Climate Sense

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bserving

, P

redicting

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OnditiOns

Crop Moisture Index (CMI) and measured soil moisture

Time series of CMI, and measured soil water content (using Sutron’s 5600-

0089 Soil Moisture/Temperature Sensor) at 10 cm depth at CIMH. The

correlation between CMI and measured soil moisture was 0.74

Source: Shontelle Stoute

also includes some islands forming an archipelago, as well as

coastal South and Central America. The only indices/indicators

of drought that would merit use on the regional scale would

therefore have to be related to rainfall – as water flows, water

levels and soil moisture would not apply. SPI maps are currently

produced, with the intention of adding deciles to the monitoring.

The first regional maps were produced on 7 April 2009, which

provided the precipitation status as of the end of March on four

timescales, reflecting the reality that different types of drought

manifest themselves after different times lengths of exposure (for

example, agricultural drought is expressed much sooner than

hydrological drought).

As many land stations as possible are being sought

for the production of these maps. Over the sea and in

areas where land data is not currently provided, NCEP/

NCAR

reanalysis data is used. Currently 14 coun-

tries, particularly in the Eastern Caribbean, contribute

monthly data to this endeavour. With time more coun-

tries in the archipelago are anticipated to contribute

data, restricting the use of reanalysis data to over the

sea. It is also important that there is some investigation

into the relationship between the reanalysis data and

actual station data. This task will also be performed.

Using the reanalysis and land station data, SPI maps for

1, 3, 6 and 12 month intervals are being produced in

under seven days after the end of each month.

National monitoring

National monitoring will occur in the three

CARIWIN partner countries of Jamaica, Guyana and

Grenada. Another collaboration between CIMH and

The Institute of Earth Sciences, University of Applied

Sciences of Southern Switzerland would allow for

two other islands (Barbados and Trinidad) to be

included in the monitoring. It has to be determined

which indices and indicators will be used to monitor

drought in these countries. Unlike Caribbean Basin

monitoring, indices and indicators utilizing data

other than precipitation can also be engaged. Possible

data sets that can be made available are currently

being investigated; for example soil moisture, soil

available water capacity, evapotranspiration, vegeta-

tion indicators, streamflow and reservoir levels. The

usefulness of PDSI and CMI has already been inves-

tigated in Barbados in a preliminary way. In Jamaica,

investigations are taking place into the use of the Soil

Mean PDSI maps for Barbados

Mean PDSI map for April (left), and PDSI for April 1998 (right), an El Niño year, which was also drier than normal in Barbados.

Note the more negative (drier) values in April 1998

Source: Shontelle Stoute