Understanding Orographic Effects on Surface Observations at Macquarie Island

Zhan, Wang; Belušić, Danijel; Huang, Yi; Siems, Steven T.; Manton, M. J.

doi:10.1175/jamc-d-15-0305.1

Cited by 8 publications

(8 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the control (Ctrl) simulation, the configuration is based on the optimal setting in previous WRF simulations over Tasmania and the SO as in Huang, Siems, Manton, and Thompson (2014) and Z. Wang, Belusic, et al. (2016). This configuration included the Rapid Radiative Transfer Model for GCMs (RRTMG) shortwave and longwave radiation scheme (Iacono et al., 2008; Mlawer et al., 1997), the Noah land surface model (Chen & Dudhia, 2001), Yonsei University (YSU; Hong et al., 2006) planetary boundary layer scheme and the Simplified Arakawa‐Schubert (SAS) cumulus scheme (Pan & Wu, 1995), which is used only on the two coarsest domains (27 and 9 km).…”

Section: Methodsmentioning

confidence: 99%

Shallow Convection and Precipitation Over the Southern Ocean: A Case Study During the CAPRICORN 2016 Field Campaign

et al. 2021

View full text Add to dashboard Cite

Marine boundary layer clouds and precipitation observed in a sustained period of open mesoscale cellular convection (MCC) over the Southern Ocean (SO) are investigated using Clouds, Aerosols, Precipitation, Radiation, and atmospherIc Composition Over the southeRn oceaN 2016 observations, Himawari‐8 products, and numerical simulations. The shallow convection was characterized by the presence of supercooled liquid water and mixed‐phase clouds in the sub‐freezing temperature range, consistent with earlier in‐situ observations where ice multiplication is found to be active in producing large quantities of ice in open MCC clouds. Ice‐phase precipitation was observed to melt below cloud base with evidence of cold pools produced in a decoupled boundary layer. Convection‐permitting simulations using the weather research and forecasting model were able to reproduce many of the surface meteorological features and their evolution. However, the evolution of the boundary layer height and the degree of decoupling were poorly simulated, along with the absence of cold pools. The observed cloud morphology and microphysical characteristics were also not well reproduced in the control simulation with the Thompson microphysics scheme, where too much supercooled water was simulated in a too homogenous cloud field. Sensitivity experiments with modified microphysical parameters led to a higher production of glaciated clouds and precipitation. Sensitivity experiments with different boundary layer schemes and vertical resolution, however, showed a smaller impact. A bias of ∼4°C in the initial boundary conditions of the sea surface temperature is discussed. This study highlights the challenge of representing the complex physical processes that underpin the cloud, precipitation, and boundary layer characteristics of the open MCC over the SO.

show abstract

Section: Methodsmentioning

confidence: 99%

Shallow Convection and Precipitation Over the Southern Ocean: A Case Study During the CAPRICORN 2016 Field Campaign

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The launch site of soundings is at an elevation of 8 m above sea level and has direct exposure to the prevailing westerly winds (Wang et al, ). Wang et al () used high‐resolution simulations to demonstrate that the orographic influence on the station measurements is not paramount under the most common synoptic conditions. As such, the station record is appropriate for long‐term climate studies in this area.…”

Section: Methodsmentioning

confidence: 99%

Characteristics of the Marine Atmospheric Boundary Layer Over the Southern Ocean in Response to the Synoptic Forcing

et al. 2018

View full text Add to dashboard Cite

The characteristics of the marine atmospheric boundary layer (MABL) in relation to synoptic meteorology over the Southern Ocean are examined using upper-air soundings and surface precipitation at Macquarie Island (54.62 ∘ S, 158.85 ∘ E), with a primary focus on the post-cold-frontal environment where large cloud and radiative biases are presented in a multitude of climate models. Thermodynamic profiles from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalyses are compared with the observations to evaluate their representation of the MABL characteristics. Observations confirm that boundary layer clouds over the Southern Ocean commonly reside within a shallow MABL under the influence of frequent midlatitude cyclones and fronts. The evaluation of MABL height shows that, for both observations and reanalysis, the inversion is higher northward of the low center and under postcold front conditions. Under cold frontal passages, however, the main inversions are not well represented by ERA-Interim, which is featured by an underestimate of the MABL height by 22%. Significant differences are found in the moisture profiles within the MABL between the observations and ERA-Interim soundings within the context of cold frontal passages. The moisture in the ERA-Interim is found to be too confined to the surface layer, which is consistent with the shallower MABL represented by the ERA-Interim. Analysis of the surface precipitation shows that ERA-Interim overestimates the amount of precipitation over Macquarie Island in the vicinity of cyclone cores but underestimates the precipitation not immediately associated with cold fronts, leading to an overall underestimate of the annual precipitation by 11%.

show abstract

Section: Discussionmentioning

confidence: 99%

“…On Heard Island, at a similar latitude to Macquarie Island (53°S), oxygen isotope ratios from snow indicate that orographic processes dominate precipitation (Allison & Keage 1986). On Macquarie Island, high-resolution climate models suggest orographic forcing results in higher precipitation on the lee side than the windward side of the island under both drizzle and frontal conditions (Wang et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Differences in cloud cover between the two slopes may also be influential, with potentially greater cloud cover on the western slope. However, Wang et al (2016) modelled higher rainfall on the downwind (eastern) side of Macquarie Island, suggesting more cloud cover on the eastern slope. Tweedie (2000) found strong correlations between meteorological data from an altitudinal transect on the eastern slope of Macquarie Island and the data from the BoM station.…”

Section: Lapse Ratesmentioning

confidence: 98%

See 1 more Smart Citation

Air temperature lapse rates and cloud cover in a hyper-oceanic climate

Fitzgerald

Kirkpatrick

2020

Antarctic Science

View full text Add to dashboard Cite

Air temperature lapse rates vary geographically and temporally. Sub-Antarctic Macquarie Island provides an opportunity to compare lapse rates between windward and leeward slopes in a hyper-oceanic climate. Lapse rates were steep by global standards, typically close to the dry adiabatic lapse rate despite the near-constant high humidity. Limited diurnal and seasonal variation occurs in lapse rates on Macquarie Island. High variability of lapse rates on the eastern (lee) slope in summer months and in the midday hours appears to be driven by solar radiation. No diurnal or seasonal pattern was evident on the western slope. Development of orographic cloud is expected to modify lapse rates, given the theoretical shift between dry and saturated adiabatic lapse rates that occurs with condensation of water vapour. Cloud cover was frequent, with higher elevations being under cloud 50% of the time, with no seasonal variation. However, cloud base level did not explain variation in lapse rates. Low cloud is likely to be of ecological importance because it influences fog precipitation, solar radiation and evapotranspiration. Year-round dominance of westerly airflows and limited seasonal variation in air temperature and humidity explain the limited seasonal variation in cloud cover and lapse rates on Macquarie Island.

show abstract

Understanding Orographic Effects on Surface Observations at Macquarie Island

Cited by 8 publications

References 68 publications

Shallow Convection and Precipitation Over the Southern Ocean: A Case Study During the CAPRICORN 2016 Field Campaign

Shallow Convection and Precipitation Over the Southern Ocean: A Case Study During the CAPRICORN 2016 Field Campaign

Characteristics of the Marine Atmospheric Boundary Layer Over the Southern Ocean in Response to the Synoptic Forcing

Air temperature lapse rates and cloud cover in a hyper-oceanic climate

Contact Info

Product

Resources

About