Diurnal Cycle Climatology of Surface Layer and Boundary Layer Parameters in the Atmospheric Component of the GFDL Global Climate Model
Abstract
This study describes the performance of two developmental versions of the atmospheric component of the GFDL global climate model (GFDL AM4) in simulating the diurnal cycles of surface layer (SL) and planetary boundary layer (PBL) parameters. The main difference between the two AM4 versions is in the PBL parameterization: one uses a prescribed K-profile PBL scheme, and the other employs a TKE PBL scheme. 10 years of 3-hourly data from the two model simulations are used to calculate the diurnal cycle climatology of 2-m temperature, 10-m wind speed, and PBL height. The simulated diurnal cycles are compared with those generated from the ERA-20C reanalysis for a 10-year period*.A comparison with the reanalysis shows that both AM4 versions reproduce the general patterns of the SL and PBL parameters, but with the following systematic biases. Both versions underestimate the diurnal cycle amplitude of 2-m temperature over most low and mid-latitude lands, while they overestimate it at high latitudes. The diurnal cycle amplitude of 10-m wind speed is underestimated over most land areas, but it is overestimated over the oceans. The overall bias patterns of PBL height and its diurnal cycle are similar to those of near-surface temperature and its diurnal cycle over the land, while they are closely related to those of wind and its diurnal cycle over the ocean.To identify more specific roles of SL and PBL processes in simulating diurnal cycles, the differences among the reanalysis and the two AM4 versions are further analyzed, linking them to surface fluxes and vertical mixing characteristics in PBL. More detail will be shown in the presentation.*To consider uncertainty in using the reanalysis data as a reference, further analysis is ongoing with NASA-MERRA and NCEP-CFSR reanalysis data sets and will be included in the presentation.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A43G0310S
- Keywords:
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- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSESDE: 3337 Global climate models;
- ATMOSPHERIC PROCESSESDE: 3354 Precipitation;
- ATMOSPHERIC PROCESSESDE: 3359 Radiative processes;
- ATMOSPHERIC PROCESSES