The National Meteorological Services Agency Satellite Data reception and processing unit First phase by Yitaktu Tesfatsion

Transcription

1 The National Meteorological Services Agency Satellite Data reception and processing unit First phase by Yitaktu Tesfatsion In Ethiopia the rain guage network is not evenly distributed over the country. Establishing dense network is not economically viable. Some of the stations are equipped with radios and thus report on regular basis. It takes months to collect data from the other stations. As a result their utility for operational purposes such as drought monitoring, pest control, flood forecasting, etc., is very limited. Therefore, this problem can be alleviated through the application of satellite data. The fact that satellite derived data is continues in space and could be obtained regularly has made it very useful for early warning purposes. The National Meteorological Agency (NMA) of Ethiopia has been using data from meteorological satellites for over two decades

2 Continued Till 1990, the information was limited to hard copy printouts; as a result, the applications were limited to routine weather forecasting. However, in 1990 and 1991 NMA obtained, in cooperation with the government of the United Kingdom, hardware and software support for the reception and processing of data from the METEOSAT and NOAA series of meteorological satellites the Primary Data Users Station (PDUS) in 1990 this PDUS system includes automatic rainfall estimation module, which is used to estimate dekadal rainfall Apart from weather forecasting the digital data is used for estimating ten-day total rainfall by applying TMSAT methodology developed at the University of Reading, UK (Milford and Dugdale, 1989). Estimates are being validated using data collected from raingauge network Results found are in good agreement with the observed data. However, the network density of conventional stations does not adequately reflect the various climatic zones of the country

3 Continued We employ a methodology developed by the TAMSAT (Tropical Application of Meteorology using Satellite and other data) group at the University of Reading, UK. The TAMSAT methodology, (Milford & Dugdale 1989) are based on the assumption that in tropical areas most of the rain comes from convective clouds. It also assumes simple linear relationship between rainfall and Cold Cloud Duration (CCD); CCD being the duration of a cloud, with top temperature below a predetermined threshold, over a given area The relation between CCD and rainfall (RR) is given as RR = a * CCD + b if CCD > 0 RR = 0 if CCD = 0

4 Continued We were also received and process data from the NOAA satelite on regular basis. The visisble (VV) and near infrared (NIR) channels have are suitable for monitoring green vegetation. The two channels are combined for better results. The most popular combination is the Normalized Difference Vegetation Index (NDVI) which is given as NDVI=(NIR-VV)/(NIR+VV) The two major outputs are satellite rainfall estimate from the half-hourly METEOSAT data and vegetation and also fire mentoring during dry periods from the NOAA satellites the NDVI map is also one of the inputs of our bulletin. We produce NDVI and Rainfall estimation maps every ten days for our bulletin. The NDVI is used as a general indicator of vegetation condition and could serve as a good supplement to field assessments. Apart from using the raw data for routine weather forecasting and assessments, the digital data received is processed into different products.

5 Continued The Satellite estimated rainfall had been essential supplement to the sparse surface rain gauge network. Over some parts of the country METEOSAT data is the only source of information on rainfall. The country faces recurrent droughts and flash floods, so that the satellite data are used in drought monitoring and water resource management activities The applications include famine early warning, flood monitoring, forest fire detection, water resources and droughts assessment, rangeland monitoring and desert locust monitoring. These satellite-based products had been disseminated to various users including government authorities and NGO s

6 Continued The remote-sensed data is used for different socio-economic sector like Agriculture, Water recourse, Constrictions, Research, Health and the like. Sample of the bulletin was shown below

7 Continued The remote-sensed data is used for different socio-economic sector like Agriculture, Water recourse, Constrictions, Research, Health and the like. Sample of the bulletin was shown below

8 Rainfall Assessment from Satellite Data 3 rd Dekad of September 2000 Rainfall Distribution:- During this dekad the rainfall distribution covered most parts of the country. Gambella, Benishangul Gumuz, Tigray, some parts Amhara, Oromia, SNNPRS, Afar and northern tip of Somali region have received rainfall ranging from 60 to 120mm of rainfall. Some parts of Amhara, southern parts of Afar few areas of Oromia, SNNPRS and Somali regions have received rainfall ranging from 7 to 30mm. Southern parts of Somali and Oromia regions were dry. Comparison with the previous dekad:-during this dekad the rainfall distribution shows slightly increase observed over Benishangul Gumuz, western parts of Tigray, Amhara, Oromia, Gambella, most parts of Afar and northern Somali regions. A decrease is observed over some parts of eastern and central Oromia, southern parts of SNNPRS and Somali regions. Comparison with Ground Observation:- An over estimation is observed over Benishangul Gumuz, most parts of Gambella, western parts of Tigray and Amhara region. An Under estimation is observed over some parts of Amhara eastern Oromia, southern parts of Afar and SNNPRS

9 Maximum Vegetation Composite for The 3 nd Dekad of September 2000 Maximum Vegetation Composite for The 3 nd Dekad of September 2000 Vegetation Assessment from Satellite Data 3 rd Dekad of September 2000 T This vegetation assessment : this dekad s NDVI is a composite of five images. The value of dense vegetation was observed over most parts of Tigray, Amhara, Oromia, Benishangul Gumuz, Gambella, and SNNPRS regions. Comparison with the previous dekad: The comparison with the previous dekad shows a slight increase over some parts of Amhara, Tigray, Oromia and few areas of Somali regions. No significant change is observed over the rest parts of the country.

10 Second phase MSG_2 When the first generation phased out and the second generation ( MSG_2) launched NMA obtained the satellite receiving station from the European Union and the MSG_2 was installed by Vcs company in 2004 we are receiving the 12 channel images and archiving the full hourly raw data for HRV, IR 1.6, IR 3.9, IR 10.8, Vis 0.6, Vis 0.8, WV 6.2 and WV 7.3. But we are not produce products because it doesn t have application software In 2005 PUMA was installed, so we are using this station for weather forecasting it receives the 12 channels, forecast products from different forecasting centers and it was upgrade to Synergy in 2010 and so it works well. For the rainfall estimation a project developed in collaboration with IRI, Reading University and NMA by using TAMSAT methodology we have done calibration by using 460 gauge station with CCD.

11 Continued Now we have RFE since 1983 and we merge with gauge and produced the blend data on ten-day bathes so we have data every 10 and 4 kms. We get the RFE in ncdf format from Reading University every ten-day and from VGT4Africa through Eumetcast NDVI, NDWI, VPI and SWB by using GIS software we produce products for our bulletin with its assessments every ten-day. We upload satellite images on our websit every 3 hours during the day time and the tenday NDVI The content of the bulletin is

12 Rainfall assessment from satellite data 1st dekad of March 2015 Rainfall distribution:- The rainfall activity of this dekad has covered some parts of the country. Some parts of Benishangul Gumuz, Oromia, Gambella, Somali, few areas over SNNPRS and pocket areas of Amhara regions received 1 30 mm of rainfall. Comparison with the previous dekad:- Increase in estimated rainfall amount was observed over Benishangul Gumuz, Oromia, Gambella and Somali regions, whereas significant decrease was observed over SNNPR region. Comparison with the ground observation:- It Shows un over estimate over western Benishangul Gumuz, Oromia, Gambella, SNNPRS and Somali regions. The rest parts of the country shows the same pattern as compared with the actual.

13 Assessment of synthesis VPI for the 1 st decade of May 2012 Most of the country comes under the domination of Better VPI probabilities. Hence most places of Tigray, Amhara, Afar, Gambella, Oromia, SNNPRS, Somali and few areas of Benishangul Gumuz have got better VPI activities (60% and more). On the other hand most parts of Benishangul Gumuz, few parts of SNNPRS and Somali, pocket areas of Afar, western areas of Tigray and Amhara, eastern parts of Gambella recorded VPI values of 20% and less.

14 Assessment of synthesis NDVI for the 1 st decade of May 2012 Generally low to moderate NDVI activity was the dominant feature in this decade over most parts of the country. However better NDVI activities have been seen over portions of southwestern and southern parts of the country. On the other hand low NDVI values covered the northern, northeastern and few areas over south eastern parts of the country. Hence some portion of western SNNPR & adjoining Gambella and Western, northern and southern Oromia recorded moderate to high greenness. Whereas most parts of Afar, pocket areas in Amhara, Tigray and some portions of Somali regions recorded low NDVI values (Refer the actual figure left-above). Compared with the previous decade, the vegetation status is in the state of Slight to moderate increase in areas over some parts of SNNPRS, most parts of Gambella, western Oromia, most parts of Somali and Benishangul Gumz regions. Slight decrease observed over southern & eastern Oromia, most portion of Amhara, Somali, Benishangul Gumz and some part of SNNPRS and Gambella regions. No change of vegetation cover has been detected over the rest of the country (Refer the difference figure right-above).

15 Assessment of NDWI for the 1 st decade of May 2012 NDWI distribution for this decade exhibited low values over southeastern, southern, northern, northwestern and western parts of the country. Where, southern, south western, western, central and north eastern parts of the country exhibited high values. Hence SNNPR, much of Amhara, Gambella, Oromia, Afar, few portion of Benishangul Gumuz and pocket areas over Tigray regions registered high values. On the contrary, much of Somali, Tigray, Amhara, Benshangul Gumz, western Gambella, Pocket areas of central and eastern Oromia, few places of Afar enjoyed low surface water values.

16 Assessment of Small Water Bodies for the 1 st decade of May 2012 Small Water Bodies distribution for this decade showed the existence of small water bodies with a size of 1km 2 and above in areas along the rift valleys. Over places in Oromia, Gambella, Benishangul and SNNPR, no detection of small water bodies observed due to humid vegetation cover.

17 Continued Now our system is not working and we are using the GEONETCast it receives segmented data we are in problem even to archive the images. The software for this system is Ilwise even it is not receiving all images during the day. The INDEXS are not available since 2 nd decade of May 2014 We also to install Radar in this year in northwest part of the country at Sahura around Tana-Beles Chachment. On the last I will ask the EUMETSAT and the JRC has to do something to solve our problem.

18 Thank you for your attention