Bias correction of global irradiance modelled with the Weather Research and Forecasting model over Paraguay

" In this contribution, we present a post-process analysis of the Weather Research and Forecasting (WRF) model which combines a Kalman Filter with Model Output Statistics for bias correction in order to improve the overall predicted values of GHI simulations over Paraguay. The hourly GHI is simulated at 4x4 km2 of spatial resolution. The annual evaluation of the hourly WRF model without post process shows relative mean bias error (rMBE) of 21% and relative root mean square error (rRMSE) of 81%. The results using several ground stations and combinations of post-process show an annual correction of systematic errors with rMBE of -0.7% and rRMSE of 70%."CONACYT - Consejo Nacional de Ciencias y TecnologíaPROCIENCI

The role of global cloud climatologies in validating numerical models

The purpose of this work is to estimate sampling errors of area-time averaged rain rate due to temporal samplings by satellites. In particular, the sampling errors of the proposed low inclination orbit satellite of the Tropical Rainfall Measuring Mission (TRMM) (35 deg inclination and 350 km altitude), one of the sun synchronous polar orbiting satellites of NOAA series (98.89 deg inclination and 833 km altitude), and two simultaneous sun synchronous polar orbiting satellites--assumed to carry a perfect passive microwave sensor for direct rainfall measurements--will be estimated. This estimate is done by performing a study of the satellite orbits and the autocovariance function of the area-averaged rain rate time series. A model based on an exponential fit of the autocovariance function is used for actual calculations. Varying visiting intervals and total coverage of averaging area on each visit by the satellites are taken into account in the model. The data are generated by a General Circulation Model (GCM). The model has a diurnal cycle and parameterized convective processes. A special run of the GCM was made at NASA/GSFC in which the rainfall and precipitable water fields were retained globally for every hour of the run for the whole year

관측과 모델 비교를 통한 북극 혼합 구름의 미세물리 특성 및 복사효과 연구

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 지구환경과학부, 2023. 8. 김상우.Clouds have a major impact on the Earth's radiative budget and climate change, yet little microphysical data has been collected on clouds in the polar regions. This lack of microphysics data is related to the challenges of deploying and operating instruments in some of the world's most challenging and remote atmospheric environments. This thesis investigates the macro- and microphysical properties of clouds based on observations over Ny-Ålesund, Svalbard, in order to better understand the role of clouds in the Arctic. The total cloud occurrence was found to be ~77.6% from February 2017 to February 2023. The most predominant cloud type is multilayer clouds with a frequency of occurrence of 39.1%, and single-layer clouds with ~37.2%. The total occurrences of single-layer ice, liquid, and mixed-phase clouds are 19%, 4.4%, and 14.9%, respectively. In addition, surface measurements of upward and downward shortwave and longwave radiation from the Baseline Surface Radiation Network (BSRN) at Ny-Ålesund station were examined. Relatively lower values of upward and downward longwave fluxes for ice and mixed-phase clouds were highly correlated with cloud top temperature by phase. The database of cloud properties and the classification method obtained in this work are used to evaluate weather prediction models. We evaluated the microphysical properties of Arctic low-level clouds simulated by four cloud microphysics parameterization schemes (Morrison, WDM6, NSSL, and P3) implemented in the Polar-optimized Weather Research and Forecasting (PWRF) model. The evaluation is based on a comparison with data from the Arctic Cloud Observations Using Airborne Measurements during the Polar Day (ACLOUD) experiment, which took place near Svalbard in May-June 2017. A significant number of clouds were observed during the campaign, mainly due to adiabatic motions and sensible/latent heat fluxes that caused air masses to warm (by 4°C) as they were transported over the sea ice and ocean transition zone. The Morrison and WDM6 schemes performed best overall, with frequency bias (FB) values close to 1 (1.07, 1.13) and high log-odds ratios (0.50, 0.48) in predicting cloud occurrence, indicating good agreement with observed cloud occurrence. On the other hand, the NSSL and P3 schemes showed a high FB value (1.30, 1.56) with a low log-odds ratio (0.17, 0.16), indicating a high overestimation of cloud occurrence. Conversely, the WDM6 scheme produced higher ice-mixing ratios than the Morrison and NSSL schemes, while the latter two tended to produce more snow and graupel. However, all schemes generally underestimated both liquid and ice water content. Longwave downward (LWD) flux depends on atmospheric temperature and humidity, which are simulated differently by each cloud microphysics scheme. The model underestimated LWD flux is highly correlated with the LWC bias of each scheme. This study highlights the critical need for observational development of cloud parameterization in the Arctic to better estimate the impact of clouds on the Arctic climate under conditions of rapid Arctic warming.북극 증폭에 대한 구름의 영향은 구름의 특성뿐만 아니라 구름이 북극 기후의 구성 요소(수증기, 해양, 해빙, 알베도, 표면 온도 등)와 밀접하게 관련되어 있기 때문에 불확실하다. 이 논문에서는 북극에서 구름의 역할을 더 잘 이해하기 위해 Cloudnet의 스발바드 니알슨 지상 관측자료를 바탕으로 구름의 거시적 및 미시적 특성을 분석하였다. 2017년 2월부터 2023년 2월까지 구름의 총 발생률은 약 77.6%로 나타났다. 가장 우세한 구름 유형은 다층 구름으로 발생 빈도는 39.1%, 단층 구름은 ~37.2%이다. 단층 얼음, 액체, 혼합상 구름의 총 발생 빈도는 각각 19%, 4.4%, 14.9%이다. 또한, 니알슨 관측소의 Baseline Surface Radiation Network (BSRN) 복사 자료를 활용하여 상하 단파 및 장파 복사에 대한 측정값을 분석하였다. 얼음과 혼합상 구름에 대한 장파 상향 및 장파 하향 플럭스의 상대적으로 낮은 값은 위상별 구름 최고 온도와 높은 상관관계를 보였다. 본 연구를 통해 얻은 구름 특성 데이터베이스와 분류 방법은 기상 예측 모델 평가에 사용되었다. 극지에 최적화된 Polar-optimized Weather Research and Forecasting (PWRF) 모델에 구현된 4가지 구름 미세물리 매개변수화 방식(Morrison, WDM6, NSSL, P3)을 활용하여 시뮬레이션한 저층 북극 혼합 구름의 미시물리적 특성을 평가하였다. 이 분석은 2017년 5월부터 6월까지 스발바드 인근에서 진행된 Arctic Cloud Observations Using Airborne Measurements during the Polar Day (ACLOUD) 캠페인 데이터와의 비교를 기반으로 한다. 이 캠페인 기간 동안 상당수의 혼합 구름이 관측되었는데, 이는 주로 해빙과 해양 전이대를 통과하는 동안 기단이 가열(4°C)되는 단열 운동과 현열/잠열 플럭스로 인해 발생했다. Morrison 및 WDM6 구름 모수화 방식은 구름 발생 예측에서 높은 로그 확률(0.50, 0.48)과 함께 1에 가까운 빈도 편향 값(1.07, 1.13)을 나타내며 구름이 발생한 지역 및 높이와 잘 일치하는 것으로 나타나 전반적으로 가장 우수한 성능을 나타났다. NSSL 와 P3 모수화 스킴은 낮은 로그 확률 비율(0.17, 0.16)과 함께 높은 빈도 편향 값(1.30, 1.56)을 보여 구름 발생을 과대평가하는 것으로 나타났다. 반대로 WDM6 모수화 스킴은 Morrison 및 NSSL 방식에 비해 더 높은 얼음 혼합 비율을 생성한 반면, 후자의 두 방식은 더 많은 눈과 싸락눈을 생성하는 경향이 있었다. 모든 방식은 일반적으로 액체와 얼음 수분의 함량을 모두 과소평가했다. 뿐만 아니라, 혼합 구름의 복사율 분석을 통해 구름 타입에 따른 장파와 단파의 상대적 중요도를 평가하고, 구름의 미세물리적 특성에 대한 의존성을 분석하였다. 장파 하강 복사율은 대기 온도와 습도에 따라 달라지며, 모델에서 과소평가된 장파 하강 복사율은 각 구름 모수화 스킴에서 모의된 구름 수분 함량 편향과 높은 상관관계를 보였다. 이 연구는 급격한 북극 온난화 조건에서 구름이 북극 기후에 미치는 영향을 보다 정확하게 추정하기 위해 북극 구름의 타입구분이 중요하며, 북극의 구름 매개 변수화에 대한 관측 기반 개발이 시급히 필요하다.Chapter 1. Introduction １ 1.1 Background and motivation １ 1.2 Scientific Questions ５ 1.3 Objectives of this study ８ Chapter 2. Data and model description ９ 2.1 ACLOUD campaign ９ 2.2 Cloud radar data １１ 2.3 Surface radiation data １３ 2.4 PWRF model configuration １４ Chapter 3. Arctic cloud properties at Ny-Ålesund, Svalbard １９ 3.1 Definition of diagnostics １９ 3.2 Classification of hydrometeors and clouds properties ２４ 3.3 Statistics of Arctic mixed-phase clouds and their radiative effect ３７ Chapter 4. Arctic mixed-phase clouds: comparison between observation and model 4 5 4.1 Meteorological contexts during the ACLOUD campaign ４９ 4.2 Cloud microphysical properties: Observation vs. model ５４ 4.3 Theoretical analysis of scheme algorithm ７７ 4.4 Radiative forcing at the surface ８７ Chapter 5. Summary and future direction ９１ References ９６ 국문 초록 １２１박

Amélioration de la paramétrisation des propriétés optiques des nuages d'eau liquide dans le spectre solaire

Représenter correctement l'impact radiatif des nuages est un vrai défi pour les modèles atmosphériques, du fait que les interactions rayonnement-nuages sont contrôlées par les propriétés optiques des particules nuageuses. Ces propriétés dépendent de la taille des particules, et de la longueur d'onde du rayonnement, deux éléments qui ne sont pas bien résolus dans les modèles atmosphériques, si bien que les propriétés optiques doivent être paramétrisées. Dans ce manuscrit nous nous efforçons de quantifier les incertitudes sur l'impact radiatif des nuages dans le spectre solaire (SW) liées à la paramétrisation des propriétés optiques des nuages liquides. Les incertitudes proviennent en premier lieu de l'hypothèse faite sur la forme de la distribution de taille des gouttelettes (DSD), qui intervient dans: 1- l'estimation du rayon effectif des gouttelettes (reff) à partir du contenu en eau (LWC) et de la concentration en nombre des gouttelettes (N); 2- le calcul des propriétés de diffusion simple (SSPs) à partir de reff. Des incertitudes sont également liées au moyennage spectral nécessaire pour calculer les SSPs sur des bandes larges. Pour rendre compte de ces incertitudes, un nouveau jeu de paramétrisations des SSPs est développé et implémenté dans le code radiatif ecRad, couvrant un grand nombre de formes de DSD et de méthodes de moyennage spectral. Cette version améliorée d'ecRad est utilisée pour simuler les propriétés radiatives (transmittance, réflectance, aborbance) d'une grande variété de nuages définis en termes de LWC et N, comprenant un nuage homogène idéalisé, des cas d'étude plus réalistes, et des sorties d'un modèle de climat. Ces simulations montrent que la transmittance/réflectance d'un nuage peut varier de 20% en changeant simplement la forme de la DSD. Des différences de l'ordre de 20% sont également obtenues pour les taux de chauffage atmosphérique. L'impact de la forme de la DSD sur l'estimation de reff contribue pour 80% à l'incertitude totale, le reste étant lié à l'impact sur les SSPs. Le moyennage spectral a moins d'influence, si ce n'est sur l'absorption au sein du nuage. A l'échelle globale nous estimons que le forçage radiatif des nuages peut varier de 6~W~m$^{-2}$ selon la forme de DSD supposée, ce qui correspond à environ 13% du forçage radiatif SW des nuages. Afin de compléter ces simulations de transfert radiatif, et d'étudier comment des différences de forçage radiatif se répercutent sur l'évolution des nuages, la version améliorée d'ecRad a été implémentée dans le modèle atmosphérique Méso-NH. Par ailleurs, la forme de la DSD utilisée dans le code radiatif est rendue cohérente avec celle supposée dans le schéma microphysique à deux moments de Méso-NH, LIMA. Des simulations 1D de stratocumulus sont réalisées en supposant différentes formes de DSD, à la fois dans LIMA et pour l'estimation de reff et des SSPs. L'impact direct de la DSD sur le forçage radiatif est évalué, et les effets indirects qui résulte des rétroactions du rayonnement sur les autres caractéristiques physiques sont également abordées. Dans ces simulations interactives, l'estimation de reff reste la principale source des différences, et les effets directs obtenus sont en accord avec les simulations hors-ligne. Au cours de la simulation les différences de flux radiatifs et de taux de réchauffement modifient progressivement les profils verticaux de température, de LWC et de N, ce qui renforce les différences liées à $r_mathrm{eff}$, puisqu'il dépend de ces quantités. Cette étude de cas souligne la complexité des interactions nuage-rayonnement, dont les processus physiques sous-jacents mériteraient d'être étudiés plus en détail. Finalement, ces simulations Méso-NH mettent en évidence que la sensibilité aux propriétés optiques des nuages dans le LW, qui devraient à l'avenir être traitées avec autant d'attention que dans le SW.Simulating the radiative impact of clouds is challenging for atmospheric models, because cloud-radiation interactions are driven by the optical properties of individual cloud particles. These properties depend on the size of the particle and the frequency of light, two quantities not fully resolved in atmospheric models, implying that cloud optical properties need to be parameterized. In this thesis we focus on quantifying the uncertainties in shortwave (SW) cloud radiative impact due to the SW optical properties parameterization of liquid clouds. Uncertainties are first due to the Droplet Size Distribution (DSD) shape assumption required in two steps: 1- to estimate the cloud droplets effective radius (reff) from liquid water content (LWC) and droplet number concentration (N); 2- to compute the single scattering properties (SSPs) as a function of reff. Uncertainties also arise from averaging SSPs over wide spectral bands. To assess these uncertainties, a set of new parameterizations corresponding to various DSD shapes and spectral averaging methods are designed and implemented in the radiative code ecRad. Using this updated version of ecRad, we perform offline simulations to compute the bulk radiative properties (reflectance, transmittance, absorptance) of various clouds (defined in terms of LWC and N), including a homogeneous cloud, more realistic case studies, and outputs of a climate model. The results show that the transmittance/reflectance of the cloud can vary up to 20% depending on the assumed DSD. Likewise, differences up to 20% are obtained for atmospheric heating rates. The impact of the DSD shape assumption on reff (resp. SSPs) estimation contributes to around 80% (resp. 20%) of the total uncertainty. Spectral averaging is less an issue, except for atmospheric absorption. Overall, global shortwave cloud radiative effect can vary by 6~W~m$^{-2}$ depending on the assumed DSD shape, which is about 13% of the best observational estimate. To complement these offline simulations and investigate how differences in radiative forcing feed back on cloud evolution, the updated version of ecRad is implemented in the atmospheric model Meso-NH. In addition, the DSD shape assumed in ecRad is made consistent with the DSD shape assumed in the 2-moment microphysical scheme of Meso-NH, LIMA. 1D simulations of a stratocumulus cloud are performed with various DSD shapes affecting simultaneously LIMA, the reff estimation and the SSPs parameterization. The direct impact of the DSD on the simulated radiative forcing is assessed, and the indirect effects that results from interactions of radiation with other components of the model are discussed as well. In these interactive simulations, the estimation of reff remains the main source of differences, and the obtained direct effects are in line with the offline simulations. Throughout the simulation, the differences in radiative fluxes and heating rates progressively impact the vertical profiles of temperature, LWC and N, enhancing the feedback since reff depends on these two quantities.This case study highlights the complexity of the cloud-radiation interactions, which deserve further investigation to fully understand the primary physical mechanisms at stake. Finally, these Meso-NH simulations point out the sensitivity to the LW cloud properties, that should in the future be treated as carefully as the SW

Modelling of thermal radiation exchange at glass-covered greenhouse surfaces under different climatic conditions

[no abstract

Global and direct solar radiation at surface over Iberian Peninsula: variability, trends and forecasting

Besides being the key to Earth's climate, global solar radiation at the surface ( ) is one of the most valuable renewable resources. This way, an adequate knowledge of the solar resource is critical as an assessment for a strategic planning of projects related to the production of solar energy. Therefore, the main goals of this thesis is to analyze past changes and variability of solar radiation fluxes in Portugal and Iberia Peninsula (IP) using observational available measurements, ERA−40 and NCEP/NCAR reanalysis datasets and, predict and characterize the solar radiation at the surface over Iberian Peninsula based on numerical weather prediction models. In a first part, this study is dedicated to the analysis of temporal and spatial variability of based on ground-based stations, as well as in ERA−40 and NCEP/NCAR reanalysis. Parametric and non-parametric tests are applied to detect trends in both reanalysis and ground-based observations. Cloud cover obtained from reanalysis is also used to examine the possible causes of the observed long-term changes in . In a second stage, is presented an assessment of the W model at high resolution ( 5 ) against observations and with another configuration. After a bias removal process, a and cloud cover climatology was obtained for IP (1950−2010 period). Finally, the performance of IFS/ECMWF is evaluated to predict Direct Normal Irradiance (DNI) over Évora city at very short (1 hour) and short term (1 to 3 days), for one year period. It is also described a new methodology to compute DNI attenuation using in situ observational data in order to estimate the transparency of the atmosphere in the absence of cloud cover datasets. To improve IFS/ECMWF outputs is also tested a bias correction methodology; Resumo: A Radiação Solar Global e Direta à Superfície na Península Ibérica: Variabilidade, Tendências e Previsão A radiação solar é um dos recursos energéticos renováveis mais valiosos. Na Península Ibérica (PI) estão em instalação muitos sistemas comerciais e de investigação para o aproveitamento da energia solar. Neste contexto, o conhecimento do fluxo de radiação solar que incide na superfície terrestre e da sua evolução torna-se de extrema importância. Pretende-se com este trabalho estudar a distribuição espacial, a variabilidade e as tendências da radiação solar de pequeno comprimento de onda ( ) à superfície, na PI e em Portugal, a partir de dados observacionais e das reanálises ERA−40/NCEP assim como, prever e caracterizar a radiação com base em modelos de previsão numérica do tempo. Na primeira parte deste estudo, efetua-se uma análise da variabilidade temporal e espacial da radiação recorrendo a estações terrestres, bem como a dados de reanálise ERA−40 e NCEP/NCAR. Para o efeito utilizam-se testes paramétricos e não paramétricos a fim de detetar tendências nas séries em estudo. A cobertura de nuvens obtida a partir das reanálises é também usada para avaliar as possíveis causas da variabilidade da radiação observada. Numa segunda etapa do estudo, obteve-se uma climatologia a 5 de resolução da radiação solar à superfície com base em simulações com o modelo regional − , para a PI, e para o período 1950−2010. Os resultados das simulações foram validados recorrendo a estações de observação e a uma outra simulação , com outra configuração, previamente validada. Na construção da climatologia e de nuvens foi aplicado um método de pós-processamento para remoção do viés. Finalmente, avalia-se o desempenho do modelo IFS, do ECMWF na previsão da radiação DNI a curto e médio prazo, sobre a região. Propõe-se uma nova metodologia para estimar a transparência da atmosfera e testa-se uma metodologia de correção de viés

Radiative energy budget estimates for the 1979 Southwest Summer Monsoon

November, 1986.Includes bibliographical references

FIRE Science Results 1989

FIRE (First ISCCP Regional Experiment) is a U.S. cloud-radiation research program formed in 1984 to increase the basic understanding of cirrus and marine stratocumulus cloud systems, to develop realistic parameterizations for these systems, and to validate and improve ISCCP cloud product retrievals. Presentations of results culminating the first 5 years of FIRE research activities were highlighted. The 1986 Cirrus Intensive Field Observations (IFO), the 1987 Marine Stratocumulus IFO, the Extended Time Observations (ETO), and modeling activities are described. Collaborative efforts involving the comparison of multiple data sets, incorporation of data measurements into modeling activities, validation of ISCCP cloud parameters, and development of parameterization schemes for General Circulation Models (GCMs) are described

Theoretical and observational comparison of cirrus cloud radiative properties, A

August 1989.Includes bibliographical references.Sponsored by NSF ATM-8812353.Sponsored by NSF ATM-8519160.Sponsored by DOD AFOSR-88-0143.Sponsored by ONR N00014-87-K-0228/P00001