GNSS掩蔽による高分解能温度プロファイルを用いて解析された熱帯対流圏界面と成層圏重力波の特性

京都大学0048新制・課程博士博士(理学)甲第21579号理博第4486号新制||理||1644(附属図書館)京都大学大学院理学研究科地球惑星科学専攻(主査)教授 橋口 浩之, 教授 塩谷 雅人, 教授 秋友 和典学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDGA

KARAKTERISTIK KETEBALAN LAPISAN BRIGHT BAND HASIL MODEL PROFIL REFLEKTIVITAS DAN GRADIEN REFLEKTIVITAS

Bright band merupakan indikator suatu lapisan pada awan stratus yang ditandai oleh peningkatan reflektivitas radar akibat kristal es yang meleleh. Hal tersebut dapat menyebabkan galat dalam menghitung estimasi presipitasi berdasarkan data radar. Oleh karena itu, deteksi bright band merupakan langkah yang penting untuk dilakukan guna mengoreksi data radar cuaca sebagai acuan dalam pengembangan model estimasi presipitasi. Penelitian ini bertujuan menginvestigasi dua model untuk identifikasi bright band hasil observasi transportable X-band radar dari data range-height indicator (RHI). Model pertama dengan menggunakan function fit, yaitu profil vertikal reflektivitas (VPR; vertical profile of reflectivity) dan model kedua dengan menggunakan gradien reflektivitas (GR). Hasil analisis menunjukkan perbedaan galat dalam menentukan batas atas (batas bawah) untuk VPR adalah 4,51% (3,1%), sedangkan model GR 9,02% (3,9%). Identifikasi bright band dengan menggunakan model VPR lebih baik dibandingkan dengan model GR untuk penentuan batas atas dan batas bawah dari bright band. Pengetahuan mengenai karakteristik ketebalan BB dapat dimanfaatkan untuk analisis lebih lanjut terkait estimasi presipitasi kuantitatif berdasarkan observasi radar

Influence of ENSO and MJO on the zonal structure of tropical tropopause inversion layer using high-resolution temperature profiles retrieved from COSMIC GPS Radio Occultation

Using COSMIC GPS Radio Occultation (RO) observations from January 2007 to December 2016, we retrieved temperature profiles with the height resolution of about 0.1&thinsp;km in the upper troposphere and lower stratosphere (UTLS). We investigated the distribution of static stability (N2) and the zonal structure of the tropopause inversion layer (TIL) in the tropics, where a large change in the temperature gradient occurs associated with sharp variations in N2. We show the variations in the mean N2 profiles in coordinates relative to the cold-point tropopause (CPT). A very thin (&lt;1&thinsp;km) layer is found with average maximum N2 in the range of 11.0–12.0×10-4&thinsp;s−2. The mean and standard deviation of TIL sharpness, defined as the difference between the maximum N2 (max⁡N2) and minimum N2 (min⁡N2) within ±1&thinsp;km of the CPT, is (10.5±3.7)×10-4&thinsp;s−2. The max⁡N2 is typically located within 0.5&thinsp;km above CPT. We focused on the variation in TIL sharpness in two longitude regions, 90–150∘&thinsp;E (Maritime Continent; MC) and 170–230∘&thinsp;E (Pacific Ocean; PO), with different land–sea distribution. Seasonal variations in TIL sharpness and thickness were related to the deep convective activity represented by low outgoing longwave radiation (OLR) during the Australian and Asian monsoons. The deviation from the mean sharpness (sharpness anomaly) was out of phase with the OLR anomaly in both the MC and PO. The correlation between the sharpness anomaly over the MC and PO and the sea surface temperature (SST) Niño 3.4 index was −0.66 and +0.88, respectively. During La Niña (SST Niño 3.4 &lt;-0.5&thinsp;K) in the MC and El Niño (SST Niño 3.4 &gt;+0.5&thinsp;K) in the PO, warmer SSTs in the MC and PO produce more active deep convection that tends to force the air upward to the tropopause layer and increase the temperature gradient there. The intraseasonal variation in sharpness anomaly during slow and fast episodes of the Madden–Julian Oscillation (MJO) demonstrates that eastward propagation of the positive sharpness anomaly is associated with organized deep convection. Deep convection during MJO will tend to decrease N2 below CPT and increase N2 above CPT, thus enlarging the TIL sharpness. Convective activity in the tropics is a major control on variations in tropopause sharpness at intraseasonal to interannual timescales.</p

UTILIZATION OF FORMOSAT-3/COSMIC GPS RADIO OCCULTATION DATA FOR PRECIPITABLE WATER VAPOR ESTIMATING IN THE ATMOSPHERE

Utilization of FORMOSAT-3/COSMIC satellite data using GPSRO for atmospheric Precipitable WaterVapor (PWV) estimating has been done. This research analyzed comparison between daily PWV profile from radiosondeand GPSRO observations during 2007. Used radiosonde data were from obervation at Soekarno-HattaAirport, Jakarta. While GPSRO data were determined by finding the nearest occultation locations with radiosondelaunching in the same day. Extrapolation method has been applied for estimating data which were not recordedabove surface. Results showed before and after applying extrapolation method on GPSRO data, the linear correlationbetween PWV derived from both of observations technique are 0.657 and 0.849 respectively. Applicationof PWV from GPSRO was shown in hovmoller diagram during 2 January to 19 May 2011. The estimation duringthat period are between 10 to 55 mm, which described the existence of Madden Julian Oscillation. Hence, theseresults depicted that GPSRO can be utilized for PWV estimation that could be continued to enhance precipitationmodelling

DINAMIKA LAPISAN STRATOSFER DI BELAHAN BUMI UTARA DAN DAMPAKNYA TERHADAP WILAYAH TROPIS: STUDI KASUS MUSIM DINGIN 2012-2013 (STRATOSPHERIC DYNAMICS IN THE NORTHERN HEMISPHERE AND ITS IMPACT TO THE TROPICS: A CASE STUDY OF 2012-2013 WINTER)

This research aims to investigate the dynamic of static stability (N2), potential energy of gravity waves (Ep), and vortex in the stratospheric northern hemisphere during 2012-2013 winter using temperature (T) and zonal wind (u) data from NCEP-DOE Reanalysis II. The results showed two occurrences of decreasing N2 ascociated with reversal of u in the first and third week of December 2012 were believed as a trigger of Sudden Stratospheric Warmings (SSW) on January 7, 2013. There was a flow from the polar to the tropics region during the SSW event. It caused the tropopause folding in the sub-tropic region indicated by the distribution of Ep on January 24, 2013. This tropopause folding triggered the convective activity over the Indonesian continents as shown by the negative OLR anomaly from 22 to 26 January 2013. The impact of SSW event in the northern hemisphere to the convective activity was 20%. This results showed the interaction between stratosphere and troposphere and also the teleconnection between the polar and the tropics.   ABSTRAKPenelitian ini bertujuan menyelidiki dinamika stabilitas statis (N2), energi potensial gelombang gravitas (Ep), dan pusaran angin di lapisan stratosfer Belahan Bumi Utara (BBU) selama musim dingin 2012-2013 menggunakan data temperatur (T) dan komponen angin zonal (u) dari NCEP-DOE Reanalysis II. Hasil riset menunjukkan bahwa dua kejadian penurunan N2 pada pekan awal dan ketiga bulan Desember 2012 diyakini sebagai pemicu kejadian Sudden Stratosphere Warmings (SSW) tanggal 7 Januari 2013. Pada saat terjadi SSW terdapat aliran dari kutub menuju tropis. Aliran ini mengakibatkan terjadinya pelipatan lapisan tropopause di wilayah sub-tropis yang terlihat pada distribusi Ep tanggal 24 Januari 2013. Pelipatan lapisan tropopause ini kemudian memicu aktivitas konvektif di atas wilayah Indonesia yang ditandai oleh anomali OLR negatif antara tanggal 22-26 Januari 2013. Dampak kejadian SSW di BBU terhadap aktivitas konvektif di atas wilayah kepulauan Indonesia sebesar 20%. Hasil ini membuktikan interaksi antara lapisan stratosfer dan troposfer serta telekoneksi wilayah kutub dan tropis

Analysis of vertical wave number spectrum of atmospheric gravity waves in the stratosphere using COSMIC GPS radio occultation data

Discussion Paper;Atmos. Meas. Tech. Discuss., 4, 2071-2097, 04 Apr 2011, DOI:10.5194/amtd-4-2071-2011GPS radio occultation (RO) is characterized by high accuracy and excellent height resolution, which has great advantages in analyzing atmospheric structures including small-scale vertical fluctuations. The vertical resolution of the geometrical optics (GO) method in the stratosphere is about 1.5 km due to Fresnel radius limitations, but full spectrum inversion (FSI) can provide superior resolutions. We applied FSI to COSMIC GPS-RO profiles from ground level up to 30 km altitude, although basic retrieval at UCAR/CDAAC sets the sewing height from GO to FSI below the tropopause. We validated FSI temperature profiles with routine high-resolution radiosonde data in Malaysia and North America collected within 400 km and about 30 min of the GPS RO events. The average discrepancy at 10–30 km altitude was less than 0.5 K, and the bias was equivalent with the GO results. Using the FSI results, we analyzed the vertical wave number spectrum of normalized temperature fluctuations in the stratosphere at 20–30 km altitude, which exhibits good consistency with the model spectra of saturated gravity waves. We investigated the white noise floor that tends to appear at high wave numbers, and the substantial vertical resolution of the FSI method was estimated as about 100–200 m in the lower stratosphere. We also examined a criterion for the upper limit of the FSI profiles, beyond which bending angle perturbations due to system noises, etc, could exceed atmospheric excess phase fluctuations. We found that the FSI profiles can be used up to about 28 km in studies of temperature fluctuations with vertical wave lengths as short as 0.5 km

EFEK PARAMETERISASI LAPISAN BATAS ATMOSFER TERHADAP PEMBENTUKAN GELOMBANG GRAVITAS DI SUMATERA BARAT [THE EFFECT OF ATMOSPHERIC BOUNDARY LAYER PARAMETERIZATION TO THE GENERATION OF GRAVITY WAVES OVER WEST SUMATERA]

Gelombang gravitas berperan dalam sirkulasi dinamika atmosfer dan mempengaruhi proses-proses di Lapisan Batas Atmosfer (LBA). Gelombang gravitas telah diidentifikasi dengan simulasi temperatur potensial dan kecepatan angin menggunakan model Weather Research and Forecasting–Advance Research WRF (WRF-ARW) dengan kondisi inisial dan kondisi batas model dari data final analyses (FNL) tanggal 16–17 Maret 2008. Simulasi dilakukan dalam tiga domain nested (bersarang) dengan resolusi horizontal paling tinggi sebesar 3 km. Metode simulasi dilakukan dengan membandingkan dua skema parameterisasi LBA yang berbeda yakni Medium Range Forecast (MRF) dan Yonsei University (YSU). Metode analisis menggunakan transformasi Fourier dan wavelet. Dari hasil simulasi, gelombang gravitas berhasil diidentifikasi dengan baik menggunakan skema MRF di atas Sumatera Barat saat aktivitas konveksi sedang terjadi dengan nilai Cloud Water Mixing Ratio (CWMR) sekitar 0,1-2,1 g/kg. Ciri-ciri gelombang gravitas yang terdeteksi merupakan gelombang gravitas berperiode singkat (~2 jam) dengan panjang gelombang horizontalnya 5–50 km. Perbedaan karakter gelombang gravitas yang dihasilkan simulasi, berhubungan dengan sensitivitas skema parameterisasi LBA dan resolusi grid horizontal. Gelombang gravitas dapat disimulasikan oleh skema MRF dengan resolusi horizontal 3 km yang dapat menghasilkan panjang gelombang yang lebih pendek.Kata kunci: Gelombang gravitas, Lapisan Batas Atmosfer, WRF-ARW, Parameterisas

Spektrum Bilangan Gelombang Gravitas Atmosfer dalam Domain Vertikal (Deskripsi Model dan Observasi)

Atmospheric gravity waves (GW) play an important role in the global circulation dynamics by transporting the energy from the lower to the upper atmosphere. This research aims to investigate the GW propagation through the model of vertical wavenumber spectrum and analysis of the results from radiosonde observation. The fluctuation of temperature and the perturbation of horizontal wind components can be represented by Brunt Vaisala frequency (N) and vertical woven umber (m). Fast Fourier Transform (FFT) analysis of normalised temperature fluctuation and horizontal wind perturbation show that GW reach the saturation condition for m 3 x 10-4 cyc/m in the troposphere and stratosphere. When the amplitude of GW become saturated, it will deposit the energy 2.25 1/kg and the longer vertical wavelength (Az) of GW will propagate to the upper atmosphere above 25 km. There are no significant different in the observed spectrum from day and night time obervations.Gelombang gravitas (GW) atmosfer memiliki peran penting dalam dinamika sirkulasi global melalui pemindahan energi dad atmosfer di lapisan bowah sampai ke lapisan atas. Penelitian ini bertujuan untuk menyelidiki perambatan vertikal GW melalui model spektrum dan analisis hasil pengamatan radiosonde. Fluktuasi temperatur don perturbasi komponen angin dapat direpresentasikan oleh Brunt Vaisala frequency (N) dan bilangan gelombang vertikal (m). Analisis Fast Fourier Transform (FFT) dad normalisasi fluktuasi temperatur dan perturbasi origin horizontal menunjukkan bahwa GW mencapai keadaan jenuh (saturasi) untuk m a. 3 x 10-4 cyc/m di lapisan troposfer don stratosfer. Ketika amplitudo GW mengalami saturasi, maka proses tersebut akan menyimpan energi sebesar 2,25 J/kg dan GW dengan panjang gelombang vertikal (Az) lebih panjang akan merambat terus sampai ke lapisan atmosfer di atas 25 km. Tidak ado perbedaan yang berarti antara spektrum hash! pengamatan di slang clan malam had. Kota kunci : spektrum bilangan gelombang vertikal, saturasi gelombang gravitas, troposfer dan stratosfer.Hal. 1-1

Deteksi pengaruh gelombang Kelvin pada fluktuasi uap air di tropopause menggunakan model inversi

Analisis pengaruh gelombang ekuatorial Kelvin terhadap fluktuasi uap air (H2O) di lapisan tropopause (paras tekanan udara 100 hPa), dilakukan dengan  memanfaatkan data Microwave Limb Sounder (MLS) Aura versi 4.2 dan angin zonal NCEP DOE Reanalysis II sepanjang tahun 2017. Model inversi gelombang melalui pendekatan Newtonian diterapkan untuk mencari parameter amplitudo (A) dan fasa (φ) gelombang dominan pada variasi anomali H2O (H2O*). Hasil penyelarasan model inversi menunjukkan perambatan H2O* positif ke arah timur bersesuaian dengan angin zonal (U) positif (angin baratan) yang identik dengan pergerakan gelombang Kelvin. Perambatan ini didominasi oleh bilangan gelombang k1 dengan A1 dan φ1 berturut–turut sebesar 0,44 dan 21,1°.  Penulis menemukan bahwa variasi uap air dipengaruhi oleh perubahan angin baratan menjadi angin timuran dan konvergensi sebesar 0,15 × 10–5 s–1. Analisis komposit diagram relatif terhadap nilai maksimum H2O* menunjukkan adanya pengaruh gelombang ekuatorial Kelvin terhadap distribusi uap air di tropopause. Penelitian terkait pengembangan model kopel troposfer dan stratosfer perlu mempertimbangkan proses dinamika gelombang Kelvin dan proses radiatif dari konsentrasi uap air di tropopause. Analysis on the influence of equatorial Kelvin wave on the fluctuations in water vapor (H2O) at tropopause (100 hPa air pressure level) has been done utilizing Microwave Limb Sounder (MLS) Aura version 4.2 and zonal wind (U) from NCEP DOE Reanalysis II data throughout the year of 2017. The inverse wave model using Newtonian approximation has been applied to determine the dominant of both wave amplitude (A) and phase (φ) parameters on the H2O anomaly (H2O*). The fitting of inverse modeling result showed an eastward propagation of positive H2O* associated with positive U (westerly wind) which is identical as Kelvin wave movement. The propagation is dominated by wavenumber k1 where A1 and φ1 is 0.44 and is 21.1°, respectively.  The authors found that water vapor variations were influenced by the reversal of zonal wind from easterly to easterly and the convergence as large as 0,15 × 10–5 s–1. The composite analysis relative to the maximum value H2O* showed the influence of equatorial Kelvin wave in the water vapor distribution at tropopause. The research on the development of the troposphere –stratosphere coupling model may need to consider the dynamical process of the equatorial Kelvin wave and radiative process of water vapor concentration in the tropopause.