Project work titled “ASSESSMENT OF PRECIS REGIONAL CLIMATE MODEL FOR SOME SELECTED CLIMATE PARAMETERS IN BANGLADESH” submitted by Aklima Haque, Roll No. AMETRA IN BANGLADESH" was made by me under the supervision of Dr. Figure: 2.1 Rain gauges used to measure rainfall manually 16 Figure: 2.2 Rain gauges used to measure rainfall.
GENERAL
BACKGROUND OF THE STUDY
The Hadley Center of UK has developed a regional climate model called PRECIS (Providing Regional Climates for Impacts Studies), which can be run on a PC and easily applied to any area of the globe to generate detailed climate change predictions. In addition to a comprehensive representation of the physical processes in the atmosphere and the Earth's surface, it also includes the sulfur cycle. In view of the above, it is now important to assess the performance of PRECIS for the past year of various climatic parameters normally available in the climate system of Bangladesh such as temperature, rainfall at different directional locations throughout the country.
OBJECTIVE OF THE STUDY
LITERATURE RIVIEW
GENERAL
HISTORY OF PRECIS IN BANGLADESH
REVIEW OF RELATED STUDIES
The model overestimates rainfall in dry and premonsoon periods, while it underestimates it in the monsoon period. The lookup tables proposed in this analysis can be used in the application of the projected rainfall and temperature in different sectors of the country. This excellent performance of PRECIS encourages its use for the projection of rainfall in the SAARC region.
METHODOLOGY
GENERAL
STUDY AREA
Tropical storms occurred during the pre-monsoon season (March-May) in the central parts of Bangladesh. Winter (November-February) Western Disturbances cause drought in northwestern Bangladesh and northern India. In addition, pre-monsoon disturbances (March-May) cause heavy rains and flash floods in the northeastern part of Bangladesh.
DATA COLLECTION
- BMD DATA COLLECTION
- BANGLADESH METEOROLOGICAL DEPARTMENT
- PRECIS DATA COLLECTION
- EMISSIONS SCENARIOS
- PRECIS MODEL DESCRIPTION
These are i) dry bulb thermometer ii) wet bulb thermometer iii) maximum thermometer and iv) minimum thermometer for measuring the maximum and minimum temperature of the day, to determine the daily average temperature dry bulb thermometer is used. The minimum thermometer is the measurement of the day's minimum temperature. Temperature data (maximum and minimum) have been collected for seven stations in Bangladesh for the period 1990 to 2010. The scenarios within each family follow the same picture of world evolution as shown. in figure 2. SRES four scenarios are explained here. i) The A1 – A1 scenarios are of a more integrated world.
PROCEDURE OF DATA ANALYSIS
- MONTHLY, SEASONAL AND ANNUAL DATA ANALYSIS PROCEDURE
- FUTURE MODEL DATA ANALYSIS PROCEDURE
Processing of data is done for calculation of monthly, seasonal and annual average rainfall and maximum and minimum temperature for this study. In order to determine the bias of observed data and PRECIS data, a look-up table has been prepared. From this point of view, we need to find the appropriate way to use model simulated outputs and lookup table preparation is one of the techniques to make the model generated scenarios useful in application purpose which is satisfactorily described throughout this research.
Therefore, preparation of Lookup table for rainfall and temperature is very essential, which is obtained through this project. The comparison of Lookup table for rainfall averages from 1990 to 2010 and all stations for observed and corrected model data are obtained. A regression equation is used in statistics to find out what relationship, if any, exists between a set of variables.
The gradient/slope of the line is m and c is the intercept/constant (the value of y when x = 0). Where RFprojection is the precipitation for projection, mRF is the slope for precipitation, RFmodel is the precipitation model generated for the year and 2050 values, and CRF is a constant value for precipitation. Where TXprojection is the maximum temperature to project, mTX is the slope for the maximum temperature, TXmodel is the generated maximum temperature model values for the year and 2050, and CTX is a constant value for the maximum temperature.
Where TNprojection is the minimum temperature for the projection, mTN is the slope for the minimum temperature, TNmodel is the minimum temperature model generated values for the year and 2050, and CTN is the constant value for the minimum temperature.
GENERAL
ASSESSMENT OF RAINFALL
- MONTHLY RAINFALL
- SEASONAL RAINFALL
- ANNUAL RAINFALL
- RAINFALL BIAS
- RAINFALL PATTERNS TO GENERATE FUTURE CLIMATE SCENARIOS
To obtain an overall monthly validation, a comparison of PRECIS-derived monthly precipitation and observations is shown in Figure 4.3, considering values from 7 selected regions in Bangladesh and the 1990–2010 average in mm/day. Figure 4.5.3 shows that the observed values are almost twice as large as the PRECIS model simulated values in the northeastern part (Sylhet) and southeastern part (Chittagong). It can be seen from Figures 4.3 and 4.4 that the PRECIS model significantly overestimates and underestimates the amount of precipitation in June and September in the Dhaka region (Figure 4.4) as compared to the average values of the country (Figure 4.3).
The PRECIS model slightly overestimates the rainfall in March over the whole country as shown in Figure 4.3, but the PRECIS model underestimates the rainfall in March in the Dhaka region as shown in Figure 4.4. Comparison of seasonal precipitation obtained from PRECIS and observations is shown in Figure 4.6 considering values from seven selected regions over Bangladesh and the average for the period 1990-2010 in mm/day. Comparison of annual precipitation obtained from PRECIS and observations is shown in Figure 4.8 considering values from 7 selected regions over Bangladesh in mm/day.
Monthly and seasonal variations of precipitation are shown in Figure 4.9 and Figure 4.10, respectively, taking into account the values from 7 selected regions in Bangladesh and the average for the period 1990-2010 in mm/day. It can be seen from Figures 4.9 and 4.10 that the seasonal deviations of precipitation are smaller than the monthly deviations of precipitation. Regional and annual rainfall variations are shown in Figure 4.11 and Figure 4.12, respectively, considering values from 7 selected regions in Bangladesh and years between 1990–.
Figures 4.11 to 4.12 show that the regional precipitation anomalies are larger than the annual precipitation anomalies.
ASSESSMENT OF TEMPERATURE
- MONTHLY TEMPERATURE
- SEASONAL TEMPERATURE
- ANNUAL TEMPERATURE
- TEMPERATURE BIASES
- PROJECTED TEMPERATURE TO PREDICT GLOBAL WARMING
A comparison of seasonal maximum temperature obtained from PRECIS and observations is shown in Figure 4.16, considering values from 7 selected regions in Bangladesh and the average value for the period 1990–2010 in degrees Celsius. A comparison of PRECIS-derived minimum seasonal temperature and observations is shown in Figure 4.17, considering values from 7 selected regions in Bangladesh and the 1990–2010 average in degrees Celsius. A comparison of the maximum annual temperature obtained from PRECIS and observations is shown in Figure 4.18 considering the values from 7 selected regions in Bangladesh in degrees Celsius (ºC).
Comparison of annual minimum temperature obtained from PRECIS and observations is shown in Figure 4.19 considering values from 7 selected regions over Bangladesh in degrees Celsius (ºC). Comparison of regional maximum temperature obtained from PRECIS and observations are shown in Figure 4.20 averages from 1990–2010 in degrees Celsius. The monthly and seasonal maximum temperature biases are shown in Figure 4.22 and Table 5 respectively considering values from 7 selected regions over Bangladesh and the average for the period 1990-2010 in degrees Celsius (ºC).
Monthly and seasonal deviations of the minimum temperature are shown in Figure 4.23 and Table 6, respectively, taking into account the values from 7 selected regions in Bangladesh and the average values for the period 1990-2010 in degrees Celsius (ºC). Regional and annual variations of maximum temperature are shown in Figure 4.24 and Figure 4.26, respectively, considering values from 7 selected regions in Bangladesh and years between 1990-2010 in degrees Celsius (ºC). Regional and annual deviations of minimum temperature are shown in Figure 4.25 and Figure 4.27, respectively, based on values from 7 selected regions in Bangladesh and years between 1990-2010 in degrees Celsius (ºC).
It can be seen from figures 4.24 to 4.26 that regional maximum and minimum temperature biases are higher than annual maximum and minimum temperature biases.
CONCLUSION
PRECIS projected precipitation and temperature in and 2050 indicate that in Bangladesh, precipitation and temperature will increase throughout the country in the future. The rate of increase in precipitation will vary from 1.7 to 5.8 mm/day in wet seasons and the rate of decrease in precipitation will vary from 0.2 to 0.7 mm/day in dry seasons respectively, whereas the maximum - and minimum temperature values vary by 1.7 to 2.0 degrees Celsius. This work conclusively revealed that the technique of annual forecasting of meteorological parameters like rainfall and temperature is acceptable in Bangladesh.
RECOMMENDATIONS
Last accessed on 3 October 2010 at http://www.metoffice.gov.uk/precis/. 2009), “Generation of PRECIS Scenarios for Bangladesh (Validation and Parameterization)”, Climate Change Cell, DoE, MoEF; Component 4b, CDMP, MoFDM., Dhaka. 2009), "Rainfall and Temperature Scenario for Bangladesh", The Open Journal of Atmospheric Science, pp Simulations of the Indian Summer Monsoon Using a Nested Regional Climate Model: Domain Size Experiments", Climate Dynamics, Vol. 2004), "Generation of High-Resolution climate change scenarios using PRECIS", Met Office Hadley Centre, Exeter, UK Domain scale experiment using PRECIS regional climate model for Bangladesh", 3rd International Conference on Water and Flood Management, ICWFM-2011. Studies on summer monsoon rainfall using the regional climate model PRECIS”, SAARC Meteorological Research Center (SMRC), Bangladesh. 2012), "Impact of climate change on developmental stages of winter rice in Bangladesh", International journal of environmental sciences, Research Fellow, Economic Policy Unit, Unnayan Onneshan- the Innovators.
Asia Pacific Journal of Environment and Development Adaptation to Climate Change in Bangladesh: Future Perspectives. In Climate Change Vulnerability and Adaptation for Bangladesh”, Kluwer Academic Publishers: Dordrecht Climate Change Impacts and Adaptation Assessment in Bangladesh Simulating SST, Sea Ice Extent and Ocean Heat Transport in a Version of the Coupled Center Model Hadley saw flux adjustments. 2009), "Assessing the predictability of the PRECIS regional climate model for downscaling climate change scenarios", in Proceedings of the ISPRS Archives XXXVIII-8/W3 Workshop: Impact of Climate Change on Agriculture, Ahmedabad, India, 17-18 Dec. for Altern Formulations including Lateral Boundary Data in Limited-Area Models”, Mon. 2005), "Regional climate simulations over North America: Interaction of local processes with large-scale enhanced flow", J. 2010), "Effect of grid resolution and domain size on the quality of the regional downscaling ensemble scale climate over South Asia during the Northeast Monsoon”, Mon. 2005), “Unidirectionally Overlaid Regional Climate Simulations and Domain Size”, J. 2008), “Climate Models: Assessing Strengths and Limitations” , A report from the US Climate Change Science Program and the Subcommittee on Global Change Research; .Department of Energy, Office of Biological and Environmental Research: Washington, DC, USA Climate Change Vulnerability of Crop Agriculture.
Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change”, Cambridge University Press: Cambridge, UK High Resolution Climate Change Scenarios for India for the 21st Century”, Curr.
