Met Society Newsletter

 For a printable pdf of this newsletter: http://metsoc.rsnz.org/Newsletter/reportsjune2009.pdf

Those members who have chosen the postal option will receive a hard copy of this in their “June” newsletter

AUCKLAND

Richard McKenzie of NIWA, a world authority on UV from Lauder, gave a talk on 7 April at NIWA Auckland, open to Met Soc members, on “How to balance your benefits and risks of solar UV exposure"

It is well known that overexposure to UV radiation causes sunburn, which can lead to skin cancer. New Zealand has one of the highest rates of skin cancer in the world. However, there is also a risk from underexposure to UV, since it leads to the production of beneficial vitamin D in our bodies. Many New Zealanders have below-optimum vitamin D for health, and it is not generally available from diet. I investigate relationships between erythemally-weighted UV radiation that leads to sunburn (which can lead to skin cancer) and vitamin D-weighted radiation that is responsible for synthesis of vitamin D (which protects against many conditions including bowel cancer). An algorithm is developed using spectral measurements undertaken at Lauder Central Otago, and is used to relate vitamin D production to the widely-used UV Index. This is then used to calculate the behavioural patterns (exposure times and attire) required to enable the public to optimize their exposure to UV radiation. In the New Zealand summer at noon, there should be sufficient UV to photosynthesize optimal vitamin D in ~1 minute for full body exposure, whereas skin damage occurs after ~15 minutes. Further, while it should be possible to photosynthesise vitamin D in the winter, the amount of skin that must be exposed is larger than from the hands and face alone. This raises the question of whether the action spectrum for vitamin D production is correct, since previous studies have reported that production of vitamin D is not possible in the winter at mid-latitudes. However, evidence suggests that some supplementation of vitamin D is desirable, at least in the south island winter. I describe how a new HRC-funded research project involving NIWA addresses these questions by tracking personal UV exposure and relating this to vitamin D status.
The presentation is based on a paper that will soon appear in photochem photobiol website at www.photobiology.org .....

For a pdf of this PowerPoint check out http://tinyurl.com/n6kxo8 (use newsletter password)

CLIMATE AND HEALTH
Guest speaker: Dr. Glenn McGregor gave a talk at NIWA, Auckland on 19 June entitled "Heat waves - Causes, consequences, and responses".

Principal climate and health research questions of interest to Glenn are (a) what is the role of climate as a stressor on health? (b) are climate based predictions of health outcomes possible for a range of timescales? (c) to what extent might climate variability and change affect health and existing or predicted stresses on health? (d) what are the uncertainties associated with climate change related health projections? (e) what is the nature of the interaction between extreme weather and climate anomalies and the urban socio-economic landscape in terms of health outcomes? (f) does society possess the capacity to adapt to climate variability and change through modifications to health infrastructure, management and policy by adopting specific adaptive measures?
Glenn has been involved with numerous climate and health research projects, such as seasonal climate forecasting and health in the UK, investigating London's urban heat island, experimental heat health watch warning systems for 5 European cities, as well as the development and testing of summer season health forecasting models.

WELLINGTON

At our Special General Meeting held in Wellington on 18 March, there were two brief seminars.

 1.  Mike Revell, our President, spoke on "The Meteorology of the recent Australian bushfires" Mike was in Melbourne on what is now known as "Black Saturday" and in this talk he  described what it feels like to be in 46.8 degrees with 100 km an hour winds.

For a pdf of this PowerPoint check out http://tinyurl.com/nxz78p (use newsletter password)

 

2.  James Renwick presented a PowerPoint compiled by Joe Kidston and Sam Dean (our Secretary), on “Climate Change and the SAM/HLM” .  This talk investigated trends in the Southern Annular Mode, and the possibilities of a poleward shift of the jetstream  

For a pdf of this PowerPoint check out http://tinyurl.com/n25tqs (use newsletter password)

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CHRISTCHURCH (Met soc Vice President Mikhail Titov)

The Christchurch branch of the Meteorological Society of New Zealand recently held several interesting lectures and presentations at the Department of Geography (the University of Canterbury).  Most of the scientific activity was at the beginning of the first semester and before winter student’s exams.

 

Prof. Nigel Tapper (Head of Department of the Environmental Science, Monash University, Australia) as visiting Erskine Fellow of the department made two presentations:

1) “The climate change – urban climate nexus: some reflections from Melbourne, Australia” (10 of March 2009)”. Prof. Tapper showed very serious problems with water in Melbourne and outlined a possibility of the Australian government to use stormy waters. This possibility is now under development at his department;

2) “Aeolian Dust in the Environment: Towards New Understandings of Some Critical Impacts” (31 of March 2009).

 Dr. Steve George (University of Canterbury) made a presentation “Ozone and Temperature over Antarctica: Co-variability and Change” (17 of March 2009) showing the results of numerical modelling over Antarctic with application of MM5 and RAMS.

Visiting Erskine Fellow Dr. Jim Hansom (University of Glasgow, Scotland) presented very interesting research: “Copying with sea level change?” and showed (using GIS) change of big cities (like London) street topography regarding to Global Warming and subsequent potential remarkable increase of sea level.

Prof. Glenn McGregor (School of Geography, Geology & Environmental Science (SGGES), University of Auckland) made a presentation “Heat Waves: Causes, Consequences and Responses” (15 of June 2009).  Originally this presentation was proposed on 18 of May but was postponed on one month. Prof. Glenn McGregor has displayed the most hazardous consequences associated with heat waves in different areas (health, engineering, hydrology-biology).   For more about this talk see the Auckland report.

 

 

 

 

Following NIWA’s recent dismissal of Jim Salinger, our President wrote a letter of support to Jim in recognition of the huge contribution that Jim has made over the past 20 years to the Met Society, including being our Secretary (a sometimes thankless role!) for most of ten years, President for two, general committee member for many more, including now, and a professional conference planner in the past and this year, helping to organise our upcoming conference wit the NZMSS Conference to be held in Auckland in September.

We consider Jim to be a valuable committee member, colleague, and scientist.  We hope that his enthusiasm and dedication to science will not be dampened by recent events and that he will continue to be an active committee member and a significant positive influence on our Society.

 

SEASONAL ANALYSIS, By Rupert Wood

Introduction

The following tables use a minor modification of an idea from the “USA Today” weather almanacs to define the temperature seasons for a particular location. Given a suitable quantity (say at least 30 years’ worth) of daily maximum and minimum temperature observations, calculate the means from these two values, and  then compute the average of those means for each day of the year. The highest and lowest of these 366 values define the annual temperature range (but see the comment below on a slight modification of this definition). Calculate the 1/4 and 3/4 marks on the scale. All values above the 3/4 line are “summer” ones, all those below the 1/4 line are “winter” ones, and the remainder are assigned to spring and autumn. For example, if the top value is 20.0 and the bottom one 10.0, the two boundaries are at 12.5 and 17.5.

 

The NZ data used

32 locations were selected. Raw data was downloaded from NIWA’s CliFlo database. Wherever possible, at least 30 years of data were used, consistent with avoiding hybrid sites if feasible, with the data as current as possible. In the case of Alexandra, several site changes made it necessary to use data prior to 1983. It is unlikely that patterns there have changed much since then. When examining the daily means, it was found that these have significant daily fluctuations even on 50+-year timescales, so to avoid outlier effects the top and bottom values used were the averages of the warmest and coolest 7-day periods, instead of those for single days.

 

Table 1 lists the stations, the length and completeness of the raw data, and the dates of the warmest and coolest 14-day periods of the year. These dates cannot be taken too literally in light of the fact that there are sometimes some close contenders for the extreme 14-day values, but the consistency of the early July dates for the coldest fortnight is striking. Even in the case of Kaitaia, July is the coldest month, though the July-August difference is small. There is considerably more variation in the dates of the warmest fortnight, reflecting the fact that January and February are equally warm for the country as a whole, with northernmost places warmest in February and a large portion of the south warmest in January.

 

Season data

 

Table 2 shows the start and duration of each season. The table is ordered by average seasonal latency (defined later – smallest values at the top), to show up the contrasts better. The length of a season is a measure of the amount of clustering in that part of the temperature spectrum, with summer slightly longer than winter on average, but with quite a large range over the sites for both (44 days for summer, 26 days for winter). For summer and winter lengths, there is quite a strong association with the overall latency – entries high in the table generally have longer summer periods and shorter winter ones, and conversely near the bottom. If one compares summer start with summer length, there is a very strong association – earlier starts correlate very highly with longer durations, so there is no correspondingly earlier finish.

 

 

Table 1: Station list