The sporadic radiant and distribution of meteors in the atmosphere as observed by VHF radar at Arctic, Antarctic and equatorial latitudes

Abstract. Results are presented of a study of the temporal and spatial variability in meteor count rate observations from three VHF meteor radars. These radar are located in the Arctic (at Esrange, 68° N), in the Antarctic (at Rothera, 68° S) and near the Equator (on Ascension Island, 8° S). It is found that for all three locations there is a strong diurnal cycle in observed hourly meteor counts and the time of maxima and minima in these counts depends on the month of the year. In addition, at high latitude there is a strong annual cycle in observed monthly-mean meteor counts, whereas for the radar at low latitude there is a semi-annual cycle. At high latitude there is also an annual cycle in the mean height at which meteors are observed. However, no such annual cycle is found in observed meteor count rates from the low latitude radar. The meteor count data from all the radars are combined to investigate the sporadic radiant distribution (i.e. the distribution of direction of arrival on the celestial sphere of sporadic meteors). This combined radiant distribution shows that there are six main source regions for meteors. The latitudinal and temporal dependence in observed meteor count rates appears to result from a combination of the sporadic radiant distribution, annual fluctuations in atmospheric density, the sensitivity of the radar to meteors from different source directions and the temporal and spatial variability in meteor fluxes.

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Temporal and spatial variability in Atlantic Water in the Arctic from observations

10.5194/egusphere-egu21-1157 ◽

2021 ◽

Author(s):

Alice Richards ◽

Helen Johnson ◽

Camille Lique

Keyword(s):

Spatial Variability ◽

Arctic Basin ◽

Water Layer ◽

Atlantic Water ◽

The Arctic ◽

Potential Influence ◽

Climatological Data ◽

Arctic Regions ◽

Temporal And Spatial Variability ◽

Temporal And Spatial

<p>Observational data from across the Arctic are used to investigate temporal and spatial variability in Atlantic Water throughout the Arctic basin from the 1980s to the present day, with a focus on Atlantic Water heat and its potential influence on the upper water column. MIMOC climatological data are also used in the analysis. The inferred mechanisms behind Atlantic Water spread in the Arctic &#8211; both vertically and laterally into sub-basin interiors &#8211; are discussed, along with the local and remote influences on the Atlantic Water layer in different Arctic regions. The usefulness of the Atlantic Water core in tracking changes in the Atlantic Water layer is also assessed.&#160;</p>

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Regional Variability and Trends of Temperature Inversions in Greenland

Journal of Climate ◽

10.1175/jcli-d-19-0962.1 ◽

2020 ◽

Vol 33 (21) ◽

pp. 9391-9407

Author(s):

Sonika Shahi ◽

Jakob Abermann ◽

Georg Heinrich ◽

Rainer Prinz ◽

Wolfgang Schöner

Keyword(s):

Spatial Variability ◽

Arctic Climate ◽

The Arctic ◽

Seasonal Patterns ◽

Regional Variability ◽

The Past ◽

Temporal And Spatial Variability ◽

Inversion Strength ◽

Temporal And Spatial ◽

Temperature Inversions

AbstractStrong and thick temperature inversions are key components of the Arctic climate system and it is important to study and better understand them. The present study quantifies the temporal and spatial variability of surface-based inversions (SBIs) and elevated inversions (EIs) over Greenland, as derived from the ERA-Interim (ERA-I) dataset for the period 1979–2017. The seasonal and multiannual variability of inversion strength, thickness, and frequency are examined. Our results clearly show regional as well as seasonal patterns of both SBIs and EIs. SBIs are more frequent and stronger than EIs, and the spatial variability of inversions is larger during winter and smaller during summer. Furthermore, during summer, there has been a trend toward stronger (0.3 K decade−1), thicker (12 m decade−1), and more frequent (3% decade−1) SBIs in the southern part of Greenland, especially in the past two decades. Evidently, the strengthening of the anticyclone over Greenland causes a reduction of cloud cover, which manifests in an increase in SBI strength and thickness, particularly in the southern part of Greenland.

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