World Meteorological Day 2015: climate knowledge for climate action

Each year on 23rd March, National Weather Services around the globe celebrate World Meteorological Day.  This marks the establishment of the World Meteorological Organization (WMO) on this day in 1950. WMO is the global co-ordinating agency for meteorological and hydrological activities, formed because weather simply doesn’t limit itself to national boundaries.  World Meteorological Day is an occasion to commemorate the work that national meteorological and hydrological agencies undertake 24 hours a day, 365 days per year – work that produces weather forecasts and warnings to help keep our communities safe.  The recent passage of Cyclone Pam near Vanuatu and past New Zealand are timely reminders of these efforts.

Collecting weather data …

The routine collection of weather data is one part of MetService’s international responsibilities under the Global Observing System (GOS). Worldwide, weather agencies take observations of pressure, temperature, wind and rainfall around the clock. Data come from ships, buoys, weather balloons and land-based weather stations, and are transmitted via the WMO Global Telecommunication System (GTS). This is a world-wide stream of data used as input into global weather forecast models. The better we can “start off” (initialise) the global computer models as to the current state of the atmosphere, the better the future state will be predicted – and the more accurate the weather forecast will be for your place.

In New Zealand alone, hundreds of weather stations from Stewart Island to Cape Reinga tell us how wet, warm, or windy it is every hour, as well as measuring pressure and humidity. Weather balloons are released twice daily at several locations around the country. Recently, MetService has collaborated with the U.K. MetOffice to enable kiwis to share their local weather data on the ‘Your Weather’ section of via the ‘Weather Observation Website’ (WOW) system.

… for climate knowledge, too

This year, the theme for World Meteorological Day is ‘climate knowledge for climate action.’ This is a timely focus. Globally, 2014 was the warmest year on record and fourteen of the fifteen hottest years have occurred this century. But how do we know this? That’s right – we looked back at historical weather data.

Think of climate as the sum of all the weather. If you smooth out all of the edges looking at things longer-term (from a climate perspective), it is possible to more clearly understand what is going on. Climate patterns such as the El Nino Southern Oscillation and the Southern Annular Mode are more ‘visible’ this way, including their effect on New Zealand wind, rain and temperature.

Reanalysis data’ is a very important tool for scientists trying to unlock the physical mechanisms behind our climate – trying to understand why we had a wet month, a warm year, or an active Cyclone season. Reanalysis datasets input historical weather data from around the globe into the same climate model, and extend it back over time. The relationships found in the past can help us forecast the future – this is the basis of seasonal climate predictions. For example, El Nino springs tend to be very cold in New Zealand, due to frequent southerly airstreams over the country. When we know an El Nino spring is coming, and in the absence of other major climate factors, the odds are that we’re in for an unusually cold spring.

Global temperature data (departure from normal), based on three different reanalysis datasets.    The data all tell the same story – a rapid increase in global average temperature since the 1960s.
Global temperature data (departure from normal), based on three different reanalysis datasets. The data all tell the same story – a rapid increase in global average temperature since the 1960s.

There are many examples of when historical weather data helps put things into climatic context. For example, people have asked, “is Cyclone Pam the worst Tropical Cyclone to hit the South Pacific?”.  The answer relies on good data being available.  Since Cyclone Zoe (2002) and Cyclone Pam (2015) both reached an estimated minimum central pressure of 890hPa, it looks like a tie.  And although satellites provide a relatively short record, their data can also help answer questions about Tropical Cyclone frequency. No increase in Tropical Cyclone numbers has been observed in the South Pacific over the last few decades since reliable satellite data have been available.

Number and intensity of cyclones in the South Pacific 1969-2014

Peter Lennox, MetService Chief Executive, is New Zealand's Permanent Representative with the United Nations World Meteorology Organization.
Peter Lennox, MetService Chief Executive, is New Zealand’s Permanent Representative with the United Nations World Meteorology Organization.

MetService also contributes to international climate activities directly.  MetService CEO Peter Lennox is New Zealand’s Permanent Representative to the World Meteorological Organization.  In addition, MetService has supported several major climate initiatives in New Zealand recently.

MetService and NIWA have collaborated to achieve official Global Climate Observing System (GCOS) Reference Upper Air Network status for the NIWA atmospheric research station at Lauder in Central Otago.

This is only the fourth upper-air site to be certified in the world, and the first in the southern hemisphere. Well-calibrated atmospheric observations are crucial to documenting climate and climate change. The standard network of upper-air meteorological observations, and also weather satellites, provide good coverage – but high-quality observations are needed against which these standard observations can be calibrated. The pairing of Lauder observations and MetService’s Invercargill radiosonde data will achieve the necessary calibration.

NASA's super pressure balloonAnd NASA’s super pressure balloon is awaiting lift off at Wanaka, being delayed due to adverse winds associated with Cyclone Pam. Designed to drift eastwards at an altitude of 110,000 feet (‘near space’), NASA expects the super pressure balloon to circumnavigate across South America and then South Africa, on its potentially record-breaking flight. Depending on the stratospheric wind speeds, the balloon should circumnavigate the earth every one to three weeks. The flight goal is to exceed the current super-balloon flight record of 54 days, and to maintain a constant float altitude. If the balloon test is validated, this opens the door for relatively inexpensive atmospheric research. You can track the balloon here.

Activity for World Meteorological Day 2014: Make Your Own Observations

On 23 March each year, national weather services around the world celebrate World Meteorological Day to commemorate the establishment of the World Meteorological Organization on this day in 1950.

In 2014, the theme for World Meteorological Day is ‘Weather and Climate: Engaging Youth’. We thought this was an ideal opportunity to provide a few do-it-yourself weather projects for the keen weather kids out there.

Why do we need weather observations?

Before weather forecasters can tell us what the weather is going to be doing tomorrow, they need to know what it is doing right now.

Every hour hundreds of weather stations across New Zealand, from Cape Reinga to Stewart Island, send in reports of how the weather is where they are. As well as telling us how windy it is, how warm it is and how much rain has fallen, the weather stations can also tell us where it is raining or snowing, how much cloud there is, and the pressure of the air.

These weather reports are really important to weather forecasters who use them along with information from radars and satellites to find out what the weather is doing across the country. These observations are also shared around the world to help build a global picture of the current conditions.

Not all of us have an official weather station in our back garden or can afford to build our very own weather radar – but that doesn’t mean we can’t take our own measurements using things we find around the house.

The weather station in Wellington’s Botanical gardens
This is the weather station in Wellington’s Botanical gardens. A is the MetService headquarters; B is a receiver on the roof which lets us collect information from satellites as they pass overhead; C is an anemometer which is used to measure wind speeds; D is a device that measures sunshine; E is the Stevenson Screen used to keep our thermometers in the shade; and F is a collection of different rain gauges.


Although we cannot see wind we can see the effects that it has on other things like trees , flags and smoke. The Beaufort scale compares wind speeds with the effects that they have over land and sea. For example, if we notice that only the leaves of a tree are moving in the wind we would describe it as a “light breeze”, but if we noticed that the whole tree was shaking we would call it a “gale”.

You can find out more about the Beaufort scale and download your own copy here:


Measuring how much rain has fallen needs a rain gauge. We can make a simple rain gauge by using a straight sided bottle, some stones and a ruler:

How to make a rain gauge - step 1How to make a rain gauge_2How to make a rain gauge - step 3

The rain gauges that MetService use are called tipping bucket rain gauges. As rain falls into the gauge it fills a little bucket at the base of a tube, then once the bucket is full it tips over and empties out the rain it has collected. A counter keeps track of how many times the bucket tips over and as we know how much rain can fit in the bucket we can work out how much rain has fallen. Because the rain gauge empties itself it never overflows.


The temperature of the air can very a lot over a short distance. To measure the temperature of the air, meteorologists [scientists who study the atmosphere] use thermometers. You might already have a thermometer in your house which will let you measure the temperature.

The thermometers that are used for the official observations are kept in special boxes called Stevenson screens. These white boxes keep the thermometers shaded while the gaps on either side of the box let the air move freely over the thermometer.

Because we share this information around the world, it is important that we are measuring the temperature in the same way as the meteorologists everywhere else in the world. This is also why we have a special calibration lab, to ensure all our measuring equipment performs exactly the same way as the equipment used by other national weather services.


There are lots of different types of weather, so as well as recording things like if it is raining or snowing, observations such as if you can hear a thunderstorm or it is foggy are useful things to note down. Why not keep track of the different types of weather you can observe over a week? You can write them down or draw a picture to show the weather. These are the symbols we use on our website to show the different types of weather – can you name them all?

Weather icons used on


As well as different types of weather there are different types of cloud. Some are high in the atmosphere and made of ice others are low down close to the ground made of large water droplets giving the underside of the cloud a menacing grey colour.  We have some great clouds in New Zealand, and this poster gives some great examples of the ones you might see:

While you are looking at the different clouds outside, try to figure out how much of the sky is covered in cloud. Is it completely covered? Perhaps it is only half the sky that has cloud covering it or perhaps you can’t see any clouds at all.

Weather observers measure the cloud cover in Oktas, or eights. A sky that is completely covered in cloud is called overcast and has 8 oktas of cloud.

How much of the sky do you think is covered in these pictures? Imagine squashing the cloud together and counting the grey coloured squares.

Measuring clouds in oktas

How much cloud do you think there is in the picture of the weather station at the top of the page?

Weather codes

As you can imagine, sending all the weather information back to the weather office and sharing it takes a lot of computer power. To make it easier, all the information is transmitted as a series of codes.

Here’s an example of an observation that gets send from a weather station:
93110 17698 /2311 10206 20137 40238 57006 60004 70300=

At first it looks like a random string of numbers, but each group gives information about different aspects of the weather. The first block gives the station number for Auckland so we know where the observation comes from. The other blocks give information about wind speed, temperature rainfall and weather. From this observation we know that there is 11 knots of wind coming from the southwest; the temperature is 20.6C; the surface pressure is 1023.8hPa; there hasn’t been any rainfall in 24 hours; and there is some cloud developing.

You can find more about decoding the observations here:

We hope you enjoy doing some or all of these weather projects!

Tropical cyclone season 2014

For the South West Pacific, tropical cyclone season is said to begin in November and continue right through to April the following year. However, the weather doesn’t follow a rigid calendar and tropical cyclones have been known to form as early as October and as late as the month of June.

Around the globe, the monitoring and forecasting of tropical systems is looked after by a Regional Specialized Meteorological Centre (RSMC) or a Tropical Cyclone Warning Centre (TCWC), depending on the location of the cyclone. TCWC Wellington, based at MetService, looks after the area that extends from 160E to 120W and between 25S and 40S. Although it is very rare for any tropical cyclones to form in TCWC Wellington’s area of responsibility, fully-fledged tropical cyclones do arrive from the Brisbane or Nadi areas and they may retain their cyclone status until 30S. Sometimes an ex-tropical cyclone will approach New Zealand and Severe Weather Watches and Warnings need to be issued. Even if land areas are not affected, warnings are issued for vessels over the open sea.

RSMC locations and areas of responsibility.
RSMC locations and areas of responsibility.

Our neighbouring TCWCs are Brisbane, run by the Australian Bureau of Meteorology, and RSMC Nadi, run by the Fiji Meteorological Service.

Cyclone categories

Cyclones are classified by a Category (Cat) system, numbering Cat 1 to Cat 5 depending on the strength of the winds near the centre of the system:

Cyclone Category

Average Wind Speed (km/h) Typical Strongest gusts(km/h) Central pressure(hPa)


Gale 63-88 Less than 125 Greater than 985


Storm 89-117 125-164 985-970


Hurricane 118-159 165-224 970-955


Major Hurricane 160-199 225-279 955-930


Major Hurricane Greater than 200 Greater than 279 Less than 930

Forecast for this season

Every year MetService works alongside NIWA as well as national meteorological services from other Pacific nations to produce a Tropical Cyclone Outlook.

Although this Outlook cannot say exactly when or where tropical cyclones will form, it is used as a guide to the expected activity over the South West Pacific. The outlook for 2013-2014 is for a near-average number of tropical cyclones (around nine) to form in the area from the Coral Sea to French Polynesia. Of these, four could potentially reach category 3 or 4. Under the forecast conditions for this season, a category 5 cyclone is unlikely but cannot be discounted. As with all forecasts, the best advice to stay up-to-date with the latest information.

The Australian Bureau of Meteorology (BOM) also produces forecasts for the areas to the north and west of Australia. You can find their latest forecast here.

How does this compare to normal?

On average there are nine tropical cyclones in a season but the actual number can vary greatly. The most active season in the SW Pacific since 1969 was the 1997-98 season when 17 tropical cyclones were recorded:

Number and intensity of Cyclones in the South Pacific
Number and intensity of Cyclones in the South Pacific

World Met Day 2011

23rd March is World Meteorological Day.

Each year meteorologists around the world celebrate a chosen theme together to commemorate the anniversary of the founding of the World Meteorological Organization (WMO) on this day in 1950.

The theme this year is “Climate for You”.

[Click on the diagram to link to the WMO ‘Climate for You’ web site – where available information includes a brochure (2.7MB) and poster (0.4MB).]

WMO held an important Climate conference at Beijing in November 2005 — the WMO Technical Conference on Climate as a Resource — to consider how climate can be used as a resource, and how best to make climate data available to benefit society by improving economic decision-making.  These data are important for they shape the availability of natural and renewable energy resources.  A knowledge of rain and temperature trends is required to optimise agricultural performance, water management and food security.

The WMO Conference on Living with Climate Variability and Change: Understanding the uncertainties and managing the risks (held in Espoo, Finland in July 2006) underscored that while climate is indeed a critical resource, we are also especially vulnerable to its variability and change.  Some actions need be taken urgently to manage the risks of climate variability and change impacts.  Others should be increasingly implemented to harvest the benefits to be derived from climate information and services, by helping socio-economic sectors maximise their efficiency and productivity.

In March 2007, WMO organised in Madrid the International Conference on Secure and Sustainable Living: Social and Economic Benefits of Weather, Climate and Water Services, which provided an outstanding opportunity for a wide exchange of views, expectations and knowledge across various societal sectors to optimise the decision-making process, and formed the Madrid Action Plan.

Moreover, 2007 was the year when the WMO co-sponsored IPCC, released its fourth Assessment Report and received the prestigious Nobel Peace Prize, as well as when the fifteenth World Meteorological Congress agreed to convene with partners at a World Climate Conference-3, or WCC-3, in the spirit of the previous two historic World Climate Conferences which WMO had organised in 1979 and 1990.

Not long before the WCC-3 began, the WMO Executive Council decided at its 61st session in June 2009 that the theme of the World Meteorological Day for 2011, commemorating the coming into force of the WMO Convention on 23 March 1950, would be “Climate for You”.

At WCC-3, a High Level Taskforce was mandated to prepare a report which will be among the key issues to be considered by WMO Members during the sixteenth World Meteorological Congress, to be held at Geneva in May 2011.  This report includes a proposal for establishing a Global Framework for Climate Services, or GFCS.  The New Zealand delegation to Congress will be led by Dr. Neil Gordon from MetService, who is the Permanent Representative of New Zealand with WMO.

Dr. Neil Gordon from MetService, the Permanent Representative of NZ with WMO.

As WMO has recently reported, 2010 ranked together with 1998 and 2005 as the warmest year on record, which only confirms the observed long-term warming trend highlighted by the IPCC report.  All of the ten warmest years on record were experienced since 1998.  Additionally, over the ten years elapsed since 2001, global temperatures averaged almost half a degree above the 1961-1990 mean, the highest ever recorded for any 10-year period since the beginning of instrumental climate observations.

WMO activities in the area of climate are focused on human safety and well-being and the realisation of economic benefits for all.   This is in line with the spirit of the WMO Convention which came into force on 23 March, sixty one years ago, as well as the patrimony of the former International Meteorological Organization IMO established by the First International Meteorological Congress in Vienna, Sept 1873.

Please join with the meteorological community around the world in a round of applause and a toast to celebrating World Meteorological Day 2011.


The above text is based on a special message from Michel Jarraud, Secretary-General of WMO,  to mark World Meteorological Day 2011.

Michel Jarraud, Secretary-General of WMO


Information about WMO activities related to climate is available at: .

The WMO online youth corner, created recently, also includes a section on climate relevant to the theme of World Meteorological Day 2011:


School Weather Assignments

This is the time of the year that many school children have been assigned to write reports on all sorts of topics.  Weather and Climate are very popular assignments as they deal with developing an understanding of our environment and its extremes.

Learning can be fun.  MetService helps students with a small and slowly growing Learning Centre that has useful articles on topics such as how to read weather maps, and provides downloadable posters.

As well as this blog page, we also have an enquiry centre for questions about our forecasts.

NIWA’s Climate Information and Common Questions pages are a useful resource. Climate maps are available on their ClimateExplorer.  For past weather data enquiries use the National Climate Database.  The data are free. You just need to subscribe, then go for it.  There is help available on the site.

The World Meteorological Organization (WMO) has a new online educational segment with weather, climate and water science for youth. This “Youth Corner” gives access to basic meteorological and hydrological science. Text is written in an easy to understand style and articles are accompanied by games, stories, videos, and experiments.

And, WMO is also on Facebook.

So, all the best for researching your school assignment about weather and climate. :)

WMO turns Sixty

23rd March is World Meteorological Day.

On this day each year meteorologists around the world celebrate a chosen theme together to commemorate the anniversary of the founding of the World Meteorological Organization (WMO) in 1950.

The theme this year is “Sixty Years Service for Your Safety and Well-Being”

Historic beginnings and a NZ connection:

Back in the mid 1800s severe storms caused an increase in shipwrecks in the Atlantic.  The weather was a problem and people needed to be warned about it.  An international meeting was convened in Brussels in 1853, instigated by Lt. Matthew F. Maury of the US Navy.  Subsequently, the British Government commissioned a former New Zealand Governor, Robert FitzRoy, as first ever “Meteorological Statist” to gather records on the weather and its behaviour.

Robert FitzRoy. as Second Governor for New Zealand , 1843-1845.

FitzRoy did more than gather records.  He started a network of observations and produced weather maps, and published his book on how to forecast the weather by watching the trends on a barometer: The Weather Book: a Manual of Practical Meteorology. (London: Longman, Green, Longman, Roberts, & Green.)  There are still many wall barometers that carry quick forecasts written around the dial – something which FitzRoy documented back in 1863.

Another conference was held in Vienna in September 1873 attended by twenty governments and called the First International Meteorological Congress.   An ad-hoc Permanent Committee was formed, presided over by C.H.D. Buys Ballot (Netherlands), and they formed The International Meteorological Organization (IMO) which was to be the basis for international collaboration for many decades.

WMO’s founding documents were signed on 23rd March 1950.  WMO became a specialized agency of the United Nations (UN) in 1951.   In 1953, the UN ratified WMO to replace the IMO.

Advances in Sixty Years

As WMO turns sixty, this is a good opportunity to reflect back on how the study of weather and climate has evolved over the past six decades.

The science of weather forecasting follows the four main elements of all science: 1) gathering data, 2) analysing these data for patterns and trends, and to gain physical insights into processes, 3) constructing mathematical models of the known physics, and implementing computer programs that extrapolate the patterns and trends into the future, and then 4) researching the results and reporting expectations to the public and various users in a manner best suited to help in decision making.

The first step is to gather data. Since meteorology does not recognize political boundaries, war is no impediment to cooperation amongst members of the WMO, and the planet’s observational network has extended to cover the entire globe.  The Global Observing System now includes about 10,000 land stations; 1,000 upper air stations; more than 1,000 ships; 1,200 drifting buoys; 200 moored buoys; 3,000 ARGO profiling floats; and 3,000 commercial aircraft.  This is supplemented by six geostationary satellites, five polar orbiting satellite,  five operational environmental satellites and about another 50 research satellites.  These facilities are all owned and operated by WMO members, each undertaking certain responsibilities in an agreed global scheme so that all can benefit.

Global Observing System, click to enlarge. NMS=National Meteorological Service

WMO’s role has evolved over the past 60 years, along with advances in technology with satellites and computing.  WMO has set up six Regional Associations around the world and several programmes with the aim of securing and enabling the same reliable weather information everywhere and for everyone:  It is now an exceptional scientific and technological institution with a primary focus on the safety and well being of all.  WMO-sponsored research is flourishing and a full summary of this is available in the official publication for World Met Day and a special message from the WMO Secretary-General, Michel Jarraud.  We have a small number of hard copies of the official World Meteorological Day (WMD) information pack (click for pdf) which we can post out with our compliments.  Email your postal details to bob dot mcdavitt at metservice dot com.

There are now 189 countries and territories in WMO, following the recent incorporation of the Democratic Republic of Timor-Leste.   New Zealand’s Permanent Representative to WMO is MetService’s General Manager of Science Research and Development,   Dr. Neil Gordon.

In the past sixty years MetService has also made great strides in weather forecasting for the safety and well-being of New Zealanders.  By extending our rain radar network, and providing our forecasters with state-of-the-art training and tools we have, in the past year, been able to start a Severe Thunderstorm Warning Service that covers most New Zealanders.  MetService is also working with neighbouring countries in the South Pacific in a regional initiative to supply web based tools and training to help in weather warning services, thereby enhancing the safety of people in the South Pacific.

Looking back at its performance over the past sixty years, WMO has been fortunate that its founders chose to set it up on a solid base laid out by the IMO, allowing for the free and unrestricted international exchange of weather data and products.  In some ways WMO is like a big club, and yet in other ways it is a unique example of how nations can work together, united by the challenges thrown at us by weather and climate.

Please join with the meteorological community around the world in a round of applause in celebrating World Meteorological Day 2010.