# Presentation: 538925

## VCC & VCFCollection 4 Reprocessing Status

- MODLAND Collection 4 Reprocessing Review
- 17 December 2002
*sohlberg@umd.edu*

## Sequence of Presentation

- MOD44C 16-day interim 250m composite
- MOD44A Vegetative Cover Conversion
- MOD44B Vegetation Continuous Fields

## MOD44C: C4 Changes & Benefits

- Incremental changes were made to Collection 3 thus differences
-   between Collections 3 and 4 are minimal.
- Improved utilization of Quality Flags:
- Converted to MOD09 internal cloud flag;
- Refined use of aerosol flags;
- Instituted newly populated cirrus flag.
- Refined the sorting routine:
- Improved format for ease of maintenance;
- Resolved one-off error in secondary layers table.
- Collection 4 data continues efforts to select the best (cloud free,
-   near nadir pixel) and will result in improved change detection.

## Example from tile h12v10 (southern Amazon basin)

- Collection 4                                                                 Collection 3

- Product quality exceeds that in Collection 3.
-  Dark features and cirrus contamination greatly reduced.
-  This will result in fewer false detections of land cover change

## MOD44C:  C4 Known Issues

- Dark features remain an issue that we would like to resolve:
- Features with spatial structure remain, particularly in arid
-  areas, that have low reflectance relative to adjacent pixels.
- Possibly related to cloud shadow or over-correction.
- Will require ongoing investigation at the SCF.
- These low values are an issue because the values have
-  characteristics consistent with forested areas.

## MOD44C: Anticipated Changes

- Incremental refinements to the use of the cirrus flags are likely.
- If we can find a resolution for the dark feature issue this will
-   be submitted as soon as possible.
- Update the QA flags that are retained to reflect current
-   configuration.
- Update production rule to accommodate case where the L2G
-   compressed SDS is not filled (late season, high latitude case).

## MOD44A:  C4 Changes & Benefits

- With Collection 4, 250m data products will be available
-  globally over the entire MODIS record.
- As such, this will be the first opportunity to produce MOD44A
-  results for large areas over an annual sample period.
- SCF results with improved LUTs and composites are
-  promising and we are quite eager to evaluate our change
-  hotspot product at continental to global scales.
- Primary C3 to C4 change is in the spectral LUTs, which to
-  date we have only been able to derive globally at 500m
-  resolution.

## VCC Change Result:  Mato Grosso Plateau, Brazil

- August 2001 to August 2002

## MOD44A:  C4 Known Issues

- Bug in output plane results in linear feature every nth line.
- Not certain if bug is in our code or the toolkit.
- Need to alter production rule to add full Julian day to name
-   of output file.
- Update 16 to 32 day compositing method to reflect recent
-  changes to MOD44C (cirrus and cloud flag).

## MOD44A:  Anticipated Changes

- Delivery of the revised LUTs.
- Delivery of fixes for known issues from last graph.
- Release of global, annual summary results.

## MOD44B:  C4 Changes & Benefits

- % Tree Cover to be distributed from LP-DAAC.
- New layers being added:
- Leaf Characteristics
- % Broadleaf and % Needleleaf
- Leaf Longevity
- % Evergreen and % Deciduous
- % Herbaceous
- %Bare
- Much better ability to discern fragmented forest than AVHRR.

## MODIS Vegetation Continuous Fields – 2000 prototype

**MODIS Vegetation Continuous Fields – 2000 prototype**

- Bare ground

- Grass/shrubs/moss

- Trees

- 0%

- 100%

- Percent cover

## This is a subset of a global land cover

- <50 bare)

- Forest (>60% tree)

- Woodland (31-60% tree)

- Parkland (11-30% tree)

- Grass/shrubs (<11% tree &

- Low veg. (50-90% bare)

- Bare ground (>90% bare ground)

- classification made by thresholding different percent cover layers

## MOD44B:  C4 Known Issues

- Collection 3 has a few areas of low signal due to persistent haze of clouds.  Hopefully C4 surface reflectance improvements and the Aqua observations will help improve these troublesome areas.

## MOD44B:  Anticipated Changes

- Will produce annual products for 2000, 2001, and 2002.
- Start dates will coincide with Spring Equinox.