Elucidating the Arctic low cloud biases in retrospective analysis data using airborne in situ data: A regime-based approach
Abstract
The Arctic Radiation - IceBridge Sea and Ice Experiment (ARISE), conducted during September 2014, examined Arctic low clouds with airborne remote and in situ instruments, and provides an opportunity to test the ability of retrospective analysis (or reanalysis) to simulate Arctic clouds. The Arctic System Reanalysis (ASR) produces about a quarter of the cloud water content that ARISE observed, with most of the disagreement occurring above 500 m. A multivariable analysis of cloud and environmental variables is used to help understand the reasons for discrepancies between ARISE and ASR.
ARISE collected data at one second intervals along the flight paths, which allows comparison with reanalysis output at both the grid-scale (when spatially averaged) and subgrid-scale. Grid-scale ARISE observations of cloud properties and meteorological environments are compared with those simulated by ASR. Errors is reanalysis cloud fields can be related to at least two types of causes originating at the grid-scale: the reanalysis may misrepresent the relationship between cloud properties and the meteorological environment; or the reanalysis may produce unrealistic meteorological environments. The low cloud water in ASR is related to the ASR meteorological environment being warm and slightly dry relative to ARISE, reducing relative humidity and hence environments favorable to clouds. In addition, ASR produces clouds only at grid-scale relative humidity values near 100%, whereas ARISE shows cloud formation at lower values. ARISE data also shows an environmental regime of low temperature, low specific humidity, and high relative humidity that coincides with large cloud water values. ASR does not appear to replicate this. The lack of cloud water in ASR appears to be connected with these discrepancies. The ASR results show a second environmental regime of high temperature, high relative humidity, and high specific humidity that coincide with large cloud water values. ARISE never sampled those environmental conditions, so it is not possible to determine with ARISE data if this regime produces large cloud water in reality. This suggests that model data may be useful in designing future field campaigns by identifying meteorological regimes that must be sampled in order to fairly compare aircraft data with the models.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC13H1251D
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSES;
- 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 4207 Arctic and Antarctic oceanography;
- OCEANOGRAPHY: GENERAL