Spatial and Temporal Patterns of Cloud Cover and Fog Inundation in Coastal California: Ecological Implications

Abstract

The presence of low-lying stratocumulus clouds and fog has been known to modify biophysical and ecological properties in coastal California where forests are frequently shaded by low-lying clouds or immersed in fog during otherwise warm and dry summer months. Summer fog and stratus can ameliorate summer drought stress and enhance soil water budgets and often have different spatial and temporal patterns. Here, this study uses remote sensing datasets to characterize the spatial and temporal patterns of cloud cover over California’s northern Channel Islands. The authors found marine stratus to be persistent from May to September across the years 2001–12. Stratus clouds were both most frequent and had the greatest spatial extent in July. Clouds typically formed in the evening and dissipated by the following early afternoon. This study presents a novel method to downscale satellite imagery using atmospheric observations and discriminate patterns of fog from those of stratus and help explain patterns of fog deposition previously studied on the islands. The outcomes of this study contribute significantly to the ability to quantify the occurrence of coastal fog at biologically meaningful spatial and temporal scales that can improve the understanding of cloud–ecosystem interactions, species distributions, and coastal ecohydrology.

Parched pines: a quantitative comparison of two multi‐year droughts and associated mass mortalities of bishop pine (Pinus muricata) on Santa Cruz Island, California

“…2) (Junak 1995). CLCF is most persistent over the four northern Channel Islands from May to September (Rastogi et al 2016).…”

Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

“…In addition, the cloud base over land rises high enough that a TWI limit to vertical extent of the clouds may result in shallower (thinner) cloud layers at the highest land elevations ( Fig. 6; Rastogi et al, 2016). When topography is close to the ocean this effect is especially pronounced, as seen in the CALIPSO data with the disproportionate effect on the clouds by the lower peak elevation but closer oceanic proximity of the northernmost peninsula of the Dominican Re-public (Fig.…”

“…We expected to find cloud base altitudes above the LCL and cloud tops at or below the TWI for tradewind conditions (Brueck et al, 2014;Malkus, 1955); thus, we used the radiosonde profiles to compute values of minimum LCL and maximum TWI base over each day to quantify frequency of stable marine boundary layers and trade-wind cloud conditions at the site (Rastogi et al, 2016;Zhang et al, 2012). The LCL calculation we used involves an air parcel representing the mean potential energy in the lowest 50 hPa of the atmosphere for a mean-layer LCL; this accounts for the fact that the thermodynamic profile of the boundary layer may not be well represented by that of the surface layer (Craven et al, 2002; for details see Appendix A).…”

Coastal dune hydrology and its influence on maritime occupation sites (12–0.2 ka) in a semiarid island, San Miguel, California, USA

“…Recent studies have shown that fog‐drip captured by island vegetation contributes significantly to the hydrology of the islands, independent from measured precipitation, especially during the dry season from May to September (Fischer, Still, & Williams, ; Rastogi et al, ; Williams, Still, Fischer & Leavitt, ). Historical overgrazing significantly reduced fog‐drip by stripping San Miguel and other Channel Islands of much of their vegetation (Gill, Fauvelle, & Erlandson, ), but the recovery of plant communities following the removal of exotic grazing animals seems to be fueling a recovery of island hydrology.…”