| snippet:
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A heat wave is an extended period of excessively hot weather on consecutive days on which temperatures are well above normal, and which may be accompanied by high humidities, in which case the temperatures `feel` even higher. Within a South African context the following three definitions have been proposed for purposes of mapping: Heat waves are occurrences (per year) with Tmxd > 30 degree Celsius on 3 on more consecutive days, Extreme heat waves are either occurrences (per year) with Tmxd ≥ 35 degree Celsius on 3 or more consecutive days, i.e. a higher temperature threshold, or occurrences (per year) with Tmxd ≥ 30 degree Celsius on 5 or more consecutive days, i.e. a longer duration threshold. Heat waves are usually associated with synoptic scale anticyclonic, i.e. high pressure, circulation systems covering thousands of 2km in size and lasting for several days to weeks. In mapping heat waves over South Africa, the temperature database created by Schulze and Maharaj (2004) was used to compute frequencies of heat waves. In this temperature database daily maximum and minimum temperatures were generated for the 50 year period 1950 - 1999 at 429 700 one arc minute grid points covering the area, by using observed daily temperatures of varying durations from 973 temperature stations with quality controlled data which were infilled and extended to the common 50 year period by techniques outlined in Schulze and Maharaj (2004) and interpolated/extrapolated using regional and monthly temperature lapse rates. |
| summary:
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A heat wave is an extended period of excessively hot weather on consecutive days on which temperatures are well above normal, and which may be accompanied by high humidities, in which case the temperatures `feel` even higher. Within a South African context the following three definitions have been proposed for purposes of mapping: Heat waves are occurrences (per year) with Tmxd > 30 degree Celsius on 3 on more consecutive days, Extreme heat waves are either occurrences (per year) with Tmxd ≥ 35 degree Celsius on 3 or more consecutive days, i.e. a higher temperature threshold, or occurrences (per year) with Tmxd ≥ 30 degree Celsius on 5 or more consecutive days, i.e. a longer duration threshold. Heat waves are usually associated with synoptic scale anticyclonic, i.e. high pressure, circulation systems covering thousands of 2km in size and lasting for several days to weeks. In mapping heat waves over South Africa, the temperature database created by Schulze and Maharaj (2004) was used to compute frequencies of heat waves. In this temperature database daily maximum and minimum temperatures were generated for the 50 year period 1950 - 1999 at 429 700 one arc minute grid points covering the area, by using observed daily temperatures of varying durations from 973 temperature stations with quality controlled data which were infilled and extended to the common 50 year period by techniques outlined in Schulze and Maharaj (2004) and interpolated/extrapolated using regional and monthly temperature lapse rates. |
| extent:
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[[16,-34],[32,-22]] |
| accessInformation:
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thumbnail/thumbnail.png |
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1 |
| typeKeywords:
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["Data","Service","Map Service","ArcGIS Server"] |
| description:
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| licenseInfo:
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|
| catalogPath:
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|
| title:
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Map |
| type:
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Map Service |
| url:
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| tags:
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["heat waves"] |
| culture:
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en-US |
| name:
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heatwaves1c |
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AC8D1BE0-3076-4D98-98D6-F447266DDB70 |
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0 |
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WGS_1984_Web_Mercator_Auxiliary_Sphere |