Sun Times v7.0 - CLIMATE MENU

1) Climate catalogue / Search

The climate information in Sun Times is gathered from a number of publicly available sources, but has not been subject to a great deal of accuracy verification. When no climate information is found for a particular town or city, data from a nearby weather station is displayed instead.

The top half the screen (title "Climate for 16 October 2007") lists historical climate information for places included in Sun Times (ie monthly Min, Max, and Mean Temperature averages and total monthly Precipitation). The set of places shown in the list will match those shown on the main Sun Times map, ie the result of applying the main population threshold and continent filters at the top of the screen:

Choosing a country (or <All>) on the right-hand side of the screen below will dsiplay climate information for a particular country only (you may also need to click the Start/Refresh button). Choosing to tick "Show all places" will result in all places being displayed for the selected country regardless of which set of locations are shown on the main map. Here, the climate for places in Argentina is shown, and I have clicked on the Pop column header to sort biggest cities first.

The average minimum, maximum and mean temperatures shown above are adjusted for the actual date shown (16th Oct in this case). In the case of average maximum temperature, the adjustment made is such that the value displayed when the date is the first of the month is almost halfway between the average maximum for the current and preceding month. The average maximum displayed is therefore an estimate of the likely maximum temperature for the specific day in question. This is quite a large correction in continental climates such as inland Siberia in spring when there is a very steep increase in average maximum temperatures from month to month. No such interpolation is applied to precipitation. The Now column shows the expected temperature at the time of day shown at the top of the screen, ie the current time within Sun Times. Some simple assumptions are made regarding normal diurnal temperature variation based on times of sunrise, midday and sunset; one assumption is that it's normally coldest about 1 hour after sunrise, another is that it's typically warmest a couple of hours after local solar midday.

The bottom section of the screen below (after the list and columns) allows you to search for a particular type of climate. This can be done on the left using absolute values, or on the right by searching for climates close to the climate in one particular location. For example, searching for climates, which for 9 months of the year, have an average monthly minimum and average maximum temperature within 3 degrees of London, returns the following list (I have sorted Southern Hemisphere locations to the top of the list by clicking twice on the Latitude column).

The above list shows that Rio Gallegos in Patagonia, southern parts of the Chilean Lake District and the south of New Zealand's South Island have climates similar to that of London, in terms of average monthly minimum and maximum temperatures.

Selecting the Rio Gallegos row will cause the climate graphs at the top right of the main Sun Times screen to be drawn with the minimum and maximum curves for London (thicker lines) compared to the curves for Rio Gallegos (thinner lines). Note that southern hemisphere climates are inverted in months on this graph when compared to northern hemisphere climates, ie September temperatures in London are plotted against March temperatures in Rio Gallegos.

The above graph shows that London actually enjoys a warmer climate than Rio Gallegos (by 2-3 degrees centigrade) for summer through to winter. Typically, the climates most similar will be found in places near the location being searched on.

2) Mean temp (this month)

Clicking on this menu option will display temperatures graphically on the main map (or a custom map). When this option is first selected the continent filter is changed to "GSN Climate". This is a set of locations chosen by the World Meteorological Organisation and member state weather agencies to be used in land-based climate monitoring. The locations are intended to be spread out over the land surface of the world, generally located far from large cities, with reliable historical records. Other population threshold and continent filters can be chosen instead of this set of GSN Climate stations. December mean temperatures are shown below showing it to be very cold in much of Russia and Canada (purple), mild temperatures in the Southern United States, Mediterranean Europe and Southern Japan (green), and very hot in much of Central Australia (red).

These mean temperatures based on long term historical averages can be compared to real observations made since 2000. To do this (if not already done in Options - Startup options), click on the Load Observations button in the Climate Viewer form top left, and then tick the Show differences (from year 2000 onwards) tick box, (and ensure that the Sun Times time is after 2000). The map below is for Apr 2007, and shows much warmer than average mean temperatures across Siberia, a colder than average eastern and mid United States, and a warmer Central Europe. It's worth noting that because of the steeply increasing temperatures in Canada and Siberia in April, extreme differences of more than 5 degrees above normal may simply indicate an onset of Spring maybe only 2 weeks early. The total number of stations with data is shown as 669, and the mean difference is 1.1 degrees C over historical norms. Stations are missing normally because of an absence of climate reports, and in a handful of stations because I have not been able to find matching historical records.

Moving the mouse over stations on the main map causes the actual temperature and precipitation differences to be displayed. In the below example, the weather station which has historical records is a small town in Okinawa (Japan) called Ogigaura, which is co-incident with the climate monitoring station identified as CHICHIJIMA. Over the course of April 2007, the monthly average mean and maximum temperatures were very close to historical averages, but the minimum was 0.7 degrees C colder. Precipitation for the month was 59mm, ie 76mm less than the historical average for April of 135mm.

3) Precipitation (this month)

Clicking on "Precipitation (this month)" from the Climate Menu, choosing a custom map to cover South Asia, and choosing a population threshold of >100,000 in the population threshold drop-down list can be used to show the normal pattern of monsoonal rains in South Asia. The sequence can be animated using the traffic lights at the top right of the screen - I changed the animation speed on the slider to the left of the traffic lights to be 1 month (you could animate on a shorter timescale, eg maybe 1 week or less, if you have a fast computer).