bandkl1 (58K)

mpilogo4 (4K)
TRACE GASES (HICRU)


Clouds retrieved by HICRU

1.INTRODUCTION

The detection of cloud parameters like cloud coverage, cloud top pressure or cloud optical thickness from satellite is an important issue:

         1. for meteorology and the investigation of climate change and
         2. for the analysis of tropospheric trace gases from space relevant to environmental and climatological issues.

Although the retrieval of different cloud parameters is useful for trace gas retrievals, especially the accurate identification of completely cloud free regions is crucial due to the shielding effect, which causes an underestimation of the vertical column density of tropospheric trace gases measured by satellite, because trace gases below a cloud cannot be seen by satellite.

The Heidelberg Iterative Cloud Retrieval Utilities (HICRU) retrieve effective cloud fraction - a combination of cloud coverage and cloud albedo - using spectra of two instruments designed for trace gas retrievals from space: The Global Ozone Monitoring Experiment (GOME) on the European Remote Sensing Satellite (ERS-2) and the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) on ENVISAT. An algorithm for the retrieval of the cloud top height (MICRA) is in development.

The images below are retrieved based on HICRU results. Composite images of the earth in different wavelength ranges (PMD channel 3: 617-705 nm (red), PMD channel 4: 805 - 900 (IR, used instead of green), PMD channel 2: 450 - 525 nm (blue)) show the earth without clouds (above) and including average cloud and ice coverage from April 2004 (below).


corr_cloudfree_feb04 (143K)



feb_cloudy (194K)


2. DOCUMENTATION OF THE HICRU ALGORITHM

GOME:

M. Grzegorski, M. Wenig, U. Platt, N. Fournier, P. Stammes, and T. Wagner. The heidelberg iterative cloud retrieval utilities (hicru) and its application to gome data. Atmosph. Chem. Phys., 6, 2006. pdf
Description of the data format pdf

SCIAMACHY:
Algorithm Specification Document pdf
Product Specification Document pdf


3. HICRU DOWNLOAD AREA

Download HICRU data for GOME (version 1.1): data should be available here data can be obtained from /downloads/GOME
Download HICRU data for SCIAMACHY (version 1.0). Data should be available here; data can be obtained from: /downloads/SCIA
Releasenotes HICRU for GOME: pdf
Releasenotes HICRU for SCIAMACHY: pdf