PROYEKSI CURAH HUJAN DAN SUHU UDARA EKSTRIM MASA DEPAN PERIODE TAHUN 2021-2050 KOTA BANJARBARU KALIMANTAN SELATAN

Peningkatan konsentrasi gas rumah kaca telah menyebabkan perubahan pada kejadian iklim ekstrim. Penelitian ini menggunakan skenario RCP 4.5 sebagai skenario perubahaan iklim masa mendatang untuk mengetahui tren indeks suhu dan curah hujan ekstrim periode 2021-2050 di Kota Banjarbaru. Data suhu maksimum, suhu minimum dan curah hujan harian hasil proyeksi tahun 2021-2050 diolah dengan Software RClimDex sehingga didapatkan data indeks temperatur dan hujan ekstrim. Indeks-indeks tersebut merupakan indeks iklim ekstrim yang ditetapkan oleh ETCCDMI yang terdiri atas TN90p, , TX90p, TNn, TNx, TXn, TXx, TMAXmean, TMINmean, RX1day, RX5day, SDII, CDD dan CWD. Hasil penelitian ini menunjukkan bahwa diproyeksikan pada 2020-2050 tren suhu udara akan meningkat signifikan di kota Banjarbaru terutama suhu udara minimum selanjutnya pola prespitasi juga mengalami peningkatan terutama akumulasi curah hujan 5 hari berturut-turut. Meningkatknya jumlah hari kering dan berkurangnya jumlah hari basah, serta semakin tinggi akumulasi curah hujan harian namun hari basah yang sedikit akan menghasilkan curah hujan harian yang tinggi (ekstrim) setiap kejadian hari basah. Kata kunci: banjarbaru, curah hujan, ekstrim, suhu. ABSTRACT Increased concentrations of greenhouse gases have caused changes in extreme climate events. This study uses the RCP 4.5 scenario as a future climate change scenario to determine the temperature index and extreme rainfall trends in the 2021-2050 period in Banjarbaru. Data of maximum temperature, minimum temperature and daily rainfall projection results in 2021-2050 are processed with RClimDex Software so that the temperature and extreme rain index data are obtained. The indices are extreme climate indices determined by ETCCDMI consisting of TN90p, TX90p, TNn, TNx, TXn, TXx, TMAXmean, TMINmean, RX1day, RX5day, SDII, CDD and CWD. The results of this study indicate that it is projected that in 2020-2050 air temperature trends will increase significantly in the city of Banjarbaru especially the minimum air temperature then the pattern of prespitations will also increase especially the accumulation of rainfall for 5 consecutive days. Increasing the number of dry days and decreasing the number of wet days, as well as the higher accumulation of daily rainfall but a small wet day will produce high daily rainfall (extreme) every event of a wet day. Keywords: banjarbaru, extreme, temperature, rainfall.

Relationship between the Future Projections of Sahel Rainfall and the Simulation Biases of Present South Asian and Western North Pacific Rainfall in Summer

Confident model projections of regional climate, in particular precipitation, could be very useful for designing climate change adaptation, particularly for vulnerable regions such as the Sahel. However, there is an extremely large uncertainty in the future Sahel rainfall projections made by current climate models. In this study, we find a close relationship between the future Sahel rainfall projections and present rainfall simulation biases in South Asia and the western North Pacific in summer, using the historical simulations and future projections of phase 5 of the Coupled Model Intercomparison Project (CMIP5). This future–present relationship can be used to calibrate Sahel rainfall projections since historical simulation biases can be much more reliably estimated than future change. The accordingly calibrated results show a substantial increase in both precipitation and precipitation minus evaporation in the future Sahel, in comparison with the multimodel ensemble (MME) result. This relationship between the historical rainfall bias and future Sahel rainfall projection is suggested to lie with the different schemes of convective parameterization among models: some schemes tend to result in both overestimated (underestimated) historical rainfall in South Asia (the western North Pacific) and enhanced future Sahel rainfall projection, while other schemes result in the opposite.

Projection of Landfalling–Tropical Cyclone Rainfall in the Eastern United States under Anthropogenic Warming

Landfalling–tropical cyclone (TC) rainfall is an important element of inland flood hazards in the eastern United States. The projection of landfalling-TC rainfall under anthropogenic warming provides insight into future flood risks. This study examines the frequency of landfalling TCs and associated rainfall using the GFDL Forecast-Oriented Low Ocean Resolution (FLOR) climate model through comparisons with observed TC track and rainfall over the July–November 1979–2005 seasons. The projection of landfalling-TC frequency and rainfall under the representative concentration pathway (RCP) 4.5 scenario for the late twenty-first century is explored, including an assessment of the impacts of extratropical transition (ET). In most regions of the southeastern United States, competition between increased storm rain rate and decreased storm frequency dominates the change of annual TC rainfall, and rainfall from ET and non-ET storms. In the northeastern United States, a prominent feature is the striking increase of ET-storm frequency but with tropical characteristics (i.e., prior to the ET phase), a key element of increased rainfall. The storm-centered rainfall composite analyses show the greatest increase at a radius of a few hundred kilometers from the storm centers. Over both ocean and land, the increase of rainfall within 500 km from the storm center exceeds the Clausius–Clapeyron scaling for TC-phase storms. Similar results are found in the front-left quadrant of ET-phase storms. Future work involving explorations of multiple models (e.g., higher atmospheric resolution version of the FLOR model) for TC-rainfall projection is expected to add more robustness to projection results.

Constraints on Southern Australian Rainfall Change Based on Atmospheric Circulation in CMIP5 Simulations

Atmospheric circulation change is likely to be the dominant driver of multidecadal rainfall trends in the midlatitudes with climate change this century. This study examines circulation features relevant to southern Australian rainfall in January and July and explores emergent constraints suggested by the intermodel spread and their impact on the resulting rainfall projection in the CMIP5 ensemble. The authors find relationships between models’ bias and projected change for four features in July, each with suggestions for constraining forced change. The features are the strength of the subtropical jet over Australia, the frequency of blocked days in eastern Australia, the longitude of the peak blocking frequency east of Australia, and the latitude of the storm track within the polar front branch of the split jet. Rejecting models where the bias suggests either the direction or magnitude of change in the features is implausible produces a constraint on the projected rainfall reduction for southern Australia. For RCP8.5 by the end of the century the constrained projections are for a reduction of at least 5% in July (with models showing increase or little change being rejected). Rejecting these models in the January projections, with the assumption the bias affects the entire simulation, leads to a rejection of wet and dry outliers.

PEMANFAATAN TEKNOLOGI MODIFIKASI CUACA UNTUK PERKEBUNAN KELAPA SAWIT

IntisariTanaman Kelapa Sawit (Elais sp) adalah sumber utama minyak nabati sesudah kelapa di Indonesia. Tanaman tersebut merupakan komoditi andalan ekonomi Indonesia karena selain merupakan penghasil devisa, kelapa sawit merupakan salah satu alternatif upaya peningkatan kesejahteraan masyarakat melalui pembukaan lapangan pekerjaan dan lapangan usaha. Distribusi tanaman kelapa sawit di Indonesia dapat dijumpai di setiap pulau seperti Sumatera, Kalimantan, Sulawesi dan Jawa. Pada tahun 2013, dari total luas perkebunan kelapa sawit sebesar 9,14 juta hektar, sekitar 65% berada di pulau Sumatera, disusul Kalimantan (31%), Sulawesi (3%), kemudian Jawa dan Papua di bawah satu persen. Tanaman kelapa sawit tergolong ke dalam tanaman xerophyte yang dapat beradaptasi dengan kondisi air yang kurang, walaupun demikian tanaman tetap akan mengalami gejala stres air pada saat musim kemarau yang berkepanjangan. Salah satu upaya untuk mengantisipasi musim kemarau panjang dan kebakaran lahan yaitu dengan melakukan Teknologi Modifikasi Cuaca (TMC). Penerapan TMC di Indonesia sudah dilakukan sejak tahun 1979 dengan berbagai tujuan, yaitu menambah curah hujan untuk mengatasi kekeringan, pengisian air waduk untuk irigasi dan PLTA; mengurangi curah hujan untuk mengatasi banjir; longsor; dan mengurangi kabut asap akibat kebakaran hutan dan lahan. Simulasi proyeksi curah hujan dengan skenario pelaksanaan TMC 120 hari dilakukan di wilayah Riau, Kalimantan Tengah dan Sumatera Utara sebagai daerah dengan luas perkebunan sawit terbesar di Indonesia. Hasil dari simulasi tersebut adalah menghitung besarnya jumlah curah hujan tahunan yang dapat dihasilkan apabila dilakukan TMC 120 hari pada bulan April-Mei 2014 dan Agustus-September 2014 dengan asumsi tingkat pertambahan hujan ketika berada pada periode penyemaian awan sebesar 30%. Berdasarkan hasil simulasi curah hujan dengan skenario pelaksanaan TMC 120 hari, untuk wilayah Riau akan didapatkan penambahan curah hujan sebesar 198 mm/tahun, wilayah Kalimantan Tengah sebesar 254 mm/tahun dan wilayah Sumatera Utara sebesar 233 mm/tahun. Abstract Palm (Elais sp) is the main source of vegetable oil after coco in Indonesia. This plant is mainstay commodity of Indonesia because in addition to foreign exchange earner, palm oil is one alternative efforts to improve the welfare of society through the opening of employment and business field. Distribution of palm oil plantations in Indonesia can be found in every island like Sumatra, Kalimantan, Sulawesi and Java. In 2013, total area of palm oil plantations amounted to 9.14 million hectares, approximately 65% were on the island of Sumatra, Kalimantan followed (31%), Sulawesi (3%), then Java and Papua under one percent. Palm oil plants belonging to the plant xerophyte that can adapt to conditions that are less water, however the plant will continue to experience symptoms of water stress during the long dry season. One effort to anticipate the long dry season and forest fires by performing the Weather Modification Technology. Application of this technology in Indonesia have been carried out since 1979 with a variety of purposes, namely to rain enhancement to overcome drought, filling water reservoirs for irrigation and hydropower; reduce rainfall to overcome floods; landslides; and reduce smog from forest fires and land. Simulation of rainfall projection with applying weather modification technology for 120 days in Riau, Central Kalimantan, and North Sumatra as the area with the largest palm oil plantations in Indonesia. Result of this simulation is to calculate the amount of annual rainfall if weather modification for 120 days applied in April-May 2014 and AugustSeptember 2014, assuming growth rate when cloud seeding period is 30%. Based on this simulation resulted for Riau regoin will get additional rainfall 198 mm/year, Central Kalimantan Region 254 mm/year and North Sumatra Region 233 mm/year