# Presentation: 696762

## MODLAND Volumes and Loads Status

- MODIS Land Science Team Workshop
- July 15, 2003
- Robert Wolfe
- MODIS Land Team Support GroupNASA GSFC Code 922, Raytheon ITSS

## Land Products @1x – EDC DAAC

- 2/96 baseline was 154GB/day
- 10/99 baseline is 330GB/day (with combined Aqua/Terra products)
- Current Collection 4 reprocessing volume is 310GB/day (no combined products)
- Land volume will be 240GB/day in Collection 5 reprocessing (reduced L2G volume and other changes) in Fall 2004

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## Land Products @1X – NSIDC DAAC

- 2/96 baseline was 13GB/day
- 10/99 baseline is 40GB/day
- Current Collection 4 reprocessing volume is 15GB/day
- Snow and Sea Ice product volume will be 25GB/day with Collection 5 reprocessing in Fall 2004

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## Proposed C5 Volume Changes

- Objective to estimate:
- how to further reduce the size of the L2G products, and
- start generating 500m data for a number of products that are currently only produced at 1km
- Changes implemented for a Collection Version 5 reprocessing
- likely to begin next fall
- will mean changes for downstream software
- Compression could also help with throughput
- will be considered separately
- Did not consider:
- changing the compositing period for 8-day products
- eliminating any products (except when replaced by 500m products)
- any Land products archived at NSIDC (only EDC products)

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## L2G Option A

- Reduce the number of L2G products archived from 7 to 2 per tile
- incorporate the pointer and geoangle products into the surface reflectance products
- Savings from:
- removing the "orb_cov" field
- eliminating the "line" and "sample" fields
- removing overlap between scans
- Impact: reduces the L2G products to less than half the current size
- From 251 GB/day to 120 GB/day
- But ... MOD09HK is now a more complicated product because it has both a 1km and 500m grid within the same file

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## L2G Option B

- Turn the L2G product into a "AGG" product
- eliminate the need to have both a daily L2G surface reflectance and a daily Aggregated surface reflectance
- Same criteria for selecting observations as in the current MODAGG code will be used
- maximal angular distribution of the good observations; no more than 4 orbits/day
- Non-compact (full) form is used
- each layer is stored as a single 2-dimensional array
- savings from reducing the need for storing the links between the different resolutions
- additional space is needed to go to the non-compact form, and to add the texture field
- Impact: the L2G products to about 2/3 of current size
- From 251 GB/day to 165 GB/day (vs. 120 GB/day for Option A)

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## Generating four current 1km products at 500m

- Candidate 1km products: BRDF/Albedo, LAI/FPAR, PSN/NPP and Land Cover
- Need an intermediate AGG/TEX at 500m or L2G option B
- Current candidate 1km product size: 6.5 GB/day
- excludes 1km AGG/TEX (current size 51.4 GB/day, reduced volume: 25.7 GB/day)
- Estimated new 500m product size: 17.8 GB/day
- excludes 500m AGG/TEX (reduced volume: 102.7 GB/day)
- Easily fits with L2G Option B or for L2G Option A if AGG/TEX is not archived

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## Summary

| L2G Option | Add 500m | Keep 1km | Archive Agg/Tex | New volume archived (GB/day) | Savings from current allocation of 330 GB/day |
| --- | --- | --- | --- | --- | --- |
| A1* | Yes | Yes | No | 195 | 41% |
| A2 | Yes | No | No | 188 | 43% |
| A3 | Yes | Yes | Yes | 323 | 2% |
| A4 | Yes | No | Yes | 291 | 12% |
| B1* | Yes | Yes | No | 240 | 27% |
| B2 | Yes | No | No | 233 | 29% |

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## Volume Drivers

- Main drivers
- Extending Terra and Aqua mission lifetimes three years (from 5 to 8+ years)
- Volume growth from ’96 baseline
- Archive management issues
- Previous collection must be kept for 6 months after current one – tape reuse is more difficult than anticipated
- Solution: Technology refresh
- Anticipated for about this time
- New drives write 3 times as much data on tapes,  current tapes are being reused

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe

## Strawman MODLAD Volume Recommendations

- Reduce size of L2G products using Option A or B and start producing new 500m products (reduces volume by ≥ 27%)
- Implement internal HDF compression where feasible
- Must consider any impact on end-user analysis tools
- Perform technology upgrades to keep tape archive current
- Plan for C5 reprocessing at 5.6X (means reprocessing time is about 1 year) – by reducing overall size (including oceans) the bottleneck will be Level 1 processing
- Increase size of data-pools and tie data-pools to ordering interface (so data in pool doesn’t need to be staged from tape)
- Work with land community to better understand product usefulness

- July 15, 2003  –  MODLAND Workshop  –  R. Wolfe