Toward a Mesoscale Observation Network in Southeast Asia

Koh, Tieh‐Yong; Teo, Chee‐Kiat

doi:10.1175/2008bams2561.1

Cited by 19 publications

(16 citation statements)

References 34 publications

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“…Many other projects over this important region have been carried out in collaboration with various countries and agencies, for example, ocean-atmosphere interaction studies with China (e.g., Yang et al 2015), aerosol studies with the USA and others (e.g., Reid et al 2016), a collaboration within Southeast Asia (e.g., Koh and Teo 2009), and a collaboration/capacity building for meteorological operations and database construction with Australia, the Netherlands, France, Germany, and others. Collaborations between projects are occurring, and contributions from Indonesian scientists are increasing (see the last paragraph of the "Conclusions" section of this article).…”

Section: Jepp−harimau and Satreps−mccoe Projectsmentioning

confidence: 99%

Maritime continent coastlines controlling Earth’s climate

Yamanaka

Ogino

et al. 2018

Prog Earth Planet Sci

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During the Monsoon Asian Hydro−Atmosphere Scientific Research and Prediction Initiative (MAHASRI; 2006-16), we carried out two projects over the Indonesian maritime continent (IMC), constructing the Hydrometeorological Array for Intraseasonal Variation−Monsoon Automonitoring (HARIMAU; 2005-10) radar network and setting up a prototype institute for climate studies, the Maritime Continent Center of Excellence (MCCOE; 2009-14). Here, we review the climatological features of the world's largest "regional" rainfall over the IMC studied in these projects. The fundamental mode of atmospheric variability over the IMC is the diurnal cycle generated along coastlines by land−sea temperature contrast: afternoon land becomes hotter than sea by clear-sky insolation before noon, with the opposite contrast before sunrise caused by evening rainfall-induced "sprinkler"-like land cooling (different from the extratropical infrared cooling on clear nights). Thus, unlike the extratropics, the diurnal cycle over the IMC is more important in the rainy season. The intraseasonal, seasonal to annual, and interannual climate variabilities appear as amplitude modulations of the diurnal cycle. For example, in Jawa and Bali the rainy season is the southern hemispheric summer, because land heating in the clear morning and water vapor transport by afternoon sea breeze is strongest in the season of maximum insolation. During El Niño, cooler sea water surrounding the IMC makes morning maritime convection and rainfall weaker than normal. Because the diurnal cycle is almost the only mechanism generating convective clouds systematically near the equator with little cyclone activity, the local annual rainfall amount in the tropics is a steeply decreasing function of coastal distance (e-folding scale 100-300 km), and regional annual rainfall is an increasing function of "coastline density" (coastal length/land area) measured at a horizontal resolution of 100 km. The coastline density effect explains why rainfall and latent heating over the IMC are twice the global mean for an area that makes up only 4% of the Earth's surface. The diurnal cycles appearing almost synchronously over the whole IMC generate teleconnections between the IMC convection and the global climate. Thus, high-resolution (<< 100 km; << 1 day) observations and models over the IMC are essential to improve both local disaster prevention and global climate prediction.

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Section: Jepp−harimau and Satreps−mccoe Projectsmentioning

confidence: 99%

Maritime continent coastlines controlling Earth’s climate

Yamanaka

Ogino

et al. 2018

Prog Earth Planet Sci

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“…This is likely due to the radiosonde networks not adequately sampling mesoscale weather. In tropical regions where mesoscale weather systems dominate, there is a dire need to build up mesoscale observation networks for better monitoring and modeling for forecast and research [ Koh and Teo , 2009]. Mass et al [2002]reports that in midlatitude regions, lower‐resolution model runs may even sometimes perform better in objective accuracy scores than higher‐resolution runs because larger‐scale frontal features are adequately captured in lower‐resolution runs while the simultaneous lack of mesoscale model details and insufficient mesoscale observations implies that location or timing errors of mesoscale weather systems are not penalized.…”

Section: Results Ii: Evaluation Of Coamps Modelmentioning

confidence: 99%

A diagnostic suite to assess NWP performance

2012

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[1] A suite of numerical weather prediction (NWP) verification diagnostics applicable to both scalar and vector variables is developed, highlighting the normalization and successive decomposition of model errors. The normalized root-mean square error (NRMSE) is broken down into contributions from the normalized bias (NBias) and the normalized pattern error (NPE). The square of NPE, or the normalized error variance a, is further analyzed into phase and amplitude errors, measured respectively by the correlation and the variance similarity. The variance similarity diagnostic is introduced to verify variability e.g. under different climates. While centered RMSE can be reduced by under-prediction of variability in the model, a penalizes over-and under-prediction of variability equally. The error decomposition diagram, the correlation-similarity diagram and the anisotropy diagram are introduced. The correlation-similarity diagram was compared with the Taylor diagram: it has the advantage of analyzing the normalized error variance geometrically into contributions from the correlation and variance similarity. Normalization of the error metrics removes the dependence on the inherent variability of a variable and allows comparison among quantities of different physical units and from different regions and seasons. This method was used to assess the Coupled Ocean/Atmospheric Mesoscale Prediction System (COAMPS). The NWP performance degrades progressively from the midlatitudes through the sub-tropics to the tropics. But similar cold and moist biases are noted and position and timing errors are the main cause of pattern errors. Although the suite of metrics is applied to NWP verification here, it is generally applicable as diagnostics for differences between two data sets.

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“…nasa.gov/AIRS/data_products.shtml) were used to calibrate and validate the nadir-correction method described in section 2. The region was selected because 1) it has large oceanic coverage; 2) its climatological sea surface temperature is relatively homogeneous, thereby reducing the effect of spatial variation in surface temperature on the observed radiance; and 3) we are particularly interested in the application of AIRS observations to the Indo-Pacific warm pool as part of our initiative toward enhancing regional observation capability in which satellite remote sensing plays a vital role (Koh and Teo 2009).…”

Section: Data Descriptionmentioning

confidence: 99%

Nadir Correction of AIRS Radiances

Teo

Koh

2010

Journal of Atmospheric and Oceanic Technology

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A statistical method to correct for the limb effect in off-nadir Atmospheric Infrared Sounder (AIRS) channel radiances is described, using the channel radiance itself and principal components (PCs) of the other channel radiances to account for the multicollinearity. A method of selecting an optimal set of predictors is proposed and demonstrated for one- and two-PC predictors. Validation results with a subset of AIRS channels in the spectral region 649–2664 cm−1 show that the mean nadir-corrected brightness temperature (BT) is largely independent of scan angle. More than 66% of the channels have a root-mean-square (rms) bias less than 0.10 K after nadir correction. Limb effect on the standard deviation (SD) of BT is discernible at larger scan angles, mainly for the atmospheric windows and the water vapor channels around 6.7 μm. After nadir correction, nearly all atmospheric window channels unaffected by solar glint and more than 76% of water vapor channels examined have BT SDs brought closer to nadir values. For the window channels affected by solar glint (wavenumber > 2490 cm−1), BT SDs at the scan angles with the strongest impact from solar reflection were improved on average by more than 0.6 K after nadir correction.

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Toward a Mesoscale Observation Network in Southeast Asia

Abstract: A coordinated network of in situ instruments, remote sensors, and satellite receiving stations could accelerate research and forecasting progress in a region where observations are currently inadequate.

Cited by 19 publications

References 34 publications

Maritime continent coastlines controlling Earth’s climate

Maritime continent coastlines controlling Earth’s climate

A diagnostic suite to assess NWP performance

Nadir Correction of AIRS Radiances

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