Documentation

Introduction

The latest release of the "Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data", HOAPS-3.2, contains global fields of precipitation and evaporation over the global ocean and all basic state variables needed for the derivation of these fluxes. Except for the NODC/RSMAS Pathfinder SST data set, all variables are derived from SSM/I passive microwave satellite data over the ice free global ocean. HOAPS-3.2 covers an extended time period from 07/1987 to 12/2008 compared to the previous version HOAPS-3. The data set now includes the entire SSM/I record, resulting in a climatology containing 21 complete years of data.
Other changes introduced in this release are an updated processing of the level-1 SSM/I brightness temperatures and a slightly different handling of the SST input data, including an optimum interpolation gap filling and diurnal cycle corrections. Furthermore, the data set is now released by the Satellite Application Facility on Climate Monitoring (CM SAF) in cooperation with the Max-Planck-Institute for Meteorology and the University of Hamburg.
The physical retrieval algorithms remain unchanged compared to HOAPS 3.0. All HOAPS products have global coverage, i.e., within ±180° longitude and ±80° latitude and are only defined over the ice-free ocean surface. The products are available as monthly averages and 6-hourly composites on a regular latitude/longitude grid with a spatial resolution of 0.5 × 0.5 degrees.

Currently available HOAPS-3.2 data products are:

HOAPS-G: Gridded monthly mean data, consisting of multi-satellite averages including all SSM/I instruments available at the same time (››see "Satellite Coverage"). The default spatial resolution of HOAPS-G is 0.5 degrees on a global grid.

HOAPS-C: This data set contains 0.5 degree globally gridded multi-satellite composite products. The temporal resolution of the composites is 6 hours. Each grid-cell contains data from only one satellite pass, there is no average from two or more satellites. Early passes are overwritten by later passes. This method provides more spatial homogeneity than averaging all available data on short time scales. The fields are stored 6-hourly, starting at 0 UTC. Timesteps in the data files are at 0 UTC (0-6 UTC overpasses), 6 UTC (06-12 UTC overpasses), 12 UTC (12-18 UTC overpasses), 18 UTC (18-24 UTC overpasses). Timesteps are stored in the "time" variable, "time_bnds" contains the start and end time of the composite. Each grid-cell contains the average of data from the satellite that passed this gridbox closest to the end of the time slots, respectively. The specific overpass time is stored in the "dtime variable".

HOAPS-S: The HOAPS-S data set contains all retrieved physical parameters in the original SSM/I scan resolution (level 2) for every individual satellite and is intended for the use in case studies or comparison experiments. HOAPS-S data is used as input to obtain the gridded HOAPS-G and HOAPS-C products. If you would like to use HOAPS-S, please send your request via Email to ().

For further information about accessing HOAPS-3.2 data at CM SAF, please refer to the ››Data Access page.

Satellite Coverage

HOAPS-3.2 is a multi satellite product consisting of all available SSM/I instruments providing utilisable data. The satellites used for the derivation of each parameter are saved within the data files (››see "File Format").
The period of record is as follows:

SSM/I instruments used
satellite idstart dateend date
F081987-07-091991-12-31
F101991-01-071996-12-31
F111992-01-011999-12-31
F131995-09-012008-12-31
F141997-06-012008-07-31
F152000-03-012006-07-31

HOAPS Version History

Several versions of the HOAPS data set have been released since 1998. Apart from version 1, previous releases are still accessible. See ››Data Access for download instructions of the current and previous versions.
Version 3.1 is available from CM SAF.

HOAPS versioning and availability
VersionYear Publisher Comment
1 1998 MPI-M/UniHH First release
2 2006 MPI-M/UniHH New retrievals, including homogenisation; Major software re-design
3 2007 MPI-M/UniHH Precipitation retrieval update; new SST data set
3.1 2009 CM SAF WVPA only, including error estimates
3.2 2012 CM SAF / MPI-M/UniHH reprocessed SSM/I input data, extended temporal coverage 1987-2008