Validation of APHRODITE Precipitation Data for Humid and Sub Humid Regions of Pakistan

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1 Pkistn Journl of Meteorology Vol.9, Issue 17: July 2012 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Ali, G. 1, 2, G. Rsul 2, T. Mhmood 2, Q. Zmn 2, S. B. Cheem 2 Astrct The Asin Precipittion Highly Resolved Oserved Dt Integrtion Towrds Evlution of wter resources (APHRODITE s wter resources) dt developed for Pkistn on 0.05 degree resolution y Reserch Institute for Humnity nd Nture (RIHN) nd the Meteorologicl Reserch Institute of Jpn Meteorologicl Agency (MRI/JMA), ws nlyzed on decdl sis for the humid nd su humid regions of Pkistn. Sctter plots of oth the APHRODITE nd oserved dily precipittion dtsets were constructed on decdl sis from 1971 to The coefficient of correltion (R 2 ) vlues vry from very poor (e.g for Kotli, ) to very good (e.g for Astore, ) for different sttions in vrious decdes. Monthly totls of oth the dtsets were verged on decdl ses nd sctter plots were gin constructed. In this cse the correltion coefficient (R 2 ) results re fr etter thn those determined for dily precipittion dtsets. The very poor correltion results in cse of dily precipittion dtsets for Islmd nd Kotli re more thn 98% in cse of men monthly nlysis. Bises etween the two precipittion dtsets were lso clculted for every sttion in the region. This nlysis shows tht the APHRODITE dt underestimtes the oserved dt for most of the sttions in those months in which hevy rinfll occurs. This is reches up to mximum of 271mm for Muzffrd in the month of July. The is is less where the rinfll mount is smll. A slight overestimtion of APHRODITE precipittion dt hs lso een recorded for some sttions. The mximum overestimtion of APHRODITE precipittion dt (out 40mm) ws oserved for Islmd in the month of Mrch for the decde Keywords: APHRODITE, Precipittion, Climtic Zones, Interpoltion. Introduction The world APHRODITE stnds for Asin Precipittion Highly Resolved Oservtionl Dt Integrtion Towrds Evlution of Wter Resources (APHRODITE's Wter Resources). The APHRODITE project develops stte-of-the-rt dily precipittion dtsets with high resolution (0.5 nd 0.25 ) grids for Asi. APHRODITE's Wter Resources project hs een executed y the Reserch Institute for Humnity nd Nture (RIHN) nd the Meteorologicl Reserch Institute of Jpn Meteorologicl Agency (MRI/JMA) since The dtsets re creted primrily with dt otined from in-situ rin-guge-oservtion network. The quntittive estimtion of precipittion nd thus the development of gridded precipittion product re crucil for mny scientific studies. Thus, mny methods of interpolting sttion dt hve een developed in the lst century, nd considerle efforts hve een mde to derive precipittion informtion from stellites over the lst two decdes. Since rin-guge-sed products hve monthly time intervl nd stellite-derived products hve short time series therefore precipittion dtsets tht were ville in the erly 2000s do not meet the demnds for vlidting high-resolution climte model outputs nd those for sttisticl downscling. Lck of rin-guge-sed dily product ws ottleneck for mny studies on the impct of climte chnge on locl environments ( scope/index.html). Long-term high-resolution dily precipittion dt re useful for evluting mesoscle models, driving river flow models, nd nlyzing temporl nd sptil vritions of precipittion fields. Oservtionl records longer thn yers enle one to investigte precipittion chnges cused y glol wrming. In ddition, gridded dt mke model evlution nd wter udget nlysis esier, when compred with point oservtion dt (Kmiguchi et l, 2010). 1 gohr.met@gmil.com 2 Pkistn Meteorologicl Deprtment 57

2 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Vol. 9 Considerle efforts hve een mde in developing gridded precipittion dtsets sed on stellite dt or stellite-sed merged nlyses (Gruer nd Levizzni 2008). However, there re incresing demnds for ccurte high resolution rin-guge-sed precipittion products over lnd for the vlidtion of simultion products of numericl models nd stellite-sed high resolution precipittion products (Turk et l. 2008). Indirect precipittion estimtes must e verified or clirted y direct oservtions, specificlly rin guge mesurements. One of the dvntges of guge oservtions is the length of the records. Hence monthly glol guge-sed precipittion dtsets developed y severl groups re widely used (New et l. 1999). Consequently, dily grid precipittion products re expected to e used to verify high-resolution climte model simultions tht include extreme events nd to drive hydrologicl models (Xie et l. 2007). To vlidte the cpility of climte model to simulte not only vrious spects of climte chnge including regionl precipittion, it is necessry to compre the model s precipittion results ginst oserved precipittion dt (Ytgi et l. 2008, ). However, no precipittion dt set with sufficiently high sptil nd temporl resolution is ville for evluting climte models for Asi, especilly, south Asi. In order to vlidte high resolution climte model, long term guge-sed high resolution dily precipittion dt set hs een developed for Pkistn s prt of APHRODITE s Wter Resources project. The primry ojectives of the APHRODITE project re to (1) relese officil stte-ofthe-rt dily gridded precipittion dt sets sed on rin-guge oservtions, (2) ssess the projections of climte models y oserving precipittion in the field, including extreme events, nd (3) to mke suggestions to regionl wter resources mngers in Asin countries. Before using this dtset it is necessry to vlidte it first y compring it with ctul precipittion dt. Therefore the min focus of the current study is on the comprison of APHRODITE dtset with oserved precipittion dt so tht one cn set the level of confidence for using the dtset for different purposes s discussed erlier. Dt nd Methodology Tle 1: R 2 Vlues etween the two dtsheets for different sttions in different decdes. Sttions Elevtion Sttion Dily Monthly Dily Monthly Dily Monthly Dily Monthly (m) Type Men Men Men Men Astore 2167 Hill Chert 1301 Hill G-Duptt 812 Hill Kkul 1308 Hill Muree 2168 Hill M-Ad 701 Hill Peshwr 359 Plne Sidu-Shrif 961 Hill Islmd 507 Plne Jhelum 231 Plne Kotli 615 Hill Blkot 980 Hill The APHRODITE precipittion dt is ville online from the site on 0.5 nd 0.25 resolutions for Asi. The dt used in this study hs een specilly developed for Pkistn on 0.05 degree resolution. Point dt hs een extrcted from this gridded dt using Grds softwre. Oserved sttion dt of dily precipittion ws otined from CDPC Krchi for different meteorologicl sttions of Pkistn for the period The APHRODITE dt is ville from 1951 to 2007, ut here only the dt from 1971 to 2007 hs een used for nlysis. The dt for the first two decdes ws dropped ecuse of very poor correltion results nd high vlue of is etween the two dtsets. This my e due to less numer of oservtories nd consequently fewer mounts of ville oserved dt in tht period of time. 58

3 Issue 17 Ali, G., G. Rsul, T. Mhmood, Q. Zmn, S. B. Cheem A comprison etween oserved nd APHRODITE dily dt ws crried out on decdl sis from 1971 to Monthly totls of oth the dtsets were verged on 10 yers sis from The correltion coefficient (R 2 ) vlues etween the two dtsets on dily s well s men monthly sis were clculted for every sttion. Tle 1 shows these vlues for the two dtsets. Results nd Discussion According to Chudhry nd Rsul (2004), Pkistn cn e clssified on gro-climtic sis in different zones such s (i) Humid (ii) Su humid (wet nd dry) (iii) Arid (iv) Su rid (wet nd dry) zones. The region locted etween 33 N nd 35 N cn e clssified into humid nd su humid regions of the country. Humid Climte The region with such type of climte hs short summer ut long nd mild with snow winter. June is the wrmest month with men temperture 20.4 C when mximum temperture my increse upto 34 C nd Jnury is the coldest month with the minimum temperture elow the freezing point. The nnul men temperture for this region is out 9 C to 17 C. The region receives oth summer nd winter rinfll with lrger contriution from the summer rinfll. The nnul men precipittion rnges from 1900mm to 2400mm (CDPC, 2005; Khn et l., 2010). Murree Murree is locted t N nd E with n elevtion of 2167m nd it flls in humid climte zone ccording to clssifiction of Chudhry nd Rsul (2004). Murree receives the highest mount of rinfll throughout the country. The correltion coefficient (R 2 ) vlues for Murree etween oserved nd APHRODITE dily dtsets shows good reltion etween the two dtsets except 0.26 for the period In cse of monthly dtsets the correltion results re even etter (0.97 to 0.99). The correltion result for the period hs risen to 0.97 in this cse. Figure 1 nd 1 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Figure 2 nd 2 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Murree during different decdes. Figure 1: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for Murree, () , ()

4 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Vol. 9 Figure 2: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for Murree, () , () The is nlysis of oserved nd APHRODITE dt for Murree shows tht APHRODITE dt underestimtes the oserved dt. This underestimtion is mximum in those months in which the mount of rinfll is mximum. Figure 3 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Murree. Figure 3: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Murree. Su-Humid (Wet) Climte The region with such type of climte hs long summer nd mild with snow winter. June is the wrmest month when mximum temperture my increse ove 40 C nd Jnury is the coldest month with the minimum temperture elow the freezing point. The regions receive oth summer nd winter rinfll with lrger contriution from the summer rinfll. The nnul men precipittion rnges from 1200mm to 1800mm (CDPC, 2005; Khn et l., 2010). Exmples of these regions include Islmd, Kotli nd Muzffrd etc. Muzffrd Muzffrd is locted t N nd E with n elevtion of 701m. The climte of Muzffrd is su humid (wet) nd the nnul men mount of rinfll in this re is 1200mm to 1800mm. The 60

5 Issue 17 Ali, G., G. Rsul, T. Mhmood, Q. Zmn, S. B. Cheem correltion results etween oserved nd APHRODITE dily dt in different decdes in this re vries from 0.26 to Reltively etter correltion results (0.49 to 0.67) were otined in cse of men monthly dtsets nlysis. Figure 4 nd 4 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Figure 5 nd 5 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Muzffrd during different decdes. Figure 4: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for Muzffrd () , () Figure 5: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for Muzffrd () , () The Bis nlysis shows tht APHRODITE dt strongly underestimtes the oserved dt in the months Jun Septemer. This ising crosses 200mm in the months of July in the decdes ( ) nd ( ). Due to this uneven is the correltion results re not so much promising, oth for dily nd men monthly dtsets. Figure 6 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Muzffrd. 61

6 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Vol. 9 Figure 6: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Muzffrd. Islmd Islmd is lso locted in the su humid (wet) region of the country. Islmd is locted t 33.7 N nd E with n elevtion of 543m. The correltion results etween oserved nd APHRODITE dily dtsets for Islmd re very poor (0.05 to 0.15). Strong correltion etween the two dtsets is Figure 7: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for Islmd () , () Figure 8: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for Islmd, () , ()

7 Issue 17 Ali, G., G. Rsul, T. Mhmood, Q. Zmn, S. B. Cheem oserved in cse of men monthly nlysis (0.98 to 0.99). Figure 7 nd 7 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Figure 8 nd 8 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Islmd during different decdes. The is nlysis for this sttion shows tht APHRODITE dt underestimtes oserved dt in the months from June Septemer. An overestimting trend is lso shown in the months of Ferury nd Figure 9: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Islmd Mrch in the decdes nd Figure 9 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Islmd. Grhi Duptt Grhi Duptt is lso locted in the su humid region of the country. It is locted t N nd E with n elevtion of 812m. The correltion results etween oserved nd APHRODITE dily dt vries from 0.58 to 0.77 in different decdes from 1971 to Much etter results (0.87 to 0.97) were otined in cse of men monthly dtsets nlysis. Figure 10 nd 10 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Figure 11 nd 11 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Grhi Duptt during different decdes. Figure 10: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for G_Duptt () , ()

8 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Vol. 9 Figure 11: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for G_Duptt () , () The is nlysis shows tht APHRODITE dt underestimtes the oserved dt in lmost ll of the months with mximum vlues in the months of July nd August. A slight overestimtion lso exists in the period Figure 12 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Grhi Duptt. Figure 12: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Grhi Duptt. Su-Humid (Dry) Climte The region with such type of climte hs long summer nd short mild winter. My nd June re the wrmest months when mximum temperture my increse thn 45 C in some res like Peshwr nd Jnury is the coldest month with the minimum temperture elow the freezing point like in Astore. Exmples of sttions under this groclimtic zone re: Astore, Chert, Jhelum nd Peshwr. The men temperture for these sttions respectively is 10 C 20 C, 16 C 20 C, nd 22 C 24 C (for oth Jhelum nd Peshwr). The regions receive oth summer nd winter rinfll with lrger contriution from the winter rinfll which is cused y the Western Disturnce (WD). The nnul men precipittion for Astore nd Peshwr is 400mm 600mm, 600mm 800mm for Chert nd mm for Jhelum. 64

9 Issue 17 Ali, G., G. Rsul, T. Mhmood, Q. Zmn, S. B. Cheem Jhelum Jhelum is situted in the su humid (dry) region of Pkistn ccording to groclimtic clssifiction of the country. It lies t N nd E. The correltion results for different decdes in the period vry from 0.49 to 0.90 etween the two dtsets on dily sis, while in cse of men monthly dtsets nlysis these results vry from 0.99 to Fig. 13 nd 13 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Fig. 14 nd 14 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Jhelum during different decdes. Figure 13: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for Jhelum, () , () Figure 14: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for Jhelum, () , () The is nlysis shows tht APHRODITE dt underestimtes oserved dt in the months hving high mount of precipittion, especilly in the months of July nd August, which corresponds to the monsoon seson in the region. The APHRODITE dt overestimtes the oserved dt in the decde Figure 15 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Jhelum. 65

10 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Vol. 9 Figure 15: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Jhelum. Astore Figure 16: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for Astore, () , () Figure 17: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for Astore, () , ()

11 Issue 17 Ali, G., G. Rsul, T. Mhmood, Q. Zmn, S. B. Cheem Astore lies t N nd 74.9 E with n elevtion of 2167m. Astore is situted in the su humid (dry) region of Pkistn ccording to Chudhry nd Rsul (2004). The correltion results for this sttion lie etween 0.79 nd 0.98 for the dily dtsets while in cse of men monthly dtsets nlysis these results lie etween 0.97 nd 0.99, showing etter correltion etween the two dtsets. Figure 16 nd 16 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Figure 17 nd 17 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Astore during different decdes. The is nlysis shows tht APHRODITE dt underestimtes oserved dt in lmost ll of the months, ut this ising is not so much high. Figure 18 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Astore. Figure 18: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Astore. Peshwr Peshwr lso lies in the su humid (dry) region ccording to groclimtic clssifiction of Pkistn. Peshwr is situted t N nd E with n elevtion of 359m. The correltion results etween the two dily dtsets rnges from 0.12 to In cse of men monthly dtsets nlysis reltively etter correltion results (0.77 to 0.96) were otined. Figure 19 nd 19 represent comprison etween APHRODITE nd oserved dily precipittion dt nd Figure 20 nd 20 represent comprison etween APHRODITE nd oserved monthly precipittion dt for Peshwr during different decdes. Figure 19: Sctter plot for comprison etween APHRODITE nd oserved dily precipittion dt for Peshwr, () , ()

12 Vlidtion of APHRODITE Precipittion Dt for Humid nd Su Humid Regions of Pkistn Vol. 9 Figure 20: Sctter plot for comprison etween APHRODITE nd oserved monthly precipittion dt for Peshwr ( ) The is nlysis shows tht APHRODITE dt underestimtes oserved dt in lmost ll of the months with slight overestimtion in some months s well. Figure 21 shows the difference etween APHRODITE nd oserved precipittion dt in different decdes for Peshwr. Figure 21: Difference of oserved nd APHRODITE precipittion dt on decdl sis for Peshwr. Conclusions The APHRODITE dt developed for Pkistn ws nlyzed in this study for the humid nd su humid regions of the country. For lmost ll of the sttions the APHRODITE dt underestimtes the oserved precipittion, prticulrly in those months in which the precipittion mount is high, with mximum is of 271mm for Muzffrd for the month of July in the decde A slight overestimtion of APHRODITE dt ws lso oserved for some sttions (like Islmd, Grhi Duptt, Peshwr) with mximum is of 40mm for Islmd in Mrch in the decde The correltion coefficient (R 2 ) vlues etween the two dily dtsets vries from very poor (e.g to 0.15 for Islmd) to very good (e.g to 0.99 for Astore) for different sttions in different decdes. The correltion coefficient vlues ecome much etter in cse of men monthly dtsets nlysis. Even the very poor results (for exmple Islmd) rises to very good (0.98 to 0.99) in this cse. 68

13 Issue 17 Ali, G., G. Rsul, T. Mhmood, Q. Zmn, S. B. Cheem Thus it is concluded tht oserved nd APHRODITE dtsets re strongly correlted on men monthly sis s compred to dily sis. Reference Chudhry, Q. Z. nd G. Rsul, 2004: Agro-Climtic Clssifiction of Pkistn, SCIENCE VISION Vol.9 No.1-2, Ghzl, N. nd G. Rsul, 2011: Investigtion of Rinfll Vriility for Pkistn, Pkistn Journl of Meteorology, Vol. 7, Issue 14, Gruer, A., nd V. Levizzni, 2008: Assessment of Glol Precipittion Products. WCRP Series Report No. 128 nd WMO TD-No. 1430, 55 IPCC. (2007), Climte Chnge 2007, The Physicl Science Bsis. Contriution of Working Group I to the Fourth Assessment Report of the Intergovernmentl Pnel on Climte Chnge, Cmridge University Press, Jvnmrd, S., A. Ytgi, M. I. Nodzu, J. BodghJmli nd H. Kwmoto, 2010: Compring highresolution gridded precipittion dt with stellite rinfll estimtes of TRMM 3B42 over Irn, Adv. Geosci., 25, Kmiguchi, K., O. Arkw, A. Kitoh, A. Ytgi, A. Hmd nd N. Ysutomi, 2010: Development of APHRO_JP, the first Jpnese high-resolution dily precipittion product for more thn 100 yers, Hydrologicl Reserch Letters, 4,60 64 Khn, S. U., M. F. Hssn, K. Khn, nd A. Bri, 2010: Climte Clssifiction of Pkistn,pper presented in the conference BALWOIS 2010 Ohrid, Repulic of Mcedoni, My 2010, New, M. G., M. Hulme, nd P. D. Jones, 1999: Representing twentieth century spce-time climte vriility. Prt I: Development of men monthly terrestril climtology. J.Climte, 12, Tkshim, H., A. Ytgi, H. Kwmoto, O. Arkw nd k. Kmiguchi, Hydrologicl lnce over northern Eursi from guge-sed high-resolution dily precipittion dt, Aville online t Turk, F. J., P. Arkin, E. E. Eert, nd M. R. P. Spino, 2008: Evluting high resolution precipittion products, Bull. Amer. Meteor. Soc., 89, Wheed Iql, 2010: Vlidtion of Regionl Climte Model Providing Regionl Climtes for Impcts Studies (PRECIS) for Different Climtes of Pkistn, MS Thesis. Xie, P., A. Ytgi, M. Chen, T. Hysk, Y. Fukushim, C. Liu nd Y. Song, 2007: A guge-sed nlysis of dily precipittion over Est Asi, J. Hydrometeor., 8, Ytgi, A. Development of dily grid precipittion dt in the Est Mediterrnen nd its ppliction for the ICCAP studies, Aville t Ytgi, A., O. Arkw, K. Kmiguchi, H. Kwmoto, M. I. Nodzu nd A. Hmd, 2009: A 44- Yer Dily Gridded Precipittion Dtset for Asi Bsed on Dense Network of Rin Guges, SOLA, Vol. 5, Ytgi, A., P. Alpert nd P. Xie, 2008: Development of dily gridded precipittion dt set for the Middle Est, Adv. Geosci., 12,