The last day

As he did every day, Stef, our tactical guy, took me apart on Tuesday evening for the weather briefing for the next day. I told him clouds were going to form between Port-Augusta and Adelaide. I didn't know exactly how far this cloud zone would reach, but around Port-Augusta the cloud zone should be less important than around Adelaide.
That way, the batteries of the Punch One could charge a lot (still 26 minutes of control stop to do), while the other teams would probably be under the couds.
I also told him that the clouds would gradually disappear in the morning.

When we woke up on Wednesday morning, this was the satellite image that I first saw.

 

We didn't know exactly where the other teams stayed during the night, but most probably, most of them were under the clouds. So maybe, there would still be a change of catching up on a team.

The Eagle was send out to find the next team and to follow it and give information to the Brains about their speed. After no more than 20 km, we found Team Tokai. They had their camp just at the edge of the cloud zone and they were able to receive solar enegry. Oh no!

We followed them and we noticed that they were getting closer to Team Michigan. Team Michigan, having spent the night and morning under the clouds. A little bit further, the Tokai solar car overtook the Michigan car, which was doing only 80 km/h. Could Punch One maybe still catch up with the Americans?

Meanwhile the sun broke trough the clouds(as predicted) and everybody was receiving solar energy.

Michigan was still driving rather slowly, but the distance to the finish had become to small to be able to catch up with them. And that is how the Punch One remained on the 5th position.

Congratulations team, for this great effort and thanks for letting me be part of this adventure!

Perfect weather for a strategic plan, but...

Today should have been MY day as Punch Powertrain Solar Team's weather man. It would have been! But other than dynamic or convective forces decided otherwise.

Already at the end of last week, I noticed that a weak perturbation, associated with a low over the Great Australian Bight, would approach from the south up to the Alice Springs region on this Tuesday. The exact timing and location were still uncertain, but it was already clear that this would be the kind of weather one could build a cunning plan upon.
As this day was getting closer, more and more team mates came to me with questions about the weather. How cloudy was it going to be? And what about that wind?

Not only would this perturbation produce cloudiness, but the winds before and after this cloud band would be totally different.

It was exactly what we observed. 

A north-westerly wind was blowing north of the cloud band, while south of it, the wind suddenly shifted to the south-west. Driving southwards on the Stuart Highway (yellow line on this satellite image) a north-westerly wind is a tailwind from the right. A south-westerly wind means a headwind from the right. So indeed, a perfect situation for a strategic plan.

But, as I mentioned, other forces decided otherwise. Due to a penalty, our team had to wait for an hour at the second control stop. And our tactical plans just went up in smoke...

Hot in the Australian savannah

On day 2 of the World Solar Challenge, the sky was clear for most of the day. In the afternoon, some higher clouds were appearing over the southern horizon, but nothing to worry about.

The weather station on our vehicle measured 36 °C. And the moderate wind was mainly easterly to north-easterly.

Being well informed about this weather, the Punch Powertrain Solar Team could do very well. 

They overtook the Japanese Tokai Team and became fourth in the race. Team Michigan, Team Twente en Team Nuon not being to far ahead. But bad luck  knocked them down to place 5 again...

Tonight, I will talk for a  moment to the weather gods. Maybe they can arrange something for us tomorrow ;-)

Fly like an eagle

During the World Solar Challenge, Punch One, the Belgian solar car, will be assisted by a convoy of no less than 6 cars plus one truck. I will take place in the first car, which is called the Eagle.

The Eagle will always stay approximately 100 km ahead of the solar car and continuously be in contact with the Brains. The Brains is the name of the car following Punch One. Aboard of this car are the people in charge of the strategy of the team.

The Eagle, with weather station at the front

The Eagle will always stay so far ahead to explore the area where the solar car will be going to. Visual observations and measurements done by instruments on board of the Eagle will give us the opportunity to fine-tune the strategy during the race. Would the forecast for the day seem to be not okay - which is very unlickely ;-) - these observations will allow us to update it.

Arrived at Darwin

This morning, around 05 o'clock local time, I finally arrived in Darwin.
The team is busy with testing the car, finetuning, testing again and later on some more testing.

Nice weather here in the north of Australia with temperatures about 33 degrees at the moment. We already had a quick outlook for what's to be expected next week, but off course, I'm not going to give this information away.

Crossing the equator

Tomorrow in the early afternoon, I will say goodbye to my wife and my two little boys and I will begin my journey to Australia. Wednesday, close to midnight (local time) my plain will cross the Equator and in the early morning, I will arrive in Darwin.

When sailors cross the Equator, they often celebrate this occasion with some kind of an initation rite for Neptune, the ancient Roman god of the sea. Sailors who have already crossed the Equator are nicknamed Shellbacks, often referred to as Sons of Neptune; those who have not are nicknamed Pollywogs.
As far as I know, no such thing exists for travellers crossing the equator by airplane. So, I will have to invent a ceremony by myself in honour of the weather gods. After all, They are the one's who have mapped out this adventure for me ;-)

For a European weather forecaster as myself, it's so obvious that air is always flowing counter-clockwise around a low and clockwise around a high-pressure area. After crossing the Equator however, this general rule will no longer be true, because at the Southern Hemisphere, everything is turning the other way around.

This can be explained with the Coriolis effect. That's the apparent deflection of moving objects when the motion is described relative to a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right. Although recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspard-Gustave Coriolis.

Coriolis did experiments on friction and hydraulics and he worked on the effects of kinetic energy on the principle of kinetic energy in the relative motion in machines. Being a fanatic pool player, he began to wonder how the balls would move on a rotating table. And that off course, was just the start of the mathematical expression of the Coriolis effect.

I found a nice Youtube-video, that well explains the Coriolis effect. Enjoy it!

Belgium x 12

The route of the upcoming World Solar Challenge is about 3000 km, from Darwin to Adelaide, through places called Katherine, Alice Springs, Coober Pedy,...

Thanks to thetruesize.com, we can easily compare the size of countries. Just to have a general idea how long the distance from Darwin to Adelaide really is, I tried to find out how many times Belgium would fit in Australia along this route.
Here's the result:

Belgium, it may me a small country, but it has great potential! ;-)

Some statistics about Australian weather

We already know that most of Australia has an arid climate. But what does that mean? What are the exact numbers?
Luckily, the Australian Bureau of Meteorology provides climatological statistics on its website.
I've looked up the mean afternoon (15:00) temperatures and relative humidities in October for the most important points along the route of the World Solar Challenge and I've plotted them on this map. The numbers are rounded.

Just to have an indistinct idea what this must feel like: in the warmest month in Belgium (July), the mean T_max at Ukkel is 23.0 °C. The lowest mean relative humidity is observed in April and measures 72,5 %!

About the Australian desert(s)

Looking at Australia in my World Atlas, I discover the Tanami Desert, Great Sandy Desert, Little Sandy Desert, Gibson Desert, Simpson Desert, Sturt Stony Desert and the Great Victoria Desert. I hope I'm not forgetting one. Apparently, most of Australia is dry and hostile for fauna and flora. But why? What makes this part of the world so dry? Why do we find so many deserts here?

It has all to do with the global circulation of air around our planet. And this circulation is driven by the differential heating by the sun.We all know that the Earth is receiving solar energy much more efficiently around the equator than around the North Pole and the South Pole. Therefore, the air around the equator is warmer and less dense than the air at the Poles, and it begins to rise. At the North Pole and the South Pole, the air sinks.
In the Tropopause, the temperature is nearly constant, and in the Stratosphere, it is getting warmer with height. This temperature inversion acts as some kind of a ceiling, through which the air around the equator can no longer rise. It has to move aside, partly to the north and partly to the south.
At the poles, the sinking air meets the surface of the Earth and there also, it has to move aside. It flows back to the equator, over the surface of the planet. That way, a circulation has started up between the equator and the poles.

But, this model is far to simple. In reality, the air also sinks around 30 ° latitude, in the northern hemisphere as well as in the southern hemisphere. When this sinking air hits the surface, it will move partly to the equator (so closing a circulation known as the "Hadley cell") and partly to the pole. Roughly between 50 and 60 degrees latitude, this poleward moving air meets the air that was moving from the pole in the direction of the equator. In that zone, the air will rise again. This zone, where these two different air masses meet, is known as the Polar Front. Depressions and perturbations are born here.

Back to the Hadley cell. Under the sinking air around 30 ° latitude, we find the subtropical highs. The most important subtropical high for Europe is the Azores' high, which brings dry and mainly sunny weather, when it is moving over the continent. Because of the sinking air in a subtropical high, clouds and precipitation have great difficulty to form. Only when the high is temporarily moving away somewhat, some rain can be observed, but mostly, the amounts of rain are very limited.

No wonder that almost all deserts of the planet are situated at or close to 30 ° latitude.

 

Australia is roughly situated between 10 and 40 degrees south. A big part of it is mostly covered by a subtropical high. Therefore there are so many deserts in Australia.

Darwin's second sea-breeze

The passage of a sea-breeze front is a regular occurence in Darwin, Northern Territory, Australia. But, on some days, something like a “second sea-breeze” is observed during the evening, a phenomenon that has puzzled local forecasters for ages. In 2008, a study conducted by Gerald Thomsen and Roger Smith at the Meteorological Institute of the University of Munich, Germany, brought the solution.

Some sea-breeze theory

A sea-breeze is a local circulation, induced by differences in surface temperature between the land and the sea. While the sea surface temperature doesn't change much throughout a sunny day, the surface temperature of the land often increases very rapidly. As a result the air above the land also warms up and becomes less dense than the air above the sea. (1) This difference in density then produces a difference in air pressure at a certain altitude (2), with a higher pressure above land and a lower pressure above the sea. A pressure difference is at the origin of an air flow (= wind) from the higher pressure to the lower pressure. (3)

As a result of this wind at a certain altitude, more air particles are being advected towards the sea and at the surface, the pressure rises, while at land, the surface pressure decreases, simply because the air is escaping aloft. (4)

Again, this difference in air pressure at the surface produces a wind, blowing from the sea to the land. (5) This is the sea-breeze.

When the sea-breeze hits the coast, the temperature may drop by several degrees and typically the wind shifts and increases. At the same time, the humidity increases, as a more moist air mass is advected by the sea-breeze.

At Darwin though

Such a circulation typically starts up around noon or in the early afternoon, but at Darwin, a similar sudden jump of the wind, increasing wind speed and increasing humidity often have been observed in the evening.

The researchers from the University of Munich found at that this second sea-breeze isn't a sea-breeze at all.

From the early morning on sunny days on, a band of dry inland air, lying over the “Top End”, is being advected northwestwards towards the Tiwi Islands by the prevailing easterly to southeasterly winds. This dry airmass subsequently is moving southwestwards to Darwin with the sea-breeze. When it passes in the late evening, it is finally replaced by moist maritime air. At this moment, a jump in the wind direction and an increasing wind speed is mostly observed.

But, although it looks like a sea-breeze, it's certainly not the same thermally driven phenomenon.

El Niño brings dryer weather to Australia

Some Climatology

Usually, the northern and eastern regions of Australia have a wet spring and summer. While October marks the beginning of the wet season, the rain doesn't just start falling on 1 October. Rather, it begins gradually with the occasional afternoon shower, and then 'builds up' to more frequent rains as the season progresses.

Although the risk is substantially higher during the first months of the year (January-April), the area might be affected by tropical cyclones from about November. There are on average 7.7 days per season when a cyclone exists in the Northern Region.

El Niño

Australia's weather is influenced by many climate drivers. El Niño and La Niña have perhaps the strongest influence on year-to-year climate variability in Australia. They are a part of a natural cycle known as the El Niño–Southern Oscillation (ENSO) and are associated with a sustained period (many months) of warming (El Niño) or cooling (La Niña) in the central and eastern tropical Pacific.

The El Niño cycle is driven by changes in the winds around the equator. North-East trade winds and South-East trade winds meet in the InterTropical Convergence Zone (ITCZ). These winds pile up warm surface water in the west Pacific, so that the sea surface is about 1/2 meter higher at Indonesia than at Ecuador. The sea surface temperature is about 8 degrees C higher in the west, with cool temperatures off South America, due to an upwelling of cold water from deeper levels. Rainfall is found in rising air over the warmest water, and the east Pacific is relatively dry.

During El Niño, the trade winds relax in the central and western Pacific leading to a depression of the thermocline in the eastern Pacific, and an elevation of the thermocline in the west. Rainfall follows the warm water eastward, with associated flooding in Peru and drought in Indonesia and Australia. On average, there are fewer tropical cyclones in the Australian region during El Niño years. This is particularly true around Queensland, where cyclones are half as likely to cross the coast during El Niño years compared to neutral years. This means a decreased likelihood of major damage and flooding related to strong winds, high seas and heavy rains associated with tropical cyclones.

During La Niña, the trade winds are stronger than usual. Warm ocean water is pushed harder to the west and the cold upwelling water along the South American coast is penetrating further towards the central part of the Pacific. Indonesia and Australia now get excessive rainfall, while Ecuador and Peru have to deal with extremely dry weather;

Current situation and outlook

There's currently a strong El Niño and it tends to persist.
The American Climate Predictions Center states that "There is a greater than 90% chance that El Niño will continue trough Northern Hemisphere winter 2015-16, and around an 85% chance it will last into early spring 2016."

I guess this means that we can hope for nice weather at the start of the World Solar Race!

About me

My name is Tom Elegeert. I've been working as an operational meteorologist for about 15 years now. At first, I worked at the Belgian coast, where I made weather forecasts for the shipping industry, activities in the Belgian harbours and coastal protection.
In August 2009, I moved to the head quarters of the Royal Meteorological Institute of Belgium in Ukkel (Brussels).
Since I previously have been involved in supporting adventures or expeditions with specific and detailed weather forecasts (such as Dixie Dansercoer's "In the wake of the Belgica" sail expedition to the Antarctic Peninsula and the 2013 World Solar Challenge in Australia), I was now again asked by the Belgian Solar Team to provide them with weather information during this year's World Solar Challenge.

The World Solar Challenge actually is the World Championship for solar cars. The competing teams will start in Darwin on October 18 and will try to arrive in Adelaide as soon as possible.

I will join the Belgian Solar Team during this race. They will use my input to determine the strategy for each day, in order to use the available solar energy in the best possible way.
Before and during this extraordinary adventure, I will share this experience - seen trough the eyes of a meteorologist - with the readers of this blog.