# Presentation: 186992

##   MAPPING ISOPRENE EMISSIONS FROM SPACE USING OMI FORMALDEHYDE MEASUREMENTSDylan B. Millet, Daniel J. Jacob, K. Folkert Boersma, Justin P. Parrella Atmospheric Chemistry Modeling Group, Harvard University Thomas Kurosu and Kelly V. ChanceHarvard/Smithsonian Center for AstrophysicsBrian G. Heikes (URI), Alan Fried and Alex B. Guenther (NCAR), Colette L. Heald (Berkeley)

**Work supported by NASA/ACMAP**

## SPACE-BASED MEASUREMENTS OF HCHO COLUMNSOFFER CONSTRAINTS ON VOLATILE ORGANIC COMPOUND (VOC) EMISSIONS

**SPACE-BASED MEASUREMENTS OF HCHO COLUMNS****OFFER CONSTRAINTS ON VOLATILE ORGANIC COMPOUND (VOC) EMISSIONS**

**VOC**

**HCHO**

**Oxidation (OH, O****3****, NO****3****)**

**several steps**

**h************nm), OH**

**lifetime of hours**

**340 nm**

**VOCs important as**** **
** ****precursors of tropospheric ozone**
** ****precursors of organic aerosols**
** ****sinks of OH**

**   ****Vegetation   Anthropogenic   Biomass burning**
**       ****~1000             ~200                  ~100 Tg C yr****-1**

## RELATING HCHO COLUMNS TO VOC EMISSION

**VOC****i**

**HCHO**

**h******** (340 nm), OH**

**oxn.**

***k ~ 0.5 h******-1***

***Emission E******i***

**smearing, displacement**

**In absence of horizontal wind, mass balance for HCHO column ********HCHO****:**

**yield *****y******i***

**... ****but wind smears this local relationship between ********HCHO ****and *****E******i***** depending on the lifetime of the parent VOC with respect to HCHO production:**

**Local linear relationship**
**between HCHO and *****E***

**VOC source **

**Distance downwind**

******HCHO**

**Isoprene**

******-pinene**

**propane**

**100 km**

**detection**
**limit**

## INVERTING HCHO COLUMN DATA FOR ISOPRENE EMISSION

**GOME slant columns (July 96)**

**GOME vertical columns (July 96)**

***E******ISOPRENE  ******=(1/S)*********HCHO****  **

**GOME **
**isoprene**
**emission **
**inventory**

**GEOS-Chem**
**chemical**
**transport**
**model**

**validation**
**With HCHO**
**surface air**
**observations**

**with bottom-up**
**isoprene **
**emission**
**inventory**

**with GOME**
**isoprene**
**emission **
**inventory**

***Palmer et al. [2001, 2003, 2006]***

***E******ISOPRENE***

**HCHO column**

**non- isoprene contribution**

**slope *****S***

## MEGAN EMISSION INVENTORY FOR BIOGENIC VOCs

**Environmental factors:**
** ****temperature**
** ****solar irradiance**
** ****leaf area index**
** ****leaf age**

**July**
**2003**

## OMI HCHO COLUMNS (Jul-Aug 2005)

**OMI HCHO COLUMNS**** (Jul-Aug 2005)**

***Thomas Kurosu, Harvard-SAO***

|  | OMI |  GOME |
| --- | --- | --- |
| Pixel resolution | 13x24 km2 |  80x320 km2 |
| Return time | 1 day |  3 days |

## OMI vs. GEOS-Chem/MEGAN HCHO COLUMNSJul-Aug 2005

**OMI vs. GEOS-Chem/MEGAN HCHO COLUMNS****Jul-Aug 2005**

**OMI**

**MEGAN**

**OMI is 35% lower **
**than GEOS-Chem/MEGAN**

***Dylan B. Millet, Harvard***

**          ****detection limit**

## In contrast, GOME was 10-30% higher than GEOS-Chem/MEGAN!

***Palmer et al. [2006]***

**Isoprene**
**emission**

## USING INTEX-A AIRCRAFT DATA AS ARBITER

**USING INTEX-A AIRCRAFT DATA AS ARBITER**

**DC-8 0-10 km HCHO profiles over N. America (summer 2004)**

***Millet et al. [in press]***

**Observed HCHO columns (NCAR)**

**GEOS-Chem w/GEIA (MEGAN forerunner)**

**R****2 ****=0.70, bias=+4% (NCAR),  +34% (URI)**

**MEGAN is on average 10% lower than GEIA**

## GEOS-Chem EVALUATION w/ INTEX-B/MILAGRO DATAMarch 2006

**GEOS-Chem EVALUATION w/ INTEX-B/MILAGRO DATA****March 2006**

**Observed**
**(URI)**
**GEOS-Chem/**
**MEGAN**

**Observed**
**(NCAR)**
**GEOS-Chem/**
**MEGAN**

**URI and NCAR measurements now agree and also agree with GEOS-Chem**

***Justin P. Parrella,***
***Harvard***

## SPATIAL PATTERNS IN OMI vs. MEGAN DISCREPANCIES

** ****Scale up OMI to remove overall bias;**
** ****Drive MEGAN with two different **
**  ****land surface data bases**

**MEGAN w/Olson [2001] data base**

**MEGAN w/ Community Land Model (CLM)**

**NORMALIZED OMI – MEGAN **
**(Jul-Aug 2005)**

** ****Large sensitivity of MEGAN to choice of land data base!**
** ****MEGAN higher than normalized OMI in Missouri (Ozarks), lower than OMI in deep South and along southeast Atlantic**

***Dylan B. Millet [Harvard] ***
***and Colette L. Heald [Berkeley]***

## WHY IS MEGAN SO HIGH OVER OZARKS AND VIRIGINIA?

**Emission factor (EF)**

**CLM land cover**

**Oak tree cover, high temperatures**

**Comparison with OMI suggests that emissions**
**from broadleaf trees are overestimated**

***Dylan B. Millet, Harvard***

## WHY IS MEGAN LOW IN DEEP SOUTH AND ATL. COAST?

**CLM land cover**

** ****suggests underestimate of pine emissions**
**In southeast**
** ****also suggests underestimate of emissions by cotton and peanuts, the two regional crops**

***Dylan B. Millet, Harvard***

## TEST GEOS-Chem HCHO YIELDS FROM ISOPRENE WITH INTEX-A AIRCRAFT DATA

**TEST GEOS-Chem HCHO YIELDS FROM ISOPRENE ****WITH INTEX-A AIRCRAFT DATA**

***Millet  et al. [in press], Palmer et al. [2006]***

**Estimate yield uncertainty of ~20%, greater in low-NO****x**** regime**

**Box model simulations:**
**GEOS-Chem and  MCM v3.1 mechanisms**

**HCHO vs. isoprene columns**
**in INTEX-A**

**Time, hours**

**HCHO yield, per C atom**