Climate Exchange

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a better control of water storage levels, minimizing

overflow and pumping costs.

To enable a better informed decision-making process on

water supply, HKOhas collaboratedwithWSD in exploring

the feasibility of forecasting yield collected in local reser-

voirs. First, the statistical relationship between monthly

yield collected at a number of reservoirs and contempora-

neous rainfall recorded at stations nearby was investigated

and regression models were built to forecast yield, using

station rainfall as a predictor. HKOprovided station-specific

rainfall forecasts, generated from statistical downscaling of

climate model outputs provided by the Global Producing

Centres for Long-Range Forecasts. Results in the past two

years suggested that this two-step forecast method (rain-

fall forecast followed by yield forecast) generally gave a

good indication of the yield anomaly in the coming month.

However, the gain in terms of absolute error when compared

to the climatological yield forecast was just marginal and the

fluctuation of forecast performance could be large at times.

This might be due to the relatively short period of rainfall

records in some stations and to error amplification through

the two-step approach. To further enhance the forecast

performance, HKO has directly downscaled global model

outputs to forecast the total yield to WSD since mid-2011

(one-step approach). Verification of the two-step approach

and one-step approach shows that, in the last year or so, the

former could achieve 12 per cent error reduction compared

to the climatological forecast while the latter could push

the figure up to 21 per cent. This investigation has demon-

strated the benefits of climate prediction for managingwater

resources in Hong Kong.

Flower cultivation

In Hong Kong, flower cultivation has gained importance in

recent years, especially for festival flowers for the celebration

of the Lunar New Year in January/February. Unseasonably

warm or cold weather before the Lunar New Year will affect

the flowering time of popular flowers such as peach blossom,

lily and gladiolus, which have a growing period of up to 100

days. Traditionally, flower farmers have relied on climatol-

ogy and folk wisdom tomake decisions regarding the timing

of planting and the need for adaptation measures to protect

their flowers or to control growth rate to ensure the flowers

will blossom just before the Lunar New Year. To better serve

the flower farming community and other agricultural sectors,

HKO is working closely with the Agriculture, Fisheries and

ConservationDepartment (AFCD) to improve climate infor-

mation and prediction services for the local farmers. Some of

the plans on hand include:

• Organizing seminars/workshops to facilitate

communications with local flower farmers and

promote the use of climate information and

predictions in various farming activities

• Providing seasonal and experimental monthly

forecast with timely updates for local flower farmers

• Establishing a new climate station in AFCD’s

experimental farm, to study the effect of weather

and climate on plant cultivation for long-term

enhancement of climate services to the farming sector.

oped to predict the abundance of Aedes mosquitoes in Hong Kong

based on climate data.

With climate information regularly provided

by HKO, DFEH makes reference to forecasts from this model in the

planning and execution of preventive and control measures against

Aedes mosquitoes.

Care of senior citizens

In the past few decades, flats in Hong Kong have become smaller due

to intense urbanization. More senior citizens are left to live on their

own after their children have grown up and moved out to start their

own family. There is a need to provide more care for the elderly in

the city. The Senior Citizen Home Safety Association (SCHSA) is a

social enterprise which operates a 24-hour emergency support and

care system for over 80,000 senior citizens. SCHSA calls up to check

on its members from time to time, and members can push a button

on a special device to request help from the association when neces-

sary. SCHSA’s workload is highly weather-sensitive, and to provide

better care for the elderly, HKO cooperates with the association on

a number of activities. Using SCHSA’s member contact data, HKO

studied the effect of hot and cold weather on the elderly.

Weather

forecasts as well as the experimental monthly climate forecasts

prepared by the Observatory are made available to SCHSA. When

cold weather is expected, SCHSA will call up and send out volun-

teers to visit its most vulnerable members to help them prepare. It

will also disseminate telephone messages recorded by HKO senior

staff to alert all members about the impending cold weather. SCHSA

also makes use of the weather and climate forecasts for planning

manpower requirements for its outreach operations.

Urban planning and building environment

The dense development of a crowded city like Hong Kong may have

significant impacts on the urban climate (such as higher average

temperatures, lower wind speed etc), resulting in uncomfortable

habitats and increases in energy consumption. To help mitigate

these negative effects and improve the quality of the living environ-

ment through integrating climatic considerations in urban planning

and design, HKO has been providing meteorological support for

the Planning Department and its consultants to establish guide-

lines to assess and regulate the impact of potential city, community

and building developments on air ventilation. Furthermore, urban

climatic maps have been drawn up by analysing and evaluating

climate data together with different geometric and urban devel-

opment data (such as land use, building density and topography)

to classify Hong Kong into different urban climatic zones, each

with recommended planning and development actions.

HKO’s

involvement includes provision of climate data (such as winds and

temperature) over the territory, and advice on the local wind climate

and the interpretation of analysis results.

Water resources

The two main sources of fresh water supply in Hong Kong are rain-

fall collected from local catchments and water imported from the

neighbouring Guangdong province of mainland China, with the

latter supplying about 70-80 per cent of local demand. Agreement

has been made between the water authority in Hong Kong (the

Water Supplies Department or WSD) and its Guangdong counter-

part to secure a reliable and flexible supply of water to meet Hong

Kong’s needs. The water supply should tie in with the seasonal or

monthly variation of yield collected at local reservoirs so as to have

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