A new climate data record of upper-tropospheric humidity from microwave observations

Theresa Lang,Stefan A Buehler,Imke Hans,Martin Burgdorf,Viju O John

doi:10.1038/s41597-020-0560-1

Abstract

We generated a new Climate Data Record (CDR) of Upper Tropospheric Humidity (UTH) based on observations from the microwave sounders Special Sensor Microwave Temperature - 2 (SSMT-2), Advanced Microwave Sounding Unit - B (AMSU-B) and Microwave Humidity Sounder (MHS). The data record covers the time period between 1994 and 2017 and provides monthly mean 183.31 ± 1 GHz brightness temperatures and derived UTH along with estimates of measurement uncertainty on a 1° × 1° latitude-longitude grid covering the tropical region (30° S to 30° N). For the UTH retrieval we introduce a new definition of UTH. Forgoing the use of the humidity Jacobian as a weighting function, it is easier to apply than the traditional definition without compromising the retrieval accuracy. The same definition can be used to derive UTH from infrared observations, allowing for a more synergistic use of infrared and microwave UTH in the future. The new UTH CDR is validated against an existing UTH data record.

Highlights

Background & SummaryIn the framework of the Horizon 2020 project Fidelity and Uncertainty in Climate Data Records from Earth Observations (FIDUCEO) a new Level 3 Climate Data Record (CDR) of Upper Tropospheric Humidity (UTH) has been generated based on observations from the microwave humidity sounders Special Sensor Microwave Temperature - 2 (SSMT-2), the Advanced Microwave Sounding Unit - B (AMSU-B) and the Microwave Humidity Sounder (MHS)
We show that this definition can be used to retrieve UTH from measurements by both microwave sounders (SSMT-2, AMSU-B and MHS) and the High-resolution Infrared Radiation Sounder 2 (HIRS/2) without loss in retrieval accuracy compared to the traditional approach
Our CDR differs from the CM-SAF CDR in the underlying Fundamental Climate Data Record (FCDR) and several aspects of processing, including the UTH scaling parameters and the pixel selection

Summary

Introduction

Background & SummaryIn the framework of the Horizon 2020 project Fidelity and Uncertainty in Climate Data Records from Earth Observations (FIDUCEO) a new Level 3 Climate Data Record (CDR) of Upper Tropospheric Humidity (UTH) has been generated based on observations from the microwave humidity sounders Special Sensor Microwave Temperature - 2 (SSMT-2), the Advanced Microwave Sounding Unit - B (AMSU-B) and the Microwave Humidity Sounder (MHS). Similar to the underlying Microwave FCDR, the FIDUCEO UTH CDR covers the time period from 1994 to 2017 and consists of 11 partly overlapping satellite missions carrying either SSMT-2, AMSU-B or MHS.

Results

Conclusion