A surface solar radiation parameterization based on deviations between 3-Dand conventional plane-parallel radiative transfer models has beenincorporated into the Weather Research and Forecasting (WRF) model tounderstand the solar insolation over mountain/snow areas and to investigatethe impact of the spatial and temporal distribution and variation of surfacesolar fluxes on land-surface processes. Using the Sierra-Nevada in thewestern United States as a testbed, we show that mountain effect couldproduce up to ?50 to + 50 W m?2 deviations in the surface solarfluxes over the mountain areas, resulting in a temperature increase of up to1 °C on the sunny side. Upward surface sensible and latent heatfluxes are modulated accordingly to compensate for the change in surfacesolar fluxes. Snow water equivalent and surface albedo both show decreases onthe sunny side of the mountains, indicating more snowmelt and hence reducedsnow albedo associated with more solar insolation due to mountain effect.Soil moisture increases on the sunny side of the mountains due to enhancedsnowmelt, while decreases on the shaded side. Substantial differences arefound in the morning hours from 8–10 a.m. and in the afternoon around3–5 p.m., while differences around noon and in the early morning and lateafternoon are comparatively smaller. Variation in the surface energy balancecan also affect atmospheric processes, such as cloud fields, through themodulation of vertical thermal structure. Negative changes of up to?40 g m?2 are found in the cloud water path, associated withreductions in the surface insolation over the cloud region. The day-averageddeviations in the surface solar flux are positive over the mountain areas andnegative in the valleys, with a range between ?12~12 W m?2.Changes in sensible and latent heat fluxes and surface skin temperaturefollow the solar insolation pattern. Differences in the domain-averageddiurnal variation over the Sierras show that the mountain area receives moresolar insolation during early morning and late afternoon, resulting inenhanced upward sensible heat and latent heat fluxes from the surface and acorresponding increase in surface skin temperature. During the middle of theday, however, the surface insolation and heat fluxes show negative changes,indicating a cooling effect. Hence overall, the diurnal variations of surfacetemperature and surface fluxes in the Sierra-Nevada are reduced through theinteractions of radiative transfer and mountains. The hourly differences ofthe surface solar insolation in higher elevated regions, however, showsmaller magnitude in negative changes during the middle of the day andpossibly more solar fluxes received during the whole day.
展开▼
机译：已将基于3-D与常规平面平行辐射传输模型之间的偏差的地表太阳辐射参数化并入天气研究和预报（WRF）模型，以了解山区/雪地上的日照情况，并研究时空分布的影响地表过程中地表太阳通量的变化。以美国西部的内华达山脉为试验平台，我们表明山区效应可能在山区地表太阳通量中产生高达50至+ 50 W m ？2 的偏差，从而导致在阳光明媚的一面，温度升高高达1°C。向上调节表面感热磁通量和潜热通量，以补偿表面太阳通量的变化。雪山水当量和地表反照率均在山阳向减少，表明更多的融雪，因此由于山地效应，雪反照率降低与日照增加有关。阴影的一面。在早上8点至10点和下午大约下午3-5点之间发现了很大的差异，而中午前后以及清晨和下午的差异相对较小。通过垂直热结构的调节，表面能平衡的变化也会影响大气过程，例如云场。在云水路径中发现了高达？40 g m ？2 的负变化，这与云区域上方的日照减少有关。在山区，地表太阳通量的日平均偏差为正，而在谷地则为负，范围在？12〜12 W m ？2 之间。感热和潜热通量以及地表皮肤的变化温度遵循日照模式。塞拉山脉全域平均日变化的差异表明，该山区在清晨和傍晚受到日照更大，导致地表向上的显热和潜热通量增加，并且表层皮肤温度相应增加。然而，在当天的中午，表面日照和热通量显示出负变化，表明有冷却作用。因此，总的来说，内华达山脉地表温度和表面通量的日变化通过辐射传递和山脉的相互作用而减少。然而，高海拔地区日照强度的小时变化在白天的中间表现出较小的负变化，并可能在一整天内收到更多的太阳通量。
展开▼
