submitted, 2005)**

## PSS Results

- • PSS HCl  > AER HCl
- • HCl differences driven by Cly
- • Timing of Cly, and peak Cly, differ
- • PSS results depend on accuracy
-   and precision of HALOE CH4
-        differences at 20 km probably
-             driven by uncertainty in CH4

- Other plots in talk:
-     – Drop 20 km
-     – Focus on UARS time period
-             (1991 to present)

## 45N

## 35N

## 05N

## 05S

## 35S

## 45S

## Second AER Model Run

- • Age of air in most models “too young” compared to empirical estimates
-          (e.g., Waugh and Hall, 2002)
- • We’ll examine another AER 2D model run, using _GSFC transport_
-           – GSFC _non-interactive_ based on observed climatology of T, O3, H2O, etc
-            – yields larger “age of air” than AER transport
-            – Jackman *et al., JGR*, 1996; Fleming *et al., JGR*, 1999; Rinsland *et al., JGR*, 2003

**Ensemble of models**
**(2D & 3D)**

- Waugh and Hall, Rev. Geophys. 2002

- SF6
-  WAS

- SF6  In Situ

- GSFC 2D _Interactive_

- CO2
-  In Situ

**Notes:**
Boxes : WAS SF6   Diamonds : In Situ SF6

## 45N

- • Timing of “rising Cly” agrees better with PSS
- •  Differences in Cly after 1999 drive model HCl
- •  PSS model agrees with “early HALOE” and
-    recent Aura MLS, esp. at 40 and 50 km
- •  AER model / GSFC transport agrees with
-    “early HALOE”, splits diff between between
-    current HALOE and Aura MLS

## 35N

- • Timing of “rising Cly” agrees better with PSS
- •  Differences in Cly after 1999 drive model HCl
- •  PSS model agrees with “early HALOE” and
-    recent Aura MLS, esp. at 40 and 50 km
- •  AER model / GSFC transport agrees with
-    “early HALOE”, splits diff between between
-    current HALOE and Aura MLS

## 05N

- • Timing of “rising Cly” agrees better with PSS
- •  Differences in Cly after 1999 drive model HCl
- •  PSS model agrees with “early HALOE” and
-    recent Aura MLS, esp. at 40 and 50 km
- •  AER model / GSFC transport agrees with
-    “early HALOE”, splits diff between between
-    current HALOE and Aura MLS

## 05S

- • Timing of “rising Cly” agrees better with PSS
- •  Differences in Cly after 1999 drive model HCl
- •  PSS model agrees with “early HALOE” and
-    recent Aura MLS, esp. at 40 and 50 km
- •  AER model / GSFC transport agrees with
-    “early HALOE”, splits diff between between
-    current HALOE and Aura MLS

## 35S

- • Timing of “rising Cly” agrees better with PSS
- •  Differences in Cly after 1999 drive model HCl
- •  PSS model agrees with “early HALOE” and
-    recent Aura MLS, esp. at 40 and 50 km
- •  AER model / GSFC transport agrees with
-    “early HALOE”, splits diff between between
-    current HALOE and Aura MLS

## 45S

- • Timing of “rising Cly” agrees better with PSS
- •  Differences in Cly after 1999 drive model HCl
- •  PSS model agrees with “early HALOE” and
-    recent Aura MLS, esp. at 40 and 50 km
- •  AER model / GSFC transport agrees with
-    “early HALOE”, splits diff between between
-    current HALOE and Aura MLS

## Summary A

- •  Model HCl above 30 km depends on:
-          – age of air
-          – CCly time series
- •  PSS model HCl agrees well with “early HALOE” and Aura MLS HCl
-           Comparison of PSS w/ HALOE very similar to results in Waugh et al., *GRL*, 2001
- •  AER model / “AER transport” agrees best with “late HALOE”
- •  AER model / “GSFC transport” agrees with “early HALOE”, lies between recent
-     HALOE and MLS

## Summary B

- •  Model HCl above 30 km depends on:
-          – age of air
-          – CCly time series
- •  PSS model HCl agrees well with “early HALOE” and Aura MLS HCl
-           Comparison of PSS w/ HALOE very similar to results in Waugh *et al., GRL*, 2001
- •  AER model / “AER transport” agrees best with “late HALOE”
- •  AER model / “GSFC transport” agrees with “early HALOE”, lies between recent
-     HALOE and MLS
- 	         ******  ****What was the level of peak CCl****y**** ???**

## Backup Material To Follow

## 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**