# Presentation: 680068

## MODIS Atmosphere Level 2 (ATM_L2) Joint Product

- B. Wind1,2

- 1NASA Goddard Space Flight Center, 2L-3 GSI

***MODIS Atmosphere Group Meeting***
- Baltimore, MD
- 14 July 2004

- MODATML2, MYDATML2

## Motivations for a MODIS joint atmosphere level 2 product

- Small
- Comprehensive and consolidated
- representative of key atmosphere solutions
- Enhanced usability

- MODATML2, MYDATML2

## Hard decisions add value

- Small is more externally usable
- Minimal set removes interesting but intimidating clutter how arrived at answer
- Depending on who you are, small *is* representative

- MODATML2, MYDATML2

## How small is small?

- Any given day on a CD?
- 288 granules per 24 hour period
- (up to)144 (summer) full-size (daytime) granules
- 	650Mb / (144 + (144*.5)) = 3.01Mb / gran.
- current size of a full granule ~ 180Mb / gran.
- 	(est. only includes MOD 04, 05, 06, 07, 35)

- MODATML2, MYDATML2

## Hard decisions

- What are people interested in?  And, ...
- 	...what do we want them to see?
- No quality assurance except where absolutely crucial to use/interpret answer
- Max. of 5x5km grid scale for size/consistency
- 1km arrays necessitate reducing resolution
- sample, not average, to retain meaning
- Exploit acceptable data representation downsize
- lat/lon 4 bytes to 2, sacrifice 1/1000th degree

- MODATML2, MYDATML2

## Slide 6

- MODATML2, MYDATML2

## Two grid scales

- ~500kb (1/5) of the product is navigational data
- Two pairs of 2-byte Latitude Longitude
- 5_km arrays are copied same as 06_L2
- 10_km arrays are computed same as 04_L2
- At 10Km solar zenith angle, viewing zenith angle, and relative azimuth are also kept

- MODATML2, MYDATML2

## More Facts and Features

*Production start date: *
*	**October 14, 2003 Terra and Aqua*
*ESDT Designation:  MODATML2, MYDATML2*
*Program Executable (PGE) 83*
- ATM L2 compatible with most popular tools
- may generate a MODATML2 sans MODAPS from input files
- Algorithm pedigree kept as SDS attributes

- MODATML2, MYDATML2

## Cloud_Phase_Daytime

- source_info:
- MOD06_L2.A2001222.1200.004.2002289223630.hdf
- pge06v4.2.0
- 	Quality_Assurance_1km
- 	Cloud_Mask_1km

- Cross-reference ATM_L2 SDS source information
- with modis-atmos website production calendar.

- _http://modis-atmos.gsfc.nasa.gov/products_calendar.html_

- MODATML2, MYDATML2

## L2 Global Time Series Animation

**L2 Global Time Series Animation**

*Time-series animation*
*Reto Stöckli*

- MODATML2, MYDATML2

## Virtual Reality from Day of L2’s

- Ice Clouds

- 50

- 30

- 2

- 16

- 28

- 39

- 17

- 9

- 23

- Water Clouds

- 6

- Terra
- October 28, 2003

*Virtual Reality Visualization*
*Reto Stöckli*

- Height
- Cloud top pressure
- Colors
- Effective radius of water and ice clouds
- Transparency
- Optical thickness

**Virtual Reality from Day of L2’s**

- MODATML2, MYDATML2

## Terra order statistics as of July 9

**Terra order statistics as of July 9**

- Statistics from _[http://edgrs.gsfc.nasa.gov:8000/soo/aspdb_provider/edgrs3.asp](http://edgrs.gsfc.nasa.gov:8000/soo/aspdb_provider/edgrs3.asp)_.

- MODATML2, MYDATML2

## Aqua order statistics as of July 9

**Aqua order statistics as of July 9**

- Statistics from _[http://edgrs.gsfc.nasa.gov:8000/soo/aspdb_provider/edgrs3.asp](http://edgrs.gsfc.nasa.gov:8000/soo/aspdb_provider/edgrs3.asp)_.

- MODATML2, MYDATML2

## Future Directions

- HDF Compression
- Additional SDS’s
- Effective_Radius_Difference (1.6 and 3.7 re retrievals)
- Collection 5 06_L2 error bars
- Suggestions?

- MODATML2, MYDATML2